Cost effectiveness of open-pit hard rock Ore Mining by sharmapd1

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									Cost effectiveness in open-pit hard rock
Ore Mining

 Cost effectiveness of open-pit hard rock Ore Mining
depends on Explosives used in terms of Energy / VOD,
       Pit-slope angle and framing strategy for
                     fragmentation
                          ***
  Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                  E.mail: sharmapd1@gmail.com,
       Blog/Website: http://miningandblasting.wordpress.com/
                                            Abstract
   Extensive in-situ testing has shown that blast fragmentation influences the
   performance of downstream processes in a mine, and as a consequence, the profit of
   the whole operation can be greatly improved through optimised fragmentation.
   Other unit operations like excavation, crushing and grinding can all be assisted by
   altering the blast-induced fragmentation. Therefore, it is necessary to couple all the
   parameters, namely selection of explosives in terms of VOD, rock properties and
   surface blast design for an efficient blasting. Fragmentation is one of the most
   important concepts of Explosives Engineering. The efficiency of these unit
   operations is directly related to the size distribution of muckpile. Therefore, reliable
   evaluation of fragmentation is a critical mining problem. Apart, cost effectiveness in
   open-pit mines is the result of maximizing pit-slope angle and reduction in blast
   damage and ore dilution which results in increased volume of final products as well.
   Slope stability and increase in pit-angle depend on blast performance and adoption
   of controlled blasting to mitigate the adverse effects. Pre-splitting of production
   blast is the way for achieving steeper slope angle in open pit ore mining. One of the
   objectives in pre-split blasting is to control over break, so that the final pit wall
   slopes are kept stable and competent. To arrive such a optimum levels, an overall
   knowledge of the process and operational aspects of rock blasting techniques are
   essential.


1. Introduction - Drilling and blasting is one of the main operations in open-pit mining,
and its performance has a major impact on the overall economy of the mine. Blasting by
design results from a large number of factors, all of which need to be brought under
control in order to achieve the right result. These include the choice of drillrig and tools,
the layout of the holes, the explosive, and the skill of the operators.

Explosives are used for rock breakage in mining and construction industry. In mining the
main objective is to break largest possible quantity of rock with optimum fragmentation
and minimum cost. In construction industry explosives are used for construction of
tunnels, caverns, dams, foundation excavations etc. Here the objective of blasting is to
have fast progress leaving behind smooth and stable rock.
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           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining


To understand the principles of rock blasting, it is necessary to start with the rock
fragmentation process that follows the detonation of the explosives in a drillhole. The
explosion is a very rapid combustion, in which the energy contained in the explosives is
released in the form of heat and gas pressure.

The geology and rock condition frequently has more effect on the fragmentation than
does the explosive used in the blast. The properties that influence the result of the blast
are compressive strength, tensile strength, density, propagation velocity, hardness and
structure. In general, rock has a tensile strength which is 8 to 10 times lower than the
compressive strength. The tensile strength has to be exceeded during the blast, otherwise
the rock will not break. High rock density requires more explosives to achieve the
displacement. The propagation velocity varies with different kinds of rock, and is reduced
by cracks and fault zones. Hard, homogeneous rocks, with high propagation velocity, are
best fragmented by an explosive having high velocity of detonation (VOD). Thus,
selection of explosives is one of the most important criteria in getting proper
performance. It has to compatible with the rock formation.

In fact, surface blast design is always in a constant state of adjustment. It involves
manipulation of numerous variables that influence the eventual outcome of using
explosives to break rock. Through proper adjustment of these variables the blst designer
can create the most favourable conditions for efficient use of explosives energy. In
addition, efficient management of explosive energy and on-site conditions will have a
direct influence on the economic of blasting, the rate of productivity through better
fragmentation and reduction of vibration, airblast, flyrock and overbreak.

Extensive in-situ testings has shown that blast fragmentation influences the performance
of downstream processes in a mine, and as a consequence, the profit of the whole
operation can be greatly improved through optimised fragmentation. Other unit
operations like excavation, crushing and grinding can all be assisted by altering the blast-
induced fragmentation.

Therefore, it is necessary to couple all the parameters, namely explosive, rock properties
and surface blast design for an efficient blasting. Fragmentation is one of the most
important concepts of Explosives Engineering. The efficiency of these unit operations is
directly related to the size distribution of muckpile. Therefore, reliable evaluation of
fragmentation is a critical mining problem.

