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By R. Ticona, J. Alarcon

In the continuous search to provide comprehensive solutions and identify opportunities to improve ore traceability, from the blastholes to mill feed, different ore traceability systems have been developed, which allow tracking the ore and associating its geometallurgical characterization of different sectors of interest from blasting to the processing plant, facilitating decision making and operational actions when detected during each stage of the plant. With the objective of improving the ore tracking from the mine to the processing plant in a Peruvian copper mine operation, the impact on the processing plant was evaluated in relation to blasting optimizations through a tracker system, relating the processes performance of the whole production chain with the geotechnical and geometallurgical properties ores in real time in the process plant: detecting when it was feed waste, high grade ore, low grade ore and ore with arsenic, among others. Unit and integral tests were carried out over a period of three months, with an implementation of tracker detection portals in the processing plant, which allowed to verify the proper communication of data and the web platform. The tests were focused on several blasts where the ore was in contact with waste and it were directly sent to the plant, with a classification by type of grade (high, medium, and low grade), type of material (ore-waste contour), this stage allowed to make operational adjustments in the field and in the mining operation. Finally, in the economic results, the special tests had 1000 trackers, obtaining for this project a sensitization of a cost benefit for the test stage, for the reduction of 50% of the waste material feed has crushed, with an estimated benefit of 1,987,646 USD.

Jan 1, 2024

By Robert Hopler

Blasting powder is a slow-acting, black, granular explosive made of sulphur, charcoal and either potassium nitrate (saltpetre) or sodium nitrate. The blasting powder containing potassium nitrate is known as “A” blasting powder; that containing sodium nitrate, as “B” blasting powder. “A” blasting powder is a little denser, a little stronger and a little less hygroscopic than “B” blasting powder.

Jan 1, 2014

By E. Vilaescusa, J. Eloranta

The work presented in this paper investigates the influence of non-ideal detonation characteristics related to the blasthole diameter, base emulsion sensitivity (micro-balloon sensitised versus unsensitised) and percent emulsion on the explosive shock energy available to break rock using ANFOemulsion blends. A series of theoretical equal powder factor bench blasting patterns with hole diameters of 127mm (5”), 140mm (5.5”), 152mm (6”) and 165mm (6.5”) are compared to assess the non-ideal confined shock-state work energies. The Non-Ideal Shock Energy Factor (NSEF), which is the available shock energy per cubic meter of blasted material (MJ/m3) or kilocalories per cubic yard (kcal/yd3), is used to compare the different blasting patterns charged with a range of ANFO-emulsion blends from zero to 50% emulsion.

Jan 1, 2012

By Raj K. Rajamani, Solomon A. Tucker, Michael K. McCarter

"In a study aimed at exploring possible improvements in operating performance at an Open Pit Copper (OPC) mine in the western U.S., the impact of blast energy changes on crushing performance was evaluated. OPC feeds its 3-stage crushing plant in 12-hour-day shifts with skarn ore from three domains: Pit_B (B), Pit_S Low-Grade (SLG) and Pit_S High-Grade (SHG), in the blending ratio 1:1:1 (B/SLG/SHG). Thecrushed product is fed to a 2-stage ball mill circuit. "

Jan 1, 2017

By Braden Lusk

A typical rural house surrounded by a surface coal mine was instrumented in 2008. Information regarding ground vibration, airblast, and sounds inside the house was collected. Previous publications have included conclusions about this data with regard to blasting source (far-field or near-field) and results as to how the residents experience the blast were made. Several events were also recorded that were not related to blasting due to the nature of the trigger system. The trigger of the monitoring system was attached to one of the mid walls of the house, thus other normal daily events produced vibration levels significant enough to trigger the monitoring system.

Jan 1, 2011

By Richard Turnbull, James Purssey

"The Northconnex Project is a twin nine kilometre tunnel in Sydney, Australia, linking the M1 PacificMotorway at Wahroonga to the Hills M2 Motorway at West Pennant Hills. Access to the tunnels will befrom portals at either end and from three vertical shafts spaced along the length of the motorway. These shafts will provide access for equipment, plant and personnel, removal of spoil during construction,ventilation, and emergency egress points during tunnel operation. The three shafts have a 12 m x 16 m (39 ft – 53 ft) cross sectional area and depths ranging from 45 m to 91 m (148 ft – 299 ft). The vibration limit for the shaft blasting was set at 10 mm/s ppv, with residential properties as close as 31 m (102 ft) and the existing M1 motorway 80 m (262 ft) away. The traffic volume for the M1 is 80,000 vehicles per day and Northconnex will provide an additional 100,000 vehicle capacity. "

Jan 1, 2017

By Shulin Nie, Mats Olsson

The mechanism of rock fracture by explosive is a fundamental in rock blasting. It is generally believed that the shock waves from the detonation initiate the fractures. Then the detonation gases penetrate into the fractures and elongate them. However, our previous researches indicated that the detonation gases do not contribute significantly to the fracture propagation. In our latest experiment, blasts have been carried out in 8 large granite blocks. The main goal was to study the fracture mechanism, namely to determine whether the shock waves or the detonation gases fracture the rock.

