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By Kurt Oakes, John Williams

Placer Dome, US operates the Bald Mountain Mine. The Bald Mountain Mine is a surface operation located in remote northwestern White Pine County in east-central Nevada, approximately midway between Elko and Ely. The mine is in the Newark Valley along the southwestern flank of Bald Mountain a part of the Ruby Mountain range, at an approximate elevation of 7,500 ft (2,286 m). The geology at the Bald Mountain Mine is highly altered, both mineralogically, and structurally. Highwall stability and control have long been an issue at the operation, due largely to the varying geologic conditions. In some blasts as many as seven distinct geologic unconformities exist. These unconformities affect both final high wall integrities, as well as blast fragmentation characteristics. A 60 million ton (54.5 million tonnes) layback expansion of the existing “Top Pit” as well as development of a new satellite pit, “Sage Flats”, is being undertaken. Design final highwall pit slopes have been steepened from the traditional 47º to 55º in order to reduce overall ore-to-waste ratios, thereby improving economic viability for the expansion over the 4.5 year life of the project. With the increased usage of electronic detonators throughout the mining industry, mine operations staff, as well as representatives from the mines explosive supplier felt that an evaluation program incorporating electronic detonators would be warranted. The areas of focus for this evaluation would be resultant highwall pre-split integrities, peak particle velocity measurements (both near field and far field), frequency measurements, loader productivity, and visual interpretation of the results. The mine incorporates 25 ft (7.6 m) benches and uses separate trim blasts in conjunction with production blasts in order to reduce blast effects along final highwalls. Hole diameters in production blasts are 7? ” (200 mm). Typical production blast patterns are 18 ft x 18 ft (5.5 m x 5.5 m), drilled in a square pattern configuration. Shot sizes vary greatly, ranging from 200 holes to as many as 800. Bulk low percentage ANFO/emulsion blends are utilized as the redominant blasting agent. Non-electric dual delay detonators (25 ms/500 ms), with non-electric surface delays are the initiation system utilized in production blasts. Typical production blast design

Jan 1, 2004

By Paul Sterk

In underground mining a great deal of time, money, effort, and resources have been used in the effort to minimize blast-induced damage. This damage occurs to the back, ribs, and pillars when the energy of the explosive is released back into the rock due to over confinement or the overloading of explosives in the perimeter holes. This damage can result in roof falls, dilution of ore, excessive rock bolting, scaling, screening, shot-creteing and other safety and support issues.

Jan 1, 2003

By Paul Downing

A typical day for a blasting company includes what seems to be an infinite list of tasks dealing with numbers. Whether determining the exact amount of explosives material in inventory, the number of holes in the shot, the exact distance from the blast site to the nearest exposure, or the capacity of bulk hoppers, the accuracy of numbers is key to ensuring the safety of the public, property and personnel.

Jan 1, 2008

By Sandra Penttinen

There are several ways to get a positive reaction from neighbors to blasting projects. When you need to enter structures to conduct a pre-blast inspection, the impression you make on the structure owner must be positive from the very start. Public relations with neighbors is the key. The purpose of all communications with persons residing near planned blasting operations is to educate structure owners as to what will take place during the blasting operations, to explain that safe blasting practices will be followed and vibration and airblast limits will be imposed to protect surrounding structures from damage. Once access into the structure is obtained, the structure owner can be shown, by careful documentation, all existing cracks and defects in the structure prior to blasting and construction. The objective of your visit and all communications is get your foot into the door and win the confidence of the structure owner so that he or she understands blasting will not compromise the structure.

Jan 1, 2006

By Kwang-Tae Kim, Yong-Kun Choi, Jeong-Soo Chong, Yun-Jae Lee

An annex building at the former Agency for National Security Planning(NSP) complex located in downtown Seoul was demolished by progressive collapse method. This work was done as a part of efforts to restore the landscape of Namsan Mountain which lies in the Center of Seoul. The five-story reinforced concrete structure was razed in 5.5 seconds by the 29kg of high powered explosives which were placed in some 320 holes in the building with floor area of 2,577 m². The asbetos and all the other finishing materials in the building were removed before the demolition and the specially coated wrap minimized the spread of blasting dust. Seismic and air overpressure waves were monitored at 8 points, which were below safety limits and the continuous communication with neighborhood prevented any complaint.