Apart from above, cost effectiveness in open-pit mines is the result of maximising pit-
slope angle and reduction in blast damage and ore dilution which results in increased
volume of final products as well.

2. Understanding theory of detonation of explosives - The self-sustained shock wave
produced by a chemical reaction was described by Chapman and Jouquet as a space. This

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           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
space of negligible thickness is bounded by two infinite planes – on one side of the wave
is the unreacted explosive and on the other, the exploded gases as shown in the Fig. 1.

There are three distinct zones:
a) The undisturbed medium ahead of the shock wave,
b) A rapid pressure at Y leading to a zone in which chemical reaction is generated by the
shock, and complete at X,
c) A steady state wave where pressure and temperature are maintained.

This condition of stability condition for stability exists at hypothetical X, which is
commonly referred to the Chapman- Jouquet (C-J) plane. Between the two planes X and
Y there is conservation of mass, momentum and energy.




                                          Fig - 1
Velocity of detonation (VOD) of explosive is function of Heat of reaction of an
explosive, density and confinement. The detonation pressure (unit in N/m2) that exists at
the C-J plane is function of VOD of explosives. The detonation of explosives in
cylindrical columns and in unconfined conditions leads to lateral expansion between the
shock and C-J planes resulting in a shorter reaction zone and loss of energy. Thus, it is
common to encounter a much lower VOD in unconfined situations than in confined ones.

a. Rock breakage by Detonation and Interaction of explosive energy with rock –
There are three sources of generation of fragments in mines: (a) Fragments formed by
new fractures created by detonating explosive charge, (b) In-situ blocks that have simply
been liberated from the rock mass without further breakage and (c) Fragments formed by
extending the in-situ fractures in combination with new fractures.

Rock fragmentation by blasting is achieved by dynamic loading introduced into the rock
mass. The explosive loading of rock can be separated into two phases, the shock wave
and gas pressure phase (Fig.2).


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           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining




                                                  Fig. 2

The detonation of an explosive charge in a blast hole gives rise to a strong initial shock
wave which then decays into stress waves, P- and S-Waves, in the surrounding rock
mass, initially as compressive strain waves radiating from the blast hole. In a plane
normal to the axis of the blast hole, the stress wave can be considered to have radial and
tangential components of stress (Fig.3). The high pressure to which the rock is exposed
shatters the area around the blast hole, the crushed zone, and exposes the space beyond
that to high tangential strains and stresses. The crushing continues until the stress has
been attenuated to below the dynamic compressive strength of the rock. When the
compressive wave meets a free surface it is reflected back to the hole as a tensile wave
and a shear wave. If the tensile stress, of the reflecting wave, is greater than the dynamic
tensile strength, spalling will occur.

The gas pressure face is a much slower, quasi-static, process than the shock wave phase,
which takes place within a few milliseconds. Even if the stress caused by the explosive
gases is much lower than the stress caused by the shock wave, it can still fracture the rock
mass due to the lower loading rate. The explosive gas pressurise the borehole and applies
a radial compressive stress, sufficiently large to initiate and propagate cracks. The high
pressure gas penetrates the primary radial cracks, and natural cracks, and extend them
further, the free rock surface in front of the blast hole yields and is moved forward. This
is how the rock is broken in rock blasting. Thus, fragmentation of rock by blasting is a
rapid disintegration of rock. In blasting practices the rock is exposed to both low loading
rate, “static”, and dynamic loading.

For rocks there is a huge different between the intact rock strength, here rock strength,
and the rock mass strength, which consists of both intact rock and the discontinuities
within the rock mass. The mechanical behaviour of rocks spans over a wide range of
scale, from microscopic cracks to regional fault systems. Dependent on the issue in
consideration different properties of the rock mass controls the strength.

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           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
As discussed, on detonation of an explosive charge, the rock immediately surrounding the
blasthole is crushed, owing to explosion pressure because of shock energy. The outgoing
shock wave, after passing through the crushed zone, travels at between 3000 m/s to 5000
m/s and sets up tangential stresses that produce radial cracks. The pressure produced by
the expanding shock wave from the blast source is compressive. The extent of the shock
zone around blast hole is nearly 2 to 4 times the radius of blast hole. When the shock
wave reaches a free face, it then reflects back toward the blasthole at a lower pressure but
in the form of a tension wave through the rock transition zone (Fig.3). The extent of this
zone is 20 to 50 times the radius of blast hole (Siskind and Furnanti, 1974).

