Effects Of Specific Charge And Edd:s On Fragmentation In An Aggregate Quarry, Building Kco Design Curves

University of Cambridge, Applied Detonation Physics and Blast Modelling, 22-26 Sept 2014

Effects of specific charge and EDD:s on fragmentation in an aggregate quarry, building KCO design curves Finn Ouchterlony, Montanuniversität Leoben, Austria Ulf Nyberg, Swebrec at Luleå Univ Techn, Sweden. Mats Olsson, EDZ-consulting, Älvsjö, Sweden Kerstin Widenberg, NCC Construction, Solna, Sweden Per Svedensten, Sandvik Construction, Svedala, Sweden.

Building KCO design curves Contents      

Purpose and consortium Test site Tests and data monitoring Fragmentation Blast design curves Conclusions

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Building KCO design curves Purpose: 

to validate earlier work with design curves in Vändle granite quarry in a quarry with different geological conditions



to evaluate EDD:s (electronic delay detonators) with respect to possible finer fragmentation and other improvements in bench blasting

Consortium: MinBaS Mineral•Ballast•Sten

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Test site 

Långåsen quarry at Arlanda airport: 0.4 Mton/yr granodiorite aggregate, test period 2007-2009

asphalt plant crusher plant

test piles

rounds Atlas SmartRig D9C

Svedala Arbrå R120×100 jaw cr.

Tests and data monitoring Round 1-N 0,8 kg/m 3 row 1: 3,4x3,4 m row 2-4: 2,6x3,4 m

1-H Nonel 1,1 kg/m 3 2 holes / 25 ms in-row 67 ms inter-row

1,1 kg/m 3 m m m m

2-N Nonel 0,8 kg/m 3 2 holes / 25 ms in-row 67 ms inter-row EPD/elektronic 0,8 kg/m 3 10 ms inter-hole in row 67 ms inter-row

3,4x3,4 m 2,6x3,4 m

EPD/elektronic 0,8 kg/m 3 5 ms inter-hole in row 67 ms inter-row

Round 2-H row 1: 2,9x2,9 row 2-4: 2,2x2,9 Round 3 row 1: 3,4x3,4 row 2-4: 2,6x3,4 Round 4 row 1: row 2-4:

round 1, Nonel 0,8+1,1 kg/m3 1-N: 7700 m3 + 1-H: 5600 m3

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round 4, elektronics 0,8 kg/m3 14000 m3

Tests and data monitoring  Joint mapping & bench geometry with Blast Metrix

 Drill collaring & MWD with Atlas Copco D9C Smart rig  Hole deviations with Devibench  Charging follow up on hole by hole basis  VOD, filming, PPV and air blast during rounds  Fragmentation from sieving and image based method

 Building test piles during digging; sorting and crushing  Special tests on pile material: LA-abrasion, ball mill, Split Hopkinson bar etc.

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Tests and data monitoring Rd 1, Nonel, normal (1-N) & high (1-H) specific charge

fine to medium grained granodiorite (1-3 mm) UCS = 206 MPa

pegmatite dikes

major joints strike N20-70°E and dip steeply towards SE

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Fragmentation Test piles:

shuffled, homogenized test piles

before homogenization

11 test piles: Pile 1A

Pile 1B

Pile 2A

Pile 2B

Pile 3B

3C

3A pegmatite

Pile 4D

4C

4D

4A pegmatite

variations within EDD rounds of interest

100 ton sieved, fractions weighed, put back, reshuffled before pile run through crusher.

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Fragmentation test pile  400 ton

100 t

bucket

bucket

Putting back sorted material in test pile reshuffling

grizzly 200 mm +200

Grizzly +200 mm weighed, put back -200 weighed, sieved

lab bucket -sample bucket sieve 125 mm

+125

truck

Sorting 1 +125 mm weighed, put back -125 weighed, to interim storage, then sieved

interim storage 0/125 mm

Sorting 2 +75 mm weighed 40/75 mm weighed -40 mm weighed

bucket sieve 40+75 mm

tray

tray

0/40 lab sample

tray

40/75

75/125

Weighing: Bucket scale, product scale, belt scale, belt motor power

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Fragmentation Median fragment size from sieving, x50 for ave. loss scenario

EDD initiation: coarser fragmentation than Nonel at normal specific charge!

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conclusions supported by image analysis

pegmatite Nonel: a higher specific charge gives finer fragmentation

Blast design curves

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Lab sieving test piles mtrl before (sorted) and after crushing:

Each curve average of 11 samples, one for each pile Curves renormalized with respect to total weight of 0/16 mm fraction of 0/125 mm samples. Agreement between curves good in 0/16 mm range useful data range 45

0/45 mm part of 0/125 mm curve represents muck pile fines

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Blast design curves Building complete sieving curves: boulder part

 fines region from lab samples, 0/45 out of 0/125  middle region from test pile sieving

 fines ’tail’ spliced to test pile data

test piles lab sieving

boulders

 use Swebrec function  consider equiv. grizzly opening  coarse region from estimating boulders

overlap 40-45 mm

Blast design curves Ppile(x) Pround(x)

Difference between pile and round (pile + oversize OS) affects x50 and whole curve

Fragmentation distribution for loaded test pile, excl. OS% Ppile(x) = Pround(x)/[1-OS/100] for x ≤ xOS Swebrec function for whole blast round, incl. oversize OS