Jan 1, 2001

By Ignacio Humeres Valdivia, Alejandro Ferrada Vergara

In the latest years, the use of innovative blasting techniques has become more frequent in mines all over the world. Such techniques allow the miner to be more aggressive in the distribution of explosive energy into the rock mass, e.g., stretching blasting patterns to improve fragmentation. Considering the different rock mass conditions and more energetic blasting designs, misfired shot events have occurred. After cause investigation, initiators have shown evidences of deformation by impact and/or loaded boreholes have resulted in emulsion desensitization, both presumably affected by dynamic pressure.

Jan 1, 2015

By Neal Lee, Braden T. Lusk, Brendan McCray

"Selection of a blasting agent for optimum performance is based on many variables. Often, a decision is made with regard to product cost and field testing. Defining optimum performance can be difficult, since downstream effects of fragmentation on loading, haulage, processing, and energy consumption are not immediately clear. Many operations are beginning to optimize their blasting programs “on the bench,” by utilizing information generated downstream at the loader and/or crusher. During the evaluation of a blasting agent, factors such as velocity of detonation, gas production, and sensitivity are typicallyconsidered. Alternatively, brisance (“the shattering power of an explosive material distinguished from its total work capacity”1) is not. Brisance affects the immediate area surrounding a borehole. Fractures produced here during the shock phase of detonation are believed to have an important effect on rock movement and fragmentation. "

Jan 1, 2017

By M. Y. Wong

Electronic detonators have been used on a trial basis for over a decade, and found more recent application in production blasting as well. The relative merits of these detonators and their applicability are outlined through examples from actual blasting operations. They offer unprecedented flexibility in the design of mass blasts and in control of vibration and blast-induced damage. However, the drive towards replacing the pyrotechnic detonators by electronic ones in general could prove to be counter productive without a re-examination of prevailing blasting practices. In fact, such an approach tends to blur the tremendous potential of the electronic detonators in redefining many standard blast designs and practices.

Jan 1, 2004

By Lazar Kricak, Vladislav Kecojevic, Dragan Bogunovic

In spite of many advantages explosives have, their usage may cause environmental problem such as seismic vibration. One of the solutions to this particular problem may be application of an artificial screen as a barrier to the seismic wave path. This paper presents the results of experimental research on the artificial screen concept, its characteristics and role in attenuation of seismic effects generated by blasting. More than 1,500 laboratory measurements were conducted with different combinations of screen sizes, positions of the screen to blasting source, and intensities of blasting impulses. The results of the study show a significant reduction of generated vibrations by employment of artificial screens.

Jan 1, 2007

By Jan Westberg, Roger Holmberg, Bernt Larsson

Over the last couple of decades there has been an increased demand from the market for precision detonators, partly because of a need for better blasting results and partly because of a need for better vibration control. Today's detonators have a pyrotechnical delay element which gives a relatively high time scatter, increasing with the length of the delay time.

Jan 1, 1988

By CVB Cunningham

"The Kuz-Ram model as originally proposed included an error in assuming that the mean fragmentsize predicted by Kuznetsov’s equation was actually the 50% passing size. In 2003 Spathis began discussions on this issue and recommended correcting the equation. The correction produced more fines in the predicted fragmentation, which had been a criticism of some users of the original model. Ouchterlony subsequently showed that the error had, if anything been beneficial, and that the Swebrec function adequately covered the fines. This author shows that the Spathis correction does not assist the fines correction in examples examined, but tends to underestimate coarser fractions. An intrinsic problem of communication between academics and engineers is a root of misunderstanding on both sides, and requires patience by both parties to enable value to arise."

Jan 1, 2016

By Zong-Xian Zhang

In sublevel caving mines, serious eyebrow break usually gives rise to lower ore recovery, higher dilution, and worse safety for the people working in the field. For example, chargers must go near the caving region and stand under the damaged eyebrow where a hanging stone may suddenly fall down or rock fragments may quickly roll down.

Jan 1, 2011

By Gungor Tuncer, Ali Kahriman, Abdulkadir Karadogan, Alper Celtikci, Serdar Celik, Yucel Karakus

This paper presents bench blasting designs based on results of vibrations analysis on test shots organized in an open pit coal mine located near to Soma district at Manisa province in Turkey. There are some structures which can be adversely affected by blasting at the coal mine. The one of the main goals of this study is to perform a preliminary assessment of possible damage effect of ground vibrations induced by blasting at these structures by risk analysis based on ground vibration measurements. During this investigation, the data pairs of scaled distance and particle velocity obtained from the 36 event records belong to 9 test shots were statistically analyzed and a PPV prediction equation specific to this site with 95% prediction line were obtained. And also, this equation was used in the derivation of the practical blasting charts specific to this site as a practical way of predicting the peak particle velocity and maximum charge per delay for future blasting. A risk analysis was performed by using this equation. In the light of this analysis, preliminary blast design model was proposed to be used in this coal mine for overburden excavation.