The crack density in the transition zone controls the distribution of the fragment size. The
explosives with high VOD induces more stress in transition zone thereby increasing crack
density. The increase in crack density reduces fragment size. Therefore, it is necessary to
use explosives having suitable VOD, in order to get optimize the fragmentation in a mine.
It has been observed that, by using pumpable bulk emulsion explosives in place of
ANFO, cost of secondary blasting, mucking and crushing is reduced considerably in a
hard rock open-pit mining.




                                                 Fig - 3

b. Cratering Theory - In a series of experiments it was discovered that a spherical
charge broke a much greater volume of rock than a cylindrical charge of the same mass.
A spherical charge is defined as a charged that has a ratio of charge diameter to charge
length less than 1/6.

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           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
If a sufficient number of tests are carried out involving detonation of a fixed amount of
charge at various depths in the rock, then the strain energy factor can be calculated from
the following empirical equation:
       B
E = --------
     Q1 /3

Where, E = strain energy factor, which is a constant for a given combination of
explosives

B = Critical distance in metres (the depth where a full crater forms, that is, a conical
cavity whose sides meet the horizontal surface at 450), in metres.

Q = Charge weight, kg

It follows that when an explosive charge of constant mass and shape is placed at different
distances from a flat free face and detonated, the amount of rock blasted is related to the
depth of burial of the charge.

c. Energy factor of Explosives – The purpose of the application of explosives during
blasting is to perform useful work. The work may be the fragmentation of rock or ore,
throw of muck-pile etc. Energy factor in an explosive is the amount of explosive energy
required to fragment a given quantity of rock. Thermo-chemical energy can be used as an
index of effectiveness of an explosive to break rock.
                        Kilocalories (Q)
Energy factor (EF) = --------------------------
                        Quantity of rock

EF is expressed in Kilocalories/Cum or Ton. It is always a better practice to design blasts
using energy factor. As the explosives of various types have different energies ranging
from 600 Kcals/kg to 1200 Kcals/kg , it is possible to match the required energy levels
varying from 100 Kcals/Ton to 300 Kcals/ton. While arriving at the energy factor for a
particular rock type, extensive trials are necessary over a considerably long period. This
experience can be gainfully used in blast designs.

3. Role of VOD in selection of explosives for effective performance - The performance
of a blast depends on various factors such as blast geometry, pattern of drill holes,
sequence of firing, initiation system used and performance of explosives. Important o
properties of explosives which influence the performance are density, strength, VOD,
sensitivity and cohesiveness. Among all these VOD has a major role in selection of
explosives. Besides reducing the drilling cost and the ground vibration, use of proper
explosives improves fragmentation and stability of the rockmass.




-------------------------------------------------------------------------------------------------------   6
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
VOD of an explosive can be defined as the velocity at which the detonation wave passes
through the explosive column. The VOD of commercial explosives vary from 2500 m/s
to 5000 m/s.

As per the rock type the selection of explosives on the basis of VOD generally takes
place. It has been found that, maximum explosive energy is transferred to the rock when
the impedance of explosives matches with the impedance of the rock to be blasted. The
energy transfer is influenced by coupling factor and impedance factor.

         (Zex - Zr)2
σ = 1 - -------------------
          (Zex + Zr)2

σ is Impedance Factor;
Zr is impedance of the rock;
Zex is impedance of explosives.

Impedance ‘Zr’ is product of rock density ‘ρr’ and seismic velocity in the rock ‘Vr’; i.e,
Zr = Vr * ρr in kg-m2 /s. Similarly, ‘Zex’ is product of explosive density ‘ρex’ and
VOD of the explosive ‘Vex’; i.e, Zex = Vex * ρex in kg-m2 /s.

The performance of an explosive not only depends on its total energy but also on rate at
which it is released. The VOD of an explosive controls its rate of energy released. It also
influences the energy partitioning with respect of Shock and Heave (Gas) energy of
explosives (Fig. 4).




                                                  Fig - 4
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           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining


An explosive with low VOD releases energy at a slower rate and large proportion of this
energy is in the form of Heave or Gas energy. Such explosives are suitable for soft and
fractured rock. Explosives with high VOD have higher Shock energy component, thus are
suitable for tough, hard and massive rock.

