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By Javier Illanes Pizarro, Gustavo Huerta Valer, Jorge Cárdenas Miranda

Bench stability is the basis of sustainability in an open pit mining operation. Taking care of the pit walls while maintaining fragmentation results can prove a challenge. In this study, technical proposals have been developed for extra hard rock mass (UCS>175MPa) with presence of unfavorable structural planes in high copper grade zones. The base case shows low compliance of fragmentation results and a significant loss in berm width, with over size boulders causing low primary crushing rates. Paradigms in current drill and blast design were overcome to improve fragmentation results and achieve objectives.

Feb 6, 2023

By Joshua Hoffman, William Chad Wedding, Braden Lusk

The University of Kentucky employs an explosively driven shock tube in the course of experimentation. A good deal of the work completed relates to the verification of blast mitigation products and strategies. The work is dependent upon reliably reproducing specific pressure time histories called out by the test in question. The facilities are located in the workings of an underground limestone quarry in Georgetown Kentucky. As such, the temperature maintains fairly consistent 60°F (15.6°C), making it a comfortable work environment year round. Unfortunately, the relative humidity follows the prevailing weather conditions allowing a wide variation, especially between the winter and summer seasons. A study was undertaken to gauge the influence of relative humidity on shock wave generation, including the positive and negative phases of the wave.

Jan 1, 2011

By Michael Burrell

This project involved the protection of an historic landfill located on the site. Construction blasting was for a permanent access road to carry traffic to and from a new metal processing plant being constructed nearby. The landfill contained materials disposed of during the closure of a Phosphorus plant that had previously occupied a portion of this site.

Jan 1, 2012

By Piet Halliday, Ellina Kharatyan

Conventionally, emulsion matrices (unsensitized) need to be sensitized to become detonable explosives. This is done either chemically or mechanically. Both methods have their advantages and disadvantages. Mechanical sensitization involves the addition of microballoons (plastic or glass) to the emulsion matrix, in order to create hot spots during detonation. This is usually done at the manufacturing site and poses a safety risk in terms of the storage, transportation and handling of a 1.1 type explosive. Many countries throughout the world make use of chemical sensitization as opposed to mechanical sensitization as this allows for the storage, handling and transportation of two 5.1 type products rather than the 1.1 type explosive. Chemical sensitization involves the addition of a small amount of a chemical that reacts with a component of the emulsion matrix causing the formation of gas bubbles that act as hot spots during detonation. The disadvantage of this is the lack of accurate density control (due to various factors affecting the reaction) and the lack of comprehensive understanding of the operators of the reaction. This can easily result in poor blast performance. Due to these disadvantages a pumpable, non-detonable (5.1 type) mechanical sensitizer was researched and developed. This product allows for pumping at a 50:50 volume ratio with the emulsion matrix, when loading into blast holes. The significance of this is that a 1.1 type explosive is formed in the blast hole. As such, the security and logistical issues of the transportation and storage of the 1.1 type explosive are eliminated. Another advantage is accurate density control of the final product, specifically in small diameter long hole applications. A cost effective, unique mini pumping system has been developed for the loading of this product. Moreover, this system can easily be used for secondary blasting applications and the on-site packaging of cartridged explosive products.

Jan 1, 2015

By Les Willan, Chris Batten, Matt Sparkes

In late 2008 Xstrata Newlands Coal Mine in Central Queensland and Orica Mining Services engaged in discussion to investigate methodologies to change their current mining practices and overcome the issues in the mining of steeply dipping coal seams, the associated coal loss risk and to assist in improving mining productivity. A strategy was developed and it was determined that through-seam blasting was essential to the success of winning the coal from the Wollombi Pit at Newlands.

Jan 1, 2010

By Ali Kahriman, Abdulkadir Karadogan, Umit Ozer, Mehmet Aksoy, Deniz Adiguzel

The environmental problems arising from ground vibration has been faced and discussed frequently in various industries such as quarry, mining, civil works, shaft, tunneling, pipe line and dam construction etc. where the blasting operations are unavoidable. In bench blast design, not only the technical and economical aspects, such as block size, uniformity and cost, but also the elimination of environmental problems resulting from ground vibration and air blast should be taken into consideration. The prediction of ground vibration components plays an important role in the minimization of the environmental complaints. This paper presents the results of ground vibration measurements carried out in the quarries located on the different sides of Çatalca district in Turkey. In order to predict peak particle velocity level for this district, ground vibration components were measured for shots during bench blasting at these quarries. In blasting operations; ANFO is commonly used as blasting agent at the quarries. The type of priming and firing differed from quarry to quarry. The parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events by using different type vibration monitors. The absolute distances between shot points and monitor stations were determined by using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity. In order to predict, and compare the influence grades to the neighboring buildings, and structures at the Çatalca district, the particle velocities and frequency values of all blast events are evaluated according to the United States Bureau of Mines (USBM) and German DIN 4150 Norms due to the lack of a national standard in Turkey. Then, the data pairs belonging to these quarries were gathered together to represent the district and were analyzed statistically. At the end of statistical evaluation of the data pairs, an empirical relation which gives average line at 95% confidence level and upper bound 95% prediction line with a reasonable correlation coefficient was established between peak particle velocity and scaled distance

Jan 1, 2007

By Panagiotis (Takis) Katsabanis, Lyall Workman, Jack Eloranta

The reduction of metallic ores to concentrate consumes a great deal of electrical energy. In the past two decades, a number of case studies have demonstrated a beneficial relationship between powder factor and grindability. However, changes in mill performance cannot be attributed to changes in feed size alone. Blasting energy and the distribution of that energy appears to affect subsequent comminution beyond crushing. This experience has prompted researchers to attempt to duplicate and quantify the mechanisms involved. To date, published reports indicate a measure of success. However, the blast engineer and the mill engineer still lack the tools and basic understanding necessary for full drill to mill optimization.

