Crushing And Grinding Course_complete.ppt
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PIC Grinding September 2005 This manual was prepared by : E. Villa (CTG) - F. Spada (CTG) - M. Santini (CTG)
Italcementi Group
PIC Grinding September 2005
1 TRAINING CORPORATE
Summary 12345-
678910 11 12 -
Introduction Crushing Process Particle size distribution Tests efficiency evaluation Grinding Mills Vertical Mills Horizontal Ball Mills Autogenous Mill Roller Press Separating Process Grinding Circuits Circuits Process Control Influent Parameters on Kwh/t Mill Check-up Data Evaluation Efficiency Evaluation
Italcementi Group
PIC Grinding September 2005
2
I - INTRODUCTION
1. Comminution Department 2 . World Energy
Italcementi Group
PIC Grinding September 2005
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1- COMMINUTION DEPARTMENT Department Manager - E. Villa Department Assistant Manager - F. Spada
Secretary and performance data monitoring (n° 1 person) Grinding process technology (n° 6 persons) Grinding mechanical section (n° 2 persons) Crushing section (n° 1 person) CAD operator (n° 1 person) Type of machines concerned: horizontal and vertical mills, static and dynamic separators, crushers, screens, cement coolers) Total n° 13 persons located in Bergamo
Italcementi Group
PIC Grinding September 2005
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1- COMMINUTION DEPARTMENT Performance data monitoring Monthly and annual reports Grinding Process Technology Evaluation and optimisation of existing plants Process design parameters evaluation (new plant, new machine or plant modification) New machine choice Start up assistance Training Study of new solutions for process (ITC patent of horizontal roller mill) Italcementi Group
PIC Grinding September 2005
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1- COMMINUTION DEPARTMENT Grinding mechanical section Existing machines evaluation New machines design (complete detail drawing of horizontal ball mills 2000-3000-4500-5500 kW, cement cooler for 160 t/h , static separators) Existing machines modifications (examples: dynamic separators from 1st and 2nd to 3rd generation, vertical ball mills for coal) Detail drawings for mill inlet, diaphragms, (intermediate, discharge, transfer) Technical specifications for purchase of new machines New materials test (liners, ball charge, diaphragms plates, abrasion resistant components) Crucial point control during machine erection (alignment, etc.) Start-up assistance Vibration measurements and analysis Training Italcementi Group
PIC Grinding September 2005
6
1- COMMINUTION DEPARTMENT
Crushing Section Evaluation and optimisation of existing machines Process design parameters evaluation and machines technical specifications definition New machines design (detail drawings of double rotors hammer crusher in the range 250 - 800 t/h, single rotor hammer crusher in the range 250 - 600 t/h, double cylindrical rotor crusher in the range 100 - 200 t/h, double cylindrical rotor tertiary crusher) New machines choice New materials tests (forged hammers, etc…) Start-up assistance Training
Italcementi Group
PIC Grinding September 2005
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1- COMMINUTION DEPARTMENT In the laboratory of the ITC grinding centre of Albino (not anymore used for industrial production) the Comminution Department has suitable instruments for samples preliminary evaluation after mill circuit check-up, like: sieve size distribution laser size distribution fineness moisture
In the same laboratory we have a batch mill for material grindability evaluation according to C.T.G. experienced method In the same grinding centre we have installed semi-industrial experimental horizontal roller mill and a small roller press manufactured according to C.T.G. design Italcementi Group
PIC Grinding September 2005
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2- WORLD ENERGY COST OF ELECTRICAL ENERGY
2 % OF THE WORLD ENERGY USED IN CEMENT MANUFACTURING
Italcementi Group
PIC Grinding September 2005
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2- WORLD ENERGY CEMENT PRODUCTION
Italcementi Group
PIC Grinding September 2005
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2- WORLD ENERGY ENERGY CONSUMPTION OF COMMINUTION PLANTS
- CRUSHING
=>
1 - 3 kWh/tproduct
- RAW GRINDING
=>
15 - 30 kWh/ tproduct
- COAL GRINDING
=>
35 - 50 kWh/ tproduct
- CEMENT GRINDING
=>
30 - 80 kWh/ tproduct
Italcementi Group
PIC Grinding September 2005
11
2- WORLD ENERGY COST OF ELECTRICAL ENERGY
WET PROCESS HEAT % kcal/kg
85%
ELECTRIC % equivalent kcal/kg
15%
DRY PROCESS
GLOBAL % kcal/kg
HEAT % kcal/kg
100%
75%
ELECTRIC % equivalent kcal/kg
25%
GLOBAL % kcal/kg
100%
COST OF ELECTRICAL ENERGY: 15 to 25 % OF GLOBAL COST
Italcementi Group
PIC Grinding September 2005
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2- WORLD ENERGY BREAKDOWN OF ELECTRICAL ENERGY USED IN A CEMENT PLANT RAW GRINDING 24%
16% OTHERS
28% CEMENT GRINDING
Italcementi Group
BURNING 22%
PIC Grinding September 2005
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2- WORLD ENERGY MAIN ELECTRICAL CONSUMPTION 70 63 60 51 50 40 30
27
30
30
kWh/t min kWh/t max
20
16
10 0,8
2,5
0 CRUSHING
Italcementi Group
RAW GRINDING
COAL GRINDING
PIC Grinding September 2005
CEMENT GRINDING
14
2- WORLD ENERGY RAW MEAL GRINDING SPECIFIC RAW MEAL GRINDING ENERGY Average kWh/t ITC Group (Italy) 24,2 24,0 23,8 23,6 23,4 23,2 23,0
Italcementi Group
PIC Grinding September 2005
01 20
00 20
99 19
98 19
97 19
96 19
95 19
94 19
93 19
19
92
22,8 22,6
15
2- WORLD ENERGY COAL GRINDING
SPECIFIC COAL GRINDING ENERGY Average kWh/t ITC Group (Italy)
Italcementi Group
PIC Grinding September 2005
01 20
00 20
99 19
98 19
97 19
96 19
95 19
94 19
93 19
19
92
38,0 37,5 37,0 36,5 36,0 35,5 35,0 34,5 34,0 33,5 33,0
16
2- WORLD ENERGY CEMENT GRINDING SPECIFIC FINISH GRINDING ENERGY Average kWh/t ITC Group (Italy) 45,5 45,0 44,5 44,0 43,5 43,0 42,5 42,0 41,5 41,0
9 19
Italcementi Group
2
9 19
3
9 19
4
9 19
5
9 19
6
9 19
7
9 19
8
PIC Grinding September 2005
9 19
9
0 20
0
0 20
1
17
2- WORLD ENERGY CONCLUSION
GRINDING AND CRUSHING CONCERN 60 TO 65% OF THE GLOBAL ELECTRIC PLANT CONSUMPTION
Italcementi Group
PIC Grinding September 2005
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2- WORLD ENERGY A WAY TO SAVE MONEY Mills installed power (MV)
Number of mills (Group data 2000)
342
231
250 117
200 150
350 300 250 200 150 100 50 0
80
100 50 0 Coal
Raw
172 25
Coal
Cement
Raw
Cement
1 % REDUCTION OF THE PLANT ELECTRICAL CONSUMPTION MAKES A TOTAL SAVING OF 5,4 MWh => SAVE Italcementi Group
PIC Grinding September 2005
$ 19
2- WORLD ENERGY HOW ?
BY OPTIMIZING THE GRINDING PROCESS
BY RUNNING THE MILL AT OPTIMUM LEVEL BY UPGRATING PLANTS WITH NEW TECHNOLOGY
Italcementi Group
PIC Grinding September 2005
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II - CRUSHING PROCESS
1. Crusher Classification 2. Machine description & main parameters 3. Crushing Circuits
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1- CRUSHERS CLASSIFICATION Crushers are classified according to: The function (product size): The main stress: primary impact secondary compression tertiary shear finishing attrition
The type of material: hard abrasive compact sticky wet Italcementi Group
The type of machine: jaw giratory hammer impact roll PIC Grinding September 2005
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2- MACHINES DESCRIPTION
JAW CRUSHERS GIRATORY CRUSHERS ROLL CRUSHERS DOUBLE-ROLL CRUSHERS SINGLE-ROTOR IMPACT CRUSHERS DOUBLE-ROTOR IMPACT CRUSHERS SINGLE-ROTOR HAMMER CRUSHERS DOUBLE-ROTOR HAMMER CRUSHERS
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (mobil jaw) motion Type of crushing process Feeding design Maximum feed opening size Mini. gap between crushing elem. Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by
Italcementi Group
: compression : alternative : primary, secondary : rectangular, horizontal : 400 to 2500 mm : 30 to 250 mm : 8 to 10 : 20 to 400 kW : 0.2 to 0.5 kWh/t : 1000 t/h : 250 t : hard, compact, abrasive, low moisture, not sticky
: nearing or moving away the inferior part of the mobil jawfrom/to the fixed jaw PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS
1. Fixed jaw 2. Swinging jaw 3. Toggles 4. Eccentric shaft 5. Connecting rod 6. Pulley - flywheel
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS GYRATORY CRUSHERS • Main stress • Crushing part (oscillating cone) motion • Type (process) of crushing • Feeding design • Maximum feed opening radial size • Mini. gap between crushing elem. • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap (between crushing elements) by Italcementi Group
: compression : rotation : primary, secondary : circular, horizontal : 600 to 1500 mm : 30 to 300 mm : 6 to 8 : 80 to 750 kW : 0.2 to 0.5 kWh/t : 3000 t/h : 550 t : hard, compact, abrasive, low moisture, not sticky : nearing or moving away the inferior part of the oscillating cone from/to the tank PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS
1. Cross slide 2. Stack 3. Pendulum 4. Eccentric
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS ROLL CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (toothed roll) motion Type (process) of crushing Feeding design Maximum roll size (D x L) Teeth peripheral speed Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by
Italcementi Group
: compression, shear : rotation : primary, secondary : rectangular, horizontal : (500 * 700 mm) to (1500 * 2000 mm) : 1 to 8 m/s :5 : 20 to 300 kW : 0.2 to 0.5 kWh/t : 1000 t/h : 200 t : medium hard, no abrasive, low moisture, sticky : nearing or moving away the mobile roll from/to the fixed jaw
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS
1. Casing 2. Toothed roll 3. Crushing wall
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE-ROLL CRUSHERS • Main stress • Crushing part (toothed rollers) motion • Type (process) of crushing • Feeding design • Maximum roll size (D x L) • Teeth peripheral speed • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap by
Italcementi Group
: compression, shear : rotation : primary, secondary, tertialy : rectangular, horizontal : (600 * 800 mm) to (2000 * 2000 mm) : 1 to 8 m/s :5 : 30 to 600 kW : 0.1 to 0.5 kWh/t : 3000 t/h : 200 t : medium hard, medium abrasive, very wet and sticky : nearing or moving away the mobile roll from/to the fixed roller PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE-ROLL CRUSHERS
1. Casing 2. Toothed rolls
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR IMPACT CRUSHERS • Main stress • Crushing part (rotor with impact bars) motion • Type(process) of crushing • Feeding design • Maximum rotor size (DxL) • Hammer peripheral speed • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap by
Italcementi Group
: impact : rotation : single stage, primary, secondary : rectangular, oblique : (800 * 1000 mm) to (2500 * 3000 mm) : 30 to 50 m/s : 25 : 150 to 2500 kW : 0.5 to 1.5 kWh/t : 2000 t/h : 200 t : hard, compact, not abrasive, not very wet, not sticky : nearing or moving away the mobile part (finishing wall) from/to the rotor PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR IMPACT CRUSHERS
1. Casing 2. Rotor 3. Crushing walls
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR IMPACT CRUSHERS • Main stress • Crushing part (rotor with impact bars) motion • Type (process) of crushing • Feeding design • Maximum rotor size (DxL) • Hammer peripheral speed • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap by
Italcementi Group
: impact
: rotation : single stage, primary : rectangular, oblique : (1000 * 1250 mm) to (2500 * 3000 mm) : 30 to 50 m/s : 40 : 400 to 3500 kW : 0.5 to 1.5 kWh/t : 3000 t/h : 300 t : hard, compact, not abrasive, not very wet, not sticky : nearing or moving away the mobile rotor from/to the secondary rotor
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR IMPACT CRUSHERS
1. Casing 2. Rotors 3. Crushing walls
Italcementi Group
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2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR HAMMER CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (rotor) motion Type (process) of crushing Feeding design Maximum rotor size (DxL) Hammers peripheral speed Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by Italcementi Group
: impact : rotation : single stage, primary, secondary, tertialy : rectangular, horizontal and oblique : (800 * 1000 mm) to (2500 * 3000 mm) : 25 to 50 m/s : 80 : 300 to 2500 kW : 0.5 to 2.5 kWh/t : 1500 t/h : 200 t : hard, not abrasive,compact, low moisture, not sticky : choice of grate opening
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR HAMMER CRUSHERS
1. Casing 2. Rotor 3. Hammers 4. Crushing walls 5. Grate
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR HAMMER CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (rotor) motion Type of crushing process Feeding design Maximum rotor size (DxL) Hammer peripheral speed Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by Italcementi Group
: impact : rotation : primary, secondary, tertialy : rectangular, horizontal and oblique : (800 * 1000 mm) to (2500 * 3000 mm) : 25 to 40 m/s : 80 : 300 to 2500 kW : 0.5 to 2.5 kWh/t : 3000 t/h : 300 t : hard, compact, not abrasive, low moisture, not sticky : choice of grate opening
PIC Grinding September 2005
38
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR HAMMER CRUSHERS
1. Casing 2. Hammer rotors 3. Breaker anvil 4. Grate
Italcementi Group
PIC Grinding September 2005
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2- MACHINES DESCRIPTION & MAIN PARAMETERS CRUSHERS CHOICE MAIN CRITERIA
Low speed crushers: jaw and gyratory type Suitable for abrasive, very hard, dry materials Low reduction ratio: more than one step required double roller crusher Suitable for very wet materials High speed crushers: hammer and impact type Not suitable for abrasive materials High reduction ratio: finishing in one step possible Italcementi Group
PIC Grinding September 2005
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3- CRUSHING CIRCUITS
1- ONE STAGE - OPEN CIRCUIT • Simple circuit design • Product size control by discharge gap • Fast machines needed • Not suitable for abrasive and sticky materials
Italcementi Group
PIC Grinding September 2005
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3- CRUSHING CIRCUITS
1- ONE STAGE - OPEN CIRCUIT Storage silo feed bin
Plate feeder
Run of mine
One stage primary crusher (finishing machine)
Finished product
Italcementi Group
PIC Grinding September 2005
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3- CRUSHING CIRCUITS
2 - DOUBLE STAGE - OPEN CIRCUIT: • Ability to direct feed to primary crusher (slow machines) • Ability to take out undersize material after primary crusher • Ability to feed only oversize material for next crushing • Control of product maximum size not always accurate • Needs fast machine as secondary crusher • Not very suitable for abrasive and sticky materials
Italcementi Group
PIC Grinding September 2005
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3- CRUSHING CIRCUITS 2 - DOUBLE STAGE - OPEN CIRCUIT: Storage silo feed bin Plate feeder
Run of mine
Primary crusher
Primary crushed material Screen
Coarse
Screening
Secondary finishing crusher Secondary crushed material Finished product
Italcementi Group
PIC Grinding September 2005
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3- CRUSHING CIRCUITS
3 - DOUBLE STAGE - CLOSED CIRCUIT: • Ability to direct feed to primary crusher (slow machines) • Ability to take out undersize material after primary crusher • Ability to feed only oversize material for next crushing • Accurate control of product maximum size • Suitable for slow machine • Suitable for abrasive and sticky materials
Italcementi Group
PIC Grinding September 2005
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3- CRUSHING CIRCUITS 3 - DOUBLE STAGE - CLOSED CIRCUIT: Run of mine
Primary crusher Primary crushed material
Screen
Coarse
Secondary crusher Secondary crushed material Finished product
Italcementi Group
PIC Grinding September 2005
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III - PARTICLE SIZE DISTRIBUTION 1. Laws
Gaudin-Schumann Law Rosin-Rammler Law Charles Law
2. Measurement Methods
Blaine Method Bet Method Alpine Laser Particles Size Analyser Sieves Italcementi Group
PIC Grinding September 2005
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1- LAWS PARTICLES SIZE DISTRIBUTION
FIRST EVALUATION OF PARTICLE SIZE DISTRIBUTION (We only need 2 points) Why using the laws?
FIRST CORRELATION WITH CHEMICAL AND MECHANICAL CEMENT AND CONCRETE PROPERTIES EVALUATION OF ENERGY CONSUMPTION
Italcementi Group
PIC Grinding September 2005
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1- LAWS GAUDIN-SCHUMANN LAW
Ln P(x) = m Ln (x) - m Ln (k) k: sieves size giving 100% passing m: slope of straight line
BASIC FORMULA
P( x )
Log
Passing (%)
100
m
No much representative for coarse particles
m = tg
K
Italcementi Group
x k
Log Particle size (µm)
PIC Grinding September 2005
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1- LAWS GAUDIN-SCHUMANN LAW
Passing
Granulometry
Size (mm)
Italcementi Group
PIC Grinding September 2005
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1- LAWS ROSIN-RAMMLER LAW
Ln Ln (1/R(x)) = n Ln (x) - n Ln (x0) x0 : sieves size for 36.8 % retained n: slope of straight line Retained (%)
Log Log
BASIC FORMULA Not very representative for fine particles
R( x )
x n e x 0
36.8
n = tg
Log
x0 Italcementi Group
Particle size (µm) PIC Grinding September 2005
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1- LAWS CHARLES LAW
100.C.m . k(1-n) • E = n-1 m-n+1 kWh/t
Workability
CHARLES LAW
If nRRS
40 20
n 0.7
•
EGrinding
1.1
Grinding energy
n: RRS slope m: Gaudin Schumann slope C: material data (between 20 & 40)
dE=-Cx(-n)dx Size x Size x-dx Italcementi Group
PIC Grinding September 2005
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2- MEASUREMENT METHODS BLAINE METHOD
Measure the specific surface of a powder in cm2/g or m2/kg => FINENESS PRINCIPLE: Time for a volume of air to pass through a layer of particles. LIMITS: => used only for cement => measure not accurate up to 6000 Blaine. Italcementi Group
PIC Grinding September 2005
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2- MEASUREMENT METHODS BET METHOD
PRINCIPLE: =>Surface nitrogen absorption => Multi-layers absorption theory =>Vaporisation & condensation balance calculation Used for limestone porosity evaluation LIMITS: => Cost => Difficulty in manipulating => Not so used in the cement industry (laboratory) Italcementi Group
PIC Grinding September 2005
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2- MEASUREMENT METHODS ALPINE
Content of coarse particles in % of weight. LIMITS: => Sieves must be clean => Sample lost => Mesh (32 mn)
Italcementi Group
PIC Grinding September 2005
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2- MEASUREMENT METHODS LASER PARTICLES SIZE ANALYSER
% of retained particles for a certain mesh. Method based on light diffraction. LIMITS: => results depends on laser types :MALVERN # CILAS (liquid) # SYMPATEC (air - liquid) => for raw and coal material, pb of particles desagglomeration (ultrasound) => laser circuit has to be cleaned every time => water (raw material) or alcohol (cement and coal) Italcementi Group
PIC Grinding September 2005
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2- MEASUREMENT METHODS MALVERN
CILAS
SAME SAMPLE and SAME TIME
Italcementi Group
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2- MEASUREMENT METHODS
TROMP CURVE
Italcementi Group
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2- MEASUREMENT METHODS SIEVES
WET/DRY FRANCE Opening Designation (mm) of sieves 0.040 17 0.050 18 0.063 19 0.080 20 0.100 21 0.125 22 0.160 23 0.200 24 0.250 25 0.315 26 0.400 27 0.500 28 0.630 29 0.800 30 1.000 31 1.250 32 1.600 33 2.000 34 2.500 35 3.150 36 4.000 37 5.000 38
USA (ASTM) Opening Designation (mm) of sieves 5.660 3.5 4.760 4 4.000 5 3.360 6 2.830 7 2.380 8 2.000 10 1.680 12 1.410 14 1.190 16 1.000 18 0.840 20 0.710 25 0.590 30 0.500 35 0.420 40 0.350 45 0.297 50 0.250 60 0.210 70 0.177 80 0.149 100 0.125 120 0.105 140 0.088 170 0.074 200 0.062 230 0.063 270 0.044 325 0.037 400
Italcementi Group
UK (BSA) Opening Designation (mm) of sieves 3.353 5 2.812 6 2.411 7 2.057 8 1.676 10 1.405 12 1.204 14 1.003 16 0.853 18 0.699 22 0.599 25 0.500 30 0.422 36 0.353 44 0.295 52 0.251 60 0.211 72 0.178 85 0.152 100 0.124 120 0.104 150 0.089 170 0.076 200 0.066 240 0.053 300
GERMANY (DIN) Opening Designation (mm) of sieves 6.000 6 5.000 5 4.000 4 3.000 3 2.500 2.5 2.000 2 1.500 1.5 1.200 1.2 1.000 1 0.750 0.75 0.600 0.6 0.500 0.5 0.430 0.43 0.400 0.4 0.300 0.3 0.250 0.25 0.200 0.2 0.150 0.15 0.120 0.12 0.100 0.1 0.090 0.09 0.075 0.075 0.060 0.06
PRINCIPLE: Give the content of coarse or fine particles by manual or mechanical sieving. Coarse and fine amount are stated in % of weight. LIMITS: => sieves have to be cleaned => unconsistancy due to men action for manual sieving => mesh limit : >10µ in laboratory >32µ in plant
PIC Grinding September 2005
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IV - TEST EFFICIENCY EVALUATION 1. General 2. Bond 3. Zeisel 4. Alsing 5. Hardgrove 6. CTG Test 7. Correlations 8. Time Evolution of Mill & Grinding Department Italcementi Group
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1- GENERAL
Grindability of the material is measured by:
Compressive strenght Bond index Alsing / CTG test Zeisel test Hardgrove
Italcementi Group
N/cm2 kWh/t kWh/t kWh/t number
PIC Grinding September 2005
(crushing) (raw material) (raw, clinker) (clinker, slag) (coal, pet coke)
61
2- BOND BOND LAW
BOND LAW : Grinding energy first approximation
1 1 W 10 x Wi x P F Wi :
F : P : W :
Work Index kWh/st wet process (Laboratory test) multiply x 1.102 => kWh/t wet process multiply x 1.33 => kWh/st dry process multiply x 1.47 => kWh/t dry process mesh giving 80% passing for Feeding mesh giving 80% passing for final Product industrial specific consumption kWh/st
Italcementi Group
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2- BOND BOND WORK INDEX BOND WORK INDEX DRY GRINDING
MATERIAL
kWh/t Bauxite Cement clinker Cement raw material Clay Clay calcined Coal Dolomite Gypsum rock Limestone for cement Magnesite dead burned Sandstone Slag Slag-iron blast furnace
Italcementi Group
PIC Grinding September 2005
14 19 15 10 11 16 16 12 15 24 17 23 17
63
2- BOND BOND TEST RAW GRINDING ENERGY CONSUMPTION DETERMINATION Mill feed and supplementary feed 90 mm - 4mm
Circulating material
< 90 mm
> 90 mm
Ball mill
Sieve 90 mm Box < 90 mm
Italcementi Group
Finished product
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3- ZEISEL ZEISEL TEST CLINKER AND SLAG GRINDING ENERGY CONSUMPTION DETERMINATION
1 - Grinding plate 2 - Steel ball 3 - Pressure ring 4 - Driving shaft 5 - Extensometer 6 - Calculator
Italcementi Group
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4- ALSING ALSING TEST
GIVES THE "INDUSTRIAL GRINDING ENERGY" NECESSARY TO GRIND THE TYPE OF MATERIAL CONSIDERED OPEN CIRCUIT
CLOSE CIRCUIT
Italcementi Group
=> Industrial grinding energy > Alsing energy (20% to 30%) => •FIRST GENERATION CLASSIFIER Industrial grinding energy > Alsing energy (#15%) => •SECOND OR THIRD GENERATION Industrial grinding energy # Alsing energy PIC Grinding September 2005
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4- ALSING ALSING ENERGY
• SAMPLING PROCEDURE: TAKE DURING 4 HOURS (EVERY HALF HOUR) AN AVERAGE 10 kg OF FEEDING MATERIAL AND HALF A POUND OF FINAL PRODUCT • CHECK LIST:
Italcementi Group
Time t0: record the energy consumption of the main motor Time t0 + 4 hours: record the energy consumption of the main motor PIC Grinding September 2005
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4- ALSING ALSING ENERGY
• BATCH MILL CARACTERISTICS:
Batch mill
BALL MILL: External diameter = 664 mm (261.4 in) Spin velocity = 38 rpm (73% of critical speed) Lining = lifter liners LOAD: steel balls: 40 mm (beginning) (1.18 in) 18 mm (end) (0.71 in)
ANALYSES WITH STRAIN GAUGES => MECHANICAL COUPLE => kWh/t for a given fineness (FCB know how: telemetry) Italcementi Group
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4- ALSING ALSING ENERGY
• TESTING PROCEDURE: Ball charge: X t0 (40mm) t0+t1
t0+t2
t0+T Italcementi Group
Ball charge: X Material sample 1
New ball charge: Y (18mm) Material sample 2
Blaine Granulometry Blaine Granulometry
Ball charge: Y Material sample having a given fineness PIC Grinding September 2005
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4- ALSING ALSING ENERGY
kWh/t
kWh/t
RESULTS: 3 types of graph: • SPECIFIC ENERGY FUNCTION • SPECIFIC ENERGY FUNCTION OF BLAINE SURFACE OF d80 (80% Passing Mesh) (Log-Log graph)
Blaine/1000
Italcementi Group
d80
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4- ALSING ALSING ENERGY
• SPECIFIC ENERGY FUNCTION OF 40µm RETAINED (Semi-Log graph)
4omm retained
Italcementi Group
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5- HARDGROVE HARDGROVE TEST Weights
COAL GRINDING ENERGY CONSUMPTION DETERMINATION
Drive Counter Box
Grinding plate
Italcementi Group
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72
6- CTG TEST CEMENT GRINDING ENERGY CONSUMPTION DETERMINATION
Ball charge: First step => 120 Kg diameter 40 mm Second step => 120 Kg diameter 18 mm Italcementi Group
PIC Grinding September 2005
73
6- CTG TEST CEMENT GRINDING ENERGY CONSUMPTION DETERMINATION
Grinding Specific Consumption =
EkWh - LkWh
= kWh/t
Tmaterial EkWh = Meter measure LkWh = Motor and gear box lost energy Tmaterial = Material weight (t) Italcementi Group
PIC Grinding September 2005
74
6- CTG TEST CEMENT GRINDING ENERGY CONSUMPTION DETERMINATION
Spec. cons. (kWh/t)
Lines comparison
ALSING TEST C.T.G. TEST
Blaine (cm2/g) Italcementi Group
PIC Grinding September 2005
75
7- CORRELATIONS
In order to have a first evaluation of the global specific electrical consumption of a cement grinding shop, from the industrial data available in ITC we have established correlations between: • the % of clinker content in cement • the kWh/t (global specific consumption in the workshop) • the mortar compressive strength, in N/mm2
Italcementi Group
PIC Grinding September 2005
76
7- CORRELATIONS MAIN CORRELATIONS ARE: For Portland cements or cements with low additives: -20,39 + 0,384 * % CK + 0,294 * kWh/t (tot.) = N/mm² (2 days) 0,508 + 0,447 * % CK + 0,249 * kWh/t (tot.) = N/mm² (28 days) For pouzzolanic or slag cements: -12,45 + 0,395 * % CK + 0,130 * kWh/t (tot.) = N/mm² (2 days) -3,480 + 0,503 * % CK + 0,392 *kWh/t (tot.) = N/mm² (28 days) Global correlation 0,37 * %CK + 0,30 * kWh/t (tot.) = N/mm2 (28 days) Italcementi Group
PIC Grinding September 2005
77
7- CORRELATIONS
IMPORTANT: CORRELATIONS ARE USEFUL ONLY IF DATA CONSIDERED FOR ENERGY CONSUMPTION ARE HOMOGENEOUS
Italcementi Group
PIC Grinding September 2005
78
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT
BY COMPARING EVERY MONTH THE PERFORMANCES OF A MILL, IT IS POSSIBLE TO FOLLOW ANY IMPORTANT CHANGE IN MILL MOTOR OR MILL CIRCUIT POWER CONSUMPTION. ACTIONS CAN BE TAKEN IN ORDER TO UNDERSTAND AND TO CORRECT ANY WRONG SITUATION.
Italcementi Group
PIC Grinding September 2005
79
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT IMPORTANT • • •
mill production measurements and electrical energy meters must be available and tested compare also long period data (5 - 10 - 15 years) in order to detect slow but constant increases check the sequence of machines start-up and stop in order to be sure that machines don't run without reason
Italcementi Group
PIC Grinding September 2005
80
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT
kWh/t
SAMATZAI plant (1998) figures of raw and coal specific consumption
months
Italcementi Group
PIC Grinding September 2005
81
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT
kWh/t
TRIESTE raw grinding figures (specific consumption)
years
Italcementi Group
PIC Grinding September 2005
82
V - GRINDING MILLS 1. Vertical Mills 2. Horizontal Ball Mills 3. Autogenous Mills 4. Roller Press 5. Horizontal Roller Mills 6. Systems and other
Italcementi Group
PIC Grinding September 2005
83
HORIZONTAL BALL MILL
ROLLER PRESS
Italcementi Group
VERTICAL MILL
PIC Grinding September 2005
84
1- VERTICAL MILLS
Grinding elements: Rollers
Grinding elements: Balls
VERTICAL ROLLER MILL Italcementi Group
VERTICAL BALL MILL
PIC Grinding September 2005
85
1- VERTICAL MILLS
Italcementi Group
PIC Grinding September 2005
86
1- VERTICAL MILLS GRINDING PERFORMANCES:
• 10 TO 20 % GLOBAL (50 % MILL ITSELF) ENERGY CONSUMPTION SAVED BETWEEN HORIZONTAL AND VERTICAL GRINDING
• DEPENDING ON : * INLET MATERIAL GRINDABILITY * MOISTURE * WEAR
Italcementi Group
PIC Grinding September 2005
87
1- VERTICAL MILLS (ROLLER MILLS)
• PFEIFFER MILL Characteristics: Three rollers Annular path of concave cross-section Hydro-pneumatic tensioned spring system Continuous contact between roller and grinding table Hot gas stream issuing from the ported air ring Hot gas inlet joint to the mill structure 60 to 100% capacity range throughput Italcementi Group
PIC Grinding September 2005
88
1- VERTICAL MILLS
(ROLLER MILLS)
PFEIFFER MILL
Italcementi Group
PIC Grinding September 2005
89
1- VERTICAL MILLS (ROLLER MILLS)
• LOESCHE MILL Characteristics: 2, 3 or 4 conical rollers Annular flat grinding table Rollers fixed on swinging arms => Lower maintenance cost Roller pressure exerted by springs on smaller machines and hydro-pneumatically on larger ones 40 to 100% capacity range throughput Wear sensible no contact between rollers and table mill structure independent of hot gas inlet. Italcementi Group
PIC Grinding September 2005
90
1- VERTICAL MILLS Gas + fine material outlet
Raw material inlet
(LOESCHE)
Separator motor
Dynamic separator
Separator reject Lining
Dam ring Grinding rollers Grinding table Hot gas inlet
Mill gear box Hydraulic cylinder
Rollers frame
Mill motor Mill reject
Italcementi Group
PIC Grinding September 2005
91
1- VERTICAL MILLS (ROLLER MILLS)
• POLYSIUS MILL Characteristics: Same PFEIFFER MILL with two double rollers and two annular grinding tables.
Higher wear resistance
Italcementi Group
PIC Grinding September 2005
92
1- VERTICAL MILLS
(ROLLER MILLS)
POLYSIUS MILL
Italcementi Group
PIC Grinding September 2005
93
1- VERTICAL MILLS (ROLLER MILLS)
• RAYMOND MILL Characteristics: Conical rollers Conical grinding table Spring or hydraulic pressure system No contact between rollers and table reduction gear integrated to the mill structure.