Base                       Type                   VOD (m/s)                    Feature
Nitro-glycerine            Dynamite               5500 - 4500                  Highly adaptable
                           geletine                                            cartridged.
                                                                               Excellent in smaller
                                                                               holes
Ammonium                   ANFO                   2500                         Low cost, high
Nitrate                                                                        safety, easy to pour
                                                                               or blow.
                                                                               No water resistance,
                                                                               contains 5-6% fuel
                                                                               oil
Water                      Slurry /               4000 – 3000                  Basically ANFO
                           Emulsion               watergel                     made water resistant
                                                                               gel.
                                                  5000 Emulsion                Stable oil/water
                                                                               emulsion – heavy
                                                  Range depend on              ANFO.
                                                  storage time                 Packaged or
                                                                               pumpable

4. Selection of explosives and drilling for minimizing drilling cost – Drilling is a
costly and time consuming operation. It can be reduced either by using large diameter
holes or by using high VOD explosives or by combining both. With high VOD
explosives the extent of transition zone increases. This permits expanded pattern, thereby
reducing the total meterage of drilling, hence reduction of drilling cost. It has been
observed that, shifting from ANFO explosive to bulk emulsion explosive, there is
substantial benefit in reduction of drilling cost in hard rock open pit ore mining.
Similarly, using higher diameter blast-holes, the pattern as well as bench height can
increased, thereby reducing overall cost and improving efficiency and productivity.

5. Fragmentation Strategy and maintaining optimum height & pit-slope angle in
open-pit mining geometry for maximum cost effectiveness – Traditionally, focusing
on the drilling cost parameter and productivity only, the predominant method in open pit
mining is large hole drilling using hole sizes in the range of about 250 mm. No doubt this
implies lower cost for drilling, ignoring the expense of excess waste, more explosives and
less controllable fragmentation.



-------------------------------------------------------------------------------------------------------   8
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining




                                             Fig.5
In fact, a major difference between open pit mining and quarries is the geological
conditions and the demand characteristics on the blasted material. Whereas quarries
deliver the majority of rock via the crushing and screening plant in various size fractions,
the open pit mine attempts to deliver the ore as pure as possible via crushers to the
dressing plant, consisting of mills, separators, and/or flotation, and/or biochemical
systems, and finally to smelters, in order to convert minerals to metals. Maintaining pit
slope angles that are as steep as possible is of vital importance to the reduction of
stripping (mining of waste rock), which will in turn have direct consequences on the
economy of the mining operation. Design of the final pit limit is thus governed not only
by the ore grade distribution and the production costs, but also by the overall rock mass
strength, stability, controlled blasting techniques adopted, type of drilling machines
(vertical or inclined) used etc.

In hard rock open-pit ore mine, without jeopardizing slope stability, it is of prime
importance to keep the pit slope angle as steep as possible, maintaining excavated waste
at a minimum. The demands on fragmentation of the waste, as it does not pass
through the crushing/dressing system, are simple. It should merely suit the loading
and trucking equipment used for subsequent removal to the waste dump. On the
other hand, good fragmentation of the blasted ore will make great savings in the
total cost of the mineral dressing process.

6. Using pre-splitting for making bigger and steeper bench to save waste extraction -
In general, in order to reduce over all mining cost, mines are adopting high capacity of
excavators thereby increasing bench height, use of larger diameter blast holes and more
powerful explosives. These changes however resulted in high-energy concentration in the
blast area which results in severe back break problems for final pit walls. If back break is
-------------------------------------------------------------------------------------------------------   9
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
not controlled, it ultimately decreases the overall slope angle, with major economic
consequences such as decreased recoverable ore reserves and increased ore to waste
ratios. Greater amount of face loose rock will be produced and wider berms will require
to be left to ensure the safety of the pit walls. There must be trade off between the money
saved by using the larger equipments and blasts, and money spent to maintain the pit
walls. The best approach is to control the effects of blasting so that the inherent strength
of the walls is not destroyed. The purpose of pre-splitting is that to isolate the blasting
area from the surrounding rock mass by forming an artificial plane to limit gas and stress
wave penetration into the remaining nearby rock formation.

The theory of pre-splitting is that when shock waves from simultaneously detonating
charges in adjoining blast holes collide, tension occurs in the rock, forming a crack in the
web between the holes. For that reason it is important that charges are detonated
simultaneously or as close as possible.

