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By Theirry Bernard

The era of non-electric systems as an initiating system has revolutionised the blasting world by introducing a very safe initiating system that is reliable, with initiation sequence possibilities that are superior to those of purely pyrotechnical or electric systems. Electronic initiation has brought with it accuracy, programming and controls that were lacking in the non-electric systems. However, it has also led to a certain degree of complexity, which works against user-friendliness, sometimes introducing a few constraints that are balancing out the intrinsic performance of electronic detonators. The introduction of a hybrid initiation system, Electronic and Non Electric, offers accuracy, and flexibility that were lacking in non-electric systems, whilst removing the inherent complexity of electronic systems. This paper endeavours to summarise the advantages and disadvantages of non-electric and electronic initiation systems that have been recorded after years of experience on site. The paper will then describe how a hybrid system only keeps the advantages whilst eradicating the disadvantages, via a case study.

Jan 1, 2007

By Thomas Kovalchuk, Kenneth Eltschlager, William Shuss

In April of 2000, two adults and their newborn infant, were poisoned by carbon monoxide in their home and received medical treatment at a Pennsylvania hospital. Carboxyhemoglobin levels were; child - 3 1%, father - 28Oh, and mother - 17%. Initially the furnace was blamed but after further review, blasting at a nearby coal mine was determined to be the source. All other sources of carbon monoxide were ruled out. The blasting was about 400 feet from the house. The conditions that led to the migration of gas include: the blasts were highly confined, the geologic structure contained fractures that served as conduits for the carbon monoxide to reach a hand-dug well outside the house, and the well was atmospherically connected to the basement floor drains.

Jan 1, 2001

By Shuli Teng, Vladimir Sujansky, Matthew Rawls, Ivan Junarsa

In recent years significant advances have been made in chemical processing technology. In particular, process intensification using micro-technology has had some success in changing and improving chemical processes including mixing. Process Intensification is the miniaturization of unit operations and processes whereby a smaller compact piece of equipment takes the place of a larger one at the same given capacity or mass flow rate. This paper summarizes research into the application of the technology for manufacture of high internal phase water in oil ammonium nitrate emulsions (ANE’s) at low energy cost and with very low oil/fuel blend content. The emulsions can be used as precursors for preparation of explosives. The quality of the emulsion prepared was assessed through droplet and crystal analysis and compared with that of emulsions made by conventional large scale jet mixing technology.

Jan 1, 2014

By R Frank' Mammele Chiappetta, Conny Postupack

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

Jan 1, 1988

By MSHA website

“Conditions at underground and surface coal mines can change dramatically during the winter months,” said Joseph A. Main, assistant secretary of labor for mine safety and health. “We must be ever mindful of the seasonal changes that can affect our work environments.”

Jan 1, 2011

By Claude R. Ayoub, Charles A. Kliche, David G. McDowall

Homestake Mining Company's Open Cut Mine is located in Lead, South Dakota, in the northern Black Hills. The mine is within 300 feet of occupied residences on the south end, and within 1200 feet on the north end. Mining began at the north end of the open pit in October, 1983, and blasting related complaints began almost immediately. Noise and ground movement comprised the majority of the structural damage claims. As a result of these complaints, Homestake purchased a recording seismograph and began monitoring nearly every blast. In addition, the company hired a consultant to review Homestake's blasting and monitoring practices. He was also asked to do a single, one-time study of the cracks in six homes. This initial work led to Homestake monitoring all blasts with three seismographs and having South Dakota School of Mines and Technology do a year-long study of crack development and propagation in five homes in Lead.

Jan 1, 1989

By David E. Siskind

Increased mineral consumption and environmental concern have caused much interest in potential damage and annoyance from ground vibration and airblast produced by production blasting in surface mines and quarries. Ground vibrations are traditionally blamed for "shaking the house to its foundations," but often the airblast is responsible, particularly when the distances from mine to structure are large. Simultaneous measurements of ground vibrations, structure vibrations, and indoor and outdoor noise from blasting are being used by the Bureau of Mines to determine the relative importance of the ground and airborne blast energy in shaking the structure and making windows, dishes, etc., rattle.