Grinding bowl
Italcementi Group
PIC Grinding September 2005
94
1- VERTICAL MILLS (BALL MILLS)
• PETERS MILL Characteristics: Grinding elements: balls Circular grinding table Hydro-pneumatic& spring tensioned system Especially used for coal grinding
Italcementi Group
PIC Grinding September 2005
95
1- VERTICAL MILLS (BALL MILLS)
• FCB "E" MILL Characteristics: Same PETERS MILL with only hydraulic tensioned system and external reject recalculation
Italcementi Group
PIC Grinding September 2005
96
1- VERTICAL MILLS ADVANTAGES: • LOW SPECIFIC ENERGY CONSUMPTION (kWh/t) • SPACE REQUIREMENT • THROUGHPUT TILL 600 t/h • HIGH DRYING CAPACITY • SIZE OF THE FEED MATERIAL (50 to 100mm) • IMPROVE THE SIZE DISTRIBUTION SLOPE => nRRS • ABLE TO USE LARGE HOT GAS FLOW AT LOW TEMPERATURE • LOW SYSTEM REACTION TIME
Italcementi Group
PIC Grinding September 2005
97
1- VERTICAL MILLS
DISADVANTAGES: • SENSIBILITY TO WEAR • SIZE DISTRIBUTION SLOPE FOR CEMENT => nRRS => Problem with cement and concrete workability and short term strength • RISK OF VIBRATION (foundation design very important)
• SENSIBLE TO DRY AND HARD RAW MATERIAL Italcementi Group
PIC Grinding September 2005
98
2- HORIZONTAL BALL MILLS Mill feed Gas /air outlet Main gearbox
Main motor Auxiliary drive
Material discharge
Italcementi Group
PIC Grinding September 2005
99
2- HORIZONTAL BALL MILLS CHARACTERISTICS: • COMMAND: => EXTERNAL DRIVE => CENTRAL DRIVE => GEARLESS DRIVE COST RATING FOR A 4400kW ENGINE POWER: 200%
160% 100%
115%
100% 0%
Italcementi Group
Cost External
Central
Gearless
PIC Grinding September 2005
100
2- HORIZONTAL BALL MILLS EXTERNAL DRIVE: Types: Single pinion drive
Dual pinion drive
Italcementi Group
Characteristics: * Single or dual pinion drive (maximum power for single one is 3500 kW or 4700 HP) * Shoe or plain bearing mills (higher air flow for plain bearing) Advantages: * Standard, inexpensive motors * Investment cost Disadvantages: * Low efficiency * Dustightness of pinion drive
PIC Grinding September 2005
101
2- HORIZONTAL BALL MILLS CENTRAL DRIVE: Types: Planetary gearing
Axially gearing (with twin or single motor drive)
Italcementi Group
Characteristics: Planetary or axially gearing (planetary gearing efficiency: 97%, axially gearing efficiency: 92%) Advantages: * No gearing on the mill itself *Low maintenance cost point of vie (balancing) * Less space requirement than external drive Disadvantages: * Problem for venting the mill
PIC Grinding September 2005
102
2- HORIZONTAL BALL MILLS GEARLESS DRIVE: Advantages : *High power mill:> 4000 kW (5400HP) *Low space requirement *Adjustable mill speed
Type:
Disadvantages: *Complex electrical feature *Low efficiency: 90% *Cost
Italcementi Group
PIC Grinding September 2005
103
2- HORIZONTAL BALL MILLS Lubrication system for double-pinion drives
1- lubrication reservoir 2- shut-off valve 3- pump 4- pressure relief valve 5- shut-off valve 6- filter 7- not-return valve 8- distribution pipe
Italcementi Group
PIC Grinding September 2005
104
2- HORIZONTAL BALL MILLS MILL MAIN SUPPORT
1 White metal bearing 2 Support casing 3 Support frame 4 Spherical surface
Italcementi Group
PIC Grinding September 2005
105
2- HORIZONTAL BALL MILLS MILL MAIN SUPPORTS LUBRICATION SYSTEM
Italcementi Group
PIC Grinding September 2005
106
2- HORIZONTAL BALL MILLS PAD SHOE BEARING
Italcementi Group
PIC Grinding September 2005
107
2- HORIZONTAL BALL MILLS LENGHT / DIAMETER OPEN CIRCUIT
5 6
RAW CLOSED CIRCUIT
2 3
SWEPT CLOSED CIRCUIT CEMENT CLOSED CIRCUIT
Italcementi Group
PIC Grinding September 2005
2 3 3.5
108
2- HORIZONTAL BALL MILLS
ONE CHAMBER : BETTER MATERIAL DISTRIBUTION INTO THE MILL PROPER LINER CARE WITH COARSE MATERIAL FEEDING USUALLY USED FOR MILL WITH L/D < 2.5 LOWER MAINTENANCE COST HIGHER VENTILATION
Italcementi Group
PIC Grinding September 2005
109
2- HORIZONTAL BALL MILLS ONE CHAMBER (K.H.D. MILL 3.4 x 6.1)
Italcementi Group
PIC Grinding September 2005
110
2- HORIZONTAL BALL MILLS
Useful diam. 5200
ONE CHAMBER (TOSI MILL 5.4 x 12)
Italcementi Group
PIC Grinding September 2005
111
2- HORIZONTAL BALL MILLS ONE CHAMBER (TOSI MILL 4 x 8)
Italcementi Group
PIC Grinding September 2005
112
2- HORIZONTAL BALL MILLS TWO CHAMBERS SECOND CHAMBER :
FIRST CHAMBER :
Material size reduction : from feed 0 - 35 mm to max 5 % > 2,5 mm Breakage effect Lifter liners Specific energy in consumption : 8-10 kWh/t (closed circuit) 10-12 kWh/t (open circuit) Specific ball charge surface: 9-11 m2/t of balls Length =30-35 % total mill length Ball average weight : 1600 - 2000 g Ball size : 100 - 60 mm Italcementi Group
Material size reduction : from 5% > 2,5 mm to 10 - 20 % < 90 µm (closed circuit) 5 % < 90 µm (open circuit) Attrition effect Classifying liners 25-40 m2 /t of balls (according to L/D ratio) Length =70-65 % total mill length Ball size 60-17 mm Cylpebs 50x25 - 16x16 mm
PIC Grinding September 2005
113
2- HORIZONTAL BALL MILLS TWO CHAMBERS (TOSI MILL 5.4 x12)
Italcementi Group
PIC Grinding September 2005
114
2- HORIZONTAL BALL MILLS TWO CHAMBERS (SMIDTH MILL 3.5 x 12)
Italcementi Group
PIC Grinding September 2005
115
2- HORIZONTAL BALL MILLS
THREE CHAMBERS : USED IN OPENED CIRCUIT LOW VENTILATION CYLPEBS IN THIRD CHAMBER => 30% TOTAL LENGHT : First chamber Second chamber => 20% Third chamber => 50%
Italcementi Group
PIC Grinding September 2005
116
2- HORIZONTAL BALL MILLS THREE CHAMBERS (MILL 2.4 x 13)
Italcementi Group
PIC Grinding September 2005
117
2- HORIZONTAL BALL MILLS DOUBLE ROTATOR MILL (MILL 10’ x 22’ + 12’) First compartment
Second compartment
Useful diam. 2878
Drying chamber
discharge Italcementi Group
PIC Grinding September 2005
118
2- HORIZONTAL BALL MILLS MILL ON PAD SHOE BEARINGS AND ANULAR MOTOR DRIVE RING MOTOR
PAD SHOE BEARING
Italcementi Group
PIC Grinding September 2005
119
2- HORIZONTAL BALL MILLS ADVANTAGES LARGE FINAL PRODUCT RANGE (final product fineness from 2800 to 5500 Blaine) LOW COST OF MAINTENANCE (care with ball charge wearing; material and internal part design) VERY WELL KNOWN COMPONENTS NO VIBRATION EASY TO OPERATE Italcementi Group
PIC Grinding September 2005
120
2- HORIZONTAL BALL MILLS DISADVANTAGES
HIGH SPECIFIC POWER CONSUMPTION (kWh/t) HIGH INSTALLATION COST
LOW VENTILATION LOW DRYING CAPACITY NOISE
Italcementi Group
PIC Grinding September 2005
121
2- HORIZONTAL BALL MILLS TREND
DOUBLE ROTATOR BALL MILL AS DRYER MILL FOR ABRASIVE MATERIAL.
FINE AND ULTRA-FINE PRODUCTS.
MAIN EVOLUTION WILL CONCERN INTERNAL PARTS (LINERS, AND DIAPHRAMS).
Italcementi Group
PIC Grinding September 2005
122
2- HORIZONTAL BALL MILLS VERTICAL MILLS
Number of vertical mills (ITC Group data 2000) 56 Raw Coal Slag
25
1
Installed power:
50 ÷ 3500 kW
(n.1 cement mill in construction not yet in operation) Italcementi Group
PIC Grinding September 2005
123
2- HORIZONTAL BALL MILLS Number of horizontal ball mills (ITC Group data 2000) 222 91
Raw Coal Cement
24
Italcementi Group
Installed power:
100 ÷ 8700 kW
Biggest mill:
Ø5.8 x 17 m (CCB)
Max capacity:
- Raw 350 t/h - Cement 300 t/h - Coal 40 t/h
PIC Grinding September 2005
124
2- HORIZONTAL BALL MILLS GRINDING MILLS
Number of roller press (ITC Group data 2000)
8 Raw Coal Cement
1 0
Italcementi Group
PIC Grinding September 2005
125
2- HORIZONTAL BALL MILLS GRINDING MILLS
Number of grinding mills (ITC Group data 2000)
80
231 Raw Coal Cement
117
Total number: 428
Italcementi Group
PIC Grinding September 2005
126
2- HORIZONTAL BALL MILLS GRINDING MILLS
Number of grinding mills (ITC Group data 2000)
337
82
Horizontal Vertical Roller press
9
Italcementi Group
PIC Grinding September 2005
127
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Gas Material
Material
Gas
LOW VENTILATION Italcementi Group
HIGH VENTILATION PIC Grinding September 2005
128
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
129
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
130
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
131
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
132
2- HORIZONTAL BALL MILLS OVERVIEW INTERNAL ELEMENTS
Italcementi Group
PIC Grinding September 2005
133
2- HORIZONTAL BALL MILLS OVERVIEW INTERNAL ELEMENTS Mill head liner
Shell liner (lifting liner)
Shell liner (classifying liner)
A: B: C: D: E:
Slot plate
Italcementi Group
Blind plate
Coarse grinding compartment Intermediate diaphragm Finish grinding compartment Discharge diaphragm Grinding media: Ø 90÷60 mm 1st chamber Ø 50÷17 mm 2nd chamber
Slot plate
PIC Grinding September 2005
134
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
LINERS: • Wet process: to decrease wearing, rubber lining can be used (except in first chamber) • Dry process: steel lining First chamber Alloy type: Function: Second chamber Alloy type: Function: Italcementi Group
12-14% of Chromium martensitic steel Protect the shell against wear & lift the balls 12-14% of Chromium martensitic steel Protect the shell against wear & classify the balls PIC Grinding September 2005
135
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
136
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
137
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS Wide wave liners
Step liners
Lifter classifying liners
Wave liners
Bar liners
Italcementi Group
Classifying liners
PIC Grinding September 2005
138
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
DIAPHRAGMS: Goals:
=> optimised the filling ratio (adjustable diaphragms) => keep the coarse into the first compartment => let the fines passed into the second compartment => separate the balls (from one chamber to the others) => allow air to pass through the mill => maximum central opening according to ball charge filling degree
Discharge diaphragm slots > central diaphragm slots Trend: Flow controlling devices Italcementi Group
PIC Grinding September 2005
139
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
DIAPHRAGMS Adjustable intermediate diaphragm for tube mills grinding dry minerals.
Italcementi Group
PIC Grinding September 2005
140
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
INTERMEDIATE DIAPHRAGMS
Blind plates
Slotted plates
lifter
Italcementi Group
PIC Grinding September 2005
141
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Flow control INTERMEDIATE DIAPHRAGMS
Adjustable lifters
Italcementi Group
PIC Grinding September 2005
142
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
143
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
144
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
145
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
146
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
147
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
148
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
149
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
150
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
151
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
OUTLET DIAPHRAGM
PIC Grinding September 2005
152
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS Slotted plates
OUTLET DIAPHRAGM frame
Italcementi Group
PIC Grinding September 2005
153
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
OUTLET DIAPHRAGM
154
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE Final outlet
Central outlet (double rotator mill)
Air swept outlet
Italcementi Group
Humid outlet
PIC Grinding September 2005
155
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
156
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
157
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
158
2- HORIZONTAL BALL MILLS VENTILATION
A particular attention has to be taken for the mill inlet & outlet head. We must also have a good idea of the ventilation in the mill. Filter exhaure False air Tube ventilation head section Mill outlet head ventilation
Italcementi Group
Open circuit: 250-350 Nm3/mt of finished product 0.5-0.8 m/s Closed circuit 300-600 Nm3/mt of finished product 1-1.5 m/s Maximum of 35 m/s
PIC Grinding September 2005
159
2- HORIZONTAL BALL MILLS VENTILATION
THE PLANT ENERGY CONSUMPTION DEPENDS ON THE PRESSURE DROPS IN FILTERS, MILL...
THE CONTROL OF PRESSURES FOR ALL STEPS OF CIRCUIT IN THE GRINDING PLANT IS CRUCIAL TO OPTIMIZE THE GRINDING ENERGY CONSUMPTION CHECK THE PROCESS FAN EFFICENCY AND THE DAMPER OPENING: THIS POINTS COULD COST A LOT OF ENERGY Italcementi Group
PIC Grinding September 2005
160
2- HORIZONTAL BALL MILLS VENTILATION
False air affects a lot the mill ventilation. False air can provide from: * Mill tube: inlet sealings outlet sealings material feed * Mill discharge * Dedusting * Bag filter jet pulsing * Flaps airtightness * High negative pressure ducts and machines *... Italcementi Group
PIC Grinding September 2005
161
2- HORIZONTAL BALL MILLS VENTILATION
Point to care after for checking false air in the grinding circuit
Italcementi Group
PIC Grinding September 2005
162
2- HORIZONTAL BALL MILLS THERMAL BALANCE
GENERAL LAW: INPUT OUTPUT
Q:Calorific power = Temperature * Specific heat * Throughput Q express in th/h, kcal/h, BTU/h or MJ/h 1 thermie = 4,186 MJoules = 1 163 kWh = 106 calories = 3968,3 BTU
Italcementi Group
PIC Grinding September 2005
163
2- HORIZONTAL BALL MILLS THERMAL BALANCE
MILL:
MECHANICAL MILL MOTOR POWER
MATERIAL GAS
MATERIAL moisture % flow t/h temperature °C specific heat Kcal/kg°C kcal./Nm3°C HEAT LOST mill shell: surface m2 temperature °C heat transfer ratio kcal./h°Cm2 Italcementi Group
MATERIAL GAS HEAT LOST GAS composition moisture % flow Nm3/h temperature °C
FALSE AIR moisture % flow Nm3/h temperature specific heat
specific heat kcal./Nm3°C MECHANICAL MILL POWER electrical absorb. kW mechanical efficiency grinding efficiency
PIC Grinding September 2005
164
2- HORIZONTAL BALL MILLS THERMAL BALANCE
MATERIAL GAS
GAS
CLASSIFIER: HEAT LOST MATERIAL MATERIAL moisture % flow t/h temperature °C specific heat Kcal./kg°C
Italcementi Group
GAS composition moisture % flow Nm3/h temperature °C specific heat (Kcal./h°Cm2) PIC Grinding September 2005
HEAT LOST separator shell surface m2 temperature °C heat transfer ratio (Kcal./h.°C.m2)
165
2- HORIZONTAL BALL MILLS THERMAL BALANCE
FURNACE:
AIR
GAS
FUEL HEAT LOST AIR moisture % flow Nm3/h temperature °C specific heat Kcal/Nm3°C
Italcementi Group
GAS composition moisture % flow Nm3/h temperature °C specific heat Kcal/Nm3°C
PIC Grinding September 2005
FUEL composition moisture % flow kg/h temperature °C specific heat (Kcal./kg°C)
HEAT LOST furnace shell surface m2 temperature °C heat transfer ratio (Kcal./h°Cm2°)
166
2- HORIZONTAL BALL MILLS THERMAL BALANCE - DEW POINT
Due to the material moisture, the dew point has to prevent bag filter from clogging. => (bag filter gas temperature - dew point temperature) > 30°C P Vaporisation pressure: Pv in Kg/cm2 Pgs.(1 %H 2 O) 1 with P: absolute pressure in Pgh .%H 2 O Kg/cm2 (mbars*0.00102) P = Patm.-chimney depressure Pgs = Volumic mass of dry gas Pgh = Volumic mass of wet gas
Italcementi Group
Temperature of condensation: 5168 Tc 273,16 in °C 13,89 ln( Pv)
PIC Grinding September 2005
167
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Water spraying system according to the CTG standard
Italcementi Group
PIC Grinding September 2005
168
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
169
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
170
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
171
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
172
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
173
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
STANDARD ITC
Water injection in the first chamber or, if possible, in the second chamber:
1.5 - 2% max of the mill cement production Italcementi Group
PIC Grinding September 2005
174
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
MAGOTTEAUX: Chamber 1 : 0.9 % x production (kg/h) Chamber 2 : water required (thermal balance) - 0.9 % x kg/h % of water needed for different kWh/t and air speeds T° clinker : 50°C, 100°C and 150°C
Italcementi Group
PIC Grinding September 2005
175
2- HORIZONTAL BALL MILLS CIMAR MARRAKECH
COMPANY PLANT
MILL POWER D useful L useful J s Vactual ball size max htot
m m % t/m3 rpm mm %
MILL TYPE
1st compart.
2nd compart.
tot/avg
m
m
m
3,440 4,008 31,3 4,5 16,2 90 0,870
3,420 3,790 25,8 4,7 % Vcritical
3,43 7,80 28,6 4,6 70,9
RAW MILL POLYSIUS 3.6 x 12 m drying compartment 3,554 D useful m L useful m
2,5
Mec kW
89,3
balls charge tons 1st compart.
2nd compart.
52
42 94
ABSORBED POWER CALCULATION MECHANICAL
ELECTRICAL
1st comp. 2nd comp. totale 1st comp. 2nd comp. totale
Italcementi Group
kW kW kW kW kW kW
Magotteaux
CMM
Slegten (old)
FCB
A. C. 2
AVERAGES
600 509 1 209 690 585 1390
630 536 1 257 725 617 1445
600 511 1 203 690 587 1383
589 482 1 160 677 554 1231
630 537 1 259 724 617 1447
610 515 1 218 701 592 1379
PIC Grinding September 2005
176
2- HORIZONTAL BALL MILLS MILL POWER
n
C = mill axle G = centre of gravity F = material and balls weight b = lever arm n = mill rotation speed
b
C
POWER = n(F b)
G
F Italcementi Group
PIC Grinding September 2005
177
2- HORIZONTAL BALL MILLS MILL POWER
MILL POWER CALCULATION FORMULA SLEGTEN formula : P = Mill length x (pm/Vcrit)1.27 x Kpm x nmotor with KJ,Kj = filling ratio x (1.36 - 1.2 x filling ratio) and KPm = 40.688 x D2.379
and nmotor = total trasmission efficiency (motor, gear box, couplings)
CMM formula : P = [0.4735 - 0.0746 x Ln (filling ratio)] x D x 12 pm x Tballs
(for mills with L/D < 2.5) Italcementi Group
PIC Grinding September 2005
178
2- HORIZONTAL BALL MILLS BALL CHARGE
FIRST CHAMBER : CEMENT AND RAW : 100 mm to 60 mm BALLS GAUDIN-SCHUMANN LAW :
P ( X ) X / Xmax
m
X max : Maximum ball diameter. P(x) : % of X mm Ball. m = 1.4 MINIMUM POROSITY Italcementi Group
PIC Grinding September 2005
179
2- HORIZONTAL BALL MILLS BALL CHARGE
SECOND CHAMBER : CEMENT AND RAW : 60 mm to 17 mm BALLS (CYLPEBS) PAPADAKIS LAW :
D
D0 L k . 1 L max
1. 5
DO : Maximum ball diameter; k = 1.92 ; Lmax: Chamber length Italcementi Group
PIC Grinding September 2005
180
2- HORIZONTAL BALL MILLS BALL CHARGE
B = 20.17 x
F(80) k
Wi x S
x 3
Cs x Di
B = Balls diameter (mm) Wi = Inlet mill material max size (mm) Cs = Work index in kWh/st (st = 907 kg) S = Material specific weight (g/cm3) Di = Mill diameter (m) k = Proportionality constant (335) Italcementi Group
PIC Grinding September 2005
181
29/04/2002
C.T.G. - Italcementi Group - Comminution Department Company Plant Department Circuit type New charge date Mill speed Critical speed
Mill Feed point Hot gases Hot gas temperature Separator g/1' g/1'
Critical speed 1st chamber
Characteristics Type of liner Diaphragm slots Measured free height Ratio steel / cement Useful diameter Useful lenght Useful lenght Total volume compart. Ball charge density Charge volume Filling degree Calculated free height Ball charge to add for each cm of free height Ball charge D = 100 mm D = 90 mm D = 80 mm D = 70 mm D = 60 mm D = 50 mm D = 40 mm D = 30 mm D = 25 mm D = 20 mm D = 17 mm Cil 25x25 mm Cil 22x22 mm Cil 19x19 mm Cil 16x16 mm
18,63 Installed power 27,8 Absorbed power 67,1% Ratio L/Ø
mm m % m m % m³ t/m³ m³ % m
Av. size ball
mm
Inlet 5,32
1st compartment
2nd compartment
6,0
6,0
Free area for gases Outlet m² m² 3rd compartment
2,320 3,200 25,9 13,5 4,49 4,0 29,9 1,53
mm m % m m % m³ t/m³ m³ % m
2,320 9,150 74,1 38,7 4,79 11,6 30,1 1,53
mm m % m m % m³ t/m³ m³ % m
t
0,32
t
0,97
t
t
%
t
%
6,42 3,75 3,75 4,28
18,2 Total compartement Mill total t 74,0 Ball S.S. Surface m² 1.711 Surface Av, weight ball g
kW kW
°C
35,3 20,6 20,6 23,5
24,6 m²/t m²
150 Av, weight ball g 33 Av. size ball mm
Italcementi Group
m
2
m
2
2- HORIZONTAL BALL MILLS
t
%
m
BALL CHARGE
2
54 36 41 54
4,22 8,45 3,56
7,6 15,1 6,4
65 161 91
39,60
70,9
1209
185 55,8 10,2 Ball S.S. 185 Surface
75,4 m²/t m²
1598 Av, weight ball g 73 Av. size ball mm
1525
27,3 Ball S.S. 1.525 Surface
m²/t m²
116 Av, weight ball g 30 Av. size ball mm
PIC Grinding September 2005
182
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
183
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
184
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
185
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
186
3- AUTOGENOUS MILL
ROTATION LINERS LIFTERS
DEFLECTOR LINERS PERIPHERAL PORTS
Italcementi Group
PIC Grinding September 2005
187
3- AUTOGENOUS MILL
Italcementi Group
PIC Grinding September 2005
188
4- ROLLER PRESS SYNOPTIC:
Italcementi Group
PIC Grinding September 2005
189
4- ROLLER PRESS CHARATERISTICS: MAIN PARAMETERS: D = Roller diameter L = Effective roller length S = Gap Width U = Circumferential velocity F = Grinding force ac = Compression angle bf = Angle of force action Pm= Maximum pressure in gap d = maximum value of solids volume (2x1250kW) Italcementi Group
PIC Grinding September 2005
190
4- ROLLER PRESS CHARACTERISTICS: • MAIN PARAMETER:
Specific Pressure =
F
= 5 or 6 MPa
D.L F
• LIMITS: => Humidity: 5 to 6% => Installed Power # 2500-3000 kW (2*1250 kW)
Italcementi Group
PIC Grinding September 2005
D
L
191
4- ROLLER PRESS ADVANTAGES: REDUCTION OF THE ELECTRICAL GRINDING DEPARTMENT CONSUMPTION : 20 to 30% LESS PRODUCTION INCREASE OF EXISTING PLANT : 30 to 35% MORE SPECIFIC WEAR REDUCTION
Italcementi Group
PIC Grinding September 2005
192
4- ROLLER PRESS DISADVANTAGES: INTEGRAL FINISH GRINDING CIRCUIT ACCEPTABLE FOR BLAINE SURFACE < 4000 cm2/g.
NOT ADAPTED TO SOFT MATERIAL VIBRATION PROBLEM LINKED WITH REGULATION
MECHANICAL PROBLEMS WITH : - REDUCTION GEAR - ROLLER - SEGMENT ROLLER Italcementi Group
PIC Grinding September 2005
193
4- ROLLER PRESS
FINISH GRINDING
HYBRID GRINDING
PRE-GRINDING
SEMI-FINISH GRINDING
Italcementi Group
PIC Grinding September 2005
194
4- ROLLER PRESS FINISH - GRINDING
Italcementi Group
PIC Grinding September 2005
195
4- ROLLER PRESS FINISH - GRINDING ADVANTAGES : • THE GREATEST ENERGY SAVING • SMALL SPACE REQUIREMENT • LOW SPECIFIC WEAR (g/t) • DRYING CAPACITY
DISADVANTAGES : • NOT ADAPTED TO HIGH FINENESS TREND • LARGE MECHANICAL ELEVATOR (HIGH CIRCULATING LOAD) AND SEPARATOR • HEAVY MAINTENANCE (SPARE ROLLERS) • CEMENT AND CONCRETE WORKABILITY • GRINDING PLANT HEIGHT Italcementi Group
PIC Grinding September 2005
196
4- ROLLER PRESS HYBRID - GRINDING
Italcementi Group
PIC Grinding September 2005
197
4- ROLLER PRESS HYBRID - GRINDING ADVANTAGES : • ADAPTED TO HIGH FINENESS TREND • GOOD CEMENT AND CONCRETE WORKABILITY • LOW BALLS SPECIFIC WEAR (g/t) • POSSIBILITY TO WORK WITHOUT PRESS DISADVANTAGES : • HEAVY MAINTENANCE • MOISTURE LIMITED • PRESS VIBRATIONS RECIRCULATING SEPARATOR REJECTS • DIFFICULT TO CONTROL CIRCUIT
Italcementi Group
PIC Grinding September 2005
198
4- ROLLER PRESS PRE- GRINDING
kWh/t = 30% less
t/h
Italcementi Group
PIC Grinding September 2005
= 80% more
199
4- ROLLER PRESS PRE- GRINDING ADVANTAGES : • ADAPTED TO HIGH FINENESS TREND • GOOD CEMENT AND CONCRETE WORKABILITY • LOW BALLS SPECIFIC WEAR (g/t) • POSSIBILITY TO WORK WITHOUT PRESS
DISADVANTAGES : • HEAVY MAINTENANCE • MOISTURE LIMITED
Italcementi Group
PIC Grinding September 2005
200
4- ROLLER PRESS SEMI-FINISH GRINDING
kWh/t = 30% less
t/h
Italcementi Group
PIC Grinding September 2005
= 80% more
201
4- ROLLER PRESS SEMI-FINISH GRINDING
ADVANTAGES : • ADAPTED TO HIGH FINENESS TREND • LOW BALLS SPECIFIC WEAR (g/t) • GOOD SPECIFIC ENERGY CONSUMPTION • DRYING POSSIBILITIES
DISADVANTAGES : • HEAVY MAINTENANCE => NUMBER OF MACHINES • TWO FINENESS CHECK POINTS
Italcementi Group
PIC Grinding September 2005
202
4- ROLLER PRESS n.5 Roller Press in Italcementi Group (1998): CCB (Belgium; Gaurain) : Raw material POLYSIUS - 1989 - Nominal power=2 x 1200kW - roller width=1000mm roller diameter=2000mm CCB (Belgium; Gaurain) : Cement POLYSIUS - 1990 - Nominal power=2 x 1200kW - roller width=1000mm roller diameter=2000mm CALCIA (France; Cruas) : White cement FCB - 1990 - Nominal power=2 x 160kW - roller width=400mm roller diameter=820mm ESSROC (USA; Nazareth): Cement KHD - 1987 - Nominal power=2 x 800kW - roller width=1000mm roller diameter=1150mm ESSROC (USA; Speed): Cement KHD - 1998 - Nominal power=2 x 450kW - roller width=800mm roller diameter=1400mm Italcementi Group
PIC Grinding September 2005
203
4- ROLLER PRESS Example of CCB (Belgium; Gaurain): Raw grinding :
MILL 7 ROLLER PRESS MILL 1775 kW WORK SHOP 2199 kW STPH 106.6 kWh/st 22.8 Maintenance Cost 5.69 $pst
MILL 8 MILL 8/MILL7 1479 kW 3547 kW 200% 6193 kW 282% 355.3 333% 19.7 - 13.6 % 4.66 $pst - 18.1 %
To fulfil the same production as the grinding plant # 8 with the grinding plant # 7 WE SHOULD NEED a 7334 kW installed power plant. Italcementi Group
PIC Grinding September 2005
204
4- ROLLER PRESS Cement grinding
MILL 8 MILL 9 MILL 9 /MILL8 ROLLER PRESS 912 kW MILL 4392 kW 8566 kW 194% WORK SHOP 4901 kW 11634 kW 237% STPH 84.2 251.7 299% kWh/st 58.2 46.2 - 20.6 % Maintenance Cost 10.7 $pst 8.1 $pst -24.3 % To fulfil the same production as the grinding plant # 9 with the grinding plant # 8 WE SHOULD NEED a 14755 kW installed power grinding plant.
Italcementi Group
PIC Grinding September 2005
205
SYSTEMES DE BROYAGE CIMENTS
Italcementi Group
PIC Grinding September 2005
206
4- ROLLER PRESS HOROMILL (FCB)
Limits: New technology New plants in the world: R.C.C. (Turkey): 1 Horomill with TSV classifier 110 stph; 3200 Blaine OPC Asian Cement (Lafarge, Turkey) 1 Horomill with TSV classifier 110 stph; 4200 Blaine; 2100 kW installed power
Italcementi Group
PIC Grinding September 2005
207
5- HORIZONTAL ROLLER MILLS COMPARISON OF THE ANGLES OF NIPS
Italcementi Group
PIC Grinding September 2005
208
5- HORIZONTAL ROLLER MILLS PROCESS PRINCIPLE INSIDE HOROMILL
Italcementi Group
PIC Grinding September 2005
209
5- HORIZONTAL ROLLER MILLS
BUILT A MILL ABLE TO GRIND: • • • • • • •
with compression effect with low mechanical strains in a steady way with a limited wear of grinding media with low investment cost without the roller press power limit with an operating flexibility
Italcementi Group
PIC Grinding September 2005
210
5- HORIZONTAL ROLLER MILLS
MILL TYPE
SPECIFIC PRESSURE (exerced by the rollers on the material layer) : 150 - 200 8-14 20-60 25
Roller press Raw vertical mill Cement vertical mill Horizontal roller mill
Italcementi Group
PIC Grinding September 2005
MPa MPa MPa MPa
211
5- HORIZONTAL ROLLER MILLS HOROMILL (FCB)
Italcementi Group
PIC Grinding September 2005
212
5- HORIZONTAL ROLLER MILLS HOROMILL (FCB)
Italcementi Group
PIC Grinding September 2005
213
5- HORIZONTAL ROLLER MILLS TREND
Italcementi Group
PIC Grinding September 2005
214
5- HORIZONTAL ROLLER MILLS
ADVANTAGES: - Grinding efficiency
DISADVANTAGES: - New design and technology - Working hours (max 1300 of industrial prototype) - High circulation load - Limited ventilation in the mill - Limits in feed moisture - Difficulty to produce OPC cement with fineness > 4000 Blaine - Difficulty to produce slag cement with slag content > 40% Italcementi Group
PIC Grinding September 2005
215
5- HORIZONTAL ROLLER MILLS Mechanical problems: - Hydraulic apparatus ( cylinders and accumulators) - Roller and track lifetime, scrapers wear - Cracks in the mill shell - Mill shell sealing - Misalignment of mill shall (material inside the mill) - Torsional vibration on drive line - Lubrication oil cooling system and pollution Process problems: - Limits in fineness with OPC cement - Two separators in series utilised in Karsdorf for OPC 42.5 cement - Difficulty to produce slag cements (> 40% of slag content) - Start-up procedure Italcementi Group
PIC Grinding September 2005
216
5- HORIZONTAL ROLLER MILLS TREND
Italcementi Group
PIC Grinding September 2005
217
5- HORIZONTAL ROLLER MILLS TREND
Italcementi Group
PIC Grinding September 2005
218
5- HORIZONTAL ROLLER MILLS COMPARISON BETWEEN HOROMILL AND CEMAX Manufacturer Spin velocity Type of circuit C,C. regulation Mill ventilation Drying capacity Inlet mill Maximum size Expected production Italcementi Group
HOROMILL Fives Cail Babcock 1.6 x critical speed mechanical inside the mill low limited single 4000 kW 220 t/h PIC Grinding September 2005
CEMAX F.L. Smidth 0.82 x critical Speed ventilated separator high good double 5500 kW 300 t/h 219
6- SYSTEMS AND OTHER COMPARISON OF MAIN PARAMETERS Specific pressure (F/LxD) Pressure nip angle Compression in single pass Substitution ratio Drying capacity kWh/t mill motor (*) kWh/t total (*) Maximum Blaine OPC Investment cost References
Roller press 6.5 6 1 1.7 - 2.2 out of the press 60 70 3500 110 > 300
Vertical mill 1.5 12 2 1.5 - 2.2 in the mill 60 75 4300 110 35
Horomill 3.5 18 5 1.5 - 2.2 out of the mill 60 70 4100 110 15
* = referred to horizontal ball mill as 100% Italcementi Group
PIC Grinding September 2005
220
6- SYSTEMS AND OTHER CEMENT VERTICAL MILL
Italcementi Group
PIC Grinding September 2005
221
6- SYSTEMS AND OTHER CEMENT VERTICAL MILL
Loesche mill LM 32.5+2S
Italcementi Group
PIC Grinding September 2005
222
6- SYSTEMS AND OTHER
MILL FRESH FEED
MILL RECIRCULATION FEED
MASTER ROLLER
THIRD GENERATION CLASSIFIER
CEMENT VERTICAL MILL SLAVE ROLLER
Loesche mill LM 32.5+2S
Italcementi Group
PIC Grinding September 2005
223
6- SYSTEMS AND OTHER CKP GRINDING SYSTEM
PRE-GRINDING
Italcementi Group
SEMI-FINISH GRINDING
PIC Grinding September 2005
224
6- SYSTEMS AND OTHER
Italcementi Group
PIC Grinding September 2005
225
6- SYSTEMS AND OTHER NEW DEVELOPMENT: CKP Process
Characteristics: No integrated separator External mechanical elevator Material outlet design Low air flow (dedusting function) low drying capacity Association with a finishing mill
Production improvements:
Italcementi Group
PIC Grinding September 2005
226
6- SYSTEMS AND OTHER CIRCUIT BEFORE CKP INSTALLATION
Italcementi Group
PIC Grinding September 2005
227
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
228
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
229
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
230
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM MARRAKECH - CEMENT MILL n°2 + CKP - CPJ 35 Pos.
