Blast Sidecasting In Surface Coal Mines

BLAST OVERBURDEN SIDECASTING By: Partha Das Sharma (E.mail: [email protected])

Definition of Explosive Casting Explosive casting is the technique used by many surface coal mines to control the displacement of overburden by means of explosive energy. The casting moves 30-80% of the overburden into the mined-out pit, while the remaining spoil is removed by draglines or other machinery. Author: Partha Das Sharma (E.mail: [email protected]

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BLAST OVERBURDEN SIDECASTING WITH PRE–SPLITTING – EFFECTIVE WAY TO OPERATE LARGE SURFACE COAL MINES ECONOMICALLY WITH CONTROLLED GROUND VIBRATION LEVEL. By: Partha Das Sharma (E.mail: [email protected]) Introduction: Overburden Blast Side-Casting is the procedure of displacement of a portion of overburden horizontally by blasting, to a desired distance in a required direction away from the working area. Generally, the area to which the overburden is directed to throw is in de-coaled area. Overburden Blast Side-Casting is directional blasting. It is also called Blast Casting, Side Casting or Throw Blast. The remaining of overburden is handled by mechanical means. Therefore, this system of overburden side-casting by blasting reduces considerable amount of work on deployment of excavating equipment for removing overburden. Moreover, this technique allows much improved fragmentation thereby causing the excavating equipment to work more efficiently and with much ease. Another important point regarding control of Ground Vibration of Blast Casting is system of Presplitting of Main block of blast. This system reduces the blast induced Ground Vibration greatly; thereby the nuisances arising due to Vibration is effectively controlled. Therefore, overall efficiency of working in Mines is improved considerably by adopting Blast Side casting with Presplitting. Advantages of Overburden Blast Casting: Conventionally, the blasted overburden is removed by Draglines, Shovels or Loaders. Now, Overburden blast Casting has emerged as cheaper alternative to the conventional method of removal of overburden. In the following ways the overburden blast casting is advantageous and reduces the cost of removal of overburden in comparison to the conventional method. •

Saving in operating and capital cost of excavating equipments for removal of overburden.

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Saving in maintenance cost of excavating equipments for removal of overburden.

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Time for removal of casting overburden by excavating machines is reduced and thereby productivity is increased.

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The saving in operating, power, capital and maintenance cost of excavating machinery is much more in comparison to the cost of additional explosives required for overburden blast casting, therefore overall economy is achieved in removal of overburden. This has been explained in Fig-1 graphically.

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Because of reduction in requirement of spares for maintenance etc., other hidden cost related to inventory management of spares of excavating machine also reduced.

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Smaller size of excavating equipment needed with lesser manpower, as they have to handle comparatively lesser volume of overburden.

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In working mines, if there is under capacity of primary stripping unit (i.e., less number of loading units to handle overburden), in other words, if there is mismatch of capacities of excavating equipment for stripping and coal removal, overburden blast casting can tackle this problem, thereby coal production can be improved.

Author: Partha Das Sharma (E.mail: [email protected]

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Fig - 1 Because of the above economical advantages, more and more opencast projects are experimenting with overburden blast casting in India. This technique has been experimented extensively in open pits in many countries like USA, Russia, South Africa, Australia etc., and found that cost can be reduced considerably in comparison with conventional method of workings. The main objective of blast Casting method is to blast the overburden bench in such a way, so that a portion of fragmented overburden material is removed directly into de-coaled area. The factors on which percentage of cast depend are: a. Geo-mining and Strata condition of the site. b. Parameter design of blast. c. Nature and characteristics of Explosives. A properly designed parameter in suitable strata condition may lead to higher percentage of cast. Recently, in several countries with better parameter design could achieve percentage of cast upto 60-65%. More the percentage of cast, better is the over all economy / saving achieved. Blast design parameters for overburden blast casting: The blast design parameters for overburden casting are mine specific. Properties and abnormalities of rock mass must be taken into consideration while designing the parameters. The Explosives energy, quantity, its distribution in the mass and timely release of it for necessary displacement are to be studied properly. In fact, overburden side casting by blasting is very much sensitive to design fluctuations. A number of experiments have been conducted in open pits to standardize the parameter. There are many factors associated with effective design of blast for overburden casting. We will discuss one by one in the following paragraphs and also profile of blasted muck.