Jan 1, 1998

By C. Navalkar

Systematic drilling & blasting techniques are currently being viewed in the mining & construction industry as a correct 8z scientific approach for optimization process in rock excavation, as drill & blast costs usually represent major share in total cost of production and also the environmental impacts plays an important role in designing of the operations. Designing a blast is a complex planning task, which for optimization, includes deciding the bench geometry with respect to the rock properties & geology of the area, capacity of the excavators, choice of explosives & detonation method, tiring sequence, etc. Optimization of blast design needs a detailed comprehensive study of all the above intersecting elements. Preblast & Post blast surveys are required for further improvements in blast designs. However, the choice of blast design depends upon the the requisite blasting results opted for and the cost you are ready to pay for the same. The blasting operation, in general, also involves numerous side effects namely, ground vibrations, fly rocks, dust, noise & gas pollution, air blast effect etc. Again these effects can be made tolerable up to a certain extent depending upon the limitations of the environmental obligations as may be specified by the concerned authorities.

Jan 1, 2001

By J Aydin Bilgin, Sedat Esen

This paper describes the ideality of some commercial explosives with the help of the detonation theory and detonation velocity measurement. Ideality of an explosive can be determined by comparing experimentally measured and ideal detonation velocities. A measured detonation velocity at a certain charge diameter markedly lower than the ideal value indicates incomplete reaction and thus non-ideal detonation. Since it is shown that commercial explosives exhibit non-ideal behavior, two-dimensional detonation theory should be used to evaluate the performance of explosives. This theory enables to compute the detonation properties of explosives (detonation velocity, detonation pressure, etc.) as a function of charge diameter and confinement. The use of the one-dimensional detonation theory to compute the detonation properties for commercial explosives has an error associated with it as these calculated properties are independent of charge diameter and confinement. It assumes that shock front is planar. Hence, it is incapable of assessing the ideality of the explosives due to its assumptions. Shock front in real situation is curved in shape but not planar as in one-dimensional detonation theory. In this paper, the non-ideal behavior of some commercial explosives is modeled using EXRINT code based on the steady-state two-dimensional detonation theory firstly. Then the degree of ideality of each explosive found from the code is checked using detonation velocity test results conducted at a quarry. It has been shown that idealities of the tested explosives determined by the code agree well with the field detonation velocity test results.

Jan 1, 1999

By Gene Baker

A new Safety Library Publication (SLP), SLP-27, which is titled “Security in Manufacturing, Transportation, Storage and Use of Commercial Explosives” was recently released by the Institute of Makers of Explosives (IME). SLP-27 makes recommendations for both general security and enhanced security at explosives sites when security risk levels, declared by the Department of Homeland Security (DHS) using its Advisory System, have temporarily increased.

Jan 1, 2006

By Michael F. Barber

"Highway slopes are intended to remain stable over a long period of time. Unexpected slope failures can be costly in terms of human life and property damage or loss. Cleanup of failures can prove to beextremely expensive."

Jan 1, 1999

By Michael J. Burrell

Sands Hill Coal, located in Wellston, Ohio produces coal for steam generation and crushed limestone for the aggregate market in southeastern Ohio. This paper concerns the blasting and production of the limestone which lies between the #5 and #4 coal seams. The limestone bed averages 8 to 10 feet in thickness and is overlain with 17 to 20 feet of shale from the floor of the #5 seam.

Jan 1, 1990

By Karl Kure, Anders M. Heltzen

Mixtures of prilled ANFO and 0,5 - 3 mm polystyrene balls are interesting substitutes to the tube charges or other types of reduced explosives or detonation fuses. Experiments have shown detonation ability even of a mixture of 95% bolt polystyrene balls and 5% ANFO. The gas and shock energy in the mixtures decrease proportional with the content of polystyrene. The detonation velocity shows higher values than expected for mixtures with more than 50% (vol.) ANFO.