Cement type
CPJ 35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Test number Additives Sent to CKP Sent to ball mill Test date Production Residue 0.040 mm Residue 0.063 mm Residue 0.080 mm Residue 0.090 mm Residue 0.200 mm Blaine Clinker Limestone Pozzuolana Gypsum
t/h % % % % % cm2/g % % % %
17 18 19 20 21 22 23 24
Mill absorbed power CKP absorbed power Services absorbed power Total absorbed power Mill specific consumption CKP specific consumption Services spec. consumpt. Total specific consumption
kW kW kW kW kWh/t kWh/t kWh/t kWh/t
25 Mill max power required
Italcementi Group
Reference
Performance
before CKP
warranties
% -
kW
1 100 lim + 0 poz cli + lim to CKP gyps to mill 08-mar 136 33,44 10,40
5 50 lim + 50 poz cli + lim to CKP poz + gyp to mill 12-mar 144 35,96 12,92
7 50 lim + 50 poz cli+lim+poz to CKP gyps to mill 13-mar 157
75 20 0 5
3,68 0,08 3650 71 24 0 5
5,04 0,12 4100 71 12 12 5
5,00 0,10 4100 71 12 12 5
21,5
2057 763 403 3223 15,13 5,61 2,96 23,70
2060 770 405 3235 14,31 5,35 2,81 22,47
2060 797 410 3267 13,12 5,08 2,61 20,81
100 lim + 0 poz cli + lim to CKP gyps to mill 100
CTG test with CKP
165
13,00
4-6
3600 75 5 - 15 5 - 15 5 2100 800 2900 21,00 8,00 29,00
2200
PIC Grinding September 2005
231
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM MARRAKECH - COTTO 2 + CKP a CPJ 45 Pos.
Tipo cemento
CPJ 45
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Test number Additives Sent to CKP Sent to ball mill Test date Production Residue 0.040 mm Residue 0.063 mm Residue 0.080 mm Residue 0.090 mm Residue 0.200 mm Blaine Clinker Limestone Pozzuolana Gypsum
% t/h % % % % % cm2/g % % % %
17 18 19 20 21 22 23 24
Mill absorbed power CKP absorbed power Services absorbed power Total absorbed power Mill specific consumption CKP specific consumption Services specific consumption Total specific consumption
kW kW kW kW kWh/t kWh/t kWh/t kWh/t
25 Mill max power required
Italcementi Group
Reference
Performance
CTG test
before CKP
warranties
86
145
with CKP 4 50 lim + 50 poz cli + lim to CKP poz + gyp to mill 11-mar 122 33,32 9,08
2-4
2-4
3600 - 3700 85 10 - 5 5 - 10 5
85 5 5 5
2150
2060 760 400 3220 16,89 6,23 3,28 26,39
602 2752 25,00 7,00 32,00
kW
2,76 0,08 3300 87 4 4 5
2200
PIC Grinding September 2005
232
6- SYSTEMS AND OTHER CKP SEMI-FINISH GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
233
6- SYSTEMS AND OTHER HORIZONTAL ROLLER MILL
Italcementi Group
PIC Grinding September 2005
234
6- SYSTEMS AND OTHER HORIZONTAL ROLLER MILL
Italcementi Group
PIC Grinding September 2005
235
6- SYSTEMS AND OTHER HORIZONTAL ROLLER MILL
Italcementi Group
PIC Grinding September 2005
236
6- SYSTEMS AND OTHER HORIZONTAL ROLLER PRESS
Italcementi Group
PIC Grinding September 2005
237
VI- SEPARATING PROCESS 1. Theory 2. Cyclone 3. Static Classifier 4. Dynamic Classifiers : First Generation Second Generation Third Generation
5. Design
Italcementi Group
PIC Grinding September 2005
238
1- THEORY PERFORMANCES:
GOOD CLASSIFIER EFFICIENCY
GOOD WORKSHOP EFFICIENCY
LOWER ELECTRIC CONSUMPTION
GLOBAL PRODUCTIVITY IMPROVEMENT Italcementi Group
PIC Grinding September 2005
239
1- THEORY • PURPOSE => SEPARATION PARTICLE SUITABLE FOR "FINISHED PRODUCT" CLASSIFIER FEED COARSE PARTICLES "OVERSIZED" TWO THINGS MUST BE ENSURED
Italcementi Group
=> NO OVERSIZED IN THE FINISH => NO FINISHED IN THE REJECTS
PIC Grinding September 2005
240
1- THEORY PRINCIPLE:
EACH PARTICLE IN AN AIR FLOW : CxSx(V2/2)xRo= Global air force = Fa
Air current
MxW2xR= Centrifugal force=Fc
MxG=Gravity force = Fg Italcementi Group
PIC Grinding September 2005
241
1- THEORY
Fg=K1 x d3 Fc=K2 x d3 Fl=K3 x d(3/2) d: particle diameter
Fg # 1/10 Fc => insignificant Fc = Fl => d0 = cut size
d > d0 => particle thrown out the inner side => Tail d < d0 => particle thrown up => Fines
Italcementi Group
PIC Grinding September 2005
242
1- THEORY A CIRCULATING LOAD: A = R + F (t / h) or A / F (ratio)
R
FRESH FEED
Italcementi Group
PIC Grinding September 2005
F
243
1- THEORY DIFFERENT KINDS OF CLASSIFIERS CYCLONE STATIC DYNAMIC TO DUST COLLECTOR
FINE MATERIAL TO DUST COLLECTOR
GAS WITH MATERIAL
GAS WITH FINES
MATERIAL
GAS REJECT PRODUCT
Italcementi Group
GAS FROM MILL
REJECT
PIC Grinding September 2005
244
2- CYCLONE FINENESS ADJUSTMENT BY : AIR FLOW REGULATION
Captation efficiency ANDERSON, ROSIN RAMMLER law
D min i
K. . n l . s.Vt
K Cst
: duct . width. ( m) l: gas. trajectory . ( m) Vt : tan gential . speed . ( m / s )
h: Gas. dynamic. vis cos ity . ( Poiseuille ) S: Material . volumic. mass. ( kg / m3)
Italcementi Group
PIC Grinding September 2005
245
3- STATIC SEPARATOR REGULATION OF THE CUT SIZE WITH: • GUIDE VANES INCLINATION (wheel) • OUTLET DUCT LENGTH (R) • AIR FLOW
Italcementi Group
PIC Grinding September 2005
246
3- STATIC SEPARATOR To mill dust collector
Fines
Adjustable guide vanes
Reject Mill vent air Italcementi Group
PIC Grinding September 2005
247
3- STATIC SEPARATOR TWO TYPES OF STATIC SEPARATORS
FINES
FINES
TAILS
TAILS
AIR FLOW + FEED Italcementi Group
PIC Grinding September 2005
AIR FLOW + FEED 248
3- STATIC SEPARATOR ADVANTAGES : • EASY TO USE • CHEAP • HIGH AIR FLOW • LOW ELECTRIC CONSUMPTION • ALLOW TO SEND FILTER MILL PRODUCT TO FINAL PRODUCT
DISADVANTAGES : • MEDIUM PRECISION OF SIEVING • CONVEYING FUNCTION (AIRSWEPT) AND SEPARATING FUNCTION LINKED TOGETHER • FINENESS LIMITED Italcementi Group
PIC Grinding September 2005
249
4- DYNAMIC SEPARATOR
• FIRST GENERATION
• SECOND GENERATION • THIRD GENERATION
Italcementi Group
PIC Grinding September 2005
250
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
STURTEVANT
Italcementi Group
Characteristics: • Single drive •Selection device (distribution plate) •Main fan 3 Functions with the same motor Fineness regulation by: •Selection blade number •Selection and fan blade size •Diaphragm valve small fineness range PIC Grinding September 2005
251
4- DYNAMIC SEPARATOR FIRST GENERATION (STURTEVANT)
Fineness adjustment by diaphragm position
Italcementi Group
PIC Grinding September 2005
252
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
POLYSIUS
Characteristics: • Double drive • Distribution plate & selection device mounted on the same shaft • Main fan • Selection device speed control
3 functions with two motors. Fineness regulation by: • Plate distribution speed • Selection blade number • Selection blade size Larger fineness range Italcementi Group
PIC Grinding September 2005
253
4- DYNAMIC SEPARATOR FIRST GENERATION (POLYSIUS)
Double drive: variable speed and fixed speed
Fan (fixed speed)
feed
Selection blades
Feed distribution plate
Fineness adjustment by variable speed reject fines Italcementi Group
PIC Grinding September 2005
254
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
RAYMOND
Characteristics : •Single drive with fix speed •Selection device (distribution plate) single or double •Main fan 3 functions with one motor Fineness regulation : •Selecting blades number •Internal deflectors position Italcementi Group
PIC Grinding September 2005
255
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
DISADVANTAGES : Inner side effect (wall effect) Fines in tails
Italcementi Group
ALL FUNCTIONS (SELECTION -VENTILATION- CAPTATION) DISPLAYED INTO ONE MACHINE BIG CYCLONE • Bad selection efficiency (feeding under selecting zone + wide selecting area) •Limited cooling function •High by-passing level (fines in tails) •Fineness limited •No air flow regulation •Bad efficiency of the main fan PIC Grinding September 2005
256
4- DYNAMIC SEPARATOR SECOND GENERATION CLASSIFIER
Main description : •Central body • Satellite cyclones • High efficiency main fan Characteristics : • Fine particle captation made by small cyclones • Regulated air flow (recirculation air flow) Fineness regulation by : • Distribution plate speed • Recirculation air flow • Selection blades number & size Italcementi Group
PIC Grinding September 2005
257
4- DYNAMIC SEPARATOR SECOND GENERATION (WEDAG)
Italcementi Group
PIC Grinding September 2005
258
4- DYNAMIC SEPARATOR SECOND GENERATION (WEDAG)
Variable speed drive
fan
feed
selection
distribution Italcementi Group
fines PIC Grinding September 2005
rejects 259
4- DYNAMIC SEPARATOR SECOND GENERATION CLASSIFIER
ADVANTAGES: FINENESS REGULATION EASY FROM THE CONTROL ROOM COOLING CAPACITY (by regulating fresh air flow) DRYING CAPACITY SEPARATION OF DIFFERENT FUNCTIONS (Separation, Ventilation, Captation ...) HIGH EFFICIENCY VENTILATOR LARGE FINENESS RANGE
Italcementi Group
PIC Grinding September 2005
260
4- DYNAMIC SEPARATOR SECOND GENERATION CLASSIFIER
DISADVANTAGES: CLASSIFIER SIZE STILL HIGH BY- PASSING LEVEL (fines in tails) FEEDING UNDER SELECTING ZONE AND WIDE SELECTION AREA
THIRD SEPARATION CLASSIFIER
Italcementi Group
PIC Grinding September 2005
261
4- DYNAMIC SEPARATOR THIRD GENERATION CLASSIFIER
CLASSIFYING PRINCIPLE:
Narrow classifying area for third generation classifier (versus first generation) Consistent centrifugal force
Italcementi Group
PIC Grinding September 2005
262
1_ csV12 2
1_ csV22 2
m2 R1
m2 R2
mg
4- DYNAMIC SEPARATOR
mg
THIRD GENERATION CLASSIFIER
THEORY 1_ csV 2 2
m2 R
mg 1_ csV 2 2
m2 R
mg
Italcementi Group
PIC Grinding September 2005
263
4- DYNAMIC SEPARATOR THIRD GENERATION CLASSIFIER
O-SEPA (Onoda, Japan)
Italcementi Group
PIC Grinding September 2005
TSV (FCB, France)
264
4- DYNAMIC SEPARATOR THIRD GENERATION (STURTEVANT)
Italcementi Group
PIC Grinding September 2005
265
4- DYNAMIC SEPARATOR THIRD GENERATION (O-SEPA)
Italcementi Group
PIC Grinding September 2005
266
4- DYNAMIC SEPARATOR THIRD GENERATION (O-SEPA)
Italcementi Group
PIC Grinding September 2005
267
4- DYNAMIC SEPARATOR THIRD GENERATION (FCB)
Italcementi Group
PIC Grinding September 2005
268
4- DYNAMIC SEPARATOR THIRD GENERATION (POLYSIUS)
Italcementi Group
PIC Grinding September 2005
269
5- DESIGN DESIGN PARAMETERS FOR A THIRD GENERATION CLASSIFIER
Ratio separator feeding / air throughput 1.75 kg/actual m3 (max : 2 kg/m3) Ratio fines/cage total surface max : 10 t/m² Ratio fines / air throughput max : 1 kg/actual m3 Italcementi Group
PIC Grinding September 2005
270
5- DESIGN SEPARATOR LOAD RATIO
CEMENT: Separator feed rate/separation air => 1.8 kg/m3 Separator product/ separation air 3000 cm2 /g acc. to Blaine => 0.75 - 0.8 kg/m3 4000 cm2 /g acc. to Blaine => 0.55 - 0.6 kg/m3 5000 cm2 /g acc. to Blaine => < 0.55 kg/m3 RAW MATERIAL: Separator feed rate/ separation air => 2.2 kg/m3 Raw meal 12 - 14% residue 90 mm => 0.55 kg/m3 Italcementi Group
PIC Grinding September 2005
271
5- DESIGN SEPARATOR COMPARISON
First generation: • all functions (selection, ventilation, product collection) in the same machine • wide separation area Second generation: • functions divided in different components • wide separation area Third generation: • high efficiency due to narrow separation area and controlled ventilation Italcementi Group
PIC Grinding September 2005
272
5- DESIGN SEPARATOR DATA SHEET
Italcementi Group
PIC Grinding September 2005
273
5- DESIGN
Italcementi Group
PIC Grinding September 2005
274
5- DESIGN
Italcementi Group
PIC Grinding September 2005
275
5- DESIGN DESIGN PARAMETERS FOR A THIRD GENERATION CLASSIFIER
Max tangential speed (peripheral speed) : Vt = 35 m/s Radial speed (air speed through the cage) : Vr = 4.5 m/s if product fineness <3200 Blaine Vr if > 4500 Blaine 4.5 m/s for small separator 3.5 - 4 m/s for big one Vr = 5 - 5.2 m/s for raw material Italcementi Group
PIC Grinding September 2005
276
5- DESIGN THIRD GENERATION CLASSIFIER
ADVANTAGES: CLASSIFIER SIZE HIGH SIEVING ACCURACY COOLING CAPACITY EASY TO CONTROL (in the control room)
Italcementi Group
PIC Grinding September 2005
277
5- DESIGN THIRD GENERATION CLASSIFIER
DISADVANTAGES: FILTER SIZE FINAL PRODUCT QUALITY
nRRS
=
• Workability • One and two days strength
Italcementi Group
PIC Grinding September 2005
278
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
279
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
280
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
281
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
282
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
283
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
284
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
285
5- DESIGN NEW
OLD
Italcementi Group
PIC Grinding September 2005
MODIFIED BY C.T.G.
286
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
287
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
288
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
289
5- DESIGN MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
290
5- DESIGN TROMP CURVE CALCULATION A (a)
G (g)
F (f) M
Vf =
Vg =
Sa - Sg Sf - Sg
Sf - Sa Sf - Sg
x 100 (%)
x 100 (%)
Italcementi Group
A = Separator feed (t/h) F = Separator fines (t/h) G = Separator reject (t/h) Ma= Fresh mill feed (t/h) Da = Granulometric size weight of separator feed (%) Df = Granulometric size weight of separator fines (%) Dg = Granulometric size weight of separator reject (%) Sa = Granulometric size passing of separator feed (%) Df = Granulometric size passing of separator fines (%) Dg = Granulometric size passing of separator reject (%) Vf = Separator fines weight (%) Vg = Separator reject weight (%) T = Separation coefficient (%)
In general: T = f (granulometric size)
Dg - Vg
T=
x 100 (%)
Dg x Vg + Df x Vf
PIC Grinding September 2005
291
5- DESIGN SEPARATOR RELATION BETWEEN SEPARATOR EFFICIENCY AND MATERIAL FLOWS A = F = G = a = f = g = h = UF =
Separator feed (t/h) Separator fines (t/h) Separator reject (t/h) Granulometric size passing of separator feed (%) Granulometric size passing of separator fines (%) Granulometric size passing of separator reject (%) Separator efficiency Circulation load A
fxF
h=
UF = F
a xA
h=
f a
Italcementi Group
a-g x
f =
f-g
f-g = a-g
1 x
a
PIC Grinding September 2005
UF
292
5- DESIGN SEPARATOR
TROMP CURVE CALCULATION
Italcementi Group
PIC Grinding September 2005
293
5- DESIGN SEPARATOR
TROMP CURVE CALCULATION
Italcementi Group
PIC Grinding September 2005
294
5- DESIGN SEPARATOR
TROMP CURVE Selectivity (%)
Tails in fines
Global by-pass (Stg)
P(t) 50 % Imperfection= (d75 - d25) / 2d50 By-pass slope (Pts) Fines in tails Particle size (μm)
Italcementi Group
PIC Grinding September 2005
Minimum by-pass (St) Log 295
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
296
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
297
5- DESIGN THIRD GENERATION CLASSIFIER
Selectivity (%)
FIRST GENERATION SECOND GENERATION THIRD GENERATION
Characteristics: Squirrel cage to make separation Fineness regulation: Rotor speed Air flow regulation Static blades inclination
Particle size (μm)
Italcementi Group
PIC Grinding September 2005
298
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
299
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
300
5- DESIGN SEPARATOR
Cement type IA-52.5
Mill TOSI 9’ x 14’ with Sturtevant 16’ separator Mill SMIDTH 3.2 X 9.3 With O-SEPA N 1000 separator Italcementi Group
PIC Grinding September 2005
301
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
302
VII - GRINDING CIRCUITS
Dry Process 1. Open Circuit 2. Closed Circuit 3. Raw Material Circuit 4. Swept Circuit 5. Coal Circuit 6. Cement Circuit
Italcementi Group
PIC Grinding September 2005
303
1- OPEN CIRCUIT
Italcementi Group
PIC Grinding September 2005
304
1- OPEN CIRCUIT ADVANTAGES :
LOW INVESTMENT COST SIMPLE LAY-OUT
SPECIFIC POWER CONSUPTION ACCEPTABLE FOR COARSE CEMENT (maximum 3000 Blaine OPC)
Italcementi Group
PIC Grinding September 2005
305
1- OPEN CIRCUIT DISADVANTAGES : RISK TO FIND COARSE PARTICLE IN CEMENT NO ACCURATE REGULATION POSSIBILITY FOR DIFFERENT KINDS OF CEMENT FINE CEMENT PRODUCTION EXPENSIVE LOW VENTILATION NO DRYING CAPACITY
Italcementi Group
PIC Grinding September 2005
306
1- OPEN CIRCUIT
Italcementi Group
PIC Grinding September 2005
307
1- OPEN CIRCUIT PARTICLE SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
308
2- CLOSED CIRCUIT
Italcementi Group
PIC Grinding September 2005
309
2- CLOSED CIRCUIT
ADVANTAGES :
GOOD EFFICIENCY (kWh/t) LARGE FINENESS RANGE HIGH RRS SLOPE DRYING & COOLING CAPACITY CIRCUIT REGULATION POSSIBILITIES
Italcementi Group
PIC Grinding September 2005
310
2- CLOSED CIRCUIT
DISADVANTAGES : HIGH INVESTMENT COST MORE MAINTENANCE COST => NUMBER OF MACHINES (vs opened circuit)
Italcementi Group
PIC Grinding September 2005
311
3- RAW MATERIAL CIRCUITS RAW GRINDING
WET PROCESS
DRY PROCESS
Disagglomerator Horizontal mill Closed circuit
Horizontal mill Airswept circuit
Opened circuit
Italcementi Group
Mechanical circuit
Central Discharge
PIC Grinding September 2005
Vertical mill
Standard 312
3- RAW MATERIAL CIRCUITS
DRY PROCESS
WET PROCESS
Italcementi Group
PIC Grinding September 2005
313
3- RAW MATERIAL CIRCUITS DRY PROCESS (VERTICAL ROLLER MILL)
Italcementi Group
PIC Grinding September 2005
314
3- RAW MATERIAL CIRCUITS DRY PROCESS (STANDARD CIRCUIT)
Italcementi Group
PIC Grinding September 2005
315
3- RAW MATERIAL CIRCUITS DRY PROCESS (DOUBLE ROTATOR)
Italcementi Group
PIC Grinding September 2005
316
4- SWEPT CIRCUIT DRY PROCESS (AIR SWEPT)
Italcementi Group
PIC Grinding September 2005
317
4- SWEPT CIRCUIT DRY PROCESS (AIR SWEPT)
AIR SWEPT CIRCUIT WITH RICICLE FAN
Italcementi Group
PIC Grinding September 2005
318
4- SWEPT CIRCUIT WET PROCESS
• NOT MORE UTILIZED FOR NEW PLANTS • SUITABLE FOR RAW MATERIALS VERY WET, HARD OR WITH HIGH LEVEL OF PLASTICITY
• REQUIRES FUELS AT VERY LOW COST
Italcementi Group
PIC Grinding September 2005
319
4- SWEPT CIRCUIT WET PROCESS ADVANTAGES: • LOWER ENERGY SPECIFIC CONSUMPTION (30-50% less than dry process) • LOWER INVESTMENT COST • NO AIR POLLUTION • EASY SLURRY TRANSPORT • EASY SLURRY HOMOGENISATION • WET KILN LESS AFFECTED BY PRESENCE OF CHLORIDES, ALKALIES OR SULFATES IN RAW MATERIALS • ABILITY TO USE HIGH SULFUR FUELS AND WASTE FUELS Italcementi Group
PIC Grinding September 2005
320
4- SWEPT CIRCUIT WET PROCESS DISADVANTAGES: • HIGH SLURRY MOISTURE CONTENT (30 - 40 %) • HIGH THERMIC ENERGY CONSUMPTION • DIFFICULTY IN GRINDING MATERIALS WITH DIFFERENT GRINDABILITY • HIGH WEAR COSTS • CLAY INCREASES SLURRY WATER CONTENT
Italcementi Group
PIC Grinding September 2005
321
4- SWEPT CIRCUIT WET PROCESS OPEN CIRCUIT • ROTARY DISAGGREGATORS (for soft materials) • HORIZONTALS BALLS MILL with 2-3 compartments ( cylpebs in 3^ compartment, rubber liner and diaphragms in 2^ and 3^ compartment) Advantages: • simple installation and control
Italcementi Group
PIC Grinding September 2005
322
4- SWEPT CIRCUIT WET PROCESS
CLOSED CIRCUIT • HORIZONTALS BALLS MILL with 1-2 compartments • SLURRY CLASSIFIER: - curved 270° screens (DSM) - FLS centrifugal screens - Hydrocyclones - MOGENSEN
Italcementi Group
PIC Grinding September 2005
323
4- SWEPT CIRCUIT WET PROCESS CLOSED CIRCUIT - SLURRY CLASSIFIERS CURVED SCREEN (DSM) • most frequently used • lifetime of screen elements acceptable • low specific investment cost • spare part low cost • high throughput (200 t/h)
Italcementi Group
PIC Grinding September 2005
324
4- SWEPT CIRCUIT WET PROCESS CLOSED CIRCUIT - SLURRY CLASSIFIERS FLS CENTRIFUGAL SCREEN • movable parts • high wear costs • investment specific cost high (4 times DSM) • kWh/t higher than DSM • throughput limited (100 t/h)
Italcementi Group
PIC Grinding September 2005
325
4- SWEPT CIRCUIT WET PROCESS CLOSED CIRCUIT - SLURRY CLASSIFIERS HYDROCYCLONS • simple machines • require small volume • efficiency affected by slurry characteristics MOGENSEN • high specific investment cost • good efficiency • good lifetime • max throughput 120 t/h
Italcementi Group
PIC Grinding September 2005
326
4- SWEPT CIRCUIT WET PROCESS
CLOSED CIRCUIT Advantages: • • • •
less wear inside the mill less electric power consumption more constant product quality less problems to grind raw materials with different grindability
Italcementi Group
PIC Grinding September 2005
327
5- COAL CIRCUIT
DIRECT FIRING
SEMI DIRECT FIRING
INDIRECT FIRING
Italcementi Group
PIC Grinding September 2005
328
5- COAL CIRCUIT DIRECT FIRING : the ground coal is sent directly to the rotary kiln without storage and mill outlet production must be adjusted to the kiln consumption.
1: Raw coal silo 2: Air heater 3: Coal mill
4: Primary air fan 5: Rotary kiln
Italcementi Group
Disadvantage: Kiln performances depend on mill performances PIC Grinding September 2005
329
5- COAL CIRCUIT SEMI DIRECT FIRING : a feed hopper with a few hours storage capacity allows the process to be more elastic 1: Raw coal silo 2: Air heater 3: Coal mill 4: Cyclone 5: Feed hopper
6: Circulating air fan 7: Primary air fan 8: Circulating air 9: Rotary kiln
Disadvantage: Kiln performances depend on mill performances Italcementi Group
PIC Grinding September 2005
330
5- COAL CIRCUIT INDIRECT FIRING: Grinding and burning process not linked 1: Raw coal silo 2: Air heater 3: Coal mill 4: Cyclone 5: Coal dust silo 6: Circulating air fan 7: Filter 8: Exhaust fan 9: Circulating air 10: Primary air fan 11: Rotary kiln
Italcementi Group
PIC Grinding September 2005
331
6- CEMENT CIRCUIT CEMENT GRINDING
BALL MILL
ROLLER PRESS
O.C.
Finish grinding
C.C.
Ball mill
VERTICAL MILL O. C.
Standard circuit
Italcementi Group
Double rotator
PIC Grinding September 2005
C.C. 332
6- CEMENT CIRCUIT
ONE FILTER CEMENT CIRCUIT ONE FILTER SERIAL CEMENT CIRCUIT
TWO FILTER CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
333
6- CEMENT CIRCUIT ONE FILTER CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
334
6- CEMENT CIRCUIT ONE FILTER CEMENT CIRCUIT ADVANTAGES : • LOW SPECIFIC ENERGY CONSUMPTION • LOW MAINTENANCE • CHEAPER INVESTMENT THAN TWO FILTER CIRCUIT
DISADVANTAGES: • TUBE VENTILATION AND SEPARATOR DEDUSTING DIFFICULT TO ADJUST • LOWER DRYING AND COOLING CAPACITY THAN TWO FILTERS CIRCUIT • TWO SEPARATORS ==> TWO FINAL PRODUCTS Italcementi Group
PIC Grinding September 2005
335
6- CEMENT CIRCUIT ONE FILTER SERIAL CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
336
6- CEMENT CIRCUIT ONE FILTER SERIAL CEMENT CIRCUIT ADVANTAGES : • ONLY ONE FINENESS CHECK POINT • LOW MAINTENANCE • CHEAPER INVESTMENT THAN TWO FILTER CIRCUIT • LOWEST POWER CONSUMPTION
DISADVANTAGES: • LIMITED COOLING CAPACITY IN THE SEPARATOR • HIGH NEGATIVE PRESSURE IN THE CIRCUIT => RISK OF FALSE AIR
Italcementi Group
PIC Grinding September 2005
337
6- CEMENT CIRCUIT TWO FILTER CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
338
6- CEMENT CIRCUIT TWO FILTER CEMENT CIRCUIT ADVANTAGES : • HIGH COOLING CAPACITY • HIGH DRYING CAPACITY • CLASSIFYING AND TUBE VENTILATION FUNCTIONS NOT LINKED
DISADVANTAGES: • HIGHER INVESTMENT COST (TWO FILTERS) • TWO FINENESS CHECK POINTS • HIGHER MAINTENANCE COST • HIGHER ENERGY CONSUMPTION IF COOLING IS NOT NECESSARY
Italcementi Group
PIC Grinding September 2005
339
VIII - CIRCUIT PROCESS CONTROL
Italcementi Group
PIC Grinding September 2005
340
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT Mill feed •
MILL FEED
BY
ELEVATOR MOTOR POWER
( affected by mechanical problems of bucket elevator ) or •
MILL FEED
BY
SEPARATOR REJECT WEIGTH
( impact weight feeder requires frequent calibration and proper installation) and •
MILL FEED
BY
MILL FIRST COMPARTMENT NOISE
( electronic ear needs proper installation and its signal is affected by surrounding noises) Italcementi Group
PIC Grinding September 2005
341
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT Mill outlet or product temperature Cooling: • MILL OUTLET TEMPERATURE BY WATER SPRYING IN
• •
- 1st compartment (from mill inlet) with hot clinker - 2nd compartment (from intermediate or outlet diaphragm) ( only for temperature > 100°C ) MILL OUTLET TEMPERATURE BY KEEPING MILL VENTILATION AT MAXIMUM LEVEL FINISH PRODUCT TEMPERATURE BY SEPARATOR FRESH AIR INTAKE ( suitable for 2nd and 3rd generation dynamic separators ) Italcementi Group
PIC Grinding September 2005
342
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT Mill outlet or product temperature Heating and drying •
•
•
MILL OUTLET TEMPERATURE BY BURNER’S FUEL => risk of cement quality by unburned => maximum mill inlet temperature for cement grinding 350 °C or MILL OUTLET TEMPERATURE BY FRESH AIR DUMPER ON HOT GASES DUCT FROM HEATING SOURCE
PRODUCT TEMPERATURE BY RECIRCULATION DUMPER AND/OR FRESH AIR DUMPER IN SEPARATOR’S AIR RECIRCULATION SYSTEM => 2nd and 3rd generation dynamic separators Italcementi Group
PIC Grinding September 2005
343
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT DOUBLE ROTATOR MILL
IN ADDITION TO THE CONTROL AS FOR STANDARD CIRCUIT • MATERIAL FILLING DEGREE OF MILL’S COMPARTMENTS ( electronic ear for each compartment ) BY DISTRIBUTION OF SEPARATOR REJECT FLOW BETWEEN GRINDING AND FINISHING COMPARTMENTS • AIR FLOW ( fresh or hot ) IN FINISHING COMPARTMENT MANUALLY ADJUSTED FOR PROPER MILL VENTILATION
Italcementi Group
PIC Grinding September 2005
344
VIII- CIRCUIT PROCESS CONTROL AIR SWEPT MILL CIRCUIT
• VENTILATION THROUGH THE MILL CONSTANT ( measured by Venturi before mill fan) BY DUMPER OF MILL FAN • MILL FEED BY DIFFERENTIAL PRESSURE THROUGH THE MILL or • MILL FEED BY MILL NOISE (ELECTRONIC EAR) • DRYING CAPACITY BY GAS RECIRCULATION Italcementi Group
PIC Grinding September 2005
345
VIII- CIRCUIT PROCESS CONTROL VERTICAL MILL CIRCUIT FOR RAW MATERIALS • VENTILATION THROUGHT THE MILL CONSTANT BY MILL EXHAUST FAN
• MILL FEED BY MILL DIFFERENTIAL PRESSURE • MILL INLET DEPRESSURE BY FRESH AIR DUMPER AT THE MILL INLET
Italcementi Group
PIC Grinding September 2005
346
VIII- CIRCUIT PROCESS CONTROL VERTICAL MILL CIRCUIT FOR RAW MATERIALS • MILL OUTLET GAS TEMPERATURE BY MILL INLET GAS TEMPERATURE ( kiln spray tower or furnace ) or / and • MILL OUTLET GAS TEMPERATURE BY WATER SPRAY INSIDE THE MILL The mill outlet temperature affects a lot the steady running of the mill ( good control of vibrations ) Italcementi Group
PIC Grinding September 2005
347
IX - INFLUENT PARAMETERS ON kWh/T 1. 2. 3. 4. 5. 6. 7. 8.