Jan 1, 1977

By R. F. Favreau, Favreau Patrice

"The economy profits from the rock excavated in mines and quarries and the excavations required for the construction of roads and buildings. However such excavations are achieved by blasting withexplosives, and explosions create fly rock and vibrations which in some cases may throw rock far intoinhabited regions and may vibrate buildings excessively in these regions. Society, however, no longeraccepts that their quality of life be disturbed by the risks of fly rock or the perturbation of vibrations.Thus it is important to know how to design blasts that do not cause excessive fly rock or vibrations, and to understand why sometimes a blast does create excessive vibration or fly rock. An article presented at the 2015 ISEE (reference 1) explains how unacceptable vibrations can be avoided, while the present article explains why dangerous fly rock occurs and how it can be avoided. The article shows by rigorous calculations with the blast simulator Blaspa that long range fly rock can be due to short collar or short burden, but mainly it explains how inadequate blasting that allows the floor to rise can cause even further reaching fly rock, a situation not usually recognized by most blasters."

Jan 1, 2016

By Francisco Sena Leite, Vincius Miranda, PhD Machado Leite, PhD Pinto, Raquel Carvalhinha, Alexandre Julio, Dorival de Carvalho

Rock blasting, in particularly the drilling process, is one of the first processes in the stage of rock fragmentation and plays a fundamental role by influencing all the following stages. Given its importance, some proposals to optimize this process have been presented over the last few years. These proposals, while having different approaches, aim (in a large part) to minimize the costs of drilling and blasting respecting the limits of fragmentation required by primary crushing. Reviewing some recent articles leads us to an enriching experience, since the authors of these articles clearly model the problem, but do not address the mathematical solution of these models, which in turn, given their non-linear nature, have no directly and easy solution. Simple and even robust optimizers present in the market show different results and often do not converge to a single solution. To address this problem, an adapted gradient heuristicbased model was developed to try to find optimum values. Heuristics search for values of stemming, subdrilling, burden and spacing that minimize the costs of blasting and drilling. This search, which by the nature of the heuristic moves the solution in the direction of the gradient with maximum decrease to find optimal solution, found values that in turn, when compared with values presented by market solutions not only equaled them as, in some situations, even improved the proposed solution. The algorithm was tested and validated on the field, and although the results have already been presented in papers published in the last year by the authors of this paper, it is now presented with its mathematical formulation and comparison with the other solutions. This approach is expected to be able to improve (and even demystify) the process of pattern expansion and be the basis for future work in the continuation of the optimization process.

Jan 1, 2019

By Clara Godoy, Álvaro Dapía, Paulo Couceiro, Håkan Schunnesson, Juan Navarro

This paper applies geostatistical tools in Measure While Drilling (MWD)data to estimate the probability distribution of values in all the points of the studied domain in order to assess the continuity of rock classes between boreholes. The analyses carried out by Ghosh et al.(2018) and Navarro et al.(2019) have been used as starting point of this work to classify the geotechnical rock condition in four classes: solid rock, fractured rock, cave-in rock and cavity. From it, an application for the geotechnical rock condition of ore bodies have been developed, aiming at characterizing the rock before the charging the holes to minimize unexpected rock conditions and to address issues associated with charging and blasting operations. Such problems are closely related with non-optimal rock fragmentation after blasting. The procedure has been applied in the geotechnical block model results obtained from Navarro et al.(2019)’s work in the Luossavaara-Kiirunavaara AB’s (LKAB) Malmberget underground iron ore mine, Sweden. Navarro et al.(2019)’s model was developed based on102 fan-holes from five ore bodies and extrapolated to the full-scale in20 drifts with 5600 fan-holes from two orebodies. A multi-step transformation of the MWD parameters was carried out in order to minimize external influences other than the rock mass. The study shows the calculations of the variogram and kriging estimation in the 3D domain for six ring-blasts, from one of the ore bodies studied in Navarro et al. (2019)’s work to assess the continuity of the rock classes along the six ring-blasts in a 3D mapping model. For that, intermediate rings between the measured ones from the MWD have been estimated. The probability distribution of values in the entire domain of rings with measured samples has been plotted together with the rock classes identified by the blasthole paths. The results show high accuracy in the matching between the kriging and the values given by the MWD data, allowing to visualize smooth trends of different rock classes along the ring. The representation of the 3D mapping model for the six ring-blast shows clear fractured and cave-in zones developed along the drift that correspond to zones with geotechnical problems found, as from internal reports.