Pround(x) = P (x) = 100/{1+[ln(xmax/x)/ln(xmax/x50)]b} Five parameters to determine; x50, xmax, b + OS and xOS

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Blast design curves: Finding Pround Stepwise procedure to find x50, xmax, b, OS and xOS. Use r2, xmax, b and residual OS to judge fits  See how closely Swebrec P(x) describes pile data  Reweight influence of residuals, w=1, OS still 0%  Equiv. grizzly mesh (//200  #220 mm), reweight 1/x0.25. OS = 5% for rounds data. xOS = 0.9-1 m  For high q rounds OS = 4%, for low q, OS = 7%

 Use same b = 4,17 or blasting harder creates less -1 mm fines

 r2 = 0,998, xmax = 5-10 m, OSres = 1-2%, b = 0

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Blast design curves

Mass Andelpassing, passerar,% %

Residuals [5]

Långåsen q = 0,99, OS=4%, #220 mm, xOS=1000 mm, w=1/x^0,25 r2=0.99885137 DF Adj r2=0.99870779 FitStdErr=0.62106081 Fstat=14783.244 a=63.067198 b=7530.5513

1.5 0.5 -0.5 -1.5

1.5 0.5 -0.5 -1.5

90

90

Ppile(x)

70

70

50

50

30

30

10

10

0.05

0.5

5

50

500

5000

Maskvidd, Mesh size, mm mm

Best case results entered into Kuz-Ram model’s x50 eqn: Fitting case: Round F1: Nonel normal q F2: Nonel high q C3: EDD normal q

Round parts 1-N + 2-N 1-H + 2-H 3+4

q Q sANFO x50round A’0,8 3 kg/m kg/hole % mm 0,722 96,7 0,813 162,5 4,69 0,992 91,6 0,813 119,4 4,48 0,776 110,1 0,813 204,3 6,11

A’0,84 4,63 4,48 6,05

Blast design curves Recalculated 100% level with 4 and 7% OS of Nonel rounds

x50 = 10A·Q1/6·(115/sANFO)19/30/q0,84 in mm Q kg expl. per hole sANFO% weight strength rel. ANFO, q kg/m3 specific charge.

A = 0,039·(RMD+RDI+HF), 0,039 best choice for Långåsen instead of Kuz-Ram value 0,06. A = 4,56 for Nonel rounds.

Pround(x) = 100/{1+[ln(xmax/x)/ln(xmax/x50)]b} gives sieving curves if b = 4,17 and xmax = f(b, x50, B och S/B) from eqns.

s50x50round0,75 = 0,2(0,0415/B)0,25 where slope s50 at x50 s50 = b/[4x50roundln(xmax/x50)] for Swebrec function Kuz-Ram (2005) predicts finer fragmentation (delay effect) and steeper curve (scatter) for EDD but the reverse is true.  EDD rounds can not be included in design formulas

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Blast design curves: Nonel

 Design curves for other conditions may be calculated from KCO formulas.

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region with lower accuracy as boulder part exaggerated

Conclusions Use of a higher specific charge in the Nonel rounds; 0,99 instead of 0,72 kg/m3, had the effect of:

 a much finer x50, down from about 160 to 120 mm Using EDD instead of Nonel initiation, at roughly normal specific charge had the effect of:

 a much coarser x50, up from about 160 to 200 mm The fragmentation of the EDD initiated rounds doesn’t follow the Nonel design curves.

Kuz-Ram prediction eqn for x50 appears to work well with minor calibrations of rock mass factor A,  C(A) = A’/A = 0,039/0,06 ≈ 0,65 for Nonel rounds  C(A) ≈ 1,0 for EDD rounds means a timing effect

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Conclusions  Previous Vändle design curves apply, with small changes, also to the Nonel rounds at Långåsen  Project goals met  Tested prediction equations for xmax and b are missing though. Here a use of oversize estimates OS = 4-7% allowed fixing a constant b-value for the Nonel rounds. Then an experimental connection between xmax and x50 and b gave reasonable estimates of xmax.  The final Swebrec report (Ouchterlony et al. 2010) contains much more data.

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Blast design curves Input data for design curves: Granodiorite

Bench height H, m

Joints: vertical +

Subdrilln. UB, m

dipping from face

Hole dip, º

3

Density, kg/m

2.677

UCS, MPa P-wave, m/s

16,0 1,5 11,2

Uncharged OL, m

1,7

206

Charge length L, m

16,1

5.275

Hole diameter, mm

86

Vb q m3/hole kg/m3 89,4 1,15

Density, kg/m3

1.100

Charge Q’, kg/m

6,4

Charge Q, kg/hole

103

First row S/B

1,0

- rows 2-4 S/B

1,3

No. of rows

x50 mm 109

4

B m 2,0

S m 2,6

S/B 1,30

+1,0 m -32 mm % % 4,4 25,8

2,1

2,7

1,29

97,2

1,06

117

5,0

24,7

2,2

2,9

1,32

110,2

0,94

130

5,7

23,0

2,3

3,0

1,30

118,8

0,87

139

6,3

22,1

2,4

3,1

1,29

127,7

0,81

147

6,9

21,2

2,5

3,3

1,32

142,6

0,72

162

7,8

19,9

2,6

3,4

1,31

152,3

0,68

171

8,4

19,1

2,7

3,5

1,30

162,4

0,64

180

9,1

18,5

2,8

3,6

1,29

172,8

0,60

190

9,8

17,8