Author: Partha Das Sharma (E.mail: [email protected]

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i)

NATURE OF OVERBURDEN, STRATA CONDITION AND GEOLOGY - Strata condition and Geo-mining condition, i.e., physical and mechanical properties of overburden rock, any discontinuities, any available weak planes, presence of water in the strata etc., of the area have great deal of influence on overburden blat casting and hence proper blast design, i.e., selecting spacing & burden, location of blast holes in a row, inclination of hole, dia. of hole etc. and selection of Explosives are essential for achieving better results and higher percentage of cast.

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NATURE AND CHARACTERISTICS OF EXPLOSIVES - It has been seen in developed countries like USA, Canada, Australia etc., high energy explosives can give better casting results. However, due to cheapness ANFO is being used in dry holes for casting purposes. In India, due to non-availability of better quality of prilled Ammonium Nitrate most of the overburden blast casting experiments in open pit workings was done with high density aluminized cartridge Slurry explosives or with Site mixed Bulk Emulsion explosives. In fact, in overburden blast casting the energy of explosives going down in boreholes is most important factor. A study of blast casting with various types of explosives using high-speed photography showed that by maintaining constant hole diameter, burden could be increased when going from ANFO to higher energy explosives. At the same time for a given hole diameter and constant burden, throw velocities could also be increased when going from ANFO to higher energy explosives. Side Casting requires increased burden ejection velocity. This can be accomplished only by increasing Energy of explosives per unit of mass of overburden thrown. The way of increasing energy is to keep higher specific charge, i.e., at higher Kg of explosives per Cum of rock. As in cast blasting the ejection velocity and lateral displacement of burden rock is most important, and are related to the weight rather than the volume, thus energy factors of the explosives used must be used in designing pattern for blast casting. Therefore, it is the amount energy rather than the quantity of explosives that controls the displacement of rock. It may be mentioned here that, breakage mechanism of rock by explosives is done by two ways, i.e., by stress wave generated from explosive detonation (Shock) force and by the borehole pressure created by the detonation gas pressure. Majority of shattering in rock, rock breakage, fragmentation etc. are effected by stress wave generated by explosive and detonation gas pressure is mainly responsible for heaving and throw. As better-fragmented rock (acquires more surface area) is displaced more effectively at longer distance than poorly fragmented rock, the explosive characteristic should be such that it provides sufficient shock wave for achieving better fragmentation and considerable amount of gas energy for maximum throw of blasted overburden. It has been observed that, Emulsion explosives address both shock and gas energy well and effective in overburden blast castings.

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PARAMETER DESIGN AND BLAST GEOMETRY - Under the parameter design and blast geometry the fixing of Spacing and Burden, Stemming height, Inclination of blast hole, Diameter of blast hole, Initiation sequence and fixing of delay intervals are the most important variables upon which one has to decide. •

Fixing of Spacing and Burden – Burden of a blast depends on various factors, like Bench Height, Hole Dia., Type of Explosives used, Rock characteristics etc. In fact, the burden should be decided by conducting number of trials in a given strata condition. Spacing is determined by taking ratio of Burden and Spacing.

Author: Partha Das Sharma (E.mail: [email protected]

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Generally, Spacing is taken as 1 to 1.3 of Burden. The main objective is, the spacing and burden are so decided to achieve Maximum ejection velocity and fragmentation. Moreover, spacing and burden are so adjusted in relation to diameter of blast hole that higher specific explosives charge (Kg/m3) can be accommodated. For effective overburden blast casting the post explosion gasses should exert tremendous push over a largest possible area in the plane of the row of the blast holes. The spacing should not be so great that gasses vent out from the face before they fully penetrate the cracks between adjacent blast holes. The standard square pattern was in use where no blast casting was involved. It has been observed 9m X 7m (S x B) with staggered pattern gives better result in overburden blast casting. It has been established that, first three rows are primarily responsible for casting overburden into the de-coaled area. Therefore, placement of first row is the most important factor; tow-burden is to be taken into consideration while deciding the location of drilling holes in the first row and if needed some relieving holes may be drilled in the front row for better fragmentation and ease in movement. For effective overburden blast casting, many authors have suggested a higher specific charge with higher explosives energy, by a factor of 1.4 to 1.6 than the conventional blast. •

Stemming – The stemming height should be such that, proper explosives energy is utilized in fragmenting the rock and for achieving maximum ejection velocity. Therefore, the quality of stemming should be checked properly to prevent loss of gasses released by explosives to atmosphere. Small decking of charges some time may be provided when there are intervening weak strata. Generally, stemming should be between 1 and 0.7 of Burden.