Mill Speed Ball-Material Filling Degree Ball Charge Liners and Diaphragms (Circulating Load) Ventilation and Air Velocities False Air Mill Feed Moisture Product Fineness
Italcementi Group
PIC Grinding September 2005
348
1- MILL SPEED
42.3
Critical speed =
= g/I’ Useful D (m) 76.6
Critical speed =
= g/I’ Useful D (feet)
Rotation speed = 70 77% critical speed
Italcementi Group
PIC Grinding September 2005
349
2- BALL-MATERIAL FILLING DEGREE % of critical speed
Ball volume in % of global volume
0
Italcementi Group
PIC Grinding September 2005
350
2- BALL-MATERIAL FILLING DEGREE
INFLUENCE OF MATERIAL FILLING DEGREE AND CIRCULATING LOAD ON MILL PERFORMANCES EXAMPLE OF SPEED PLANT CEMENT (95% CK + 5% G) MILL SEPARATOR THROUGHPUT t/h MILL POWER kW MILL CONSUMPTION kW/t CIRCULATING LOAD t/h BLAINE cm²/g
Italcementi Group
PIC Grinding September 2005
SPEED TYPE 1 FLS 13 * 43 OSEPA N1500 68.9 73.5 2900 2900 42.1 39.5 226.7 283.0 3600 3580
351
2- BALL-MATERIAL FILLING DEGREE
t/h kWh/t
% volume load
Italcementi Group
PIC Grinding September 2005
352
2- BALL-MATERIAL FILLING DEGREE BALL/MATERIAL VOLUME LOAD First chamber
Second chamber
Second chamber
First chamber
Mill material level
HOW TO CHECK CORRECT MATERIAL FILLING: • CIRCULATING LOAD • MILL INSPECTION AFTER CRUSH STOP • MILL NOISE Italcementi Group
PIC Grinding September 2005
353
3- BALL CHARGE
PLANT MILL SEPARATOR WORKSHOP PRODUCT FINENESS THROUGHPUT MILL POWER MILL CONSUMPTION FIRST CHAMBER SECOND CHAMBER FIRST CHAMBER SECOND CHAMBER
Italcementi Group
t/h kW kWh/t t t m²/t m²/t
CRUAS FCB 2.2*13.0 Polysius TSU-DSE Cement 2 CPJ (white cement) Blaine=4230 cm²/g 14.2 15.3 560 529 39.5 34.6 13.8 13.9 47.2 43.7 10.8 10.6 26.7 31.8
PIC Grinding September 2005
TRIESTE TOSI 10' * 22' Stutevant 16' Raw 2 Raw product R90=6.0 to 6.6% 29.5 34.9 754 762 31.1 21.8 18.7 18.0 37.5 35.6 9.5 9.2 19.4 14.2
354
4- LINERS AND DIAPHRAGMS CIRCULATING LOAD
Circulating load Italcementi Group
PIC Grinding September 2005
355
5- VENTILATION AND AIR VELOCITIES VENTILATION IN THE MILL
• Goal:
=> Decreases the cement temperature (finished mill) => Dries the raw material in raw mills (hot gas) => Helps the ultra-fines to escape from the mill (improve the by-pass of fines and avoid overgrinding and coating)
• Characteristics: => Ventilation in the mill (closed circuit): 1 to 2 m/s (*) => Ventilation in the mill (closed circuit + drying chamber mill): 4 to 7 m/s (*) => Mill design (type of command, bearing & diaphragm) (*) referred to free volume inside the mill and outlet mill air flow Italcementi Group
PIC Grinding September 2005
356
5- VENTILATION AND AIR VELOCITIES MILL VENTILATION AND AIR VELOCITIES
Italcementi Group
PIC Grinding September 2005
357
6- FALSE AIR Point to care after for checking false air in the mill circuit
Italcementi Group
PIC Grinding September 2005
358
6- FALSE AIR
•
kWh/t
•
Mill ventilation
•
Mill efficiency
•
Drying capacity
How to fight false air: * Control air tightness into the circuit * Temperature through the circuit * Gas analysis (only with furnace or kiln gas) Italcementi Group
PIC Grinding September 2005
359
7- MILL FEED MOISTURE
MAXIMUM DRYING CAPACITY OF HORIZONTAL MILLS WITHOUT DRYING CHAMBER: => 1.5% OF WATER IN FRESH FEED MATERIAL
FURTHER THIS PERCENTAGE THE ENERGY MAY BE BROUGHT BY EXTERNAL HEAT SOURCE (care about quality !!!)
Italcementi Group
PIC Grinding September 2005
360
7- MILL FEED MOISTURE
PLANT CEMENT MILL SEPARATOR MATERIAL INLET MOISTURE BLAINE cm²/g THROUGHPUT t/h CONSUMPTION kWh/t R90 µm % CLINKER °C HOT GAS °C
Italcementi Group
HALYPS II35 (16.5% pozzolane) KHD 3*8.2 O & K 5000 2.7 TO 2.8% 3500 27.3 29.1 33.5 32.9 30.1 26.1 4.6 4.4 COLD 125 125 No No 160
PIC Grinding September 2005
361
8- PRODUCT FINENESS PRODUCTION INCREASE THEORETICAL FOR CEMENT MILL WITH PREGRINDING
Production increase theoretical for cement mill with pregrinding, calculation according to BOND (with correction factors), reduction of mill fresh feed P80 from 15 mm down to x mm
Italcementi Group
PIC Grinding September 2005
362
8- PRODUCT FINENESS FRESH FEED GRANULOMETRY: 0 30 mm 0 120 mm
Horizontal mills Vertical mills
P80 = 20 mm P80 = 80 mm (depending on rollers size)
FINISH PRODUCT FINENESS: Raw meal
residue 90 mm 5 15 % residue 200 mm 0 1.5 %
(depending on kiln type)
Coal
residue 90 mm 5 18 % residue 200 mm 0 2 %
(depending on coal type)
OPCement 32.5 OPCement 42.5 OPCement 52.5
Blaine 2800 3300 cm2/g Blaine 3300 3800 cm2/g Blaine 3800 5000 cm2/g
(depending on clinker reactivity)
Italcementi Group
PIC Grinding September 2005
363
X - MILL CHECK UP 1. 2. 3. 4. 5.
Timing before Check-Up To do before Crash-stop Mill Visit Circulating Load Measurement Data Evaluation
Italcementi Group
PIC Grinding September 2005
364
1- TIMING BEFORE CHECK-UP Mill and circuit evaluation, from control room and on the field, during steady and current mill running conditions. If necessary, adjust the running conditions in order to optimize the mill operation. Try to get a good knowledge of the problems affecting the installation. In the case of production of two different products, a check-up has to be foreseen for each quality. If not possible, choose the product with lower fineness (higher mill capacity).
Italcementi Group
PIC Grinding September 2005
365
1- TIMING BEFORE CHECK-UP
TO BE PREPARED BY THE CEMENT PLANT :
Workshop visit with somebody from manufacturing. Sampling points identification, accessibility and reliability. Process data of last months or weeks. Feeders and electrical energy meters reliability.
Italcementi Group
PIC Grinding September 2005
366
2- TO DO BEFORE CRASH-STOP
Workshop visit with somebody from manufacturing department (somebody used to run the mill). Take in control room the running mill parameters (screen printing and production report). Electrical energy meters state and values Feeders state and values. Take samples of material in the circuit (from feeders to finish product) for moisture content and size distribution analysis. Make flow, pressure and temperature measurements into the gas circuit. Take material temperatures into the circuit. Gas analysis, if possible (O2 mainly), in case of kiln gas or furnace gas use.
Italcementi Group
PIC Grinding September 2005
367
2- TO DO BEFORE CRASH-STOP FLOW SHEET
Italcementi Group
PIC Grinding September 2005
368
2- TO DO BEFORE CRASH-STOP PLANT DATA
Italcementi Group
PIC Grinding September 2005
369
2- TO DO BEFORE CRASH-STOP PLANT DATA
Italcementi Group
PIC Grinding September 2005
370
2- TO DO BEFORE CRASH-STOP MEASURE POINTS
Italcementi Group
PIC Grinding September 2005
371
2- TO DO BEFORE CRASH-STOP CYCLE SAMPLING
Italcementi Group
PIC Grinding September 2005
372
2- TO DO BEFORE CRASH-STOP
S:duct section (m) Ps:static pressure (pa) T:temperature (°C) Patm:atmospheric pressure (Pa) Patm=101325Pa=14.7 PSI Pd:dynamic pressure (Pa) d:density (Kg/Nm3):dair=1.293 (See values on following page) Q:throughput (Nm3/h) k: for a Pitot => k=1 for a Beri =>0.7
( Patm Ps).273 K' Patm. (273 T )
Gas velocity V (m/s)
V k.
2. Pd 2 k . Pd K '. d K '. d
Gas throughput (Nm3/h)
Q S .V . K '.3600 Italcementi Group
PIC Grinding September 2005
373
2- TO DO BEFORE CRASH-STOP Density values: %O2 in gas DRY PROCESS 2% 1% H2O in Raw 4% PF=35,06% 6% 500 ppm CO 8% 10% 12% SEMI-DRY PROCESS 2% 13% H2O Raw 4% PF=35.68% 6% 500 ppm CO 8% 10% 12% WET PROCESS 2% 35% H2O Raw 4% PF=35,41% 6% 500 ppm CO 8% 10% 12%
Italcementi Group
Coal 1.46 1.44 1.42 1.41 1.39 1.37 1.36 1.36 1.35 1.34 1.33 1.32 1.23 1.23 1.24 1.24 1.25 1.25
PIC Grinding September 2005
Fuel 1.39 1.38 1.37 1.36 1.35 1.34 1.34 1.34 1.33 1.33 1.32 1.32 1.20 1.21 1.22 1.22 1.23 1.24
Gas 1.35 1.35 1.34 1.33 1.33 1.32 1.29 1.29 1.29 1.29 1.29 1.29 1.17 1.18 1.19 1.20 1.21 1.22
374
2- TO DO BEFORE CRASH-STOP CRASH STOP
Machines have to be stopped in emergency (all at the same time)
The plant has to prepare the visit inside the mill (doors opening, ladders, lights, plastic bags, spoons) taking care about
Safety procedures
Italcementi Group
PIC Grinding September 2005
375
3- MILL VISIT BALL CHARGE MATERIAL SAMPLING First chamber
Second chamber
Take samples (# 10 balls in first chamber and 15 to 20 in second chamber) every meter all along the mill. Material (0.5 kg) has to be taken at the same places. Italcementi Group
PIC Grinding September 2005
Samples have to be taken on this side
376
3- MILL VISIT Why ? To calculate the ball charge filling ratio and check the mill power consumption according to CTG - CMM formula. To evaluate the material filling degree of each compartment. Why ? To evaluate material flow capacity and air speed through the diaphragm, the risk to have balls passing through the diaphragm, the maximum filling degree and forecast maintenance
slot plugging ratio thickness Italcementi Group
PIC Grinding September 2005
377
3- MILL VISIT • Inlet and outlet mill heads: thickness Why? To check gas velocity, the maximum filling degree and forecast maintenance • * * Number of liner raws * Check liners thickness, wear, breakage and the eventual gaps between liners * Coating on balls and on liners Italcementi Group
PIC Grinding September 2005
Why? Grinding efficiency Maintenance
378
3- MILL VISIT
Points to check: • • • • •
Italcementi Group
Material spread Maximum and minimum ball size Balls wear, breakage and deformation Balls charge spread Coating on balls, liners, diaphragms
PIC Grinding September 2005
379
3- MILL VISIT MILL INTERNAL SITUATION
Italcementi Group
PIC Grinding September 2005
380
3- MILL VISIT CLASSIFIER INTERNAL CHARACTERISTICS N° of fan blades
N° of valves
Short Medium Long
Ring
Italcementi Group
N° of selector blades
PIC Grinding September 2005
381
4- CIRCULATING LOAD MEASUREMENT A CIRCULATING LOAD: A = R + F (t / h) or A / F (ratio)
R
FRESH FEED
Italcementi Group
PIC Grinding September 2005
F
382
4- CIRCULATING LOAD MEASUREMENT
Weight some (3 - 4) buckets of the mill discharge elevator to check the circulating load (calculated by size distribution curve analysis of separator). If an impact flow meter on the separator rejects has been installed, check the indication.
Italcementi Group
PIC Grinding September 2005
383
4- CIRCULATING LOAD MEASUREMENT
Italcementi Group
PIC Grinding September 2005
384
XI - DATA EVALUATION
Italcementi Group
PIC Grinding September 2005
385
DATA EVALUATION Italcementi Group
GRINDING EFFICIENCY SEPARATOR BALL CHARGE BALLS / MATERIAL BALLS CLASSIFICATION COATING LINERS AND DIAPHRAGMS VENTILATION AND FALSE AIR THERMAL BALANCE MATERIAL SIZE DISTRIBUTION MILL FEED MOISTURE PIC Grinding September 2005
386
XII - EFFICIENCY EVALUATION 1. 2. 3. 4. 5. 6.
Grinding Efficiency Material Size Distribution Mill Separator Circuit Ventilation Review of parameters
Italcementi Group
PIC Grinding September 2005
387
1- GRINDING EFFICIENCY
ENERGY LOST: • Attrition / impact between balls and liners • Attrition / impact between balls • Strain elastic energy • Acoustic energy (noise) and vibration • Overgrinding and reagglomeration
Italcementi Group
PIC Grinding September 2005
388
1- GRINDING EFFICIENCY
=> Impact
=> => =>
Temperature Liner wear Ball wear
=> Attrition
=> => =>
Temperature Liner wear Ball wear
=> =>
Temperature Ball wear
=> Impact & Attrition Italcementi Group
PIC Grinding September 2005
389
1- GRINDING EFFICIENCY ENERGY CONVERSION
310%
100%
9097% Italcementi Group
PIC Grinding September 2005
390
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
391
1- GRINDING EFFICIENCY
CONCLUSION:
1 to 3 % OF THE GLOBAL GRINDING ENERGY IS USEFULL ENERGY FOR PARTICLE SIZE REDUCTION Italcementi Group
PIC Grinding September 2005
392
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
393
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
394
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
395
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
396
2- MATERIAL SIZE DISTRIBUTION
Evaluate the influence of mill filter fineness on the final product quality (in some case, it can be opportune to recycle the filter product into circuit). Care: dedusting points can affect the final product fineness.
Italcementi Group
PIC Grinding September 2005
397
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
398
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
399
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
400
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
401
3- MILL Material filling degree versus ball charge
Max filling ratio filling ratio
Actual
Mill installed power absorbed power
Mill
Possibility to increase production Italcementi Group
PIC Grinding September 2005
402
3- MILL
% volume load
Italcementi Group
PIC Grinding September 2005
403
3- MILL Low filling material level in the mill First chamber
Second chamber
Mill material level
Italcementi Group
PIC Grinding September 2005
404
3- MILL High filling material level in the mill First chamber
Second chamber
Mill material level
Italcementi Group
PIC Grinding September 2005
405
3- MILL Correct filling material level in the mill First chamber
Second chamber
Mill material level
Italcementi Group
PIC Grinding September 2005
406
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
Average balls diameter Criteria : • Straight line in C1 • Decreasing line in C2 C.1.1
C.1. n
C.2.1
C.2.n
Ball classification affected by : • ball charge filling degree • material filling degree Italcementi Group
PIC Grinding September 2005
407
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
Italcementi Group
PIC Grinding September 2005
408
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
BAD CLASSIFICATION Italcementi Group
PIC Grinding September 2005
409
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
GOOD CLASSIFICATION Italcementi Group
PIC Grinding September 2005
410
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
BAD CLASSIFICATION Italcementi Group
PIC Grinding September 2005
411
3- MILL
85-95 75-85 65-75 First chamber length
Italcementi Group
Second chamber: Correct Charge classification inversion Ball percentage
Ball percentage
First chamber: No classification for a correct efficiency
"V" classification
22-27
Second chamber length
PIC Grinding September 2005
412
3- MILL
Results of ball charge sampling using the average balls diameter Mono-chamber mill (diameter 10' x 22'). MONOPOLI plant (Italy)
100 80 60 40 20 0
84
69
60
er s
Average ball diameter 29
6
m et
er s
m et
er s 5
m et
er s 4
m et
er s 3
m et
er
40
2
m et 1 Italcementi Group
74
PIC Grinding September 2005
413
3- MILL BALLS CHARGE BULK DENSITY
lbs/ft3
mt/m3
Compartment 1
280.91
4.50
Compartment 2
290.27
4.65
Mono chamber
284.03
4.55
Italcementi Group
PIC Grinding September 2005
414
3- MILL METER SAMPLING AND CHARGE MOVEMENT
Italcementi Group
PIC Grinding September 2005
415
3- MILL CUMULATED SIZE DISTRIBUTION CURVE Criteria :
% retained
•end of C1 : max 5% > 2.5 mm
µ
•end of C2 : 10 - 20% < 90 µm for closed circuit •decreasing line in C1 & C2
C1.1
C1.n
C2.1
C2.n
Sieving : 20 mm, 10 mm, 5 mm, 2.5 mm; 1.5 mm, 630 µm, 320 µm, 160 µm, 80 µm, 40 µm. Italcementi Group
PIC Grinding September 2005
416
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
417
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
418
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
419
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
420
29/04/2002
C.T.G. - Italcementi Group - Comminution Department Company Plant Department Circuit type New charge date Mill speed Critical speed
g/1' g/1'
Critical speed 1st chamber
Characteristics Type of liner Diaphragm slots Measured free height Ratio steel / cement Useful diameter Useful lenght Useful lenght Total volume compart. Ball charge density Charge volume Filling degree Calculated free height Ball charge to add for each cm of free height Ball charge D = 100 mm D = 90 mm D = 80 mm D = 70 mm D = 60 mm D = 50 mm D = 40 mm D = 30 mm D = 25 mm D = 20 mm D = 17 mm Cil 25x25 mm Cil 22x22 mm Cil 19x19 mm Cil 16x16 mm
18,63 Installed power 27,8 Absorbed power 67,1% Ratio L/Ø
Av. size ball
mm
kW kW
mm m % m m % m³ t/m³ m³ % m
°C
Inlet 5,32
1st compartment
2nd compartment
6,0
6,0
Free area for gases Outlet m² m² 3rd compartment
2,320 3,200 25,9 13,5 4,49 4,0 29,9 1,53
mm m % m m % m³ t/m³ m³ % m
2,320 9,150 74,1 38,7 4,79 11,6 30,1 1,53
mm m % m m % m³ t/m³ m³ % m
t
0,32
t
0,97
t
t
%
t
%
6,42 3,75 3,75 4,28
18,2 Total compartement Mill total t 74,0 Ball S.S. Surface m² 1.711 Surface Av, weight ball g
3- MILL
Mill Feed point Hot gases Hot gas temperature Separator
35,3 20,6 20,6 23,5
24,6 m²/t m²
150 Av, weight ball g 33 Av. size ball mm
Italcementi Group
m
2
m
2
t
%
m
MILL BALL CHARGE
2
54 36 41 54
4,22 8,45 3,56
7,6 15,1 6,4
65 161 91
39,60
70,9
1209
185 55,8 10,2 Ball S.S. 185 Surface
75,4 m²/t m²
1598 Av, weight ball g 73 Av. size ball mm
1525
27,3 Ball S.S. 1.525 Surface
m²/t m²
116 Av, weight ball g 30 Av. size ball mm
PIC Grinding September 2005
421
3- MILL
COATING
30% of grinding efficiency can be lost
Reasons: Important retention time into the mill High temperature in second chamber ( >110° C at mill discharge) Raw material moisture + low temperature in first chamber Low filling degree of material versus balls in the compartments Grinding of cement types with high limestone content
Italcementi Group
PIC Grinding September 2005
422
3- MILL COATING Remedies : Appropriate ventilation in the mill Add water (calculated by thermal balance) in order to maintain a correct temperature at the mill outlet (< 105 °C) Use grinding aid If possible, use 2-3 % of abrasive material (slag, sand, ...) Concerning a possible coating in first chamber due to moisture, the remedy is to increase t° ( tails, clinker t°, hot gas into mill).
Italcementi Group
PIC Grinding September 2005
423
3- MILL Diaphragm slots dimensions
– outlet diaphragm slots dimension > intermediate diaphragm slots dimension – slots clogging affect material retention time and mill ventilation (clogging degrees < 40% of free area) Liners wear
– affect the reliability of liners
Italcementi Group
PIC Grinding September 2005
424
3- MILL
Circulating load Italcementi Group
PIC Grinding September 2005
425
4- SEPARATOR
Tromp (%) curve
Separator efficiency
Selectivity = f (securing) Material sampling evaluation Feeding (A)
Tails (T)
Fines (F)
Italcementi Group
Laser & Alpine Results
Selectivity
What percentage of a given particle size in the classifier feed is discharged in the tailing.
PIC Grinding September 2005
426
4- SEPARATOR KNOW HOW !!!
Italcementi Group
SELECTIVITY
PIC Grinding September 2005
427
4- SEPARATOR Monselice plant - Finish mill #4 Separator UM 6700
Italcementi Group
PIC Grinding September 2005
428
4- SEPARATOR TROMP CURVE Selectivity (%)
Tails in fines
Global by-pass (Stg)
P(t) 50 % Imperfection= (d75 - d25) / 2d50 By-pass slope (Pts) Fines in tails Particle size (μm)
Italcementi Group
PIC Grinding September 2005
Minimum by-pass (St) Log 429
4- SEPARATOR
Italcementi Group
PIC Grinding September 2005
430
4- SEPARATOR
Italcementi Group
PIC Grinding September 2005
431
5- CIRCUIT VENTILATION • Goal: => Decreases the cement temperature (finished mill) => Dries the raw material in raw mills (hot gas) => Helps the ultra-fines to escape from the mill (improve the by- pass of fines and avoid overgrinding and coating) • Characteristics: => Ventilation in the mill (closed circuit): 1 to 2 m/s (*) => Ventilation in the mill (closed circuit + drying chamber mill): 4 to 7 m/s (*) => Mill design (type of command, bearing & diaphragm) (*) referred to free volume inside the mill and outlet mill air flow Italcementi Group
PIC Grinding September 2005
432
5- CIRCUIT VENTILATION We must have a good idea of the ventilation through the mill. A particular attention has to be taken to the false air entrances in the circuit. Tube ventilation: Open circuit: 250-350 Nm3/mt of finished product 0.5-0.8 m/s (gas net speed inside mill) Closed circuit: 300-600 Nm3/mt of finished product 0.7-2. m/s (gas net speed inside mill) Mill inlet / outlet head ventilation: Maximum of 35 m/s False air : to be kept to the minimum normal range: 20 - 40% of the inlet gas flow Italcementi Group
PIC Grinding September 2005
433
5- CIRCUIT VENTILATION False air affects a lot the mill ventilation and energy power consumption False air can provide from: Mill tube: inlet joints outlet joints material feed Mill discharge Dedusting Bag filter jet pulsing Flaps airtightness high negative pressure ducts and machines ... Italcementi Group
PIC Grinding September 2005
434
5- CIRCUIT VENTILATION Point to care after for checking false air in the mill circuit
Italcementi Group
PIC Grinding September 2005
435
5- CIRCUIT VENTILATION THE PLANT ENERGY CONSUPTION DEPENDS ON THE PRESSURE DROPS IN FILTER, MILL, ...
THE CONTROL OF PRESSURE IN DIFFERENT POINTS OF THE CIRCUIT IN THE GRINDING PLANT IS CRUCIAL TO MINIMIZE THE GRINDING ENERGY CONSUMPTION CHECK THE PROCESS FAN EFFICIENCY AND THE DAMPER OPENING: THIS POINTS COULD COST A LOT OF ENERGY Italcementi Group
PIC Grinding September 2005
436
6- REVIEW OF PARAMETERS THERMAL BALANCE - DEW POINT
Due to the material moisture, the dew point has to prevent bag filter from clogging. => (bag filter gas temperature - dew point temperature) > 30°C P in Kg/cm2 Vaporisation pressure: Pv Pgs.(1 %H 2 O) 1 with P: absolute pressure in Pgh .%H 2 O Kg/cm2 (mbars*0.00102) P = Patm.-chimney depressure Pgs = Volumic mass of dry gas Pgh = Volumic mass of wet gas
Italcementi Group
Temperature of condensation: Tc
5168 273,16 in °C 13,89 ln( Pv)
PIC Grinding September 2005
437
6- REVIEW OF PARAMETERS MATERIAL SIZE DISTRIBUTION
Evaluate the influence of mill filter fineness on the final product quality (in some case, it can be opportune to recycle the filter product into circuit). Care: dedusting points can affect the final product fineness.
Italcementi Group
PIC Grinding September 2005
438
6- REVIEW OF PARAMETERS BALL - MATERIAL FILLING
INFLUENCE OF MATERIAL FILLING DEGREE AND CIRCULATING LOAD ON MILL PERFORMANCES EXAMPLE OF SPEED PLANT CEMENT (95% CK + 5% G) MILL SEPARATOR THROUGHPUT t/h MILL POWER kW MILL CONSUMPTION kW/t CIRCULATING LOAD t/h BLAINE cm²/g
Italcementi Group
PIC Grinding September 2005
SPEED TYPE 1 FLS 13 * 43 OSEPA N1500 68.9 73.5 2900 2900 42.1 39.5 226.7 283.0 3600 3580
439
6- REVIEW OF PARAMETERS BALL CHARGE PLANT MILL SEPARATOR WORKSHOP PRODUCT FINENESS THROUGHPUT MILL POWER MILL CONSUMPTION FIRST CHAMBER SECOND CHAMBER FIRST CHAMBER SECOND CHAMBER
Italcementi Group
t/h kW kWh/t t t m²/t m²/t
CRUAS FCB 2.2*13.0 Polysius TSU-DSE Cement 2 CPJ (white cement) Blaine=4230 cm²/g 14.2 15.3 560 529 39.5 34.6 13.8 13.9 47.2 43.7 10.8 10.6 26.7 31.8
PIC Grinding September 2005
TRIESTE TOSI 10' * 22' Stutevant 16' Raw 2 Raw product R90=6.0 to 6.6% 29.5 34.9 754 762 31.1 21.8 18.7 18.0 37.5 35.6 9.5 9.2 19.4 14.2
440
6- REVIEW OF PARAMETERS MILL FEED MOISTURE
MAXIMUM DRYING CAPACITY OF HORIZONTAL MILLS WITHOUT DRYING CHAMBER: => 1.5% OF WATER IN FRESH FEED MATERIAL
FURTHER THIS PERCENTAGE THE ENERGY MAY BE BROUGHT BY EXTERNAL HEAT SOURCE (care about quality !!!)
Italcementi Group
PIC Grinding September 2005
441
6- REVIEW OF PARAMETERS MILL VENTILATION
CASE OF WET MATERIAL PLANT MILL SEPARATOR CEMENT THROUGHPUT MILL POWER MILL CONSUMPTION AUXILIARY POWER AUXILIARY CONSUMPTION GLOBAL POWER GLOBAL CONSUMPTION MILL VENTILATION DAMPER SEPARATOR VENTILATION DAMPER ELEVATOR ABSORPTION PRESEPARATOR EXIT DEPRESSION
ventilation => Italcementi Group
3400 cm²/g t/h wet kW kWh/t kW kWh/t kW kWh/t % % A mmCA
throughput & PIC Grinding September 2005
ANKARA FLS 4*11.5 FLS Sepax KC32.5 (16% pozzolane) 96.75 103.95 2672 2639 27.62 25.39 395 458 4.08 4.41 3067 3097 31.70 29.79 35 MAX 80 42 MAX 50 64 70 148 223.0
kWh/t 442
6- REVIEW OF PARAMETERS MILL FEED MOISTURE PLANT CEMENT MILL SEPARATOR MATERIAL INLET MOISTURE BLAINE cm²/g THROUGHPUT t/h CONSUMPTION kWh/t R90 µm % CLINKER °C HOT GAS °C
Italcementi Group
HALYPS II35 (16.5% pozzolane) KHD 3*8.2 O & K 5000 2.7 TO 2.8% 3500 27.3 29.1 33.5 32.9 30.1 26.1 4.6 4.4 COLD 125 125 No No 160
PIC Grinding September 2005
443
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY
Independent of material grindability Lied to plant efficiency Usually equal to: 0.85 for open circuit 0.87 for closed circuit with first generation separator 0.95 to 1 for closed circuit with 2nd and 3rd generation separator
Limit: air swept mills Italcementi Group
PIC Grinding September 2005
444
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY
LABORATORY TEST => specific energy at given Blaine fineness [Elab.mech. x (kWh/t at given fineness)] INDUSTRIAL DATA => Eindustrial electr (kWh/t at given fineness) Elab.mech / drive eff. = Elab.electr. ball mill efficiency = Elab.electr. / Eindustrial electr. With drive efficiency = 0.91 for pinion and girth drive = 0.92 for central drive Italcementi Group
PIC Grinding September 2005
445
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY CALCULATION
ALSING TEST => Alsing specific energy for a given Blaine fineness [E mecha. (kWh/t / given fineness)] INDUSTRIAL DATA => E industrial elec. (kWh/t / given fineness) EAl sin g . elec . hBall . mill Eindustrial . elec
Emecha . EAl sin g . elec . hmecha .
