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By Claude Cunningham

Blasthole pressure is the starting point for many blast design calculations, but the way in which it is usually derived, from measured detonation velocity, indicates that more thought is needed as to its true meaning and implication. The general impression is given that the energy in the hole is defined by VoD, but rarely is this the case. VoD is defined by the energy released in the Detonation Driving Zone between the shock front and the Sonic (or 'CJ') surface, and for commercial explosives it is normal for reaction not to be complete within this zone. Reaction and energy delivery continues behind it, not reflected by VoD. Thus it would be more appropriate to use the theoretical VoD, not the measured VoD, to derive the starting pressure, since this would reflect the energy input of full reaction. In decoupled situations, the derivation of pressure at the blasthole wall using a polynomial decay concept is also of debatable value, and an alternative is offered.

Jan 1, 2006

By Richard J. Mainiero, T S. Bajpayee

The Bureau of Mines, U.S. Department of the Interior, has developed test procedures and criteria for evaluating explosive reactivity of explosive contaminated solid waste substances generated by U.S. Army Ammunition Plants. These substances are produced as explosive-contaminated sludge from waste water treatment plants, residues from the burning of munitions and explosives on open ground, and residues from deactivation furnaces. The characterization of explosive reactivity is a prerequisite for disposal of such waste materials, which may be contaminated with primary explosives, propellants, or pyrotechnic materials. The Bureau has proposed two tests for this purpose. These tests were developed to evaluate the explosive reactivity as defined in Title 40, Code of Federal Regulations, Part 261.23(a)(6) and (7). These are Bureau of Mines Gap and Bureau of Mines Internal Ignition tests, which determine the sensitivity to shock and thermal stimuli, respectively. This paper also includes gap and internal ignition reference data for typical blasting agents, high explosives, propellants, and marginally reactive substances. These reference data were used to establish test criteria. The Bureau has evaluated over 400 samples of contaminated soil, sludge, and burning residues using these two test methods.

Jan 1, 1988

By D. C. Valdemeri, Oppermann J. P. Z., R. G. Schaarschmidt, C. S. Mendonca

This case study was conducted in an aggregate company, located at Estância Velha town, RS, Brazil. The study was based on the results of vibration monitoring mainly in terms of PPV (peak particle velocity) and frequency. Changes in the blasting design were performed to adjust the limits determined by the Brazilian standard NBR 9653:2005. Understanding the seismic wave attenuation for the site, changes in the blasting design were tested to fit the limits, such as reduction of maximum charge per delay, initiation orientation and sequencing and finally the replacement of accessories like "shock tube" by electronic initiation system. The results are shown below.

Jan 1, 2015

By Lon Santis, David Leidel, John Tatom, Meredith Hardwick

This paper describes the development and methodology of the Institute of Makers of Explosives’ Safety Analysis for Risk (IMESAFR), a risk analysis software program for commercial explosives operations. IME is a nonprofit safety and security association devoted to the safe and secure manufacture, transportation, storage, and use or disposal of commercial explosives in the US and Canada since 1913. The software methodology’s basis is the U.S. Department of Defense Risk Based Explosives Safety Criteria Team’s Safety Assessment for Explosives Risk (SAFER) software. A diverse group of industry and government experts contributed to modifications to SAFER that reflect commercial operations. IMESAFR is intended to supplement the American Table of Distances (ATD) and offer standardized methods of managing risk from a wide variety of commercial explosives operations where the ATD does not apply. The modifications made to SAFER primarily involved the addition of commercial activities and potential explosives sites (PES). A review of commercial explosives accidents and operations over the last 20 years served as the basis for establishing probability of event values. An industry survey of commercial PES types in the U.S. and Canada was conducted to identify and address critical differences in commercial structures as compared to the military structures in SAFER. The paper concludes with discussion of the potential uses for quantitative risk analysis (QRA) and a description of other explosion effects software