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Blast hole Inclination – it is a well-known fact that if the blast hole is inclined from vertical, the fragmentation is improved. Because of difficulties in drilling inclined holes of large diameter, Indian mines rarely use inclined drill in open pit. As per the projectile theory, the throw is maximum if the inclination is kept 45°. However, in practice it is difficult to have hole inclination at 45°. Therefore, it recommended as far as possible (if suitable drill machines are available with the mines) for overburden blast casting inclined holes are to be used. Some of the experiments have also achieved throw of approximately two times by using inclined holes keeping the same specific charge. Inclined holes parallel to the slope of the high wall could be adequate for effective side cast. High wall should be as nearly vertical as possible to get an effective throw with vertical holes. A number of mines have introduced the Pre-splitting operation to control front row burden. Apart from preventing Back-break formation, pre-splitting have the added advantages of controlling ground vibration and improving safety standard in the mines.

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Blast hole Diameter - Diameter of blast holes generally depend upon the available drill machine with the mines, Bench height, geology and strata condition. In practice generally, in India, the diameter of blasted holes approximately kept as per the following formula:

Author: Partha Das Sharma (E.mail: [email protected]

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D=H/(90 to 120); where D is dia. of blast hole and H is bench height or depth of high wall. •

Initiation sequences and selection of Delay Intervals - Initiation of sequences and selection of delay intervals are one of the most important criteria in overburden blast casting. Effectiveness of casting can be increased when all the holes in the rows are detonated simultaneously and subsequent rows are detonated with milli-second delays. Here our prime objective is to have throw, row by row without hindrances. For that, clear free faces are to be achieved for each row and the movement of materials of each row should not have any hindrances like air collisions or flight collisions of the fragmented material. For that purpose, row-by-row initiation sequence is preferable for creation of free faces at the front of each row. Secondly, the delay intervals between rows should be selected in such a way to prevent any hindrances in movement of fragments like air collision. It has been observed with increasing inter-row delay intervals from front to rear row the casting of overburden is better (Fig - 4). On an average, the delay interval of about 10 milli-second per meter of burden between first and second rows, while increasing proportionately to bout 20 milli-second per meter of burden between fifth and sixth rows, should be given. Where there is restriction in respect of ground vibration, a group of holes in the row, subject to allowable maximum charge per delay can be fired with minimum delay interval between the groups of holes in the same row (Fig – 5).

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OTHER RELATED ASPECTS IN REGARD TO OVERBURDEN CASTING Following additional points are to be considered in regard to achieve efficient overburden blast casting. •

Relationship between Bench height and Bench width - Higher the height of Bench more percentage of material thrown into spoil dump. Percentage of cast also depends upon width, i.e., distance of high wall from the free face. More energy needed to throw overburden, if the distance of high wall is more from the free face, i.e., if width of bench is more. Thus, there exists relationship between the percentage of blasted material thrown and H/W ratio (Bench height and bench width ratio). The relationship between percentage of cast and H/W ratio is shown in Fig-2 below. For successful overburden blast casting H/W ratio should be kept between 0.7 and 1.0.

Author: Partha Das Sharma (E.mail: [email protected]

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Fig – 2 •

Characteristics of Overburden material - Overburden blast casting is suitable in hard and medium hard rock, when heavy blasting is required for fragmentation. In general, overburden blast casting is not feasible enough in unconsolidated, loose rock like soft clay, loose sand etc., which does not require blasting at all. Blast casting can effectively be done in dry as well as wet ground conditions, only suitable explosives are to be selected as per ground condition.