with hmecha . = 0.91 for pinion and gearless drive = 0.92 for central drive Italcementi Group
PIC Grinding September 2005
446
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY CALCULATION
Characteristics of hBall . mill :
• Independent of material grindability • Lied to plant efficiency • Usually equal to: * 0.85 for opened circuit * 0.87 for closed circuit with first generation separator * 0.95 to 1 for closed circuit with 2nd and 3rd generation separator
• Limit: airswept mills Italcementi Group
PIC Grinding September 2005
447
6- REVIEW OF PARAMETERS PLANT MILL EFFICIENCY CALCULATION
PGrinding . plant ESpecific. CA ESpecific. roller . press ESpecific. ball . mill Pr oduction
EAl sin g . CA PLANT . EFFICIENCY hBall . mill hRoller. . press C ESpecific . A Why? Because the Alsing test is considered like a standard test and so hBall . mill = 100% for an optimized ball charge and a third generation classifier Italcementi Group
PIC Grinding September 2005
448
6- REVIEW OF PARAMETERS PLANT MILL EFFICIENCY CALCULATION
Example: CCB-DR8 (Belgium):
EAl sin g . CA PLANT . EFFICIENCY hBall . mill hRoller. . press C ESpecific . A Plant efficiency = 13.9/(10.6+4.1) = 94.5%
Italcementi Group
PIC Grinding September 2005
449
Italcementi Group
PIC Grinding September 2005
1 TRAINING CORPORATE
Summary 12345-
678910 11 12 -
Introduction Crushing Process Particle size distribution Tests efficiency evaluation Grinding Mills Vertical Mills Horizontal Ball Mills Autogenous Mill Roller Press Separating Process Grinding Circuits Circuits Process Control Influent Parameters on Kwh/t Mill Check-up Data Evaluation Efficiency Evaluation
Italcementi Group
PIC Grinding September 2005
2
I - INTRODUCTION
1. Comminution Department 2 . World Energy
Italcementi Group
PIC Grinding September 2005
3
1- COMMINUTION DEPARTMENT Department Manager - E. Villa Department Assistant Manager - F. Spada
Secretary and performance data monitoring (n° 1 person) Grinding process technology (n° 6 persons) Grinding mechanical section (n° 2 persons) Crushing section (n° 1 person) CAD operator (n° 1 person) Type of machines concerned: horizontal and vertical mills, static and dynamic separators, crushers, screens, cement coolers) Total n° 13 persons located in Bergamo
Italcementi Group
PIC Grinding September 2005
4
1- COMMINUTION DEPARTMENT Performance data monitoring Monthly and annual reports Grinding Process Technology Evaluation and optimisation of existing plants Process design parameters evaluation (new plant, new machine or plant modification) New machine choice Start up assistance Training Study of new solutions for process (ITC patent of horizontal roller mill) Italcementi Group
PIC Grinding September 2005
5
1- COMMINUTION DEPARTMENT Grinding mechanical section Existing machines evaluation New machines design (complete detail drawing of horizontal ball mills 2000-3000-4500-5500 kW, cement cooler for 160 t/h , static separators) Existing machines modifications (examples: dynamic separators from 1st and 2nd to 3rd generation, vertical ball mills for coal) Detail drawings for mill inlet, diaphragms, (intermediate, discharge, transfer) Technical specifications for purchase of new machines New materials test (liners, ball charge, diaphragms plates, abrasion resistant components) Crucial point control during machine erection (alignment, etc.) Start-up assistance Vibration measurements and analysis Training Italcementi Group
PIC Grinding September 2005
6
1- COMMINUTION DEPARTMENT
Crushing Section Evaluation and optimisation of existing machines Process design parameters evaluation and machines technical specifications definition New machines design (detail drawings of double rotors hammer crusher in the range 250 - 800 t/h, single rotor hammer crusher in the range 250 - 600 t/h, double cylindrical rotor crusher in the range 100 - 200 t/h, double cylindrical rotor tertiary crusher) New machines choice New materials tests (forged hammers, etc…) Start-up assistance Training
Italcementi Group
PIC Grinding September 2005
7
1- COMMINUTION DEPARTMENT In the laboratory of the ITC grinding centre of Albino (not anymore used for industrial production) the Comminution Department has suitable instruments for samples preliminary evaluation after mill circuit check-up, like: sieve size distribution laser size distribution fineness moisture
In the same laboratory we have a batch mill for material grindability evaluation according to C.T.G. experienced method In the same grinding centre we have installed semi-industrial experimental horizontal roller mill and a small roller press manufactured according to C.T.G. design Italcementi Group
PIC Grinding September 2005
8
2- WORLD ENERGY COST OF ELECTRICAL ENERGY
2 % OF THE WORLD ENERGY USED IN CEMENT MANUFACTURING
Italcementi Group
PIC Grinding September 2005
9
2- WORLD ENERGY CEMENT PRODUCTION
Italcementi Group
PIC Grinding September 2005
10
2- WORLD ENERGY ENERGY CONSUMPTION OF COMMINUTION PLANTS
- CRUSHING
=>
1 - 3 kWh/tproduct
- RAW GRINDING
=>
15 - 30 kWh/ tproduct
- COAL GRINDING
=>
35 - 50 kWh/ tproduct
- CEMENT GRINDING
=>
30 - 80 kWh/ tproduct
Italcementi Group
PIC Grinding September 2005
11
2- WORLD ENERGY COST OF ELECTRICAL ENERGY
WET PROCESS HEAT % kcal/kg
85%
ELECTRIC % equivalent kcal/kg
15%
DRY PROCESS
GLOBAL % kcal/kg
HEAT % kcal/kg
100%
75%
ELECTRIC % equivalent kcal/kg
25%
GLOBAL % kcal/kg
100%
COST OF ELECTRICAL ENERGY: 15 to 25 % OF GLOBAL COST
Italcementi Group
PIC Grinding September 2005
12
2- WORLD ENERGY BREAKDOWN OF ELECTRICAL ENERGY USED IN A CEMENT PLANT RAW GRINDING 24%
16% OTHERS
28% CEMENT GRINDING
Italcementi Group
BURNING 22%
PIC Grinding September 2005
13
2- WORLD ENERGY MAIN ELECTRICAL CONSUMPTION 70 63 60 51 50 40 30
27
30
30
kWh/t min kWh/t max
20
16
10 0,8
2,5
0 CRUSHING
Italcementi Group
RAW GRINDING
COAL GRINDING
PIC Grinding September 2005
CEMENT GRINDING
14
2- WORLD ENERGY RAW MEAL GRINDING SPECIFIC RAW MEAL GRINDING ENERGY Average kWh/t ITC Group (Italy) 24,2 24,0 23,8 23,6 23,4 23,2 23,0
Italcementi Group
PIC Grinding September 2005
01 20
00 20
99 19
98 19
97 19
96 19
95 19
94 19
93 19
19
92
22,8 22,6
15
2- WORLD ENERGY COAL GRINDING
SPECIFIC COAL GRINDING ENERGY Average kWh/t ITC Group (Italy)
Italcementi Group
PIC Grinding September 2005
01 20
00 20
99 19
98 19
97 19
96 19
95 19
94 19
93 19
19
92
38,0 37,5 37,0 36,5 36,0 35,5 35,0 34,5 34,0 33,5 33,0
16
2- WORLD ENERGY CEMENT GRINDING SPECIFIC FINISH GRINDING ENERGY Average kWh/t ITC Group (Italy) 45,5 45,0 44,5 44,0 43,5 43,0 42,5 42,0 41,5 41,0
9 19
Italcementi Group
2
9 19
3
9 19
4
9 19
5
9 19
6
9 19
7
9 19
8
PIC Grinding September 2005
9 19
9
0 20
0
0 20
1
17
2- WORLD ENERGY CONCLUSION
GRINDING AND CRUSHING CONCERN 60 TO 65% OF THE GLOBAL ELECTRIC PLANT CONSUMPTION
Italcementi Group
PIC Grinding September 2005
18
2- WORLD ENERGY A WAY TO SAVE MONEY Mills installed power (MV)
Number of mills (Group data 2000)
342
231
250 117
200 150
350 300 250 200 150 100 50 0
80
100 50 0 Coal
Raw
172 25
Coal
Cement
Raw
Cement
1 % REDUCTION OF THE PLANT ELECTRICAL CONSUMPTION MAKES A TOTAL SAVING OF 5,4 MWh => SAVE Italcementi Group
PIC Grinding September 2005
$ 19
2- WORLD ENERGY HOW ?
BY OPTIMIZING THE GRINDING PROCESS
BY RUNNING THE MILL AT OPTIMUM LEVEL BY UPGRATING PLANTS WITH NEW TECHNOLOGY
Italcementi Group
PIC Grinding September 2005
20
II - CRUSHING PROCESS
1. Crusher Classification 2. Machine description & main parameters 3. Crushing Circuits
Italcementi Group
PIC Grinding September 2005
21
1- CRUSHERS CLASSIFICATION Crushers are classified according to: The function (product size): The main stress: primary impact secondary compression tertiary shear finishing attrition
The type of material: hard abrasive compact sticky wet Italcementi Group
The type of machine: jaw giratory hammer impact roll PIC Grinding September 2005
22
2- MACHINES DESCRIPTION
JAW CRUSHERS GIRATORY CRUSHERS ROLL CRUSHERS DOUBLE-ROLL CRUSHERS SINGLE-ROTOR IMPACT CRUSHERS DOUBLE-ROTOR IMPACT CRUSHERS SINGLE-ROTOR HAMMER CRUSHERS DOUBLE-ROTOR HAMMER CRUSHERS
Italcementi Group
PIC Grinding September 2005
23
2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (mobil jaw) motion Type of crushing process Feeding design Maximum feed opening size Mini. gap between crushing elem. Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by
Italcementi Group
: compression : alternative : primary, secondary : rectangular, horizontal : 400 to 2500 mm : 30 to 250 mm : 8 to 10 : 20 to 400 kW : 0.2 to 0.5 kWh/t : 1000 t/h : 250 t : hard, compact, abrasive, low moisture, not sticky
: nearing or moving away the inferior part of the mobil jawfrom/to the fixed jaw PIC Grinding September 2005
24
2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS
1. Fixed jaw 2. Swinging jaw 3. Toggles 4. Eccentric shaft 5. Connecting rod 6. Pulley - flywheel
Italcementi Group
PIC Grinding September 2005
25
2- MACHINES DESCRIPTION & MAIN PARAMETERS GYRATORY CRUSHERS • Main stress • Crushing part (oscillating cone) motion • Type (process) of crushing • Feeding design • Maximum feed opening radial size • Mini. gap between crushing elem. • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap (between crushing elements) by Italcementi Group
: compression : rotation : primary, secondary : circular, horizontal : 600 to 1500 mm : 30 to 300 mm : 6 to 8 : 80 to 750 kW : 0.2 to 0.5 kWh/t : 3000 t/h : 550 t : hard, compact, abrasive, low moisture, not sticky : nearing or moving away the inferior part of the oscillating cone from/to the tank PIC Grinding September 2005
26
2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS
1. Cross slide 2. Stack 3. Pendulum 4. Eccentric
Italcementi Group
PIC Grinding September 2005
27
2- MACHINES DESCRIPTION & MAIN PARAMETERS ROLL CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (toothed roll) motion Type (process) of crushing Feeding design Maximum roll size (D x L) Teeth peripheral speed Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by
Italcementi Group
: compression, shear : rotation : primary, secondary : rectangular, horizontal : (500 * 700 mm) to (1500 * 2000 mm) : 1 to 8 m/s :5 : 20 to 300 kW : 0.2 to 0.5 kWh/t : 1000 t/h : 200 t : medium hard, no abrasive, low moisture, sticky : nearing or moving away the mobile roll from/to the fixed jaw
PIC Grinding September 2005
28
2- MACHINES DESCRIPTION & MAIN PARAMETERS JAW CRUSHERS
1. Casing 2. Toothed roll 3. Crushing wall
Italcementi Group
PIC Grinding September 2005
29
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE-ROLL CRUSHERS • Main stress • Crushing part (toothed rollers) motion • Type (process) of crushing • Feeding design • Maximum roll size (D x L) • Teeth peripheral speed • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap by
Italcementi Group
: compression, shear : rotation : primary, secondary, tertialy : rectangular, horizontal : (600 * 800 mm) to (2000 * 2000 mm) : 1 to 8 m/s :5 : 30 to 600 kW : 0.1 to 0.5 kWh/t : 3000 t/h : 200 t : medium hard, medium abrasive, very wet and sticky : nearing or moving away the mobile roll from/to the fixed roller PIC Grinding September 2005
30
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE-ROLL CRUSHERS
1. Casing 2. Toothed rolls
Italcementi Group
PIC Grinding September 2005
31
2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR IMPACT CRUSHERS • Main stress • Crushing part (rotor with impact bars) motion • Type(process) of crushing • Feeding design • Maximum rotor size (DxL) • Hammer peripheral speed • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap by
Italcementi Group
: impact : rotation : single stage, primary, secondary : rectangular, oblique : (800 * 1000 mm) to (2500 * 3000 mm) : 30 to 50 m/s : 25 : 150 to 2500 kW : 0.5 to 1.5 kWh/t : 2000 t/h : 200 t : hard, compact, not abrasive, not very wet, not sticky : nearing or moving away the mobile part (finishing wall) from/to the rotor PIC Grinding September 2005
32
2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR IMPACT CRUSHERS
1. Casing 2. Rotor 3. Crushing walls
Italcementi Group
PIC Grinding September 2005
33
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR IMPACT CRUSHERS • Main stress • Crushing part (rotor with impact bars) motion • Type (process) of crushing • Feeding design • Maximum rotor size (DxL) • Hammer peripheral speed • Maximum reduction ratio • Drive motor power • Electrical specific consumption • Maximum throughput • Maximum weight • Type of feeding material • Regulation of minimum gap by
Italcementi Group
: impact
: rotation : single stage, primary : rectangular, oblique : (1000 * 1250 mm) to (2500 * 3000 mm) : 30 to 50 m/s : 40 : 400 to 3500 kW : 0.5 to 1.5 kWh/t : 3000 t/h : 300 t : hard, compact, not abrasive, not very wet, not sticky : nearing or moving away the mobile rotor from/to the secondary rotor
PIC Grinding September 2005
34
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR IMPACT CRUSHERS
1. Casing 2. Rotors 3. Crushing walls
Italcementi Group
PIC Grinding September 2005
35
2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR HAMMER CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (rotor) motion Type (process) of crushing Feeding design Maximum rotor size (DxL) Hammers peripheral speed Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by Italcementi Group
: impact : rotation : single stage, primary, secondary, tertialy : rectangular, horizontal and oblique : (800 * 1000 mm) to (2500 * 3000 mm) : 25 to 50 m/s : 80 : 300 to 2500 kW : 0.5 to 2.5 kWh/t : 1500 t/h : 200 t : hard, not abrasive,compact, low moisture, not sticky : choice of grate opening
PIC Grinding September 2005
36
2- MACHINES DESCRIPTION & MAIN PARAMETERS SINGLE ROTOR HAMMER CRUSHERS
1. Casing 2. Rotor 3. Hammers 4. Crushing walls 5. Grate
Italcementi Group
PIC Grinding September 2005
37
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR HAMMER CRUSHERS • • • • • • • • • • • • •
Main stress Crushing part (rotor) motion Type of crushing process Feeding design Maximum rotor size (DxL) Hammer peripheral speed Maximum reduction ratio Drive motor power Electrical specific consumption Maximum throughput Maximum weight Type of feeding material Regulation of minimum gap (between crushing elements) by Italcementi Group
: impact : rotation : primary, secondary, tertialy : rectangular, horizontal and oblique : (800 * 1000 mm) to (2500 * 3000 mm) : 25 to 40 m/s : 80 : 300 to 2500 kW : 0.5 to 2.5 kWh/t : 3000 t/h : 300 t : hard, compact, not abrasive, low moisture, not sticky : choice of grate opening
PIC Grinding September 2005
38
2- MACHINES DESCRIPTION & MAIN PARAMETERS DOUBLE ROTOR HAMMER CRUSHERS
1. Casing 2. Hammer rotors 3. Breaker anvil 4. Grate
Italcementi Group
PIC Grinding September 2005
39
2- MACHINES DESCRIPTION & MAIN PARAMETERS CRUSHERS CHOICE MAIN CRITERIA
Low speed crushers: jaw and gyratory type Suitable for abrasive, very hard, dry materials Low reduction ratio: more than one step required double roller crusher Suitable for very wet materials High speed crushers: hammer and impact type Not suitable for abrasive materials High reduction ratio: finishing in one step possible Italcementi Group
PIC Grinding September 2005
40
3- CRUSHING CIRCUITS
1- ONE STAGE - OPEN CIRCUIT • Simple circuit design • Product size control by discharge gap • Fast machines needed • Not suitable for abrasive and sticky materials
Italcementi Group
PIC Grinding September 2005
41
3- CRUSHING CIRCUITS
1- ONE STAGE - OPEN CIRCUIT Storage silo feed bin
Plate feeder
Run of mine
One stage primary crusher (finishing machine)
Finished product
Italcementi Group
PIC Grinding September 2005
42
3- CRUSHING CIRCUITS
2 - DOUBLE STAGE - OPEN CIRCUIT: • Ability to direct feed to primary crusher (slow machines) • Ability to take out undersize material after primary crusher • Ability to feed only oversize material for next crushing • Control of product maximum size not always accurate • Needs fast machine as secondary crusher • Not very suitable for abrasive and sticky materials
Italcementi Group
PIC Grinding September 2005
43
3- CRUSHING CIRCUITS 2 - DOUBLE STAGE - OPEN CIRCUIT: Storage silo feed bin Plate feeder
Run of mine
Primary crusher
Primary crushed material Screen
Coarse
Screening
Secondary finishing crusher Secondary crushed material Finished product
Italcementi Group
PIC Grinding September 2005
44
3- CRUSHING CIRCUITS
3 - DOUBLE STAGE - CLOSED CIRCUIT: • Ability to direct feed to primary crusher (slow machines) • Ability to take out undersize material after primary crusher • Ability to feed only oversize material for next crushing • Accurate control of product maximum size • Suitable for slow machine • Suitable for abrasive and sticky materials
Italcementi Group
PIC Grinding September 2005
45
3- CRUSHING CIRCUITS 3 - DOUBLE STAGE - CLOSED CIRCUIT: Run of mine
Primary crusher Primary crushed material
Screen
Coarse
Secondary crusher Secondary crushed material Finished product
Italcementi Group
PIC Grinding September 2005
46
III - PARTICLE SIZE DISTRIBUTION 1. Laws
Gaudin-Schumann Law Rosin-Rammler Law Charles Law
2. Measurement Methods
Blaine Method Bet Method Alpine Laser Particles Size Analyser Sieves Italcementi Group
PIC Grinding September 2005
47
1- LAWS PARTICLES SIZE DISTRIBUTION
FIRST EVALUATION OF PARTICLE SIZE DISTRIBUTION (We only need 2 points) Why using the laws?
FIRST CORRELATION WITH CHEMICAL AND MECHANICAL CEMENT AND CONCRETE PROPERTIES EVALUATION OF ENERGY CONSUMPTION
Italcementi Group
PIC Grinding September 2005
48
1- LAWS GAUDIN-SCHUMANN LAW
Ln P(x) = m Ln (x) - m Ln (k) k: sieves size giving 100% passing m: slope of straight line
BASIC FORMULA
P( x )
Log
Passing (%)
100
m
No much representative for coarse particles
m = tg
K
Italcementi Group
x k
Log Particle size (µm)
PIC Grinding September 2005
49
1- LAWS GAUDIN-SCHUMANN LAW
Passing
Granulometry
Size (mm)
Italcementi Group
PIC Grinding September 2005
50
1- LAWS ROSIN-RAMMLER LAW
Ln Ln (1/R(x)) = n Ln (x) - n Ln (x0) x0 : sieves size for 36.8 % retained n: slope of straight line Retained (%)
Log Log
BASIC FORMULA Not very representative for fine particles
R( x )
x n e x 0
36.8
n = tg
Log
x0 Italcementi Group
Particle size (µm) PIC Grinding September 2005
51
1- LAWS CHARLES LAW
100.C.m . k(1-n) • E = n-1 m-n+1 kWh/t
Workability
CHARLES LAW
If nRRS
40 20
n 0.7
•
EGrinding
1.1
Grinding energy
n: RRS slope m: Gaudin Schumann slope C: material data (between 20 & 40)
dE=-Cx(-n)dx Size x Size x-dx Italcementi Group
PIC Grinding September 2005
52
2- MEASUREMENT METHODS BLAINE METHOD
Measure the specific surface of a powder in cm2/g or m2/kg => FINENESS PRINCIPLE: Time for a volume of air to pass through a layer of particles. LIMITS: => used only for cement => measure not accurate up to 6000 Blaine. Italcementi Group
PIC Grinding September 2005
53
2- MEASUREMENT METHODS BET METHOD
PRINCIPLE: =>Surface nitrogen absorption => Multi-layers absorption theory =>Vaporisation & condensation balance calculation Used for limestone porosity evaluation LIMITS: => Cost => Difficulty in manipulating => Not so used in the cement industry (laboratory) Italcementi Group
PIC Grinding September 2005
54
2- MEASUREMENT METHODS ALPINE
Content of coarse particles in % of weight. LIMITS: => Sieves must be clean => Sample lost => Mesh (32 mn)
Italcementi Group
PIC Grinding September 2005
55
2- MEASUREMENT METHODS LASER PARTICLES SIZE ANALYSER
% of retained particles for a certain mesh. Method based on light diffraction. LIMITS: => results depends on laser types :MALVERN # CILAS (liquid) # SYMPATEC (air - liquid) => for raw and coal material, pb of particles desagglomeration (ultrasound) => laser circuit has to be cleaned every time => water (raw material) or alcohol (cement and coal) Italcementi Group
PIC Grinding September 2005
56
2- MEASUREMENT METHODS MALVERN
CILAS
SAME SAMPLE and SAME TIME
Italcementi Group
PIC Grinding September 2005
57
2- MEASUREMENT METHODS
TROMP CURVE
Italcementi Group
PIC Grinding September 2005
58
2- MEASUREMENT METHODS SIEVES
WET/DRY FRANCE Opening Designation (mm) of sieves 0.040 17 0.050 18 0.063 19 0.080 20 0.100 21 0.125 22 0.160 23 0.200 24 0.250 25 0.315 26 0.400 27 0.500 28 0.630 29 0.800 30 1.000 31 1.250 32 1.600 33 2.000 34 2.500 35 3.150 36 4.000 37 5.000 38
USA (ASTM) Opening Designation (mm) of sieves 5.660 3.5 4.760 4 4.000 5 3.360 6 2.830 7 2.380 8 2.000 10 1.680 12 1.410 14 1.190 16 1.000 18 0.840 20 0.710 25 0.590 30 0.500 35 0.420 40 0.350 45 0.297 50 0.250 60 0.210 70 0.177 80 0.149 100 0.125 120 0.105 140 0.088 170 0.074 200 0.062 230 0.063 270 0.044 325 0.037 400
Italcementi Group
UK (BSA) Opening Designation (mm) of sieves 3.353 5 2.812 6 2.411 7 2.057 8 1.676 10 1.405 12 1.204 14 1.003 16 0.853 18 0.699 22 0.599 25 0.500 30 0.422 36 0.353 44 0.295 52 0.251 60 0.211 72 0.178 85 0.152 100 0.124 120 0.104 150 0.089 170 0.076 200 0.066 240 0.053 300
GERMANY (DIN) Opening Designation (mm) of sieves 6.000 6 5.000 5 4.000 4 3.000 3 2.500 2.5 2.000 2 1.500 1.5 1.200 1.2 1.000 1 0.750 0.75 0.600 0.6 0.500 0.5 0.430 0.43 0.400 0.4 0.300 0.3 0.250 0.25 0.200 0.2 0.150 0.15 0.120 0.12 0.100 0.1 0.090 0.09 0.075 0.075 0.060 0.06
PRINCIPLE: Give the content of coarse or fine particles by manual or mechanical sieving. Coarse and fine amount are stated in % of weight. LIMITS: => sieves have to be cleaned => unconsistancy due to men action for manual sieving => mesh limit : >10µ in laboratory >32µ in plant
PIC Grinding September 2005
59
IV - TEST EFFICIENCY EVALUATION 1. General 2. Bond 3. Zeisel 4. Alsing 5. Hardgrove 6. CTG Test 7. Correlations 8. Time Evolution of Mill & Grinding Department Italcementi Group
PIC Grinding September 2005
60
1- GENERAL
Grindability of the material is measured by:
Compressive strenght Bond index Alsing / CTG test Zeisel test Hardgrove
Italcementi Group
N/cm2 kWh/t kWh/t kWh/t number
PIC Grinding September 2005
(crushing) (raw material) (raw, clinker) (clinker, slag) (coal, pet coke)
61
2- BOND BOND LAW
BOND LAW : Grinding energy first approximation
1 1 W 10 x Wi x P F Wi :
F : P : W :
Work Index kWh/st wet process (Laboratory test) multiply x 1.102 => kWh/t wet process multiply x 1.33 => kWh/st dry process multiply x 1.47 => kWh/t dry process mesh giving 80% passing for Feeding mesh giving 80% passing for final Product industrial specific consumption kWh/st
Italcementi Group
PIC Grinding September 2005
62
2- BOND BOND WORK INDEX BOND WORK INDEX DRY GRINDING
MATERIAL
kWh/t Bauxite Cement clinker Cement raw material Clay Clay calcined Coal Dolomite Gypsum rock Limestone for cement Magnesite dead burned Sandstone Slag Slag-iron blast furnace
Italcementi Group
PIC Grinding September 2005
14 19 15 10 11 16 16 12 15 24 17 23 17
63
2- BOND BOND TEST RAW GRINDING ENERGY CONSUMPTION DETERMINATION Mill feed and supplementary feed 90 mm - 4mm
Circulating material
< 90 mm
> 90 mm
Ball mill
Sieve 90 mm Box < 90 mm
Italcementi Group
Finished product
PIC Grinding September 2005
64
3- ZEISEL ZEISEL TEST CLINKER AND SLAG GRINDING ENERGY CONSUMPTION DETERMINATION
1 - Grinding plate 2 - Steel ball 3 - Pressure ring 4 - Driving shaft 5 - Extensometer 6 - Calculator
Italcementi Group
PIC Grinding September 2005
65
4- ALSING ALSING TEST
GIVES THE "INDUSTRIAL GRINDING ENERGY" NECESSARY TO GRIND THE TYPE OF MATERIAL CONSIDERED OPEN CIRCUIT
CLOSE CIRCUIT
Italcementi Group
=> Industrial grinding energy > Alsing energy (20% to 30%) => •FIRST GENERATION CLASSIFIER Industrial grinding energy > Alsing energy (#15%) => •SECOND OR THIRD GENERATION Industrial grinding energy # Alsing energy PIC Grinding September 2005
66
4- ALSING ALSING ENERGY
• SAMPLING PROCEDURE: TAKE DURING 4 HOURS (EVERY HALF HOUR) AN AVERAGE 10 kg OF FEEDING MATERIAL AND HALF A POUND OF FINAL PRODUCT • CHECK LIST:
Italcementi Group
Time t0: record the energy consumption of the main motor Time t0 + 4 hours: record the energy consumption of the main motor PIC Grinding September 2005
67
4- ALSING ALSING ENERGY
• BATCH MILL CARACTERISTICS:
Batch mill
BALL MILL: External diameter = 664 mm (261.4 in) Spin velocity = 38 rpm (73% of critical speed) Lining = lifter liners LOAD: steel balls: 40 mm (beginning) (1.18 in) 18 mm (end) (0.71 in)
ANALYSES WITH STRAIN GAUGES => MECHANICAL COUPLE => kWh/t for a given fineness (FCB know how: telemetry) Italcementi Group
PIC Grinding September 2005
68
4- ALSING ALSING ENERGY
• TESTING PROCEDURE: Ball charge: X t0 (40mm) t0+t1
t0+t2
t0+T Italcementi Group
Ball charge: X Material sample 1
New ball charge: Y (18mm) Material sample 2
Blaine Granulometry Blaine Granulometry
Ball charge: Y Material sample having a given fineness PIC Grinding September 2005
69
4- ALSING ALSING ENERGY
kWh/t
kWh/t
RESULTS: 3 types of graph: • SPECIFIC ENERGY FUNCTION • SPECIFIC ENERGY FUNCTION OF BLAINE SURFACE OF d80 (80% Passing Mesh) (Log-Log graph)
Blaine/1000
Italcementi Group
d80
PIC Grinding September 2005
70
4- ALSING ALSING ENERGY
• SPECIFIC ENERGY FUNCTION OF 40µm RETAINED (Semi-Log graph)
4omm retained
Italcementi Group
PIC Grinding September 2005
71
5- HARDGROVE HARDGROVE TEST Weights
COAL GRINDING ENERGY CONSUMPTION DETERMINATION
Drive Counter Box
Grinding plate
Italcementi Group
PIC Grinding September 2005
72
6- CTG TEST CEMENT GRINDING ENERGY CONSUMPTION DETERMINATION
Ball charge: First step => 120 Kg diameter 40 mm Second step => 120 Kg diameter 18 mm Italcementi Group
PIC Grinding September 2005
73
6- CTG TEST CEMENT GRINDING ENERGY CONSUMPTION DETERMINATION
Grinding Specific Consumption =
EkWh - LkWh
= kWh/t
Tmaterial EkWh = Meter measure LkWh = Motor and gear box lost energy Tmaterial = Material weight (t) Italcementi Group
PIC Grinding September 2005
74
6- CTG TEST CEMENT GRINDING ENERGY CONSUMPTION DETERMINATION
Spec. cons. (kWh/t)
Lines comparison
ALSING TEST C.T.G. TEST
Blaine (cm2/g) Italcementi Group
PIC Grinding September 2005
75
7- CORRELATIONS
In order to have a first evaluation of the global specific electrical consumption of a cement grinding shop, from the industrial data available in ITC we have established correlations between: • the % of clinker content in cement • the kWh/t (global specific consumption in the workshop) • the mortar compressive strength, in N/mm2
Italcementi Group
PIC Grinding September 2005
76
7- CORRELATIONS MAIN CORRELATIONS ARE: For Portland cements or cements with low additives: -20,39 + 0,384 * % CK + 0,294 * kWh/t (tot.) = N/mm² (2 days) 0,508 + 0,447 * % CK + 0,249 * kWh/t (tot.) = N/mm² (28 days) For pouzzolanic or slag cements: -12,45 + 0,395 * % CK + 0,130 * kWh/t (tot.) = N/mm² (2 days) -3,480 + 0,503 * % CK + 0,392 *kWh/t (tot.) = N/mm² (28 days) Global correlation 0,37 * %CK + 0,30 * kWh/t (tot.) = N/mm2 (28 days) Italcementi Group
PIC Grinding September 2005
77
7- CORRELATIONS
IMPORTANT: CORRELATIONS ARE USEFUL ONLY IF DATA CONSIDERED FOR ENERGY CONSUMPTION ARE HOMOGENEOUS
Italcementi Group
PIC Grinding September 2005
78
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT
BY COMPARING EVERY MONTH THE PERFORMANCES OF A MILL, IT IS POSSIBLE TO FOLLOW ANY IMPORTANT CHANGE IN MILL MOTOR OR MILL CIRCUIT POWER CONSUMPTION. ACTIONS CAN BE TAKEN IN ORDER TO UNDERSTAND AND TO CORRECT ANY WRONG SITUATION.
Italcementi Group
PIC Grinding September 2005
79
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT IMPORTANT • • •
mill production measurements and electrical energy meters must be available and tested compare also long period data (5 - 10 - 15 years) in order to detect slow but constant increases check the sequence of machines start-up and stop in order to be sure that machines don't run without reason
Italcementi Group
PIC Grinding September 2005
80
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT
kWh/t
SAMATZAI plant (1998) figures of raw and coal specific consumption
months
Italcementi Group
PIC Grinding September 2005
81
8- TIME EVOLUTION OF MILL AND GRINDING DEPARTMENT
kWh/t
TRIESTE raw grinding figures (specific consumption)
years
Italcementi Group
PIC Grinding September 2005
82
V - GRINDING MILLS 1. Vertical Mills 2. Horizontal Ball Mills 3. Autogenous Mills 4. Roller Press 5. Horizontal Roller Mills 6. Systems and other
Italcementi Group
PIC Grinding September 2005
83
HORIZONTAL BALL MILL
ROLLER PRESS
Italcementi Group
VERTICAL MILL
PIC Grinding September 2005
84
1- VERTICAL MILLS
Grinding elements: Rollers
Grinding elements: Balls
VERTICAL ROLLER MILL Italcementi Group
VERTICAL BALL MILL
PIC Grinding September 2005
85
1- VERTICAL MILLS
Italcementi Group
PIC Grinding September 2005
86
1- VERTICAL MILLS GRINDING PERFORMANCES:
• 10 TO 20 % GLOBAL (50 % MILL ITSELF) ENERGY CONSUMPTION SAVED BETWEEN HORIZONTAL AND VERTICAL GRINDING
• DEPENDING ON : * INLET MATERIAL GRINDABILITY * MOISTURE * WEAR
Italcementi Group
PIC Grinding September 2005
87
1- VERTICAL MILLS (ROLLER MILLS)
• PFEIFFER MILL Characteristics: Three rollers Annular path of concave cross-section Hydro-pneumatic tensioned spring system Continuous contact between roller and grinding table Hot gas stream issuing from the ported air ring Hot gas inlet joint to the mill structure 60 to 100% capacity range throughput Italcementi Group
PIC Grinding September 2005
88
1- VERTICAL MILLS
(ROLLER MILLS)
PFEIFFER MILL
Italcementi Group
PIC Grinding September 2005
89
1- VERTICAL MILLS (ROLLER MILLS)
• LOESCHE MILL Characteristics: 2, 3 or 4 conical rollers Annular flat grinding table Rollers fixed on swinging arms => Lower maintenance cost Roller pressure exerted by springs on smaller machines and hydro-pneumatically on larger ones 40 to 100% capacity range throughput Wear sensible no contact between rollers and table mill structure independent of hot gas inlet. Italcementi Group
PIC Grinding September 2005
90
1- VERTICAL MILLS Gas + fine material outlet
Raw material inlet
(LOESCHE)
Separator motor
Dynamic separator
Separator reject Lining
Dam ring Grinding rollers Grinding table Hot gas inlet
Mill gear box Hydraulic cylinder
Rollers frame
Mill motor Mill reject
Italcementi Group
PIC Grinding September 2005
91
1- VERTICAL MILLS (ROLLER MILLS)
• POLYSIUS MILL Characteristics: Same PFEIFFER MILL with two double rollers and two annular grinding tables.
Higher wear resistance
Italcementi Group
PIC Grinding September 2005
92
1- VERTICAL MILLS
(ROLLER MILLS)
POLYSIUS MILL
Italcementi Group
PIC Grinding September 2005
93
1- VERTICAL MILLS (ROLLER MILLS)
• RAYMOND MILL Characteristics: Conical rollers Conical grinding table Spring or hydraulic pressure system No contact between rollers and table reduction gear integrated to the mill structure.