Jan 1, 2015

By Jorge Flores, Dean Nichols

Some view quantitative risk assessment (QRA) as difficult to understand and complicated to use. They are comfortable with the proven reliability of quantity distance (QD) and question the benefits of applying QRA principles to explosive safety. In response to such questions, a review of the history of the American Table of Distances (ATD) provides insight to the strengths and weaknesses of the concepts behind QD tables. Additionally, a closer look at QRA features that are available today will reveal stunning capabilities and improved user friendliness not available previously. This paper looks at the early days of explosive safety, the use and limitations of QD, the meaning of risk in the context of QRA and discusses recent developments that knock down barriers previously hindering acceptance of QRA among regulatory agencies.

Jan 1, 2015

By H. S. Venkatesh, G. Gopinath, R. Balachander, G. C. Naveen

Punatsangchu Hydroelectric Project Authority is constructing 1020 MW underground hydroelectric project in Bhutan. The project envisages construction of concrete dam, Desilting Chamber, Head Race Tunnel, Power House Complex and Tail Race Tunnel. Tunneling is one of the major activity in any underground projects as they are driven for multiple activities. By and large the tunnels are a major part of connecting networks from surface to caverns/underground working sites. Many tunnels in hydropower project are part of water conducting systems and one such important tunnel is the Tail Race Tunnel in this project and had to be excavated in thinly foliated rockmass conditions by D&B method.

Feb 1, 2020

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 Ph. D. Favreau, Favreau Patrice B. Eng, R. F.

Geology is important in mining by helping to identify the rocks which contain sufficient valuable ore to justify their excavation. Geologists give a geological name to each rock type, so geology is a player in blasting; when a blaster has successfully blasted rock of a given geological name at a former site, and he later has to blast rock at another site whose rock has the same geological name, then his first trial often is the same method as he used at the former site, since the geological name of the rock is the same

Jan 1, 2019

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 Corry Goumans, Ron J. Elliot

This paper discusses the challenges encountered in drilling and blasting of a small diameter shaft underneath a parking garage in historic Gastown, Vancouver, BC. This project involved drilling in a restricted headroom area, blasting in a confined space environment, and excavating using a novel vacuum technique. The 1.2m x 1.2 m x 8.5m deep shaft was required for installation of a hydraulic piston for a show lift. The project called for very accurate drilling through inter-bedded sandstone and siltstone within the water table. Development of a unique blast design was required for blast vibration control on a historic structure located just 15.8 meters away. The shaft was successfully completed without damage to any of the surrounding structures.

Jan 1, 2004

A major problem that has continued to plague the surface coal industry is blast induced damage to the coal seam. Atlas Powder Company has addresssed this situation through seven years of field research in full-scale production environments. Many operations across the United States have been evaluated.

Jan 1, 1990

By D. Scott Scovira, Remi Proulx

The Meikle Mine is a high grade, underground gold mine utilizing primary-secondary longhole open stoping with delayed backfill to produce 3000 stpd of ore. Hot and reactive ground conditions were encountered early on in the mine life. Ground temperatures up to 330” F were measured. In the early stages of mining, the mine experienced premature detonations using different explosives. The learning curve to safely mine this high-grade gold deposit in hot and severely reactive ground was indeed very steep. Currently, the Meikle Mine uses a special buffered bulk emulsion in all blasts to address hot and reactive ground concerns. In addition, exacting procedures are also followed to ensure safe work with explosives. The combination of new explosives technology and strict loading procedures permits high mine productivity with the highest degree of safety.

Jan 1, 2000

By Jennifer Williams, Donald J. Berger

Originally built between 1913 and 1916, the Ashton Dam & Hydroelectric Facility has experienced various seepage and piping incidents since completion. Ashton Dam is located within 15 miles (24 km) of the historical Teton Dam failure site and about 2.3 miles (3.7 km) west of Ashton, Idaho. Numerous repairs conducted over the years ranged from filling sinkholes on the crest of the dam to placement of rockfill on the upstream slope to improve seismic stability. In addition, the existing low level outlet works was grouted full and abandoned in 1991 due to significant vibrations induced on the dam during its operation.

Jan 1, 2014

Currently there exist several explosive quantity-distance (Q-D) rules variously exercised by most countries to protect personnel and property against the effects of accidental explosions. These regulations apply to manufacture, transport and storage of explosive products. This paper reviews the technical basis behind these regulations, as they apply to commercial and military explosives. The characteristics of a blast wave and missiles issuing out of an explosion site and their role in determining the level of damage to a target are discussed. The need for further research on the effect of detonation of charges of non-standard geometry, and under confined conditions such as tunnels is discussed. The challenge in estimating the net quantity of explosives involved and calculation of its TNT-equivalency is also highlighted.

Jan 1, 2011

By Andreas Gaich

A new 3D fragmentation analysis method for muck piles is presented. It works with aerial imagery from UAVs (drones) and handles entire muck piles with minimum user intervention.

Feb 1, 2020

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 Joseph Indeck, Seokbin Lim, Andrew Thompson

In the design of explosively driven penetration devices, understanding the impact conditions between the explosively propelled penetrator and the target is one of the most important steps in optimizing the performance of the device. These impact conditions are especially prevalent when a shaped charge jet impacts concrete, which is not an ideal target material. The specific impact conditions, including but not limited to the impact angle and jet properties, create a great deal of variability that affects the performance and penetration of the shaped charge. The large amount of impurities and voids in concrete, along with its heterogeneous nature and the general strength characteristics, make concrete a non-ideal material for shaped charge jet penetration. These material characteristics lead to a highly non-linear deformation behavior of the concrete target during a hyper-velocity impact.

Jan 1, 2011