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Ground vibration due to overburden blast casting - For effective blast casting of overburden the requirement of specific charge (i.e., requirement of explosives in Kg per Volume of rock blasted in Kg/ Cum) is quite high as compared to blasting required for conventional workings. Because of that, the ground vibration, in case of overburden blast casting is higher than that of conventional method of workings. But strangely, the degree of increase in ground vibration is not as per the increase in specific charge. This may be because in successful overburden blast casting the excess energy of explosives used for better fragmentation and for moving the blasted material away from the blasting site and not in generating ground vibration. Since, slightly higher ground vibration is generated in case of overburden blast casting, it is suggested to adopt this technique in the mines where residential / industrial buildings and permanent structures are far away from blast site, and in mines closer to permanent structures should carryout some experimental blasts to assess the effects on ground vibrations before carrying out this technique on a regular basis. Techniques such as, introduction of some delays for group of holes in a row subject to restriction of maximum charge per delay and use of pre-splitting of production blast, may be tried, in order to reduce ground vibration. In fact, in Mega blasts (as of Side Cast Blast in Large Opencast Mines) conducted in opencast mines, the Interference of Ground Waves result. A very complex phenomenon of resultant waveform occurs, which is very difficult to

Author: Partha Das Sharma (E.mail: [email protected]

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control only by use of delays for group of holes in a row, NONEL or Electronic Detonators. Pre-splitting of production blast is the best method of controlling or restricting the waveform to propagate outside such Mega blasting zone and thereby enhancing the safety standard (Details of Pre-Splitting has been discussed at later part. Refer Fig - 6 and Fig -7). v)

POST BLAST PROFILE OF BLASTED MUCK - The post-blast profile of blasted muck, in case of successful overburden blast casting, is shown in Fig – 3 below. Please note that, a sizable portion of the overburden is thrown in de-coaled area. The maximum depression is generally observed at the high wall side from the top and the blasted muck profile smoothly goes towards de-coaled area resulting notable depression at the free face side also.

Fig - 3

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Blast pattern and other details of some Blast Castings (Case Studies): Details of patterns used for overburden blast casting carried out in some of the open pits in India are given in Annexure - I. It can be observed that direct cost saving have been obtained by using blast casting is quite substantial, in comparison to conventional blast without blast casting. Also, the cost effectiveness is dependent on the percentage of casting obtained in individual cases.

Typical Blast Initiation Sequence and Delay Patterns for Blast Side Castings : General blast initiation sequences used and their delay pattern for blast side casting are shown below. Row to row delays has been shown (Fig – 4). In some cases to reduce ground vibration, delays for a group holes in rows are also shown in Fig -5.

Author: Partha Das Sharma (E.mail: [email protected]

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Fig – 4

Fig - 5

Author: Partha Das Sharma (E.mail: [email protected]

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Pre – splitting of Main Blast in order to control Ground Vibration: An effective way of controlling Ground vibration is by Pre-splitting of the production blast. As discussed above, the Ground Vibration generated in Side Cast blast is more than the conventional blast, the reduction of vibration level is all the more necessary. Pre-splitting helps in isolating blasting area from remaining rock mass by creating an artificial discontinuity along the final designed excavation line / plane against which subsequent main blast breaks. A row of holes are drilled at the periphery (three sides) of the main blasting block at a closer spacing, charged preferably with lesser quantity of explosives than the production blast and blasted prior to the main blast in an effort to create a fracture line and a reflective plane at the excavation limit or plane. Some of the shock waves from subsequent main blast are reflected at the pre-split plane which results in arresting a considerable portion of blast induced ground vibration generated in the main blast to propagate. The theory of pre-splitting is that when two charges are shot simultaneously in adjoining holes, collision of shock waves between the holes places the web in tension and causes cracking that give a sheared zone between the holes to open a narrow crack / separation along the three sides of the production or main block before the main blast goes-off (Fig – 6). This results in a smooth wall with little or no over break. The pre-sheared plane reflect some of the shockwaves generated from the primary blasts that follow, which prevent them from being transmitted into the finished wall and minimizes shattering and over break.