Jan 1, 1980

By Jorge Cárdenas, José Luis Hurtado

The critical distance determination test through direct recording for the mine in Phase 03 was carried out in January 2024, and in it the vibration and pressure models were obtained for the Sedimentary breccia unit. The method of obtaining the records is based on the capture of individual pressure waves generated by distant loads, sequenced in periods of 600 ms for easy identification. The test set up corresponds to a variation of that used to obtain the vibration model, and uses 08 wells for loads and 04 for instrumentation. The results apply a safety factor of 1.2 and 1.5, being 16,000 PSI and 13,250 PSI respectively. The values are valid for any distance greater than 5.5 m, this being the minimum established between wells for loads according to the configuration defined in the field, also considering that in 5.0 m of instrumentation the section of the drill hole with the sensor called S1 collapsed. The results of the analysis of the test, generated with Heavy Anfo 82 explosive, with a final density of 1.15 g/cc, are presented. The results of the modeling and generation of the graphs and tables presented show behavior in line with the concept of scaled distance. It is important to consider that in water conditions there is a high impact by the condition, which causes the records to be higher than those expected in dry conditions and present less variability. It is for the above reason that the row corresponding to distance with safety factor 1.5 is declared valid. The results are only valid for the rock analyzed, whose medium is homogeneous and constant in terms of lithological composition and that present similar resistance characteristics, fracture frequency and water table levels. As future steps, the objective is to quantify the increase in pressure generated between wells by analyzing time and sequence factors. This analysis aims to explain the occurrence of dynamic pressure events in areas where critical safety distances are observed.

Jan 21, 2025

By H. Rossmanith

This contribution introduces the fundamental concepts of wave propagation and fracture mechanics which form the basis of electronic blasting, i.e. precise initiation timing using electronic detonators. The concept of Lagrange diagrams will be frequently used for the calculation of the delay time between blast-holes in a row and rows of blast-holes. The effect of burden and structural geology will be briefly touched. It is found that the advanced blasting technology based on the use of electronic detonators introduces a change of paradigm. It will be shown that knowledge in wave propagation and fracture mechanics is essential for the successful application of the new blasting technique in industry. In particular, the delay time, the wave speeds in the rock mass, the shape of the wave pulse and the acoustic impedance mismatch have become decisive parameters in advanced blasting. Utilizing the wave speed and wave shapes of detonations, large scale tests Utilizing the wave speed and wave shapes of detonations, large scale tests in various countries (Australia, Chile, etc.) have shown that optimal delay timing requires shorter delay times in conjunction with allowing for a wider drilling pattern and the use of a reduced amount of explosives, i.e. a lower powder factor. This seemingly contradictory arrangement is fully justified by using scientific principles in blasting, and converting blasting from an art to a scientific discipline.

Jan 1, 2003

By P Geddes, K Grohs, C K. McKenzie, M Morrish

Low grade surface gold mining at the Acacia Resources, Union Reefs Gold Mine in Australia's Northern Territory, involves the excavation of benches in three slices after blasting. Blast patterns span zones of high and low grade ore, as well as zones of waste, and selective excavation is required in order to maintain economical head grades for the carbon-in-leach processing plant.