Grinding bowl
Italcementi Group
PIC Grinding September 2005
94
1- VERTICAL MILLS (BALL MILLS)
• PETERS MILL Characteristics: Grinding elements: balls Circular grinding table Hydro-pneumatic& spring tensioned system Especially used for coal grinding
Italcementi Group
PIC Grinding September 2005
95
1- VERTICAL MILLS (BALL MILLS)
• FCB "E" MILL Characteristics: Same PETERS MILL with only hydraulic tensioned system and external reject recalculation
Italcementi Group
PIC Grinding September 2005
96
1- VERTICAL MILLS ADVANTAGES: • LOW SPECIFIC ENERGY CONSUMPTION (kWh/t) • SPACE REQUIREMENT • THROUGHPUT TILL 600 t/h • HIGH DRYING CAPACITY • SIZE OF THE FEED MATERIAL (50 to 100mm) • IMPROVE THE SIZE DISTRIBUTION SLOPE => nRRS • ABLE TO USE LARGE HOT GAS FLOW AT LOW TEMPERATURE • LOW SYSTEM REACTION TIME
Italcementi Group
PIC Grinding September 2005
97
1- VERTICAL MILLS
DISADVANTAGES: • SENSIBILITY TO WEAR • SIZE DISTRIBUTION SLOPE FOR CEMENT => nRRS => Problem with cement and concrete workability and short term strength • RISK OF VIBRATION (foundation design very important)
• SENSIBLE TO DRY AND HARD RAW MATERIAL Italcementi Group
PIC Grinding September 2005
98
2- HORIZONTAL BALL MILLS Mill feed Gas /air outlet Main gearbox
Main motor Auxiliary drive
Material discharge
Italcementi Group
PIC Grinding September 2005
99
2- HORIZONTAL BALL MILLS CHARACTERISTICS: • COMMAND: => EXTERNAL DRIVE => CENTRAL DRIVE => GEARLESS DRIVE COST RATING FOR A 4400kW ENGINE POWER: 200%
160% 100%
115%
100% 0%
Italcementi Group
Cost External
Central
Gearless
PIC Grinding September 2005
100
2- HORIZONTAL BALL MILLS EXTERNAL DRIVE: Types: Single pinion drive
Dual pinion drive
Italcementi Group
Characteristics: * Single or dual pinion drive (maximum power for single one is 3500 kW or 4700 HP) * Shoe or plain bearing mills (higher air flow for plain bearing) Advantages: * Standard, inexpensive motors * Investment cost Disadvantages: * Low efficiency * Dustightness of pinion drive
PIC Grinding September 2005
101
2- HORIZONTAL BALL MILLS CENTRAL DRIVE: Types: Planetary gearing
Axially gearing (with twin or single motor drive)
Italcementi Group
Characteristics: Planetary or axially gearing (planetary gearing efficiency: 97%, axially gearing efficiency: 92%) Advantages: * No gearing on the mill itself *Low maintenance cost point of vie (balancing) * Less space requirement than external drive Disadvantages: * Problem for venting the mill
PIC Grinding September 2005
102
2- HORIZONTAL BALL MILLS GEARLESS DRIVE: Advantages : *High power mill:> 4000 kW (5400HP) *Low space requirement *Adjustable mill speed
Type:
Disadvantages: *Complex electrical feature *Low efficiency: 90% *Cost
Italcementi Group
PIC Grinding September 2005
103
2- HORIZONTAL BALL MILLS Lubrication system for double-pinion drives
1- lubrication reservoir 2- shut-off valve 3- pump 4- pressure relief valve 5- shut-off valve 6- filter 7- not-return valve 8- distribution pipe
Italcementi Group
PIC Grinding September 2005
104
2- HORIZONTAL BALL MILLS MILL MAIN SUPPORT
1 White metal bearing 2 Support casing 3 Support frame 4 Spherical surface
Italcementi Group
PIC Grinding September 2005
105
2- HORIZONTAL BALL MILLS MILL MAIN SUPPORTS LUBRICATION SYSTEM
Italcementi Group
PIC Grinding September 2005
106
2- HORIZONTAL BALL MILLS PAD SHOE BEARING
Italcementi Group
PIC Grinding September 2005
107
2- HORIZONTAL BALL MILLS LENGHT / DIAMETER OPEN CIRCUIT
5 6
RAW CLOSED CIRCUIT
2 3
SWEPT CLOSED CIRCUIT CEMENT CLOSED CIRCUIT
Italcementi Group
PIC Grinding September 2005
2 3 3.5
108
2- HORIZONTAL BALL MILLS
ONE CHAMBER : BETTER MATERIAL DISTRIBUTION INTO THE MILL PROPER LINER CARE WITH COARSE MATERIAL FEEDING USUALLY USED FOR MILL WITH L/D < 2.5 LOWER MAINTENANCE COST HIGHER VENTILATION
Italcementi Group
PIC Grinding September 2005
109
2- HORIZONTAL BALL MILLS ONE CHAMBER (K.H.D. MILL 3.4 x 6.1)
Italcementi Group
PIC Grinding September 2005
110
2- HORIZONTAL BALL MILLS
Useful diam. 5200
ONE CHAMBER (TOSI MILL 5.4 x 12)
Italcementi Group
PIC Grinding September 2005
111
2- HORIZONTAL BALL MILLS ONE CHAMBER (TOSI MILL 4 x 8)
Italcementi Group
PIC Grinding September 2005
112
2- HORIZONTAL BALL MILLS TWO CHAMBERS SECOND CHAMBER :
FIRST CHAMBER :
Material size reduction : from feed 0 - 35 mm to max 5 % > 2,5 mm Breakage effect Lifter liners Specific energy in consumption : 8-10 kWh/t (closed circuit) 10-12 kWh/t (open circuit) Specific ball charge surface: 9-11 m2/t of balls Length =30-35 % total mill length Ball average weight : 1600 - 2000 g Ball size : 100 - 60 mm Italcementi Group
Material size reduction : from 5% > 2,5 mm to 10 - 20 % < 90 µm (closed circuit) 5 % < 90 µm (open circuit) Attrition effect Classifying liners 25-40 m2 /t of balls (according to L/D ratio) Length =70-65 % total mill length Ball size 60-17 mm Cylpebs 50x25 - 16x16 mm
PIC Grinding September 2005
113
2- HORIZONTAL BALL MILLS TWO CHAMBERS (TOSI MILL 5.4 x12)
Italcementi Group
PIC Grinding September 2005
114
2- HORIZONTAL BALL MILLS TWO CHAMBERS (SMIDTH MILL 3.5 x 12)
Italcementi Group
PIC Grinding September 2005
115
2- HORIZONTAL BALL MILLS
THREE CHAMBERS : USED IN OPENED CIRCUIT LOW VENTILATION CYLPEBS IN THIRD CHAMBER => 30% TOTAL LENGHT : First chamber Second chamber => 20% Third chamber => 50%
Italcementi Group
PIC Grinding September 2005
116
2- HORIZONTAL BALL MILLS THREE CHAMBERS (MILL 2.4 x 13)
Italcementi Group
PIC Grinding September 2005
117
2- HORIZONTAL BALL MILLS DOUBLE ROTATOR MILL (MILL 10’ x 22’ + 12’) First compartment
Second compartment
Useful diam. 2878
Drying chamber
discharge Italcementi Group
PIC Grinding September 2005
118
2- HORIZONTAL BALL MILLS MILL ON PAD SHOE BEARINGS AND ANULAR MOTOR DRIVE RING MOTOR
PAD SHOE BEARING
Italcementi Group
PIC Grinding September 2005
119
2- HORIZONTAL BALL MILLS ADVANTAGES LARGE FINAL PRODUCT RANGE (final product fineness from 2800 to 5500 Blaine) LOW COST OF MAINTENANCE (care with ball charge wearing; material and internal part design) VERY WELL KNOWN COMPONENTS NO VIBRATION EASY TO OPERATE Italcementi Group
PIC Grinding September 2005
120
2- HORIZONTAL BALL MILLS DISADVANTAGES
HIGH SPECIFIC POWER CONSUMPTION (kWh/t) HIGH INSTALLATION COST
LOW VENTILATION LOW DRYING CAPACITY NOISE
Italcementi Group
PIC Grinding September 2005
121
2- HORIZONTAL BALL MILLS TREND
DOUBLE ROTATOR BALL MILL AS DRYER MILL FOR ABRASIVE MATERIAL.
FINE AND ULTRA-FINE PRODUCTS.
MAIN EVOLUTION WILL CONCERN INTERNAL PARTS (LINERS, AND DIAPHRAMS).
Italcementi Group
PIC Grinding September 2005
122
2- HORIZONTAL BALL MILLS VERTICAL MILLS
Number of vertical mills (ITC Group data 2000) 56 Raw Coal Slag
25
1
Installed power:
50 ÷ 3500 kW
(n.1 cement mill in construction not yet in operation) Italcementi Group
PIC Grinding September 2005
123
2- HORIZONTAL BALL MILLS Number of horizontal ball mills (ITC Group data 2000) 222 91
Raw Coal Cement
24
Italcementi Group
Installed power:
100 ÷ 8700 kW
Biggest mill:
Ø5.8 x 17 m (CCB)
Max capacity:
- Raw 350 t/h - Cement 300 t/h - Coal 40 t/h
PIC Grinding September 2005
124
2- HORIZONTAL BALL MILLS GRINDING MILLS
Number of roller press (ITC Group data 2000)
8 Raw Coal Cement
1 0
Italcementi Group
PIC Grinding September 2005
125
2- HORIZONTAL BALL MILLS GRINDING MILLS
Number of grinding mills (ITC Group data 2000)
80
231 Raw Coal Cement
117
Total number: 428
Italcementi Group
PIC Grinding September 2005
126
2- HORIZONTAL BALL MILLS GRINDING MILLS
Number of grinding mills (ITC Group data 2000)
337
82
Horizontal Vertical Roller press
9
Italcementi Group
PIC Grinding September 2005
127
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Gas Material
Material
Gas
LOW VENTILATION Italcementi Group
HIGH VENTILATION PIC Grinding September 2005
128
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
129
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
130
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
131
2- HORIZONTAL BALL MILLS INLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
132
2- HORIZONTAL BALL MILLS OVERVIEW INTERNAL ELEMENTS
Italcementi Group
PIC Grinding September 2005
133
2- HORIZONTAL BALL MILLS OVERVIEW INTERNAL ELEMENTS Mill head liner
Shell liner (lifting liner)
Shell liner (classifying liner)
A: B: C: D: E:
Slot plate
Italcementi Group
Blind plate
Coarse grinding compartment Intermediate diaphragm Finish grinding compartment Discharge diaphragm Grinding media: Ø 90÷60 mm 1st chamber Ø 50÷17 mm 2nd chamber
Slot plate
PIC Grinding September 2005
134
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
LINERS: • Wet process: to decrease wearing, rubber lining can be used (except in first chamber) • Dry process: steel lining First chamber Alloy type: Function: Second chamber Alloy type: Function: Italcementi Group
12-14% of Chromium martensitic steel Protect the shell against wear & lift the balls 12-14% of Chromium martensitic steel Protect the shell against wear & classify the balls PIC Grinding September 2005
135
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
136
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
137
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS Wide wave liners
Step liners
Lifter classifying liners
Wave liners
Bar liners
Italcementi Group
Classifying liners
PIC Grinding September 2005
138
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
DIAPHRAGMS: Goals:
=> optimised the filling ratio (adjustable diaphragms) => keep the coarse into the first compartment => let the fines passed into the second compartment => separate the balls (from one chamber to the others) => allow air to pass through the mill => maximum central opening according to ball charge filling degree
Discharge diaphragm slots > central diaphragm slots Trend: Flow controlling devices Italcementi Group
PIC Grinding September 2005
139
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
DIAPHRAGMS Adjustable intermediate diaphragm for tube mills grinding dry minerals.
Italcementi Group
PIC Grinding September 2005
140
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
INTERMEDIATE DIAPHRAGMS
Blind plates
Slotted plates
lifter
Italcementi Group
PIC Grinding September 2005
141
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Flow control INTERMEDIATE DIAPHRAGMS
Adjustable lifters
Italcementi Group
PIC Grinding September 2005
142
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
143
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
144
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
145
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
146
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
147
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
148
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
149
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS INTERMEDIATE DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
150
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
INTERMEDIATE DIAPHRAGMS
151
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
OUTLET DIAPHRAGM
PIC Grinding September 2005
152
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS Slotted plates
OUTLET DIAPHRAGM frame
Italcementi Group
PIC Grinding September 2005
153
2- HORIZONTAL BALL MILLS LINERS & DIAPHRAGMS
Italcementi Group
PIC Grinding September 2005
OUTLET DIAPHRAGM
154
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE Final outlet
Central outlet (double rotator mill)
Air swept outlet
Italcementi Group
Humid outlet
PIC Grinding September 2005
155
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
156
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
157
2- HORIZONTAL BALL MILLS OUTLET MILL CHUTE
Italcementi Group
PIC Grinding September 2005
158
2- HORIZONTAL BALL MILLS VENTILATION
A particular attention has to be taken for the mill inlet & outlet head. We must also have a good idea of the ventilation in the mill. Filter exhaure False air Tube ventilation head section Mill outlet head ventilation
Italcementi Group
Open circuit: 250-350 Nm3/mt of finished product 0.5-0.8 m/s Closed circuit 300-600 Nm3/mt of finished product 1-1.5 m/s Maximum of 35 m/s
PIC Grinding September 2005
159
2- HORIZONTAL BALL MILLS VENTILATION
THE PLANT ENERGY CONSUMPTION DEPENDS ON THE PRESSURE DROPS IN FILTERS, MILL...
THE CONTROL OF PRESSURES FOR ALL STEPS OF CIRCUIT IN THE GRINDING PLANT IS CRUCIAL TO OPTIMIZE THE GRINDING ENERGY CONSUMPTION CHECK THE PROCESS FAN EFFICENCY AND THE DAMPER OPENING: THIS POINTS COULD COST A LOT OF ENERGY Italcementi Group
PIC Grinding September 2005
160
2- HORIZONTAL BALL MILLS VENTILATION
False air affects a lot the mill ventilation. False air can provide from: * Mill tube: inlet sealings outlet sealings material feed * Mill discharge * Dedusting * Bag filter jet pulsing * Flaps airtightness * High negative pressure ducts and machines *... Italcementi Group
PIC Grinding September 2005
161
2- HORIZONTAL BALL MILLS VENTILATION
Point to care after for checking false air in the grinding circuit
Italcementi Group
PIC Grinding September 2005
162
2- HORIZONTAL BALL MILLS THERMAL BALANCE
GENERAL LAW: INPUT OUTPUT
Q:Calorific power = Temperature * Specific heat * Throughput Q express in th/h, kcal/h, BTU/h or MJ/h 1 thermie = 4,186 MJoules = 1 163 kWh = 106 calories = 3968,3 BTU
Italcementi Group
PIC Grinding September 2005
163
2- HORIZONTAL BALL MILLS THERMAL BALANCE
MILL:
MECHANICAL MILL MOTOR POWER
MATERIAL GAS
MATERIAL moisture % flow t/h temperature °C specific heat Kcal/kg°C kcal./Nm3°C HEAT LOST mill shell: surface m2 temperature °C heat transfer ratio kcal./h°Cm2 Italcementi Group
MATERIAL GAS HEAT LOST GAS composition moisture % flow Nm3/h temperature °C
FALSE AIR moisture % flow Nm3/h temperature specific heat
specific heat kcal./Nm3°C MECHANICAL MILL POWER electrical absorb. kW mechanical efficiency grinding efficiency
PIC Grinding September 2005
164
2- HORIZONTAL BALL MILLS THERMAL BALANCE
MATERIAL GAS
GAS
CLASSIFIER: HEAT LOST MATERIAL MATERIAL moisture % flow t/h temperature °C specific heat Kcal./kg°C
Italcementi Group
GAS composition moisture % flow Nm3/h temperature °C specific heat (Kcal./h°Cm2) PIC Grinding September 2005
HEAT LOST separator shell surface m2 temperature °C heat transfer ratio (Kcal./h.°C.m2)
165
2- HORIZONTAL BALL MILLS THERMAL BALANCE
FURNACE:
AIR
GAS
FUEL HEAT LOST AIR moisture % flow Nm3/h temperature °C specific heat Kcal/Nm3°C
Italcementi Group
GAS composition moisture % flow Nm3/h temperature °C specific heat Kcal/Nm3°C
PIC Grinding September 2005
FUEL composition moisture % flow kg/h temperature °C specific heat (Kcal./kg°C)
HEAT LOST furnace shell surface m2 temperature °C heat transfer ratio (Kcal./h°Cm2°)
166
2- HORIZONTAL BALL MILLS THERMAL BALANCE - DEW POINT
Due to the material moisture, the dew point has to prevent bag filter from clogging. => (bag filter gas temperature - dew point temperature) > 30°C P Vaporisation pressure: Pv in Kg/cm2 Pgs.(1 %H 2 O) 1 with P: absolute pressure in Pgh .%H 2 O Kg/cm2 (mbars*0.00102) P = Patm.-chimney depressure Pgs = Volumic mass of dry gas Pgh = Volumic mass of wet gas
Italcementi Group
Temperature of condensation: 5168 Tc 273,16 in °C 13,89 ln( Pv)
PIC Grinding September 2005
167
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Water spraying system according to the CTG standard
Italcementi Group
PIC Grinding September 2005
168
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
169
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
170
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
171
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
172
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
Italcementi Group
PIC Grinding September 2005
173
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
STANDARD ITC
Water injection in the first chamber or, if possible, in the second chamber:
1.5 - 2% max of the mill cement production Italcementi Group
PIC Grinding September 2005
174
2- HORIZONTAL BALL MILLS THERMAL BALANCE WATER INJECTION
MAGOTTEAUX: Chamber 1 : 0.9 % x production (kg/h) Chamber 2 : water required (thermal balance) - 0.9 % x kg/h % of water needed for different kWh/t and air speeds T° clinker : 50°C, 100°C and 150°C
Italcementi Group
PIC Grinding September 2005
175
2- HORIZONTAL BALL MILLS CIMAR MARRAKECH
COMPANY PLANT
MILL POWER D useful L useful J s Vactual ball size max htot
m m % t/m3 rpm mm %
MILL TYPE
1st compart.
2nd compart.
tot/avg
m
m
m
3,440 4,008 31,3 4,5 16,2 90 0,870
3,420 3,790 25,8 4,7 % Vcritical
3,43 7,80 28,6 4,6 70,9
RAW MILL POLYSIUS 3.6 x 12 m drying compartment 3,554 D useful m L useful m
2,5
Mec kW
89,3
balls charge tons 1st compart.
2nd compart.
52
42 94
ABSORBED POWER CALCULATION MECHANICAL
ELECTRICAL
1st comp. 2nd comp. totale 1st comp. 2nd comp. totale
Italcementi Group
kW kW kW kW kW kW
Magotteaux
CMM
Slegten (old)
FCB
A. C. 2
AVERAGES
600 509 1 209 690 585 1390
630 536 1 257 725 617 1445
600 511 1 203 690 587 1383
589 482 1 160 677 554 1231
630 537 1 259 724 617 1447
610 515 1 218 701 592 1379
PIC Grinding September 2005
176
2- HORIZONTAL BALL MILLS MILL POWER
n
C = mill axle G = centre of gravity F = material and balls weight b = lever arm n = mill rotation speed
b
C
POWER = n(F b)
G
F Italcementi Group
PIC Grinding September 2005
177
2- HORIZONTAL BALL MILLS MILL POWER
MILL POWER CALCULATION FORMULA SLEGTEN formula : P = Mill length x (pm/Vcrit)1.27 x Kpm x nmotor with KJ,Kj = filling ratio x (1.36 - 1.2 x filling ratio) and KPm = 40.688 x D2.379
and nmotor = total trasmission efficiency (motor, gear box, couplings)
CMM formula : P = [0.4735 - 0.0746 x Ln (filling ratio)] x D x 12 pm x Tballs
(for mills with L/D < 2.5) Italcementi Group
PIC Grinding September 2005
178
2- HORIZONTAL BALL MILLS BALL CHARGE
FIRST CHAMBER : CEMENT AND RAW : 100 mm to 60 mm BALLS GAUDIN-SCHUMANN LAW :
P ( X ) X / Xmax
m
X max : Maximum ball diameter. P(x) : % of X mm Ball. m = 1.4 MINIMUM POROSITY Italcementi Group
PIC Grinding September 2005
179
2- HORIZONTAL BALL MILLS BALL CHARGE
SECOND CHAMBER : CEMENT AND RAW : 60 mm to 17 mm BALLS (CYLPEBS) PAPADAKIS LAW :
D
D0 L k . 1 L max
1. 5
DO : Maximum ball diameter; k = 1.92 ; Lmax: Chamber length Italcementi Group
PIC Grinding September 2005
180
2- HORIZONTAL BALL MILLS BALL CHARGE
B = 20.17 x
F(80) k
Wi x S
x 3
Cs x Di
B = Balls diameter (mm) Wi = Inlet mill material max size (mm) Cs = Work index in kWh/st (st = 907 kg) S = Material specific weight (g/cm3) Di = Mill diameter (m) k = Proportionality constant (335) Italcementi Group
PIC Grinding September 2005
181
29/04/2002
C.T.G. - Italcementi Group - Comminution Department Company Plant Department Circuit type New charge date Mill speed Critical speed
Mill Feed point Hot gases Hot gas temperature Separator g/1' g/1'
Critical speed 1st chamber
Characteristics Type of liner Diaphragm slots Measured free height Ratio steel / cement Useful diameter Useful lenght Useful lenght Total volume compart. Ball charge density Charge volume Filling degree Calculated free height Ball charge to add for each cm of free height Ball charge D = 100 mm D = 90 mm D = 80 mm D = 70 mm D = 60 mm D = 50 mm D = 40 mm D = 30 mm D = 25 mm D = 20 mm D = 17 mm Cil 25x25 mm Cil 22x22 mm Cil 19x19 mm Cil 16x16 mm
18,63 Installed power 27,8 Absorbed power 67,1% Ratio L/Ø
mm m % m m % m³ t/m³ m³ % m
Av. size ball
mm
Inlet 5,32
1st compartment
2nd compartment
6,0
6,0
Free area for gases Outlet m² m² 3rd compartment
2,320 3,200 25,9 13,5 4,49 4,0 29,9 1,53
mm m % m m % m³ t/m³ m³ % m
2,320 9,150 74,1 38,7 4,79 11,6 30,1 1,53
mm m % m m % m³ t/m³ m³ % m
t
0,32
t
0,97
t
t
%
t
%
6,42 3,75 3,75 4,28
18,2 Total compartement Mill total t 74,0 Ball S.S. Surface m² 1.711 Surface Av, weight ball g
kW kW
°C
35,3 20,6 20,6 23,5
24,6 m²/t m²
150 Av, weight ball g 33 Av. size ball mm
Italcementi Group
m
2
m
2
2- HORIZONTAL BALL MILLS
t
%
m
BALL CHARGE
2
54 36 41 54
4,22 8,45 3,56
7,6 15,1 6,4
65 161 91
39,60
70,9
1209
185 55,8 10,2 Ball S.S. 185 Surface
75,4 m²/t m²
1598 Av, weight ball g 73 Av. size ball mm
1525
27,3 Ball S.S. 1.525 Surface
m²/t m²
116 Av, weight ball g 30 Av. size ball mm
PIC Grinding September 2005
182
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
183
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
184
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
185
2- HORIZONTAL BALL MILLS GRINDING SPECIFIC RATIO
Italcementi Group
PIC Grinding September 2005
186
3- AUTOGENOUS MILL
ROTATION LINERS LIFTERS
DEFLECTOR LINERS PERIPHERAL PORTS
Italcementi Group
PIC Grinding September 2005
187
3- AUTOGENOUS MILL
Italcementi Group
PIC Grinding September 2005
188
4- ROLLER PRESS SYNOPTIC:
Italcementi Group
PIC Grinding September 2005
189
4- ROLLER PRESS CHARATERISTICS: MAIN PARAMETERS: D = Roller diameter L = Effective roller length S = Gap Width U = Circumferential velocity F = Grinding force ac = Compression angle bf = Angle of force action Pm= Maximum pressure in gap d = maximum value of solids volume (2x1250kW) Italcementi Group
PIC Grinding September 2005
190
4- ROLLER PRESS CHARACTERISTICS: • MAIN PARAMETER:
Specific Pressure =
F
= 5 or 6 MPa
D.L F
• LIMITS: => Humidity: 5 to 6% => Installed Power # 2500-3000 kW (2*1250 kW)
Italcementi Group
PIC Grinding September 2005
D
L
191
4- ROLLER PRESS ADVANTAGES: REDUCTION OF THE ELECTRICAL GRINDING DEPARTMENT CONSUMPTION : 20 to 30% LESS PRODUCTION INCREASE OF EXISTING PLANT : 30 to 35% MORE SPECIFIC WEAR REDUCTION
Italcementi Group
PIC Grinding September 2005
192
4- ROLLER PRESS DISADVANTAGES: INTEGRAL FINISH GRINDING CIRCUIT ACCEPTABLE FOR BLAINE SURFACE < 4000 cm2/g.
NOT ADAPTED TO SOFT MATERIAL VIBRATION PROBLEM LINKED WITH REGULATION
MECHANICAL PROBLEMS WITH : - REDUCTION GEAR - ROLLER - SEGMENT ROLLER Italcementi Group
PIC Grinding September 2005
193
4- ROLLER PRESS
FINISH GRINDING
HYBRID GRINDING
PRE-GRINDING
SEMI-FINISH GRINDING
Italcementi Group
PIC Grinding September 2005
194
4- ROLLER PRESS FINISH - GRINDING
Italcementi Group
PIC Grinding September 2005
195
4- ROLLER PRESS FINISH - GRINDING ADVANTAGES : • THE GREATEST ENERGY SAVING • SMALL SPACE REQUIREMENT • LOW SPECIFIC WEAR (g/t) • DRYING CAPACITY
DISADVANTAGES : • NOT ADAPTED TO HIGH FINENESS TREND • LARGE MECHANICAL ELEVATOR (HIGH CIRCULATING LOAD) AND SEPARATOR • HEAVY MAINTENANCE (SPARE ROLLERS) • CEMENT AND CONCRETE WORKABILITY • GRINDING PLANT HEIGHT Italcementi Group
PIC Grinding September 2005
196
4- ROLLER PRESS HYBRID - GRINDING
Italcementi Group
PIC Grinding September 2005
197
4- ROLLER PRESS HYBRID - GRINDING ADVANTAGES : • ADAPTED TO HIGH FINENESS TREND • GOOD CEMENT AND CONCRETE WORKABILITY • LOW BALLS SPECIFIC WEAR (g/t) • POSSIBILITY TO WORK WITHOUT PRESS DISADVANTAGES : • HEAVY MAINTENANCE • MOISTURE LIMITED • PRESS VIBRATIONS RECIRCULATING SEPARATOR REJECTS • DIFFICULT TO CONTROL CIRCUIT
Italcementi Group
PIC Grinding September 2005
198
4- ROLLER PRESS PRE- GRINDING
kWh/t = 30% less
t/h
Italcementi Group
PIC Grinding September 2005
= 80% more
199
4- ROLLER PRESS PRE- GRINDING ADVANTAGES : • ADAPTED TO HIGH FINENESS TREND • GOOD CEMENT AND CONCRETE WORKABILITY • LOW BALLS SPECIFIC WEAR (g/t) • POSSIBILITY TO WORK WITHOUT PRESS
DISADVANTAGES : • HEAVY MAINTENANCE • MOISTURE LIMITED
Italcementi Group
PIC Grinding September 2005
200
4- ROLLER PRESS SEMI-FINISH GRINDING
kWh/t = 30% less
t/h
Italcementi Group
PIC Grinding September 2005
= 80% more
201
4- ROLLER PRESS SEMI-FINISH GRINDING
ADVANTAGES : • ADAPTED TO HIGH FINENESS TREND • LOW BALLS SPECIFIC WEAR (g/t) • GOOD SPECIFIC ENERGY CONSUMPTION • DRYING POSSIBILITIES
DISADVANTAGES : • HEAVY MAINTENANCE => NUMBER OF MACHINES • TWO FINENESS CHECK POINTS
Italcementi Group
PIC Grinding September 2005
202
4- ROLLER PRESS n.5 Roller Press in Italcementi Group (1998): CCB (Belgium; Gaurain) : Raw material POLYSIUS - 1989 - Nominal power=2 x 1200kW - roller width=1000mm roller diameter=2000mm CCB (Belgium; Gaurain) : Cement POLYSIUS - 1990 - Nominal power=2 x 1200kW - roller width=1000mm roller diameter=2000mm CALCIA (France; Cruas) : White cement FCB - 1990 - Nominal power=2 x 160kW - roller width=400mm roller diameter=820mm ESSROC (USA; Nazareth): Cement KHD - 1987 - Nominal power=2 x 800kW - roller width=1000mm roller diameter=1150mm ESSROC (USA; Speed): Cement KHD - 1998 - Nominal power=2 x 450kW - roller width=800mm roller diameter=1400mm Italcementi Group
PIC Grinding September 2005
203
4- ROLLER PRESS Example of CCB (Belgium; Gaurain): Raw grinding :
MILL 7 ROLLER PRESS MILL 1775 kW WORK SHOP 2199 kW STPH 106.6 kWh/st 22.8 Maintenance Cost 5.69 $pst
MILL 8 MILL 8/MILL7 1479 kW 3547 kW 200% 6193 kW 282% 355.3 333% 19.7 - 13.6 % 4.66 $pst - 18.1 %
To fulfil the same production as the grinding plant # 8 with the grinding plant # 7 WE SHOULD NEED a 7334 kW installed power plant. Italcementi Group
PIC Grinding September 2005
204
4- ROLLER PRESS Cement grinding
MILL 8 MILL 9 MILL 9 /MILL8 ROLLER PRESS 912 kW MILL 4392 kW 8566 kW 194% WORK SHOP 4901 kW 11634 kW 237% STPH 84.2 251.7 299% kWh/st 58.2 46.2 - 20.6 % Maintenance Cost 10.7 $pst 8.1 $pst -24.3 % To fulfil the same production as the grinding plant # 9 with the grinding plant # 8 WE SHOULD NEED a 14755 kW installed power grinding plant.
Italcementi Group
PIC Grinding September 2005
205
SYSTEMES DE BROYAGE CIMENTS
Italcementi Group
PIC Grinding September 2005
206
4- ROLLER PRESS HOROMILL (FCB)
Limits: New technology New plants in the world: R.C.C. (Turkey): 1 Horomill with TSV classifier 110 stph; 3200 Blaine OPC Asian Cement (Lafarge, Turkey) 1 Horomill with TSV classifier 110 stph; 4200 Blaine; 2100 kW installed power
Italcementi Group
PIC Grinding September 2005
207
5- HORIZONTAL ROLLER MILLS COMPARISON OF THE ANGLES OF NIPS
Italcementi Group
PIC Grinding September 2005
208
5- HORIZONTAL ROLLER MILLS PROCESS PRINCIPLE INSIDE HOROMILL
Italcementi Group
PIC Grinding September 2005
209
5- HORIZONTAL ROLLER MILLS
BUILT A MILL ABLE TO GRIND: • • • • • • •
with compression effect with low mechanical strains in a steady way with a limited wear of grinding media with low investment cost without the roller press power limit with an operating flexibility
Italcementi Group
PIC Grinding September 2005
210
5- HORIZONTAL ROLLER MILLS
MILL TYPE
SPECIFIC PRESSURE (exerced by the rollers on the material layer) : 150 - 200 8-14 20-60 25
Roller press Raw vertical mill Cement vertical mill Horizontal roller mill
Italcementi Group
PIC Grinding September 2005
MPa MPa MPa MPa
211
5- HORIZONTAL ROLLER MILLS HOROMILL (FCB)
Italcementi Group
PIC Grinding September 2005
212
5- HORIZONTAL ROLLER MILLS HOROMILL (FCB)
Italcementi Group
PIC Grinding September 2005
213
5- HORIZONTAL ROLLER MILLS TREND
Italcementi Group
PIC Grinding September 2005
214
5- HORIZONTAL ROLLER MILLS
ADVANTAGES: - Grinding efficiency
DISADVANTAGES: - New design and technology - Working hours (max 1300 of industrial prototype) - High circulation load - Limited ventilation in the mill - Limits in feed moisture - Difficulty to produce OPC cement with fineness > 4000 Blaine - Difficulty to produce slag cement with slag content > 40% Italcementi Group
PIC Grinding September 2005
215
5- HORIZONTAL ROLLER MILLS Mechanical problems: - Hydraulic apparatus ( cylinders and accumulators) - Roller and track lifetime, scrapers wear - Cracks in the mill shell - Mill shell sealing - Misalignment of mill shall (material inside the mill) - Torsional vibration on drive line - Lubrication oil cooling system and pollution Process problems: - Limits in fineness with OPC cement - Two separators in series utilised in Karsdorf for OPC 42.5 cement - Difficulty to produce slag cements (> 40% of slag content) - Start-up procedure Italcementi Group
PIC Grinding September 2005
216
5- HORIZONTAL ROLLER MILLS TREND
Italcementi Group
PIC Grinding September 2005
217
5- HORIZONTAL ROLLER MILLS TREND
Italcementi Group
PIC Grinding September 2005
218
5- HORIZONTAL ROLLER MILLS COMPARISON BETWEEN HOROMILL AND CEMAX Manufacturer Spin velocity Type of circuit C,C. regulation Mill ventilation Drying capacity Inlet mill Maximum size Expected production Italcementi Group
HOROMILL Fives Cail Babcock 1.6 x critical speed mechanical inside the mill low limited single 4000 kW 220 t/h PIC Grinding September 2005
CEMAX F.L. Smidth 0.82 x critical Speed ventilated separator high good double 5500 kW 300 t/h 219
6- SYSTEMS AND OTHER COMPARISON OF MAIN PARAMETERS Specific pressure (F/LxD) Pressure nip angle Compression in single pass Substitution ratio Drying capacity kWh/t mill motor (*) kWh/t total (*) Maximum Blaine OPC Investment cost References
Roller press 6.5 6 1 1.7 - 2.2 out of the press 60 70 3500 110 > 300
Vertical mill 1.5 12 2 1.5 - 2.2 in the mill 60 75 4300 110 35
Horomill 3.5 18 5 1.5 - 2.2 out of the mill 60 70 4100 110 15
* = referred to horizontal ball mill as 100% Italcementi Group
PIC Grinding September 2005
220
6- SYSTEMS AND OTHER CEMENT VERTICAL MILL
Italcementi Group
PIC Grinding September 2005
221
6- SYSTEMS AND OTHER CEMENT VERTICAL MILL
Loesche mill LM 32.5+2S
Italcementi Group
PIC Grinding September 2005
222
6- SYSTEMS AND OTHER
MILL FRESH FEED
MILL RECIRCULATION FEED
MASTER ROLLER
THIRD GENERATION CLASSIFIER
CEMENT VERTICAL MILL SLAVE ROLLER
Loesche mill LM 32.5+2S
Italcementi Group
PIC Grinding September 2005
223
6- SYSTEMS AND OTHER CKP GRINDING SYSTEM
PRE-GRINDING
Italcementi Group
SEMI-FINISH GRINDING
PIC Grinding September 2005
224
6- SYSTEMS AND OTHER
Italcementi Group
PIC Grinding September 2005
225
6- SYSTEMS AND OTHER NEW DEVELOPMENT: CKP Process
Characteristics: No integrated separator External mechanical elevator Material outlet design Low air flow (dedusting function) low drying capacity Association with a finishing mill
Production improvements:
Italcementi Group
PIC Grinding September 2005
226
6- SYSTEMS AND OTHER CIRCUIT BEFORE CKP INSTALLATION
Italcementi Group
PIC Grinding September 2005
227
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
228
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
229
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
230
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM MARRAKECH - CEMENT MILL n°2 + CKP - CPJ 35 Pos.