Blasting will not only break the rock that is planned to be excavated, but will also cause
damage to the slopes that form the boundaries of the pit. The extent of this overbreak is
mainly dependent on the size of the individual charge and its proximity. A common
means of minimizing overbreak is to use smaller diameter holes, making provision for
restricted blasting in the zone next to the planned bench slope. A typical drilling pattern
applied in connection with pre-split blasting, to achieve increased slope stability with
reduced back break shown in Fig.6.

In order to achieve better result number of experimental trials is required to carryout
before establishment of full-proof system. Different combinations of blast pattern,
explosives, drilling diameter, angle etc., are to be tried. For example, varying the spacing,
hole angle, charge per square metre, use of gas bags, bottom initiation, cartridge
diameter, stand off distance between pre split and buffer row, number of buffer rows,
hole diameter of buffer rows, different drill patterns, different blast designs, powder
factor, number of rows in a blast, blast size etc. trials to be carried out.




------------------------------------------------------------------------------------------------------- 10
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining




                                                 Fig.6

It should be remembered during trials that, not only the dynamic tensile strength of rock
but also the overall Rock Mass Rating, the joint sets and foliation planes do also plays an
important role in success for pre-split blasting. Stability at steeper angle and higher bench
height depends much on success of pre-split blast. The type of explosive used plays a
great role, and its quantity should be gradually reduced till an optimum powder factor is
obtained. Gaining experience by analyzing various results obtained during trials is the
most important factor in achieving subsequent satisfactory pre-split results.




                                                 Fig.7

For effective pre-splitting, another technical point to be taken into consideration that,
there needs to be a “stand-off” distance between the pre-split plane and the buffer (or
nearest production) blast-holes. Where ever this stand-off distance is too small, the
production blast generates break backs beyond the pre-split plane. Where the stand-off
------------------------------------------------------------------------------------------------------- 11
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
distance is too large, it may be difficult to expose the pre-split plane. Sometime, there
may be a possibility of leaving layer of unbroken rock, adhering to the pre-split plane.
Therefore, thorough study of the rockmass and its changing pattern is called for before
deciding the blast pattern, quantity of explosives to be used and delay sequence. If
introduction of stab holes between inclined pre-split holes and buffer are needed, these
are to be provided (Fig.7 and Fig.8).




                                                 Fig.8

Slope stability, increase in bench height and increase in pit-angle depend on blast
performance and efficiency of controlled blasting adopted to mitigate the adverse effects.
Blasting adverse effects such as overbreak, ground vibration etc., are directly
proportional to the loading density of explosives and borehole pressure exerted by the
explosives. Again, borehole pressure is function of VOD of explosives used (P = 2.5 *
10-6 * ρ * V2 ; where, P is borehole pressure in kilobar, ρ is density of explosives and V is
VOD of explosives in m/s). Thus control of adverse effects, to some extent, depend on
selection of explosives as per VOD.

Conclusion - Success of pre-splitting depends on number of factors, such as blast pattern,
explosive used, drilling diameter, angle etc. It should be realized that, there is
tremendous scope of saving in rock excavation, by just making the pit slopes one
degree steeper. Again, there is substantial amount of savings in waste extraction by
increasing the pit as well; with suitable combinations of earth moving machineries
employed.

Moreover, strategy of fragmentation, which is to be implemented in the mines, should be
very clear to everybody and accordingly blasts are to be designed. Fragmentation of
waste rock to be kept maximum as per capacity of earthmoving machineries deployed,
------------------------------------------------------------------------------------------------------- 12
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
whereas, the fragmentation of ore has to be kept low to increase crusher and mill
throughput.

Therefore, substantial savings can be made if proper drilling, selection of explosives,
blasting and fragmentation strategy is followed in an optimum way.