Jan 1, 1998

By Dale S. Preece

A carefully designed and controlled in-place destruction experiment was performed on a concrete bunker buried in 4.27 m (14 ft.) of soil. The objective was to determine if the explosive charges would collapse the structure in-place without requiring mechanical excavation. Collapse of the buried structure was fi rst attempted by drilling holes in the soil and placing four 13.38 Kg (29.5 lb) Comp B explosive charges at a depth of 2.13 m (6.7 ft.). The confi guration of the charges when detonated was 2.13 m (6.7 ft.) off the top of the concrete roof and 3.66 m (12 ft.) apart in a square pattern. Detonation of these charges created a crater ~4.88 m (16 ft.) in diameter and 2.13 m (6.7 ft.) deep, leaving ~2.13 m (6.7 ft.) of soil covering. Very limited spalling occurred on the ceiling of the concrete structure as a result of detonating these four charges. The second attempt to collapse the structure consisted of placing another single 13.38 Kg (29.5 lb) charge, identical to the fi rst four, near the geometrical center of the bunker roof. This charge was detonated in the soil cover 100 to 200 mm (4 to 8 in.) above the reinforced concrete roof, collapsing it. Due to the collapsed roof and remaining soil cover, the structure had been collapsed in place, requiring no further demolition. A computer simulation of the above explosive destruction scenario was completed using the computer hydrocode AUTODYN with a granular material model to treat the soil and the RHT brittle material model to represent the concrete. AUTODYN accurately recreated the scenario including the slightly damaged response of the concrete structure to the initial four charges and the collapse of the structure resulting from the second single charge close to the roof.

Jan 1, 2007

By Robert Martin, Brian W. Stump

As part of a series of seismic experiments designed to improve the understanding of the impact of mining blasts on verifying a Comprehensive Test Ban Treaty, a sixteen station network of three-component seismic sensors were deployed around a large cast shot in the Black Thunder Mine. The seismic stations were placed, where possible, at a range of 2.5 kilometers with a constant inter-station spacing of 22.5 degrees. All of the data were recorded with the seismometers oriented such that the radial component pointed to the middle point of the approximately 2 kilometer long shot. High quality data were recorded at each station. Data were scaled to a range of 2.5 kilometers and the sum of the absolute value of the vertical, radial, and transverse channels computed. These observations were used to construct radiation patterns of the seismic energy propagating from the cast shot. It is obvious that cast shots do not radiate seismic energy isotropically. Most of the vertical motion occurs behind the highwall while radial and transverse components of motion are enhanced in directions parallel to the highwall.

Jan 1, 1997

By Richard A. Dick

Few topics in the blasting industry are more controversial than the proper riming procedure for large-diameter ammonium nitrate-fuel oil (AN-FO) charges, despite the considerable amount of research that has been done both in the laboratory and in the field. The January, April, and June 1975 issues of Emphasis on Blasting contain interesting discussions on priming (5). An ideal primer is one that will surely and efficiently initiate the AN-FO column at the correct location to assure optimum blasting performance. During the 20 years of AN-FO's existence, singlepoint priming, axial priming, multiple-point priming, thermal priming, and shock riming have all been advocated as the "optimum" method. This is not surprising because blasting specialists have often differed on even the most fundamental concepts. To define the optimum primer, we must know what detonation characteristics in the AN-FO column are most desirable. Again, authorities disagree. This paper will discuss conclusions of various studies in an attempt to clear up some of the confusion.

Jan 1, 1976

By B Mohanty, Y C. Lizotte

Optimization of blast fragmentation in underground hardrock mining requires analysis of its effects on loading and haulage equipment, together with the downstream materials handling system, with the objective of minimizing total mine operating costs. A methodology is reported which has been developed to quantify the actual fragmentation and equipment performance in the field. This is data which has seldom been practicable to capture nor received serious attention in mines. Based upon the experience gained in underground studies, a prototype standard is proposed which aims to summarize the pertinent data, collection and analysis for fragmentation assessment. This relates to parameters of direct measure, such as mean size and distribution, as well as muckpile and work environment. The paper concludes by defining the impact of fragmentation on the loading and downstream handling system.

Jan 1, 1991

Blasting in a development heading or breasting operations starts from a cut. The void created by the cut provides a free face for the remainder of the round. It is the most critical part of the round because the later firing charges cannot pull to the desired depth unless the cut comes out as planned. The Burn cut is most commonly used in Canadian mines.

Jan 1, 1995

By P J. Dailey, S L. Burchell, R F. Chiappetta

High-speed motion picture photography and its application to the mining, quarry, construction, and explosive industries has proven to be a valuable diagnostic tool. The techniques developed allow one to evaluate blasting performance, compare explosive efficiencies in relation to burden velocity, and estimate optimum delay times to provide adequate forward relief.

Jan 1, 1983