By Cathy Aimone-Martin, Kristin Dunlap Kolden

Blasting was conducted for the Army Corps of Engineers (Corps) in the Columbia River near Saint Helens, Oregon during 2009 and 2010 to deepen the navigation channel as a final phase of a dredging project to accommodate larger container ships. The Columbia River Channel Improvement Project (CRCI) required 4 months to blast and dredge 300,000 yd3 (229,366 m3) of basalt from the bottom of the channel to allow Post-Panamax vessels with drafts up to 50 ft (15.2 m) access to the Ports along the River. Explosives charges were limited to 90 lbs (40.8 kg) per delay for the protection of fish and marine life in the area. A fish mortality study and marine mammal monitoring program was also required by the Corps. Underwater overpressure monitoring was required for each blast and peak overpressures measured 10 ft (3.1 m) above the river bottom 140 ft (42.7 m) from the closest blast hole were not to exceed 70 psi (483 kPa) with a cautionary level of 40 psi (276 kPa). Specifications required sampling rates of 500k S/s and PCB Peizotronics tourmaline pressure sensors. The Corps granted permission to co-locate additional ceramic-type sensors at different sampling rates to design redundant monitoring systems 140 and 300 ft (42.7 and 91.4 m) from blasting and develop a site-specific overpressure attenuation model for the project. This paper presents the correlations of overpressure with cube-root scaled distance factors, a comparison of measurements using three different pressure sensor systems, and a discussion of blast design influence on overpressure measurements.

Jan 1, 2014

By Wilfrid Comeau

Vibrograms, which last significantly longer than the actual blast (say 10 to 15 cycles or more), may be signalling an elastic response, which is not uniquely blast related. For example, geophones mounted on a part of a structure, which can elastically resonate at a frequency included in the seismogram, may not show the structure’s real reaction to the blast. This resonance usually amplifies the ground vibration. This contribution examines one particular case where blasting excited and amplified a resonant ground response, and the method used to significantly reduce or eliminate this undesirable condition.

Jan 1, 2007

By Jean M. Bouvet, Pierre M. Vuillaume

There is not just one ANFO: ANFO explosive behaviour depends significantly on the blasting conditions and on its physico-chemical characteristics. For instance, ANFO effficiency increases whereas AN porosity is higher and consequently loading density of the explosive is less. This can be argued against generally admitted ideas. Therefore, the efficiency of industrial explosives related to ANFO (for example "relative weight strength" or "relative bulk strength") is a tool that must be used with caution.

Jan 1, 1993

By John T. Watson, Jim Bailey

Increasing public awareness is probably the single most important challenge faced by any blasting contractor today. This increased awareness usually results in an outcry for tighter regulations and restrictions on those in the blasting industry. Those affected do not often understand the dynamics of blasting and are simply fearful of the unknown. This reaction very often results in more regulations and restrictions which frequently fail to address the real problems.

Jan 1, 1990

By David Harrison

The Charleroi Locks and Dam (Figure 1) was completed in 1932 and is located on the Monongahela River, approximately 22 miles (35 km) south of Pittsburgh, in Charleroi, Pennsylvania. It is comprised of a 420 foot (128 m) gated dam, and a 720 foot (219 m) by 56 foot (17 m) land side lock which provides for a 16.6 foot (5 m) vertical lift.