Jan 1, 2012

By Daniel Johansson, Markus Danielsson, Håkan Schunnesson

In sublevel caving, blasted material flows gravitationally into the drawpoint from above in a periodical manner. This type of flow behavior entails muck pile conditions that are variable along the course of extraction. The effect of this variability on the LHD (Load-Haul-Dump) operation in terms of loading efficiency and ability to undermine the blasted ring is not fully understood as of today. This paper presents results from a field test in LKABs Malmberget mine in Sweden, where the influence of fragmentation on the loading operation has been studied in detail. Drawpoint filming was conducted for extraction of two rings equivalent of roughly 10000 metric tons (~9842 long tons) of material each. The analysis includes fragmentation measurements, muck pile classification, and general estimations in terms of loadability. Further, an evaluation of LHD machines from two different manufacturers was conducted to identify and highlight differences. The results show that fragmentation, muck pile compactness, and flow characteristics are all interdependent. Flow disturbances and the subsequent loading of compacted fine material in the back of the ring have been identified as the main reason for occurring problems and prolonged digging times. However, the ability to sufficiently undermine the blasted ring has been identified to primarily depend on digging depth which is only observed to be high during flow disturbances. An absence of flow disturbances seem to promote high loading efficiency but simultaneously limit the maximum digging depth. A mid-range particle size distribution with a low amount of fines has proven beneficial for overall loading efficiency. The various LHDs employed showed significant variations in terms of ability to handle difficult loading situations (e.g. compactness, boulders, etc.).

Jan 1, 2018

By Andrew Wetherelt

Blast vibrations are of paramount importance in a society where ever increasing development is putting more stringent requirements on their control. Increasing civil development and more complex extraction scenarios make the trade off between proficient vibration control and productivity difficult to ascertain. Historically, reduction of induced vibrations levels was achieved through a reduction of MIC’s leading to smaller but more frequent blasts in order to meet extraction targets.

Jan 1, 2007

By Travis A. Davidsavor, Charles Dowding, David A. Provost, Yonggang Gou

This paper compares measured blast induced strains on operating, full scale, buried pipelines with three similar past studies. The recently performed study represents realistic and modern pipeline blasting techniques combined with modern data acquisition. The evaluation compares measured PPV and strain, as well as calculated stress, at equivalent scaled distances.

Feb 1, 2020

By Neal Lee

Often the effects of wet boreholes are not taken into consideration when designing a blasting program to exhibit a certain amount of explosive energy per unit of rock such as design by powder factor, expressed in lbs./bcy (pounds explosives per bank cubic yard) or kg/bcm (kilograms per cubic meter), often the effects of wet holes are not considered. This paper examines different methods of loading wet holes and the effects they have on actual explosive quantities/unit of rock. In particular, we are looking at the amount of water trapped within the explosive column (bulk loading from the collar), or the annular space left void of explosives product around and between cartridges (wet-bags) with many of the current wet hole loading methods in use. We will focus on the effect this has on actual powder factor relative to “as designed” dry hole loading values, as well as the effect on performance of the explosives.

Jan 1, 2011

By Tapan Goswami

The main objective of the blasting phase in a coal mining operation is to maximise the coal recovery. However, coal loss due to blasting is a serious problem. The Australian Coal Association Research Programme (ACARP) reported in 2011 that in Australia one in every ten coal mines is completely wasted due to such losses. Coal is either lost in the spoil, largely due to the blasting operation or becomes diluted and cannot be recovered entirely. The major coal loss mechanisms include losses from the coal seam roof, the floor, the front edge and from dilution. Coal damage and loss mechanisms during cast blasting that have been observed by various authors include: •Excessive cast dragging the coal edge in the cast direction. Movements of this nature are oftenassociated with the formation of trenches. •Spatial movement of overburden where rock shears and moves in a plane above the coal seam,which damages and dilutes the coal. •Rock falling over the coal during the blast often producing indentations in the exposed coal. •The inappropriate use of bulk and initiating explosives that often results in coal damage. •Insufficient stand-off distances from the coal. The Australian coal mining industry has gone a long way towards addressing the coal loss issues since 2011: almost all operations now deploy touch-coal drilling and sporadically use gamma logging for loading overburden. A study was conducted to compare the effectiveness of touch-coal information in which some touch-coal blastholes were drilled on a fixed or random pattern. In another study, some blastholes were drilled to the touch-coal, gamma-logged and mapped to determine stand-off distances. It was found that the coal roof surface created by gamma-logged holes was the most effective option for minimising coal loss. As a result, a variable stand-off distance was found to be the key to minimising losses. This paper discusses the importance of coal mapping, the rock properties of the roof and floor interface of the coal seam, and the significance of loading and initiating designs in minimising coal damage. Furthermore, the importance of using electronic initiators cannot be emphasised enough. This paper also discusses how a cast blast can be initiated from many locations by mitigating geological abnormalities and thereby avoiding spatial movement of rock shearing in a plane above the coal seam.