Cement type
CPJ 35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Test number Additives Sent to CKP Sent to ball mill Test date Production Residue 0.040 mm Residue 0.063 mm Residue 0.080 mm Residue 0.090 mm Residue 0.200 mm Blaine Clinker Limestone Pozzuolana Gypsum
t/h % % % % % cm2/g % % % %
17 18 19 20 21 22 23 24
Mill absorbed power CKP absorbed power Services absorbed power Total absorbed power Mill specific consumption CKP specific consumption Services spec. consumpt. Total specific consumption
kW kW kW kW kWh/t kWh/t kWh/t kWh/t
25 Mill max power required
Italcementi Group
Reference
Performance
before CKP
warranties
% -
kW
1 100 lim + 0 poz cli + lim to CKP gyps to mill 08-mar 136 33,44 10,40
5 50 lim + 50 poz cli + lim to CKP poz + gyp to mill 12-mar 144 35,96 12,92
7 50 lim + 50 poz cli+lim+poz to CKP gyps to mill 13-mar 157
75 20 0 5
3,68 0,08 3650 71 24 0 5
5,04 0,12 4100 71 12 12 5
5,00 0,10 4100 71 12 12 5
21,5
2057 763 403 3223 15,13 5,61 2,96 23,70
2060 770 405 3235 14,31 5,35 2,81 22,47
2060 797 410 3267 13,12 5,08 2,61 20,81
100 lim + 0 poz cli + lim to CKP gyps to mill 100
CTG test with CKP
165
13,00
4-6
3600 75 5 - 15 5 - 15 5 2100 800 2900 21,00 8,00 29,00
2200
PIC Grinding September 2005
231
6- SYSTEMS AND OTHER CKP PRE-GRINDING SYSTEM MARRAKECH - COTTO 2 + CKP a CPJ 45 Pos.
Tipo cemento
CPJ 45
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Test number Additives Sent to CKP Sent to ball mill Test date Production Residue 0.040 mm Residue 0.063 mm Residue 0.080 mm Residue 0.090 mm Residue 0.200 mm Blaine Clinker Limestone Pozzuolana Gypsum
% t/h % % % % % cm2/g % % % %
17 18 19 20 21 22 23 24
Mill absorbed power CKP absorbed power Services absorbed power Total absorbed power Mill specific consumption CKP specific consumption Services specific consumption Total specific consumption
kW kW kW kW kWh/t kWh/t kWh/t kWh/t
25 Mill max power required
Italcementi Group
Reference
Performance
CTG test
before CKP
warranties
86
145
with CKP 4 50 lim + 50 poz cli + lim to CKP poz + gyp to mill 11-mar 122 33,32 9,08
2-4
2-4
3600 - 3700 85 10 - 5 5 - 10 5
85 5 5 5
2150
2060 760 400 3220 16,89 6,23 3,28 26,39
602 2752 25,00 7,00 32,00
kW
2,76 0,08 3300 87 4 4 5
2200
PIC Grinding September 2005
232
6- SYSTEMS AND OTHER CKP SEMI-FINISH GRINDING SYSTEM
Italcementi Group
PIC Grinding September 2005
233
6- SYSTEMS AND OTHER HORIZONTAL ROLLER MILL
Italcementi Group
PIC Grinding September 2005
234
6- SYSTEMS AND OTHER HORIZONTAL ROLLER MILL
Italcementi Group
PIC Grinding September 2005
235
6- SYSTEMS AND OTHER HORIZONTAL ROLLER MILL
Italcementi Group
PIC Grinding September 2005
236
6- SYSTEMS AND OTHER HORIZONTAL ROLLER PRESS
Italcementi Group
PIC Grinding September 2005
237
VI- SEPARATING PROCESS 1. Theory 2. Cyclone 3. Static Classifier 4. Dynamic Classifiers : First Generation Second Generation Third Generation
5. Design
Italcementi Group
PIC Grinding September 2005
238
1- THEORY PERFORMANCES:
GOOD CLASSIFIER EFFICIENCY
GOOD WORKSHOP EFFICIENCY
LOWER ELECTRIC CONSUMPTION
GLOBAL PRODUCTIVITY IMPROVEMENT Italcementi Group
PIC Grinding September 2005
239
1- THEORY • PURPOSE => SEPARATION PARTICLE SUITABLE FOR "FINISHED PRODUCT" CLASSIFIER FEED COARSE PARTICLES "OVERSIZED" TWO THINGS MUST BE ENSURED
Italcementi Group
=> NO OVERSIZED IN THE FINISH => NO FINISHED IN THE REJECTS
PIC Grinding September 2005
240
1- THEORY PRINCIPLE:
EACH PARTICLE IN AN AIR FLOW : CxSx(V2/2)xRo= Global air force = Fa
Air current
MxW2xR= Centrifugal force=Fc
MxG=Gravity force = Fg Italcementi Group
PIC Grinding September 2005
241
1- THEORY
Fg=K1 x d3 Fc=K2 x d3 Fl=K3 x d(3/2) d: particle diameter
Fg # 1/10 Fc => insignificant Fc = Fl => d0 = cut size
d > d0 => particle thrown out the inner side => Tail d < d0 => particle thrown up => Fines
Italcementi Group
PIC Grinding September 2005
242
1- THEORY A CIRCULATING LOAD: A = R + F (t / h) or A / F (ratio)
R
FRESH FEED
Italcementi Group
PIC Grinding September 2005
F
243
1- THEORY DIFFERENT KINDS OF CLASSIFIERS CYCLONE STATIC DYNAMIC TO DUST COLLECTOR
FINE MATERIAL TO DUST COLLECTOR
GAS WITH MATERIAL
GAS WITH FINES
MATERIAL
GAS REJECT PRODUCT
Italcementi Group
GAS FROM MILL
REJECT
PIC Grinding September 2005
244
2- CYCLONE FINENESS ADJUSTMENT BY : AIR FLOW REGULATION
Captation efficiency ANDERSON, ROSIN RAMMLER law
D min i
K. . n l . s.Vt
K Cst
: duct . width. ( m) l: gas. trajectory . ( m) Vt : tan gential . speed . ( m / s )
h: Gas. dynamic. vis cos ity . ( Poiseuille ) S: Material . volumic. mass. ( kg / m3)
Italcementi Group
PIC Grinding September 2005
245
3- STATIC SEPARATOR REGULATION OF THE CUT SIZE WITH: • GUIDE VANES INCLINATION (wheel) • OUTLET DUCT LENGTH (R) • AIR FLOW
Italcementi Group
PIC Grinding September 2005
246
3- STATIC SEPARATOR To mill dust collector
Fines
Adjustable guide vanes
Reject Mill vent air Italcementi Group
PIC Grinding September 2005
247
3- STATIC SEPARATOR TWO TYPES OF STATIC SEPARATORS
FINES
FINES
TAILS
TAILS
AIR FLOW + FEED Italcementi Group
PIC Grinding September 2005
AIR FLOW + FEED 248
3- STATIC SEPARATOR ADVANTAGES : • EASY TO USE • CHEAP • HIGH AIR FLOW • LOW ELECTRIC CONSUMPTION • ALLOW TO SEND FILTER MILL PRODUCT TO FINAL PRODUCT
DISADVANTAGES : • MEDIUM PRECISION OF SIEVING • CONVEYING FUNCTION (AIRSWEPT) AND SEPARATING FUNCTION LINKED TOGETHER • FINENESS LIMITED Italcementi Group
PIC Grinding September 2005
249
4- DYNAMIC SEPARATOR
• FIRST GENERATION
• SECOND GENERATION • THIRD GENERATION
Italcementi Group
PIC Grinding September 2005
250
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
STURTEVANT
Italcementi Group
Characteristics: • Single drive •Selection device (distribution plate) •Main fan 3 Functions with the same motor Fineness regulation by: •Selection blade number •Selection and fan blade size •Diaphragm valve small fineness range PIC Grinding September 2005
251
4- DYNAMIC SEPARATOR FIRST GENERATION (STURTEVANT)
Fineness adjustment by diaphragm position
Italcementi Group
PIC Grinding September 2005
252
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
POLYSIUS
Characteristics: • Double drive • Distribution plate & selection device mounted on the same shaft • Main fan • Selection device speed control
3 functions with two motors. Fineness regulation by: • Plate distribution speed • Selection blade number • Selection blade size Larger fineness range Italcementi Group
PIC Grinding September 2005
253
4- DYNAMIC SEPARATOR FIRST GENERATION (POLYSIUS)
Double drive: variable speed and fixed speed
Fan (fixed speed)
feed
Selection blades
Feed distribution plate
Fineness adjustment by variable speed reject fines Italcementi Group
PIC Grinding September 2005
254
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
RAYMOND
Characteristics : •Single drive with fix speed •Selection device (distribution plate) single or double •Main fan 3 functions with one motor Fineness regulation : •Selecting blades number •Internal deflectors position Italcementi Group
PIC Grinding September 2005
255
4- DYNAMIC SEPARATOR FIRST GENERATION CLASSIFIER
DISADVANTAGES : Inner side effect (wall effect) Fines in tails
Italcementi Group
ALL FUNCTIONS (SELECTION -VENTILATION- CAPTATION) DISPLAYED INTO ONE MACHINE BIG CYCLONE • Bad selection efficiency (feeding under selecting zone + wide selecting area) •Limited cooling function •High by-passing level (fines in tails) •Fineness limited •No air flow regulation •Bad efficiency of the main fan PIC Grinding September 2005
256
4- DYNAMIC SEPARATOR SECOND GENERATION CLASSIFIER
Main description : •Central body • Satellite cyclones • High efficiency main fan Characteristics : • Fine particle captation made by small cyclones • Regulated air flow (recirculation air flow) Fineness regulation by : • Distribution plate speed • Recirculation air flow • Selection blades number & size Italcementi Group
PIC Grinding September 2005
257
4- DYNAMIC SEPARATOR SECOND GENERATION (WEDAG)
Italcementi Group
PIC Grinding September 2005
258
4- DYNAMIC SEPARATOR SECOND GENERATION (WEDAG)
Variable speed drive
fan
feed
selection
distribution Italcementi Group
fines PIC Grinding September 2005
rejects 259
4- DYNAMIC SEPARATOR SECOND GENERATION CLASSIFIER
ADVANTAGES: FINENESS REGULATION EASY FROM THE CONTROL ROOM COOLING CAPACITY (by regulating fresh air flow) DRYING CAPACITY SEPARATION OF DIFFERENT FUNCTIONS (Separation, Ventilation, Captation ...) HIGH EFFICIENCY VENTILATOR LARGE FINENESS RANGE
Italcementi Group
PIC Grinding September 2005
260
4- DYNAMIC SEPARATOR SECOND GENERATION CLASSIFIER
DISADVANTAGES: CLASSIFIER SIZE STILL HIGH BY- PASSING LEVEL (fines in tails) FEEDING UNDER SELECTING ZONE AND WIDE SELECTION AREA
THIRD SEPARATION CLASSIFIER
Italcementi Group
PIC Grinding September 2005
261
4- DYNAMIC SEPARATOR THIRD GENERATION CLASSIFIER
CLASSIFYING PRINCIPLE:
Narrow classifying area for third generation classifier (versus first generation) Consistent centrifugal force
Italcementi Group
PIC Grinding September 2005
262
1_ csV12 2
1_ csV22 2
m2 R1
m2 R2
mg
4- DYNAMIC SEPARATOR
mg
THIRD GENERATION CLASSIFIER
THEORY 1_ csV 2 2
m2 R
mg 1_ csV 2 2
m2 R
mg
Italcementi Group
PIC Grinding September 2005
263
4- DYNAMIC SEPARATOR THIRD GENERATION CLASSIFIER
O-SEPA (Onoda, Japan)
Italcementi Group
PIC Grinding September 2005
TSV (FCB, France)
264
4- DYNAMIC SEPARATOR THIRD GENERATION (STURTEVANT)
Italcementi Group
PIC Grinding September 2005
265
4- DYNAMIC SEPARATOR THIRD GENERATION (O-SEPA)
Italcementi Group
PIC Grinding September 2005
266
4- DYNAMIC SEPARATOR THIRD GENERATION (O-SEPA)
Italcementi Group
PIC Grinding September 2005
267
4- DYNAMIC SEPARATOR THIRD GENERATION (FCB)
Italcementi Group
PIC Grinding September 2005
268
4- DYNAMIC SEPARATOR THIRD GENERATION (POLYSIUS)
Italcementi Group
PIC Grinding September 2005
269
5- DESIGN DESIGN PARAMETERS FOR A THIRD GENERATION CLASSIFIER
Ratio separator feeding / air throughput 1.75 kg/actual m3 (max : 2 kg/m3) Ratio fines/cage total surface max : 10 t/m² Ratio fines / air throughput max : 1 kg/actual m3 Italcementi Group
PIC Grinding September 2005
270
5- DESIGN SEPARATOR LOAD RATIO
CEMENT: Separator feed rate/separation air => 1.8 kg/m3 Separator product/ separation air 3000 cm2 /g acc. to Blaine => 0.75 - 0.8 kg/m3 4000 cm2 /g acc. to Blaine => 0.55 - 0.6 kg/m3 5000 cm2 /g acc. to Blaine => < 0.55 kg/m3 RAW MATERIAL: Separator feed rate/ separation air => 2.2 kg/m3 Raw meal 12 - 14% residue 90 mm => 0.55 kg/m3 Italcementi Group
PIC Grinding September 2005
271
5- DESIGN SEPARATOR COMPARISON
First generation: • all functions (selection, ventilation, product collection) in the same machine • wide separation area Second generation: • functions divided in different components • wide separation area Third generation: • high efficiency due to narrow separation area and controlled ventilation Italcementi Group
PIC Grinding September 2005
272
5- DESIGN SEPARATOR DATA SHEET
Italcementi Group
PIC Grinding September 2005
273
5- DESIGN
Italcementi Group
PIC Grinding September 2005
274
5- DESIGN
Italcementi Group
PIC Grinding September 2005
275
5- DESIGN DESIGN PARAMETERS FOR A THIRD GENERATION CLASSIFIER
Max tangential speed (peripheral speed) : Vt = 35 m/s Radial speed (air speed through the cage) : Vr = 4.5 m/s if product fineness <3200 Blaine Vr if > 4500 Blaine 4.5 m/s for small separator 3.5 - 4 m/s for big one Vr = 5 - 5.2 m/s for raw material Italcementi Group
PIC Grinding September 2005
276
5- DESIGN THIRD GENERATION CLASSIFIER
ADVANTAGES: CLASSIFIER SIZE HIGH SIEVING ACCURACY COOLING CAPACITY EASY TO CONTROL (in the control room)
Italcementi Group
PIC Grinding September 2005
277
5- DESIGN THIRD GENERATION CLASSIFIER
DISADVANTAGES: FILTER SIZE FINAL PRODUCT QUALITY
nRRS
=
• Workability • One and two days strength
Italcementi Group
PIC Grinding September 2005
278
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
279
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
280
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
281
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
282
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
283
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
284
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
285
5- DESIGN NEW
OLD
Italcementi Group
PIC Grinding September 2005
MODIFIED BY C.T.G.
286
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
287
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
288
5- DESIGN
MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
289
5- DESIGN MODIFIED BY C.T.G.
Italcementi Group
PIC Grinding September 2005
290
5- DESIGN TROMP CURVE CALCULATION A (a)
G (g)
F (f) M
Vf =
Vg =
Sa - Sg Sf - Sg
Sf - Sa Sf - Sg
x 100 (%)
x 100 (%)
Italcementi Group
A = Separator feed (t/h) F = Separator fines (t/h) G = Separator reject (t/h) Ma= Fresh mill feed (t/h) Da = Granulometric size weight of separator feed (%) Df = Granulometric size weight of separator fines (%) Dg = Granulometric size weight of separator reject (%) Sa = Granulometric size passing of separator feed (%) Df = Granulometric size passing of separator fines (%) Dg = Granulometric size passing of separator reject (%) Vf = Separator fines weight (%) Vg = Separator reject weight (%) T = Separation coefficient (%)
In general: T = f (granulometric size)
Dg - Vg
T=
x 100 (%)
Dg x Vg + Df x Vf
PIC Grinding September 2005
291
5- DESIGN SEPARATOR RELATION BETWEEN SEPARATOR EFFICIENCY AND MATERIAL FLOWS A = F = G = a = f = g = h = UF =
Separator feed (t/h) Separator fines (t/h) Separator reject (t/h) Granulometric size passing of separator feed (%) Granulometric size passing of separator fines (%) Granulometric size passing of separator reject (%) Separator efficiency Circulation load A
fxF
h=
UF = F
a xA
h=
f a
Italcementi Group
a-g x
f =
f-g
f-g = a-g
1 x
a
PIC Grinding September 2005
UF
292
5- DESIGN SEPARATOR
TROMP CURVE CALCULATION
Italcementi Group
PIC Grinding September 2005
293
5- DESIGN SEPARATOR
TROMP CURVE CALCULATION
Italcementi Group
PIC Grinding September 2005
294
5- DESIGN SEPARATOR
TROMP CURVE Selectivity (%)
Tails in fines
Global by-pass (Stg)
P(t) 50 % Imperfection= (d75 - d25) / 2d50 By-pass slope (Pts) Fines in tails Particle size (μm)
Italcementi Group
PIC Grinding September 2005
Minimum by-pass (St) Log 295
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
296
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
297
5- DESIGN THIRD GENERATION CLASSIFIER
Selectivity (%)
FIRST GENERATION SECOND GENERATION THIRD GENERATION
Characteristics: Squirrel cage to make separation Fineness regulation: Rotor speed Air flow regulation Static blades inclination
Particle size (μm)
Italcementi Group
PIC Grinding September 2005
298
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
299
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
300
5- DESIGN SEPARATOR
Cement type IA-52.5
Mill TOSI 9’ x 14’ with Sturtevant 16’ separator Mill SMIDTH 3.2 X 9.3 With O-SEPA N 1000 separator Italcementi Group
PIC Grinding September 2005
301
5- DESIGN SEPARATOR
Italcementi Group
PIC Grinding September 2005
302
VII - GRINDING CIRCUITS
Dry Process 1. Open Circuit 2. Closed Circuit 3. Raw Material Circuit 4. Swept Circuit 5. Coal Circuit 6. Cement Circuit
Italcementi Group
PIC Grinding September 2005
303
1- OPEN CIRCUIT
Italcementi Group
PIC Grinding September 2005
304
1- OPEN CIRCUIT ADVANTAGES :
LOW INVESTMENT COST SIMPLE LAY-OUT
SPECIFIC POWER CONSUPTION ACCEPTABLE FOR COARSE CEMENT (maximum 3000 Blaine OPC)
Italcementi Group
PIC Grinding September 2005
305
1- OPEN CIRCUIT DISADVANTAGES : RISK TO FIND COARSE PARTICLE IN CEMENT NO ACCURATE REGULATION POSSIBILITY FOR DIFFERENT KINDS OF CEMENT FINE CEMENT PRODUCTION EXPENSIVE LOW VENTILATION NO DRYING CAPACITY
Italcementi Group
PIC Grinding September 2005
306
1- OPEN CIRCUIT
Italcementi Group
PIC Grinding September 2005
307
1- OPEN CIRCUIT PARTICLE SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
308
2- CLOSED CIRCUIT
Italcementi Group
PIC Grinding September 2005
309
2- CLOSED CIRCUIT
ADVANTAGES :
GOOD EFFICIENCY (kWh/t) LARGE FINENESS RANGE HIGH RRS SLOPE DRYING & COOLING CAPACITY CIRCUIT REGULATION POSSIBILITIES
Italcementi Group
PIC Grinding September 2005
310
2- CLOSED CIRCUIT
DISADVANTAGES : HIGH INVESTMENT COST MORE MAINTENANCE COST => NUMBER OF MACHINES (vs opened circuit)
Italcementi Group
PIC Grinding September 2005
311
3- RAW MATERIAL CIRCUITS RAW GRINDING
WET PROCESS
DRY PROCESS
Disagglomerator Horizontal mill Closed circuit
Horizontal mill Airswept circuit
Opened circuit
Italcementi Group
Mechanical circuit
Central Discharge
PIC Grinding September 2005
Vertical mill
Standard 312
3- RAW MATERIAL CIRCUITS
DRY PROCESS
WET PROCESS
Italcementi Group
PIC Grinding September 2005
313
3- RAW MATERIAL CIRCUITS DRY PROCESS (VERTICAL ROLLER MILL)
Italcementi Group
PIC Grinding September 2005
314
3- RAW MATERIAL CIRCUITS DRY PROCESS (STANDARD CIRCUIT)
Italcementi Group
PIC Grinding September 2005
315
3- RAW MATERIAL CIRCUITS DRY PROCESS (DOUBLE ROTATOR)
Italcementi Group
PIC Grinding September 2005
316
4- SWEPT CIRCUIT DRY PROCESS (AIR SWEPT)
Italcementi Group
PIC Grinding September 2005
317
4- SWEPT CIRCUIT DRY PROCESS (AIR SWEPT)
AIR SWEPT CIRCUIT WITH RICICLE FAN
Italcementi Group
PIC Grinding September 2005
318
4- SWEPT CIRCUIT WET PROCESS
• NOT MORE UTILIZED FOR NEW PLANTS • SUITABLE FOR RAW MATERIALS VERY WET, HARD OR WITH HIGH LEVEL OF PLASTICITY
• REQUIRES FUELS AT VERY LOW COST
Italcementi Group
PIC Grinding September 2005
319
4- SWEPT CIRCUIT WET PROCESS ADVANTAGES: • LOWER ENERGY SPECIFIC CONSUMPTION (30-50% less than dry process) • LOWER INVESTMENT COST • NO AIR POLLUTION • EASY SLURRY TRANSPORT • EASY SLURRY HOMOGENISATION • WET KILN LESS AFFECTED BY PRESENCE OF CHLORIDES, ALKALIES OR SULFATES IN RAW MATERIALS • ABILITY TO USE HIGH SULFUR FUELS AND WASTE FUELS Italcementi Group
PIC Grinding September 2005
320
4- SWEPT CIRCUIT WET PROCESS DISADVANTAGES: • HIGH SLURRY MOISTURE CONTENT (30 - 40 %) • HIGH THERMIC ENERGY CONSUMPTION • DIFFICULTY IN GRINDING MATERIALS WITH DIFFERENT GRINDABILITY • HIGH WEAR COSTS • CLAY INCREASES SLURRY WATER CONTENT
Italcementi Group
PIC Grinding September 2005
321
4- SWEPT CIRCUIT WET PROCESS OPEN CIRCUIT • ROTARY DISAGGREGATORS (for soft materials) • HORIZONTALS BALLS MILL with 2-3 compartments ( cylpebs in 3^ compartment, rubber liner and diaphragms in 2^ and 3^ compartment) Advantages: • simple installation and control
Italcementi Group
PIC Grinding September 2005
322
4- SWEPT CIRCUIT WET PROCESS
CLOSED CIRCUIT • HORIZONTALS BALLS MILL with 1-2 compartments • SLURRY CLASSIFIER: - curved 270° screens (DSM) - FLS centrifugal screens - Hydrocyclones - MOGENSEN
Italcementi Group
PIC Grinding September 2005
323
4- SWEPT CIRCUIT WET PROCESS CLOSED CIRCUIT - SLURRY CLASSIFIERS CURVED SCREEN (DSM) • most frequently used • lifetime of screen elements acceptable • low specific investment cost • spare part low cost • high throughput (200 t/h)
Italcementi Group
PIC Grinding September 2005
324
4- SWEPT CIRCUIT WET PROCESS CLOSED CIRCUIT - SLURRY CLASSIFIERS FLS CENTRIFUGAL SCREEN • movable parts • high wear costs • investment specific cost high (4 times DSM) • kWh/t higher than DSM • throughput limited (100 t/h)
Italcementi Group
PIC Grinding September 2005
325
4- SWEPT CIRCUIT WET PROCESS CLOSED CIRCUIT - SLURRY CLASSIFIERS HYDROCYCLONS • simple machines • require small volume • efficiency affected by slurry characteristics MOGENSEN • high specific investment cost • good efficiency • good lifetime • max throughput 120 t/h
Italcementi Group
PIC Grinding September 2005
326
4- SWEPT CIRCUIT WET PROCESS
CLOSED CIRCUIT Advantages: • • • •
less wear inside the mill less electric power consumption more constant product quality less problems to grind raw materials with different grindability
Italcementi Group
PIC Grinding September 2005
327
5- COAL CIRCUIT
DIRECT FIRING
SEMI DIRECT FIRING
INDIRECT FIRING
Italcementi Group
PIC Grinding September 2005
328
5- COAL CIRCUIT DIRECT FIRING : the ground coal is sent directly to the rotary kiln without storage and mill outlet production must be adjusted to the kiln consumption.
1: Raw coal silo 2: Air heater 3: Coal mill
4: Primary air fan 5: Rotary kiln
Italcementi Group
Disadvantage: Kiln performances depend on mill performances PIC Grinding September 2005
329
5- COAL CIRCUIT SEMI DIRECT FIRING : a feed hopper with a few hours storage capacity allows the process to be more elastic 1: Raw coal silo 2: Air heater 3: Coal mill 4: Cyclone 5: Feed hopper
6: Circulating air fan 7: Primary air fan 8: Circulating air 9: Rotary kiln
Disadvantage: Kiln performances depend on mill performances Italcementi Group
PIC Grinding September 2005
330
5- COAL CIRCUIT INDIRECT FIRING: Grinding and burning process not linked 1: Raw coal silo 2: Air heater 3: Coal mill 4: Cyclone 5: Coal dust silo 6: Circulating air fan 7: Filter 8: Exhaust fan 9: Circulating air 10: Primary air fan 11: Rotary kiln
Italcementi Group
PIC Grinding September 2005
331
6- CEMENT CIRCUIT CEMENT GRINDING
BALL MILL
ROLLER PRESS
O.C.
Finish grinding
C.C.
Ball mill
VERTICAL MILL O. C.
Standard circuit
Italcementi Group
Double rotator
PIC Grinding September 2005
C.C. 332
6- CEMENT CIRCUIT
ONE FILTER CEMENT CIRCUIT ONE FILTER SERIAL CEMENT CIRCUIT
TWO FILTER CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
333
6- CEMENT CIRCUIT ONE FILTER CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
334
6- CEMENT CIRCUIT ONE FILTER CEMENT CIRCUIT ADVANTAGES : • LOW SPECIFIC ENERGY CONSUMPTION • LOW MAINTENANCE • CHEAPER INVESTMENT THAN TWO FILTER CIRCUIT
DISADVANTAGES: • TUBE VENTILATION AND SEPARATOR DEDUSTING DIFFICULT TO ADJUST • LOWER DRYING AND COOLING CAPACITY THAN TWO FILTERS CIRCUIT • TWO SEPARATORS ==> TWO FINAL PRODUCTS Italcementi Group
PIC Grinding September 2005
335
6- CEMENT CIRCUIT ONE FILTER SERIAL CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
336
6- CEMENT CIRCUIT ONE FILTER SERIAL CEMENT CIRCUIT ADVANTAGES : • ONLY ONE FINENESS CHECK POINT • LOW MAINTENANCE • CHEAPER INVESTMENT THAN TWO FILTER CIRCUIT • LOWEST POWER CONSUMPTION
DISADVANTAGES: • LIMITED COOLING CAPACITY IN THE SEPARATOR • HIGH NEGATIVE PRESSURE IN THE CIRCUIT => RISK OF FALSE AIR
Italcementi Group
PIC Grinding September 2005
337
6- CEMENT CIRCUIT TWO FILTER CEMENT CIRCUIT
Italcementi Group
PIC Grinding September 2005
338
6- CEMENT CIRCUIT TWO FILTER CEMENT CIRCUIT ADVANTAGES : • HIGH COOLING CAPACITY • HIGH DRYING CAPACITY • CLASSIFYING AND TUBE VENTILATION FUNCTIONS NOT LINKED
DISADVANTAGES: • HIGHER INVESTMENT COST (TWO FILTERS) • TWO FINENESS CHECK POINTS • HIGHER MAINTENANCE COST • HIGHER ENERGY CONSUMPTION IF COOLING IS NOT NECESSARY
Italcementi Group
PIC Grinding September 2005
339
VIII - CIRCUIT PROCESS CONTROL
Italcementi Group
PIC Grinding September 2005
340
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT Mill feed •
MILL FEED
BY
ELEVATOR MOTOR POWER
( affected by mechanical problems of bucket elevator ) or •
MILL FEED
BY
SEPARATOR REJECT WEIGTH
( impact weight feeder requires frequent calibration and proper installation) and •
MILL FEED
BY
MILL FIRST COMPARTMENT NOISE
( electronic ear needs proper installation and its signal is affected by surrounding noises) Italcementi Group
PIC Grinding September 2005
341
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT Mill outlet or product temperature Cooling: • MILL OUTLET TEMPERATURE BY WATER SPRYING IN
• •
- 1st compartment (from mill inlet) with hot clinker - 2nd compartment (from intermediate or outlet diaphragm) ( only for temperature > 100°C ) MILL OUTLET TEMPERATURE BY KEEPING MILL VENTILATION AT MAXIMUM LEVEL FINISH PRODUCT TEMPERATURE BY SEPARATOR FRESH AIR INTAKE ( suitable for 2nd and 3rd generation dynamic separators ) Italcementi Group
PIC Grinding September 2005
342
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT Mill outlet or product temperature Heating and drying •
•
•
MILL OUTLET TEMPERATURE BY BURNER’S FUEL => risk of cement quality by unburned => maximum mill inlet temperature for cement grinding 350 °C or MILL OUTLET TEMPERATURE BY FRESH AIR DUMPER ON HOT GASES DUCT FROM HEATING SOURCE
PRODUCT TEMPERATURE BY RECIRCULATION DUMPER AND/OR FRESH AIR DUMPER IN SEPARATOR’S AIR RECIRCULATION SYSTEM => 2nd and 3rd generation dynamic separators Italcementi Group
PIC Grinding September 2005
343
VIII- CIRCUIT PROCESS CONTROL CLOSED CIRCUIT DOUBLE ROTATOR MILL
IN ADDITION TO THE CONTROL AS FOR STANDARD CIRCUIT • MATERIAL FILLING DEGREE OF MILL’S COMPARTMENTS ( electronic ear for each compartment ) BY DISTRIBUTION OF SEPARATOR REJECT FLOW BETWEEN GRINDING AND FINISHING COMPARTMENTS • AIR FLOW ( fresh or hot ) IN FINISHING COMPARTMENT MANUALLY ADJUSTED FOR PROPER MILL VENTILATION
Italcementi Group
PIC Grinding September 2005
344
VIII- CIRCUIT PROCESS CONTROL AIR SWEPT MILL CIRCUIT
• VENTILATION THROUGH THE MILL CONSTANT ( measured by Venturi before mill fan) BY DUMPER OF MILL FAN • MILL FEED BY DIFFERENTIAL PRESSURE THROUGH THE MILL or • MILL FEED BY MILL NOISE (ELECTRONIC EAR) • DRYING CAPACITY BY GAS RECIRCULATION Italcementi Group
PIC Grinding September 2005
345
VIII- CIRCUIT PROCESS CONTROL VERTICAL MILL CIRCUIT FOR RAW MATERIALS • VENTILATION THROUGHT THE MILL CONSTANT BY MILL EXHAUST FAN
• MILL FEED BY MILL DIFFERENTIAL PRESSURE • MILL INLET DEPRESSURE BY FRESH AIR DUMPER AT THE MILL INLET
Italcementi Group
PIC Grinding September 2005
346
VIII- CIRCUIT PROCESS CONTROL VERTICAL MILL CIRCUIT FOR RAW MATERIALS • MILL OUTLET GAS TEMPERATURE BY MILL INLET GAS TEMPERATURE ( kiln spray tower or furnace ) or / and • MILL OUTLET GAS TEMPERATURE BY WATER SPRAY INSIDE THE MILL The mill outlet temperature affects a lot the steady running of the mill ( good control of vibrations ) Italcementi Group
PIC Grinding September 2005
347
IX - INFLUENT PARAMETERS ON kWh/T 1. 2. 3. 4. 5. 6. 7. 8.