Jan 1, 2015

By Khushaal Popli, Vanessa Roeland, Brian Hall, Carl Diederichs

Highland Valley Copper (HVC) has embraced an integrated Mine to Mill approach to comminution since the late 1990s. Previous blasting optimization was carried out through adjustments to blast pattern geometry (i.e., reduction of burden and spacing). This approach proved very effective and HVC reduced the burden and spacing of high energy ore blast patterns to what was considered the practical limit that still allowed for efficient drilling and bulk truck loading operations. While mining in the bottom of the Valley pit near the end of the previous pushback, HVC encountered high static groundwater conditions which enabled the transmission of elevated inter-blasthole pressures that had the potential to exceed safe operating limits for initiation products. This risk was mitigated through an expansion of burden and spacing for the high energy ore patterns, reducing the application of blasting energy and increasing the average particle size in Mill feed.

Feb 6, 2023

By Robert B. Hopler

The hazards which naturally prevail in underground coal mines, always severe and unpredictable due to the loosely-consolidated strata in which coal is frequently found, are increased by the commonly-occurring combination of coal dust, methane, and explosives. It was recognized by the mid-nineteenth century that coal dust was the basic factor contributing to disastrous explosions killing hundreds of miners, and that the ignition of methane gas was often the source of the coal dust explosions. It was apparent that preventing the ignition of methane was a critical part of avoiding these disasters, and it was also apparent that one cause of such ignitions was the firing of explosives. In addition, it was found that dust explosions were often initiated by blown-out shots of explosives in the absence of methane.

Jan 1, 1996

By Sunil Vytla, Akash Adhikari, Purushotham Tukkaraja

Blasting operations produces gases and fumes that may be toxic or non-toxic in nature. A detonation of commercial explosives such as ANFO, emulsion, and dynamite would ideally produce only nontoxic products such as steam (H2O), carbon dioxide (CO2) and nitrogen (N2). However, in the real world, the detonation of explosives produces toxic products such as nitrogen dioxide (NO2), nitric oxide (NO) and carbon monoxide (CO). The focus of this study is the blast fumes entrapped in the muckpile. Fume clearance and workplace re-entry time studies performed in the past have overlooked the toxic gases entrapped in the muckpile. Studies show that as much as 60% to 70% of the fumes or gases produced during blasting underground can remain entrapped in the adjacent rock mass or in the muckpile. The toxic fumes trapped inside the muckpile are slowly released and could be fully uncovered during the mucking process. Exposure to these gases or fumes is hazardous to mine workers. In this study, author have analyzed the nature of fume flow, i.e. accurately predicting where and how the fumes flow after an underground development/tunnel blast. This will help in determining i) precise re-entry times for the workers ii) rate and direction of the fume flow. Computational Fluid Dynamics (CFD), a mathematical simulation technique that predicts fluid dynamics phenomena is used for this purpose. CFD is preferred over physical models because it is inexpensive, once the accuracy is established, a wide range of scenarios can be simulated quickly, and the toxic gas flow patterns through underground openings can be analyzed efficiently. For this study, CFD is performed using SC/Tetra software owned by MSC software company.

By Benedict C. Di Duca

In the underground construction industry. when bidding work, not only is the contractor faced with determining if rock: is in existence within the parameters of his work. he must also estimate the quantity and the most efficient method of removal.

Jan 1, 1990

By Greg S. Williams, David L. McDorman, Richard W. Givens

This paper examines the effect of prill size consistency, internal particle density, and oil absorbency on Ammonium Nitrate Fuel Oil (ANFO)-emulsion blends. By analyzing these physical properties of prill and the nature of the blending process, a mathematical model has been developed to theoretically predict blend densities. Calculated densities can now be compared to actual field densities to give an operator a basis for comparing various manufacturers' emulsions and Ammonium Nitrate (AN) during bid solicitation. The lowest priced emulsion and/or AN may not be the most economical, due to the impact of specific physical characteristics. These factors dictate the blending mechanics and resulting density yields for various mixes. The research was driven from observed 'field' mixing relationships and data. Ultimately, such a model can be an effective tool in evaluating blends from a cost and performance basis.

Jan 1, 1990