Fig - 6 The separation of timing between blasting of pre-splitting holes and production blast are kept with the help of delays. The delay gap of 200ms to 250ms between pre-split and main blast is considered to be enough. The quantity of explosives to be used in pre-split holes, burden and spacing are estimated keeping in view the insitu tensile strength of rock mass. The borehole spacing of pre-split holes is normally kept at 8 to 12 times the blast hole diameter and the burden may be kept as of the burden of the Main Blast. Depth may be kept as of last row of main blast. Mostly, light

Author: Partha Das Sharma (E.mail: [email protected]

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distributed decoupled charges are used in pre-splitting holes. Air-deck in between deck charges improve the quality of pre-split fracture and avoid extension of radial cracks around the holes (Fig – 7). Generally, the quantity of explosives kept in pre-splitting holes is 8 to 12 % of the explosives charged in one hole in the Main Blast.

Fig - 7 Advantages of Pre-splitting: (1) Field observation reveals that with the introduction of presplitting the back breaks are eliminated, improving the stability of high-wall slopes and to provide uniform burden to the front row of holes for next blasting round. (2) As back breaks are eliminated, formations of pre-formed boulders are reduced resulting better fragmentation in the subsequent blasts. (3) Field observation reveals that, there is substantial reduction of ground vibration level to the tune of nearly 1/3rd of normal production blast due to pre-splitting. (4) Presplitting is most suitable for controlling ground vibration level in the case of Overburden Side Cast Blasts. (5) In the Mega blasts (as of Side Cast Blast in Large Opencast Mines) conducted in opencast mines, the Interference of Ground Waves result. A very complex phenomenon of resultant waveform occurs, which is very difficult to control only by use of delays for group of holes in a row, NONEL or Electronic Detonators. Pre-splitting of production blast is the best method of controlling or restricting the intensity of the waveform to propagate outside the Mega blasting zone and thereby, enhancing the safety of Surface Structures located in the vicinity of blast site. Modern Technology & Equipment used: The various design parameters for cast blasting discussed above are broadly Geology, Face height to width ratio, Blast hole Dia. & angle, Burden to Spacing ratio, Explosive energy, Shot timing, Mine plan & equipment, Potential problem areas and Economics. The utilization of these parameters the blasting engineers must use the data at hand and that gained from previous blasts as a basis for current and future designs. Although, trial and error and common sense are still part of equation for design, modern technology has provided a means of obtaining accurate and usable data. Some of the modern equipments available which can be employed purposefully are: a) Modern surveying equipment and its Computer Software provide a wealth of valuable information on a blast and post-blast scenario. These include overburden – coal ratio, optimum front hole location, custom loading information for front row hole burden, pre-blast

Author: Partha Das Sharma (E.mail: [email protected]

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mapping, post-blast mapping & determination of cast / throw, volumetric calculation for swell factor and cast percentage for basis of evaluation of economic advantages. b) High Speed Photography recording is very efficient and extremely useful instrument for analyzing of blasts. Any hindrance in free movement of projectiles or air collision of fragments can be detected and accordingly delay sequence timing can be adjusted. Now a days, high speed photography to the tune of more than 500 frames per second is in vogue, which is very useful for the purpose. c) Velocity of Detonation Recorder is another useful instrument which can be used to determine explosive performance in the hole. d) Seismograph or Ground vibration recorder is essential in documenting the unwanted side effects of blasting such as Ground vibration and Air blast. e) It has been observed by use of sophisticated, precise and perfect timing Electronic Detonators in Mega blast in opencast mines reduces intensity of Ground Vibration as compare to NONEL or Cord Relays, as the scattering (deviation of actual timing from nominal delay timing) of delay timing is almost negligible or nil. Because of precise timing the higher percentage of casting of overburden has been reported by many Authors. Conclusion : Thus, it has been observed from the above examples that the technique of overburden side casting by blasting is very much cost effective. The optimum blasting parameter is mine specific. Therefore, more experimental blasts required to carryout, in order to establish the technique in a particular mines for effective cost benefits. Some of the inherent problems should be addressed while planning for side casting by blasting. Since the concentrated amount of explosives energy is used for displacement o overburden, highwall stability may pose a problem. Also, as discussed, blast induced ground vibration may slightly be higher. If proper precautionary measure is not taken, coal damage may occur due to rapid horizontal displacement of overburden. As discussed, for achieving higher percentage of cast in order to maximize overall cost benefit, the energy factor of explosives used is one of the most important criteria; for effective overburden casting explosives with higher energy / strength is necessary. Therefore, the Coal Mining Authorities should evolve proper strategy / pricing policy to encourage explosives manufacturers for supply of explosives with higher energy / strength for this purpose, in order to achieve decent percentage of cast. Also, the aspect of peculiar phenomena of vibration waveform arises in Mega Blast (like Overburden Side Casting by blasting ), when Ground Vibration waves interfere with each other and the resultant waveform is very much complex in nature. The Pre – Splitting of such Blasting block is the effective way to restrict / control blast induced vibration to propagate. Therefore, overall efficiency of working in Mines is improved considerably by adopting Blast Side casting with Pre-splitting.