Mill Speed Ball-Material Filling Degree Ball Charge Liners and Diaphragms (Circulating Load) Ventilation and Air Velocities False Air Mill Feed Moisture Product Fineness
Italcementi Group
PIC Grinding September 2005
348
1- MILL SPEED
42.3
Critical speed =
= g/I’ Useful D (m) 76.6
Critical speed =
= g/I’ Useful D (feet)
Rotation speed = 70 77% critical speed
Italcementi Group
PIC Grinding September 2005
349
2- BALL-MATERIAL FILLING DEGREE % of critical speed
Ball volume in % of global volume
0
Italcementi Group
PIC Grinding September 2005
350
2- BALL-MATERIAL FILLING DEGREE
INFLUENCE OF MATERIAL FILLING DEGREE AND CIRCULATING LOAD ON MILL PERFORMANCES EXAMPLE OF SPEED PLANT CEMENT (95% CK + 5% G) MILL SEPARATOR THROUGHPUT t/h MILL POWER kW MILL CONSUMPTION kW/t CIRCULATING LOAD t/h BLAINE cm²/g
Italcementi Group
PIC Grinding September 2005
SPEED TYPE 1 FLS 13 * 43 OSEPA N1500 68.9 73.5 2900 2900 42.1 39.5 226.7 283.0 3600 3580
351
2- BALL-MATERIAL FILLING DEGREE
t/h kWh/t
% volume load
Italcementi Group
PIC Grinding September 2005
352
2- BALL-MATERIAL FILLING DEGREE BALL/MATERIAL VOLUME LOAD First chamber
Second chamber
Second chamber
First chamber
Mill material level
HOW TO CHECK CORRECT MATERIAL FILLING: • CIRCULATING LOAD • MILL INSPECTION AFTER CRUSH STOP • MILL NOISE Italcementi Group
PIC Grinding September 2005
353
3- BALL CHARGE
PLANT MILL SEPARATOR WORKSHOP PRODUCT FINENESS THROUGHPUT MILL POWER MILL CONSUMPTION FIRST CHAMBER SECOND CHAMBER FIRST CHAMBER SECOND CHAMBER
Italcementi Group
t/h kW kWh/t t t m²/t m²/t
CRUAS FCB 2.2*13.0 Polysius TSU-DSE Cement 2 CPJ (white cement) Blaine=4230 cm²/g 14.2 15.3 560 529 39.5 34.6 13.8 13.9 47.2 43.7 10.8 10.6 26.7 31.8
PIC Grinding September 2005
TRIESTE TOSI 10' * 22' Stutevant 16' Raw 2 Raw product R90=6.0 to 6.6% 29.5 34.9 754 762 31.1 21.8 18.7 18.0 37.5 35.6 9.5 9.2 19.4 14.2
354
4- LINERS AND DIAPHRAGMS CIRCULATING LOAD
Circulating load Italcementi Group
PIC Grinding September 2005
355
5- VENTILATION AND AIR VELOCITIES VENTILATION IN THE MILL
• Goal:
=> Decreases the cement temperature (finished mill) => Dries the raw material in raw mills (hot gas) => Helps the ultra-fines to escape from the mill (improve the by-pass of fines and avoid overgrinding and coating)
• Characteristics: => Ventilation in the mill (closed circuit): 1 to 2 m/s (*) => Ventilation in the mill (closed circuit + drying chamber mill): 4 to 7 m/s (*) => Mill design (type of command, bearing & diaphragm) (*) referred to free volume inside the mill and outlet mill air flow Italcementi Group
PIC Grinding September 2005
356
5- VENTILATION AND AIR VELOCITIES MILL VENTILATION AND AIR VELOCITIES
Italcementi Group
PIC Grinding September 2005
357
6- FALSE AIR Point to care after for checking false air in the mill circuit
Italcementi Group
PIC Grinding September 2005
358
6- FALSE AIR
•
kWh/t
•
Mill ventilation
•
Mill efficiency
•
Drying capacity
How to fight false air: * Control air tightness into the circuit * Temperature through the circuit * Gas analysis (only with furnace or kiln gas) Italcementi Group
PIC Grinding September 2005
359
7- MILL FEED MOISTURE
MAXIMUM DRYING CAPACITY OF HORIZONTAL MILLS WITHOUT DRYING CHAMBER: => 1.5% OF WATER IN FRESH FEED MATERIAL
FURTHER THIS PERCENTAGE THE ENERGY MAY BE BROUGHT BY EXTERNAL HEAT SOURCE (care about quality !!!)
Italcementi Group
PIC Grinding September 2005
360
7- MILL FEED MOISTURE
PLANT CEMENT MILL SEPARATOR MATERIAL INLET MOISTURE BLAINE cm²/g THROUGHPUT t/h CONSUMPTION kWh/t R90 µm % CLINKER °C HOT GAS °C
Italcementi Group
HALYPS II35 (16.5% pozzolane) KHD 3*8.2 O & K 5000 2.7 TO 2.8% 3500 27.3 29.1 33.5 32.9 30.1 26.1 4.6 4.4 COLD 125 125 No No 160
PIC Grinding September 2005
361
8- PRODUCT FINENESS PRODUCTION INCREASE THEORETICAL FOR CEMENT MILL WITH PREGRINDING
Production increase theoretical for cement mill with pregrinding, calculation according to BOND (with correction factors), reduction of mill fresh feed P80 from 15 mm down to x mm
Italcementi Group
PIC Grinding September 2005
362
8- PRODUCT FINENESS FRESH FEED GRANULOMETRY: 0 30 mm 0 120 mm
Horizontal mills Vertical mills
P80 = 20 mm P80 = 80 mm (depending on rollers size)
FINISH PRODUCT FINENESS: Raw meal
residue 90 mm 5 15 % residue 200 mm 0 1.5 %
(depending on kiln type)
Coal
residue 90 mm 5 18 % residue 200 mm 0 2 %
(depending on coal type)
OPCement 32.5 OPCement 42.5 OPCement 52.5
Blaine 2800 3300 cm2/g Blaine 3300 3800 cm2/g Blaine 3800 5000 cm2/g
(depending on clinker reactivity)
Italcementi Group
PIC Grinding September 2005
363
X - MILL CHECK UP 1. 2. 3. 4. 5.
Timing before Check-Up To do before Crash-stop Mill Visit Circulating Load Measurement Data Evaluation
Italcementi Group
PIC Grinding September 2005
364
1- TIMING BEFORE CHECK-UP Mill and circuit evaluation, from control room and on the field, during steady and current mill running conditions. If necessary, adjust the running conditions in order to optimize the mill operation. Try to get a good knowledge of the problems affecting the installation. In the case of production of two different products, a check-up has to be foreseen for each quality. If not possible, choose the product with lower fineness (higher mill capacity).
Italcementi Group
PIC Grinding September 2005
365
1- TIMING BEFORE CHECK-UP
TO BE PREPARED BY THE CEMENT PLANT :
Workshop visit with somebody from manufacturing. Sampling points identification, accessibility and reliability. Process data of last months or weeks. Feeders and electrical energy meters reliability.
Italcementi Group
PIC Grinding September 2005
366
2- TO DO BEFORE CRASH-STOP
Workshop visit with somebody from manufacturing department (somebody used to run the mill). Take in control room the running mill parameters (screen printing and production report). Electrical energy meters state and values Feeders state and values. Take samples of material in the circuit (from feeders to finish product) for moisture content and size distribution analysis. Make flow, pressure and temperature measurements into the gas circuit. Take material temperatures into the circuit. Gas analysis, if possible (O2 mainly), in case of kiln gas or furnace gas use.
Italcementi Group
PIC Grinding September 2005
367
2- TO DO BEFORE CRASH-STOP FLOW SHEET
Italcementi Group
PIC Grinding September 2005
368
2- TO DO BEFORE CRASH-STOP PLANT DATA
Italcementi Group
PIC Grinding September 2005
369
2- TO DO BEFORE CRASH-STOP PLANT DATA
Italcementi Group
PIC Grinding September 2005
370
2- TO DO BEFORE CRASH-STOP MEASURE POINTS
Italcementi Group
PIC Grinding September 2005
371
2- TO DO BEFORE CRASH-STOP CYCLE SAMPLING
Italcementi Group
PIC Grinding September 2005
372
2- TO DO BEFORE CRASH-STOP
S:duct section (m) Ps:static pressure (pa) T:temperature (°C) Patm:atmospheric pressure (Pa) Patm=101325Pa=14.7 PSI Pd:dynamic pressure (Pa) d:density (Kg/Nm3):dair=1.293 (See values on following page) Q:throughput (Nm3/h) k: for a Pitot => k=1 for a Beri =>0.7
( Patm Ps).273 K' Patm. (273 T )
Gas velocity V (m/s)
V k.
2. Pd 2 k . Pd K '. d K '. d
Gas throughput (Nm3/h)
Q S .V . K '.3600 Italcementi Group
PIC Grinding September 2005
373
2- TO DO BEFORE CRASH-STOP Density values: %O2 in gas DRY PROCESS 2% 1% H2O in Raw 4% PF=35,06% 6% 500 ppm CO 8% 10% 12% SEMI-DRY PROCESS 2% 13% H2O Raw 4% PF=35.68% 6% 500 ppm CO 8% 10% 12% WET PROCESS 2% 35% H2O Raw 4% PF=35,41% 6% 500 ppm CO 8% 10% 12%
Italcementi Group
Coal 1.46 1.44 1.42 1.41 1.39 1.37 1.36 1.36 1.35 1.34 1.33 1.32 1.23 1.23 1.24 1.24 1.25 1.25
PIC Grinding September 2005
Fuel 1.39 1.38 1.37 1.36 1.35 1.34 1.34 1.34 1.33 1.33 1.32 1.32 1.20 1.21 1.22 1.22 1.23 1.24
Gas 1.35 1.35 1.34 1.33 1.33 1.32 1.29 1.29 1.29 1.29 1.29 1.29 1.17 1.18 1.19 1.20 1.21 1.22
374
2- TO DO BEFORE CRASH-STOP CRASH STOP
Machines have to be stopped in emergency (all at the same time)
The plant has to prepare the visit inside the mill (doors opening, ladders, lights, plastic bags, spoons) taking care about
Safety procedures
Italcementi Group
PIC Grinding September 2005
375
3- MILL VISIT BALL CHARGE MATERIAL SAMPLING First chamber
Second chamber
Take samples (# 10 balls in first chamber and 15 to 20 in second chamber) every meter all along the mill. Material (0.5 kg) has to be taken at the same places. Italcementi Group
PIC Grinding September 2005
Samples have to be taken on this side
376
3- MILL VISIT Why ? To calculate the ball charge filling ratio and check the mill power consumption according to CTG - CMM formula. To evaluate the material filling degree of each compartment. Why ? To evaluate material flow capacity and air speed through the diaphragm, the risk to have balls passing through the diaphragm, the maximum filling degree and forecast maintenance
slot plugging ratio thickness Italcementi Group
PIC Grinding September 2005
377
3- MILL VISIT • Inlet and outlet mill heads: thickness Why? To check gas velocity, the maximum filling degree and forecast maintenance • * * Number of liner raws * Check liners thickness, wear, breakage and the eventual gaps between liners * Coating on balls and on liners Italcementi Group
PIC Grinding September 2005
Why? Grinding efficiency Maintenance
378
3- MILL VISIT
Points to check: • • • • •
Italcementi Group
Material spread Maximum and minimum ball size Balls wear, breakage and deformation Balls charge spread Coating on balls, liners, diaphragms
PIC Grinding September 2005
379
3- MILL VISIT MILL INTERNAL SITUATION
Italcementi Group
PIC Grinding September 2005
380
3- MILL VISIT CLASSIFIER INTERNAL CHARACTERISTICS N° of fan blades
N° of valves
Short Medium Long
Ring
Italcementi Group
N° of selector blades
PIC Grinding September 2005
381
4- CIRCULATING LOAD MEASUREMENT A CIRCULATING LOAD: A = R + F (t / h) or A / F (ratio)
R
FRESH FEED
Italcementi Group
PIC Grinding September 2005
F
382
4- CIRCULATING LOAD MEASUREMENT
Weight some (3 - 4) buckets of the mill discharge elevator to check the circulating load (calculated by size distribution curve analysis of separator). If an impact flow meter on the separator rejects has been installed, check the indication.
Italcementi Group
PIC Grinding September 2005
383
4- CIRCULATING LOAD MEASUREMENT
Italcementi Group
PIC Grinding September 2005
384
XI - DATA EVALUATION
Italcementi Group
PIC Grinding September 2005
385
DATA EVALUATION Italcementi Group
GRINDING EFFICIENCY SEPARATOR BALL CHARGE BALLS / MATERIAL BALLS CLASSIFICATION COATING LINERS AND DIAPHRAGMS VENTILATION AND FALSE AIR THERMAL BALANCE MATERIAL SIZE DISTRIBUTION MILL FEED MOISTURE PIC Grinding September 2005
386
XII - EFFICIENCY EVALUATION 1. 2. 3. 4. 5. 6.
Grinding Efficiency Material Size Distribution Mill Separator Circuit Ventilation Review of parameters
Italcementi Group
PIC Grinding September 2005
387
1- GRINDING EFFICIENCY
ENERGY LOST: • Attrition / impact between balls and liners • Attrition / impact between balls • Strain elastic energy • Acoustic energy (noise) and vibration • Overgrinding and reagglomeration
Italcementi Group
PIC Grinding September 2005
388
1- GRINDING EFFICIENCY
=> Impact
=> => =>
Temperature Liner wear Ball wear
=> Attrition
=> => =>
Temperature Liner wear Ball wear
=> =>
Temperature Ball wear
=> Impact & Attrition Italcementi Group
PIC Grinding September 2005
389
1- GRINDING EFFICIENCY ENERGY CONVERSION
310%
100%
9097% Italcementi Group
PIC Grinding September 2005
390
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
391
1- GRINDING EFFICIENCY
CONCLUSION:
1 to 3 % OF THE GLOBAL GRINDING ENERGY IS USEFULL ENERGY FOR PARTICLE SIZE REDUCTION Italcementi Group
PIC Grinding September 2005
392
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
393
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
394
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
395
1- GRINDING EFFICIENCY
Italcementi Group
PIC Grinding September 2005
396
2- MATERIAL SIZE DISTRIBUTION
Evaluate the influence of mill filter fineness on the final product quality (in some case, it can be opportune to recycle the filter product into circuit). Care: dedusting points can affect the final product fineness.
Italcementi Group
PIC Grinding September 2005
397
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
398
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
399
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
400
2- MATERIAL SIZE DISTRIBUTION
Italcementi Group
PIC Grinding September 2005
401
3- MILL Material filling degree versus ball charge
Max filling ratio filling ratio
Actual
Mill installed power absorbed power
Mill
Possibility to increase production Italcementi Group
PIC Grinding September 2005
402
3- MILL
% volume load
Italcementi Group
PIC Grinding September 2005
403
3- MILL Low filling material level in the mill First chamber
Second chamber
Mill material level
Italcementi Group
PIC Grinding September 2005
404
3- MILL High filling material level in the mill First chamber
Second chamber
Mill material level
Italcementi Group
PIC Grinding September 2005
405
3- MILL Correct filling material level in the mill First chamber
Second chamber
Mill material level
Italcementi Group
PIC Grinding September 2005
406
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
Average balls diameter Criteria : • Straight line in C1 • Decreasing line in C2 C.1.1
C.1. n
C.2.1
C.2.n
Ball classification affected by : • ball charge filling degree • material filling degree Italcementi Group
PIC Grinding September 2005
407
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
Italcementi Group
PIC Grinding September 2005
408
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
BAD CLASSIFICATION Italcementi Group
PIC Grinding September 2005
409
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
GOOD CLASSIFICATION Italcementi Group
PIC Grinding September 2005
410
3- MILL BALLS CLASSIFICATION INSIDE THE MILL
BAD CLASSIFICATION Italcementi Group
PIC Grinding September 2005
411
3- MILL
85-95 75-85 65-75 First chamber length
Italcementi Group
Second chamber: Correct Charge classification inversion Ball percentage
Ball percentage
First chamber: No classification for a correct efficiency
"V" classification
22-27
Second chamber length
PIC Grinding September 2005
412
3- MILL
Results of ball charge sampling using the average balls diameter Mono-chamber mill (diameter 10' x 22'). MONOPOLI plant (Italy)
100 80 60 40 20 0
84
69
60
er s
Average ball diameter 29
6
m et
er s
m et
er s 5
m et
er s 4
m et
er s 3
m et
er
40
2
m et 1 Italcementi Group
74
PIC Grinding September 2005
413
3- MILL BALLS CHARGE BULK DENSITY
lbs/ft3
mt/m3
Compartment 1
280.91
4.50
Compartment 2
290.27
4.65
Mono chamber
284.03
4.55
Italcementi Group
PIC Grinding September 2005
414
3- MILL METER SAMPLING AND CHARGE MOVEMENT
Italcementi Group
PIC Grinding September 2005
415
3- MILL CUMULATED SIZE DISTRIBUTION CURVE Criteria :
% retained
•end of C1 : max 5% > 2.5 mm
µ
•end of C2 : 10 - 20% < 90 µm for closed circuit •decreasing line in C1 & C2
C1.1
C1.n
C2.1
C2.n
Sieving : 20 mm, 10 mm, 5 mm, 2.5 mm; 1.5 mm, 630 µm, 320 µm, 160 µm, 80 µm, 40 µm. Italcementi Group
PIC Grinding September 2005
416
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
417
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
418
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
419
3- MILL MILL INTERNAL SAMPLING
Italcementi Group
PIC Grinding September 2005
420
29/04/2002
C.T.G. - Italcementi Group - Comminution Department Company Plant Department Circuit type New charge date Mill speed Critical speed
g/1' g/1'
Critical speed 1st chamber
Characteristics Type of liner Diaphragm slots Measured free height Ratio steel / cement Useful diameter Useful lenght Useful lenght Total volume compart. Ball charge density Charge volume Filling degree Calculated free height Ball charge to add for each cm of free height Ball charge D = 100 mm D = 90 mm D = 80 mm D = 70 mm D = 60 mm D = 50 mm D = 40 mm D = 30 mm D = 25 mm D = 20 mm D = 17 mm Cil 25x25 mm Cil 22x22 mm Cil 19x19 mm Cil 16x16 mm
18,63 Installed power 27,8 Absorbed power 67,1% Ratio L/Ø
Av. size ball
mm
kW kW
mm m % m m % m³ t/m³ m³ % m
°C
Inlet 5,32
1st compartment
2nd compartment
6,0
6,0
Free area for gases Outlet m² m² 3rd compartment
2,320 3,200 25,9 13,5 4,49 4,0 29,9 1,53
mm m % m m % m³ t/m³ m³ % m
2,320 9,150 74,1 38,7 4,79 11,6 30,1 1,53
mm m % m m % m³ t/m³ m³ % m
t
0,32
t
0,97
t
t
%
t
%
6,42 3,75 3,75 4,28
18,2 Total compartement Mill total t 74,0 Ball S.S. Surface m² 1.711 Surface Av, weight ball g
3- MILL
Mill Feed point Hot gases Hot gas temperature Separator
35,3 20,6 20,6 23,5
24,6 m²/t m²
150 Av, weight ball g 33 Av. size ball mm
Italcementi Group
m
2
m
2
t
%
m
MILL BALL CHARGE
2
54 36 41 54
4,22 8,45 3,56
7,6 15,1 6,4
65 161 91
39,60
70,9
1209
185 55,8 10,2 Ball S.S. 185 Surface
75,4 m²/t m²
1598 Av, weight ball g 73 Av. size ball mm
1525
27,3 Ball S.S. 1.525 Surface
m²/t m²
116 Av, weight ball g 30 Av. size ball mm
PIC Grinding September 2005
421
3- MILL
COATING
30% of grinding efficiency can be lost
Reasons: Important retention time into the mill High temperature in second chamber ( >110° C at mill discharge) Raw material moisture + low temperature in first chamber Low filling degree of material versus balls in the compartments Grinding of cement types with high limestone content
Italcementi Group
PIC Grinding September 2005
422
3- MILL COATING Remedies : Appropriate ventilation in the mill Add water (calculated by thermal balance) in order to maintain a correct temperature at the mill outlet (< 105 °C) Use grinding aid If possible, use 2-3 % of abrasive material (slag, sand, ...) Concerning a possible coating in first chamber due to moisture, the remedy is to increase t° ( tails, clinker t°, hot gas into mill).
Italcementi Group
PIC Grinding September 2005
423
3- MILL Diaphragm slots dimensions
– outlet diaphragm slots dimension > intermediate diaphragm slots dimension – slots clogging affect material retention time and mill ventilation (clogging degrees < 40% of free area) Liners wear
– affect the reliability of liners
Italcementi Group
PIC Grinding September 2005
424
3- MILL
Circulating load Italcementi Group
PIC Grinding September 2005
425
4- SEPARATOR
Tromp (%) curve
Separator efficiency
Selectivity = f (securing) Material sampling evaluation Feeding (A)
Tails (T)
Fines (F)
Italcementi Group
Laser & Alpine Results
Selectivity
What percentage of a given particle size in the classifier feed is discharged in the tailing.
PIC Grinding September 2005
426
4- SEPARATOR KNOW HOW !!!
Italcementi Group
SELECTIVITY
PIC Grinding September 2005
427
4- SEPARATOR Monselice plant - Finish mill #4 Separator UM 6700
Italcementi Group
PIC Grinding September 2005
428
4- SEPARATOR TROMP CURVE Selectivity (%)
Tails in fines
Global by-pass (Stg)
P(t) 50 % Imperfection= (d75 - d25) / 2d50 By-pass slope (Pts) Fines in tails Particle size (μm)
Italcementi Group
PIC Grinding September 2005
Minimum by-pass (St) Log 429
4- SEPARATOR
Italcementi Group
PIC Grinding September 2005
430
4- SEPARATOR
Italcementi Group
PIC Grinding September 2005
431
5- CIRCUIT VENTILATION • Goal: => Decreases the cement temperature (finished mill) => Dries the raw material in raw mills (hot gas) => Helps the ultra-fines to escape from the mill (improve the by- pass of fines and avoid overgrinding and coating) • Characteristics: => Ventilation in the mill (closed circuit): 1 to 2 m/s (*) => Ventilation in the mill (closed circuit + drying chamber mill): 4 to 7 m/s (*) => Mill design (type of command, bearing & diaphragm) (*) referred to free volume inside the mill and outlet mill air flow Italcementi Group
PIC Grinding September 2005
432
5- CIRCUIT VENTILATION We must have a good idea of the ventilation through the mill. A particular attention has to be taken to the false air entrances in the circuit. Tube ventilation: Open circuit: 250-350 Nm3/mt of finished product 0.5-0.8 m/s (gas net speed inside mill) Closed circuit: 300-600 Nm3/mt of finished product 0.7-2. m/s (gas net speed inside mill) Mill inlet / outlet head ventilation: Maximum of 35 m/s False air : to be kept to the minimum normal range: 20 - 40% of the inlet gas flow Italcementi Group
PIC Grinding September 2005
433
5- CIRCUIT VENTILATION False air affects a lot the mill ventilation and energy power consumption False air can provide from: Mill tube: inlet joints outlet joints material feed Mill discharge Dedusting Bag filter jet pulsing Flaps airtightness high negative pressure ducts and machines ... Italcementi Group
PIC Grinding September 2005
434
5- CIRCUIT VENTILATION Point to care after for checking false air in the mill circuit
Italcementi Group
PIC Grinding September 2005
435
5- CIRCUIT VENTILATION THE PLANT ENERGY CONSUPTION DEPENDS ON THE PRESSURE DROPS IN FILTER, MILL, ...
THE CONTROL OF PRESSURE IN DIFFERENT POINTS OF THE CIRCUIT IN THE GRINDING PLANT IS CRUCIAL TO MINIMIZE THE GRINDING ENERGY CONSUMPTION CHECK THE PROCESS FAN EFFICIENCY AND THE DAMPER OPENING: THIS POINTS COULD COST A LOT OF ENERGY Italcementi Group
PIC Grinding September 2005
436
6- REVIEW OF PARAMETERS THERMAL BALANCE - DEW POINT
Due to the material moisture, the dew point has to prevent bag filter from clogging. => (bag filter gas temperature - dew point temperature) > 30°C P in Kg/cm2 Vaporisation pressure: Pv Pgs.(1 %H 2 O) 1 with P: absolute pressure in Pgh .%H 2 O Kg/cm2 (mbars*0.00102) P = Patm.-chimney depressure Pgs = Volumic mass of dry gas Pgh = Volumic mass of wet gas
Italcementi Group
Temperature of condensation: Tc
5168 273,16 in °C 13,89 ln( Pv)
PIC Grinding September 2005
437
6- REVIEW OF PARAMETERS MATERIAL SIZE DISTRIBUTION
Evaluate the influence of mill filter fineness on the final product quality (in some case, it can be opportune to recycle the filter product into circuit). Care: dedusting points can affect the final product fineness.
Italcementi Group
PIC Grinding September 2005
438
6- REVIEW OF PARAMETERS BALL - MATERIAL FILLING
INFLUENCE OF MATERIAL FILLING DEGREE AND CIRCULATING LOAD ON MILL PERFORMANCES EXAMPLE OF SPEED PLANT CEMENT (95% CK + 5% G) MILL SEPARATOR THROUGHPUT t/h MILL POWER kW MILL CONSUMPTION kW/t CIRCULATING LOAD t/h BLAINE cm²/g
Italcementi Group
PIC Grinding September 2005
SPEED TYPE 1 FLS 13 * 43 OSEPA N1500 68.9 73.5 2900 2900 42.1 39.5 226.7 283.0 3600 3580
439
6- REVIEW OF PARAMETERS BALL CHARGE PLANT MILL SEPARATOR WORKSHOP PRODUCT FINENESS THROUGHPUT MILL POWER MILL CONSUMPTION FIRST CHAMBER SECOND CHAMBER FIRST CHAMBER SECOND CHAMBER
Italcementi Group
t/h kW kWh/t t t m²/t m²/t
CRUAS FCB 2.2*13.0 Polysius TSU-DSE Cement 2 CPJ (white cement) Blaine=4230 cm²/g 14.2 15.3 560 529 39.5 34.6 13.8 13.9 47.2 43.7 10.8 10.6 26.7 31.8
PIC Grinding September 2005
TRIESTE TOSI 10' * 22' Stutevant 16' Raw 2 Raw product R90=6.0 to 6.6% 29.5 34.9 754 762 31.1 21.8 18.7 18.0 37.5 35.6 9.5 9.2 19.4 14.2
440
6- REVIEW OF PARAMETERS MILL FEED MOISTURE
MAXIMUM DRYING CAPACITY OF HORIZONTAL MILLS WITHOUT DRYING CHAMBER: => 1.5% OF WATER IN FRESH FEED MATERIAL
FURTHER THIS PERCENTAGE THE ENERGY MAY BE BROUGHT BY EXTERNAL HEAT SOURCE (care about quality !!!)
Italcementi Group
PIC Grinding September 2005
441
6- REVIEW OF PARAMETERS MILL VENTILATION
CASE OF WET MATERIAL PLANT MILL SEPARATOR CEMENT THROUGHPUT MILL POWER MILL CONSUMPTION AUXILIARY POWER AUXILIARY CONSUMPTION GLOBAL POWER GLOBAL CONSUMPTION MILL VENTILATION DAMPER SEPARATOR VENTILATION DAMPER ELEVATOR ABSORPTION PRESEPARATOR EXIT DEPRESSION
ventilation => Italcementi Group
3400 cm²/g t/h wet kW kWh/t kW kWh/t kW kWh/t % % A mmCA
throughput & PIC Grinding September 2005
ANKARA FLS 4*11.5 FLS Sepax KC32.5 (16% pozzolane) 96.75 103.95 2672 2639 27.62 25.39 395 458 4.08 4.41 3067 3097 31.70 29.79 35 MAX 80 42 MAX 50 64 70 148 223.0
kWh/t 442
6- REVIEW OF PARAMETERS MILL FEED MOISTURE PLANT CEMENT MILL SEPARATOR MATERIAL INLET MOISTURE BLAINE cm²/g THROUGHPUT t/h CONSUMPTION kWh/t R90 µm % CLINKER °C HOT GAS °C
Italcementi Group
HALYPS II35 (16.5% pozzolane) KHD 3*8.2 O & K 5000 2.7 TO 2.8% 3500 27.3 29.1 33.5 32.9 30.1 26.1 4.6 4.4 COLD 125 125 No No 160
PIC Grinding September 2005
443
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY
Independent of material grindability Lied to plant efficiency Usually equal to: 0.85 for open circuit 0.87 for closed circuit with first generation separator 0.95 to 1 for closed circuit with 2nd and 3rd generation separator
Limit: air swept mills Italcementi Group
PIC Grinding September 2005
444
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY
LABORATORY TEST => specific energy at given Blaine fineness [Elab.mech. x (kWh/t at given fineness)] INDUSTRIAL DATA => Eindustrial electr (kWh/t at given fineness) Elab.mech / drive eff. = Elab.electr. ball mill efficiency = Elab.electr. / Eindustrial electr. With drive efficiency = 0.91 for pinion and girth drive = 0.92 for central drive Italcementi Group
PIC Grinding September 2005
445
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY CALCULATION
ALSING TEST => Alsing specific energy for a given Blaine fineness [E mecha. (kWh/t / given fineness)] INDUSTRIAL DATA => E industrial elec. (kWh/t / given fineness) EAl sin g . elec . hBall . mill Eindustrial . elec
Emecha . EAl sin g . elec . hmecha .
with hmecha . = 0.91 for pinion and gearless drive = 0.92 for central drive Italcementi Group
PIC Grinding September 2005
446
6- REVIEW OF PARAMETERS BALL MILL EFFICIENCY CALCULATION
Characteristics of hBall . mill :
• Independent of material grindability • Lied to plant efficiency • Usually equal to: * 0.85 for opened circuit * 0.87 for closed circuit with first generation separator * 0.95 to 1 for closed circuit with 2nd and 3rd generation separator
• Limit: airswept mills Italcementi Group
PIC Grinding September 2005
447
6- REVIEW OF PARAMETERS PLANT MILL EFFICIENCY CALCULATION
PGrinding . plant ESpecific. CA ESpecific. roller . press ESpecific. ball . mill Pr oduction
EAl sin g . CA PLANT . EFFICIENCY hBall . mill hRoller. . press C ESpecific . A Why? Because the Alsing test is considered like a standard test and so hBall . mill = 100% for an optimized ball charge and a third generation classifier Italcementi Group
PIC Grinding September 2005
448
6- REVIEW OF PARAMETERS PLANT MILL EFFICIENCY CALCULATION
Example: CCB-DR8 (Belgium):
EAl sin g . CA PLANT . EFFICIENCY hBall . mill hRoller. . press C ESpecific . A Plant efficiency = 13.9/(10.6+4.1) = 94.5%
Italcementi Group
PIC Grinding September 2005
449
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