References:
* Langefors, U. Kihlström, B. 1963, The modern technique of rock blasting. Almqvist &
Wiksell/Gebergs Förlag, Stockholm, Sweden
* Siskind,D.E., Fumanti,R.R., (1974), “blast produced Fractures in Lithuania Granite”,
USBM, RI 7901 (pp. 38).
* “Explosives and Rock Blasting”, Atlas powder Co., USA.
* Hagan, T.N. 1973, Rock Breakage by Explosives. Proc. Nat. Symp. on Rock Frag. Aust.
Geomech. Soc., pp 1-7.
* Persson, A., Holmberg, R. and Lee, J. 1994, Rock Blasting and Explosives Engineering
, CRC Press, Inc.
* Rustan, A. 1990, Burden, spacing and borehole diameter at rock blasting. Proc 3rd Int
Symp on Rock Fragmentation by Blasting, Brisbane, pp 303-310.
* Scott, A. (Ed) Cocker, A. Djordjevic, N. Higgins, M. La Rosa, D. Sarma, KS.
Wedmair, R. 1996, Open Pit Blast Design-Analysis and Optimization. Julius Kruttschnitt
Mineral Research Center, University of Queensland.
* Thornton, D. Kanchibotla, S. and Brunton, I. 2001b, Modelling the impact of rockmass
and blast design variation on blast fragmentation. Explo 2001, AusIMM, Hunter Valley,
NSW, pp197-205.
* Hall, J., and Brunton, I. 2001, Critical comparison of Julius Kruttschnitt Mineral
Research Centre (JKMRC) blast fragmentation models. Explo 2001, AusIMM, Hunter
Valley, NSW, pp207-212.
* Jaeger, J.C. and Cook, N.G.W. 1979, Fundamentals of Rock Mechanics, 3rd edition,
Chapman and Hall, London.
* Kuznetsov, V.M. 1973, The mean diameter of fragments formed by blasting rock,
Soviet Mining Science, Vol. 9 No. 2.
* Sjöberg, J. 1999, Analysis of Large Scale Rock Slopes. Luleå University of Technology.
Doctoral Thesis 1999:01.
* Winzer, S.R. Ritter, A.P. 1980, The role of stress waves and discontinuities in rock
fragmentation: a study of fragmentation in large limestone blocks. Proc. 21st Symp. on
Rock Mech., I.S.R.M., pp 362-370.
* Chiappetta, R.F. 2001. The importance of pre-splitting and field controls to maintain
stable high walls, eliminate coal damage and over break. Proc. 10th Hightech Seminar on
State of the Art Blasting Technology, Instrumentation and Explosives Application, GI-48,
Nashville, Tennesse, USA, July 22–26.
* Firouzadj, A., Farsangi, M.A.E., Mansouri, H. & Esfahani, S.K. 2006. Application of
controlled blasting (Pre-splitting) in Sarcheshmeh copper mine. Proc. 8th Int. Symp. on
Rock Fragmentation by Blasting, Santiago, Chile, 7–11 May, pp. 383–387. Santiago:
Editec.

------------------------------------------------------------------------------------------------------- 13
           Author: Partha Das Sharma, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/
Cost effectiveness in open-pit hard rock
Ore Mining
* Olofsson, S.O. 1998. Applied explosives technology for construction and mining: 183–
186. Rotterdam: Balkema.
* Bhandari, S., 1997, Engineering rock blasting operations, A.A.Balkema, Rotterdam.
* Singh, P.K., Roy, M.P., Joshi, A., Joshi, V.P., 2009, Controlled blasting (pre-splitting)
at an open-pit mine in India, Proc. Int. symposium on “Rock fragmentation by blasting”,
Fragblast9, Granada (Spain), pp 481-489.
* Partha Das Sharma; ‘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).

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Author’s Bio-data:
Partha Das Sharma is Graduate (B.Tech – Hons.) in Mining Engineering from IIT, Kharagpur,
India (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, Solar Group of Explosives Industries at Nagpur (India), 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), Hot hole blasting,
Signature hole blast analysis with Electronic detonator etc.

Author’s Published Books:
1. "Acid mine drainage (AMD) and It's control", Lambert Academic Publishing, Germany,
(ISBN 978-3-8383-5522-1).
2. “Mining and Blasting Techniques”, LAP Lambert Academic Publishing, Germany,
(ISBN 978-3-8383-7439-0).
3. “Mining Operations”, LAP Lambert Academic Publishing, Germany,
(ISBN: 978-3-8383-8172-5).

Currently, author has following useful blogs on Web:
   • http://miningandblasting.wordpress.com/
   • http://saferenvironment.wordpress.com
   • http://www.environmentengineering.blogspot.com
   • www.coalandfuel.blogspot.com

Author can be contacted at E-mail: sharmapd1@gmail.com, sharmapd1@rediffmail.com,
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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, B.Tech(Hons.) in Mining Engineering,
                                E.mail: sharmapd1@gmail.com,
                  Blog/Website: http://miningandblasting.wordpress.com/

								
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