Author: Partha Das Sharma (E.mail: [email protected]

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ANNEXURE – I Blast pattern and other details of some Overburden Blast Castings (Case Studies) Blast pattern Details & cost effectiveness Av. Type of Strata Av. Spacing x Burden Dia. of Blast Hole Av. Bench height Av. Hole depth Av. Width of the Bench Av. H/W ratio No. of Rows Sub-grade drilling Total No. of holes blasted Av. Deck height Av. Stemming height Type of explosives used

Total explosives used Av. Charge per hole Delay sequence used

Total insitu vol. blasted Insitu Powder factor kept for blast casting Estimated %age of Casting obtained Av. Cost Effectiveness percentage (estimated)

Mine No. 1

Mine No. 2

Mine No. 3

Mine No. 4

Med. Hard Sandstone 10.0m x8.5m

Med. Hard Sandstone 10.0m x8.5m

Med. Hard Sandstone 10.0m x8.5m

270 mm 32.5m 32.5m 36 m

270mm 26.5m 28m 34m

270mm 26.5m 28m 42.5m

270mm 26.5m 28m 51m

0.9 04 Nil 49

0.78 04 1.5m 39

0.62 05 1.5m 39

0.52 06 1.5m 39

Nil 7m

Nil 6.5m

Nil 6.5m

Nil 6.5m

0.2%Cast Booster as prime charge and Al. Bulk Slurry as column charge.

0.2%Cast Booster + Site Mixed Bulk Emulsion Explosives as column charge 72140 kg

0.2%Cast Booster + Site Mixed Bulk Emulsion Explosives as column charge

75624.20 kg

0.2%Cast Booster + Site Mixed Bulk Emulsion Explosives as column charge 58500 kg

88200 kg

1543.35 kg / hole

1500 kg / hole

1470 kg / hole

1470 kg / hole

Row to row delays used. 100 ms delay between 1st & 2nd row; 125 ms between 2nd & 3rd row and 150 ms between 3rd & 4th row. 128992.50 Cum

Staggered pattern with row to row delays increasing from 50 ms to 150 ms

Staggered pattern with row to row delays increasing from 50 ms to 150 ms

Staggered pattern with row to row delays increasing from 50 ms to 150 ms

90257 Cum

113400 Cum

135150Cum

1.70 Cum/kg of Expl.

1.54 Cum/kg of Expl.

1.57 Cum/Kg of Expl.

1.53 Cum/Kg of Expl.

49%(Insitu)

40 % (Insitu)

36 % (Insitu)

30 % (Insitu)

37.5 % (Approx.)

35.0 % (Approx.)

32.0 % (Approx.)

26.4 % (Approx.)

Med. Sandstone 9m x 9m

Hard

Author: Partha Das Sharma (E.mail: [email protected]

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REFERENCES 1. Chernigovskii, A.A – Application of Directional Blasting in Mining and Civil Engineering, Oxomian Press Pvt. Ltd., 1985 (Translated from Russian). 2. Langefors, U & Kihlstom, B.K. – The Modern Technique of Rock Blasting, John Willy & sons, 1963. 3. Hagan, T.N & Just, G.D. – Rock Breakage by Explosives – Theory, Practice and Optimization., Int. Proc. 3rd Congress, ISRAM, Danver 1974. 4. Gupta, R.N. – Design of Optimum Blasting Pattern for Surface Mines, J of Mining Engg. Society, 1990. 5. Gupta., R.N., Ghose., A.K., Mozumdar., B.K., Nabibullah., Md. - ‘Design of Blasting rounds with Airdeck pre splitting for Dragline and Shovel benches near populated Areas – A case study’, Int. Symposium on Explosives and Blasting techniques, N.Delhi, Nov. – 1990. 6. Rzhuvsky, V.V – ‘Opencast Mining, Unit Operations’, MIR Publisher, Moscow. 7. Sharma, P.D. – Overburden Blast Casting with SMS Explosives – A case Study, Special Issue on Explosives & Blasting, Indian Mining & Engineering Journal, November 1998. 8. Gupta, R.N; Adhikary, G.R., etal – Advances in Overburden Blast Casting, JMMF, November 1986. 9. Chiappetta, R.F. etal – Design of Overburden Casting by Blasting – Recent developments, JMMF, Sept. 1990. 10. Chronis, N.P. – Blast Casting succeeds at Multi-seam Western Mines, Coal Age, Nov. 1985. 11. Sharma, U.D & Sharma, P.D. –Blast Casting with SMS – A case study at Sasti Opencast mine, “Visfotak” ‘98, National Seminar on Explosives, Nagpur (India) 12. Lal, M & Agarwal, M.R. – Planning for large scale Blast and scope of Side Casting on Dragline Benches in opencast mines, Experience at Jayant Opencast mines of NLC, JMMF, Sept. 1990. 13. Mereer, J.K. & Hagan, T. – Program towards Optimum Blasting – a key to increase Productivity and Profitability, Proceedings of the Eleventh Commonwealth Mining & Metal Congress, 1978. 14. Nicolson, Kai – Optimization of Open pit Bench Blasting, Procc. of 1st International Symposium on Rock Fragmentation with Blasting, Sweden, 1983.

Author: Partha Das Sharma (E.mail: [email protected]

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15. Sharma, P.D. - Overburden Side-casting by blasting-An effective way of reducing operating cost in large opencast coal mines; Journal of Mines, Metals & Fuels, November 2004 (Sp. issue on development in surface mining technology- Calcutta) 16. Atlas Powder Company, Dallas, Texas, USA - “Explosive and Rock Blasting” 1987. 17. Sharma., P.D. – ‘Overburden Side casting by Blasting – Operating large opencast Mines in a cost effective way’ , Proc., of 1st Asian Mining Congress, 16-18 January 2006, Kolkata, India, (Page No. 307 – 315), MGMI Centenary Vol.-1. 18. Watson., John. T. – ‘Developments with Electronic Detonators’, Proc., of Int. Conf. On Expl. & Blasting Tech, ISEE (2002). 19. Blasters’ Handbook – E.I.du Pont de Nemours & Co. (Inc.), Wilmington, Delaware 19898. 20. Sharma, P.D.; - ‘Controlled Blasting Techniques – Means to mitigate adverse impact of blasting’; Procc. of 2nd Asian Mining Congress, organized by MGMI at Kolkata (India) dt. 17th – 19th January 2008 (pp: 286 – 295).

Author’s Bio-data: Author is Graduate (B.Tech – Hons.) in Mining Engineering from IIT, Kharagpur (1979) and was associated with number of mining and explosives organizations, namely MOIL, BALCO, Century Cement, Anil Chemicals, VBC Industries, Mah. Explosives etc., before joining the present organization M/s Solar Explosives Ltd., Nagpur, few years ago. Author has presented number of technical papers in many of the seminars and journals on varied topics like Overburden side casting by blasting, Blast induced Ground Vibration and its control, Tunnel blasting, Drilling & blasting in metalliferous underground mines, Controlled blasting techniques, Development of Non-primary explosive detonators (NPED) etc. Currently, author has following useful blogs on Web: http://saferenvironment.wordpress.com • http://www.environmentengineering.blogspot.com • www.coalandfuel.blogspot.com • Author can be contacted at E-mail: [email protected], [email protected] Disclaimer: Views expressed in the article are solely of the author’s own and do not necessarily belong to any of the Company.

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Author: Partha Das Sharma (E.mail: [email protected]

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