Jan 1, 2007

By Claude Cunningham

AEL has been developing electronic detonators continuously since 1986. It launched its first system for opencast mining in 1993, and now has two distinct product lines. The path has not been without great difficulty, but the determination to persevere was always buoyed by the strong encouragement of customers who experienced the transformed blasting results, as well as a clear vision of the enormous intrinsic value of the concept. The path of growth to dominant global supplier is traced through the separate application channels of coal stripping, quarrying, massive mining, opencast mining and narrow reef mining, to the first allelectronic detonator demolition blast in June 2001. Reasons for the slow coming to market of this highly desirable concept, which often coincide with reasons for the demise of various other systems, include the difficulty of safely mating electronics and explosives in a low cost environment; the extreme difficulties of achieving proper connection under mining conditions; the rapid rate of evolution of the technology, and the safety concerns raised by various accidents and incidents along the way. ED.s are now established as the way forward and are set to displace other systems in all serious applications. There is place for both programmable and pre-set delay systems.

Jan 1, 2002

By Michael S. Wieland

Toxic fume concentrations from industrial mining explosives depend somewhat upon the type of rock (or other strata) confinement. Though traditional detonation theory disregards this influence, the work principal from thermodynamics reveals it, when the violent interactions that transpire within the rock blast are taken into proper account. Resolution of the work principle technique requires total thermodynamic equilibrium under constraint, so the nonequilibrium dynamics is rendered in that way, using an old trick from theoretical mechanics that revises the representation of forces. The rock pressure reduces to a four-component sum: the rock compressive strength and natural atmospheric pressure, as reckoned quasi-statically, and the gravitational influence and reversed inertial resistance, as reckoned dynamically. Tabulated specie concentrations and graphical trends reveal the dependency upon rock pressure, rock temperature and the fuel-oil percentage in ammonium nitrate mixtures (ANFO), used to illustrate the model. Rigid-wall test chambers have notable ullage (residual space), where rapid expansion influences the reaction quenching, yielding a fume spectrum unlike that for rock confinement; reported rock tests are therefore used for comparisons. For the thermodynamic regime where quenching occurs, seven concentrations are resolved, including carbon monoxide (CO) and total nitrogen oxides (NOX). Their trends yield inferences regarding the way unwanted charge desensitization from transitory hole-to-hole wave impact in conjunction with reduced rock pressure can yield nasty toxic fumes, the dark rusty cloud phenomenon!

Jan 1, 2005

By W. Birch

The traditional concept of scaled-distance modelling for predicting blast induced ground vibration holds many drawbacks, not least of which is the major effect data scatter imparts on confidence determination. An investigation by the Department of Mining and Mineral Engineering, The University of Leeds, England has resulted in the development of simple but effective method of improving prediction capacity through the reduction of effective error by incorporating individual location response into a scaled-distance model. The work is the product of an l&month blast-monitoring campaign at a limestone quarry situated in North Yorkshire, England. The data, when presented in the form of a scaled-distance model, indicates a typical scenario where a good overall correlation becomes marred by the extent of data scatter. Examination of the individual monitoring locations however indicates that the response of the individual location is an important factor in the explanation of the large residuals. The novel approach thathas been developed incorporates a series of locational site factors which when incorporated into a scaled distance model reduces the effective error and therefore improves prediction capacity. The approach is based on using a standard computer package “spread sheet” on the understanding that these are commonly available on all quarry or home computers. This approach has been validated by comparison with a more rigorous statistics method.

Jan 1, 2001

By Duane Skidmore, Calvin Konya

The supply crunch and cost rise for ammonium nitrate (AN) over the past year have been influenced by a number of factors. These include a general inflationary tendency, particularly great cost rises in fuel, and by a market condition in which demand for ammonium nitrate is great and supply is limited. Demand is largely confined to agricultural and explosives uses with explosives subdivided into mining, construction, and quarrying. The projections show that demand may be expected to increase markedly for the indefinite future in the agricultural and mining sectors of the ammonium nitrate market while fluctuating with indicators of economic activity for the construction and the quarrying sectors. Supply is projected to increase with plants being designed and built due to high need levels and commensurately high profit potential but not enough are planned to provide an equilibrium market. Constraints upon supply increases to match demand increases include shortages in the raw material, natural gas, high cost of investment capital, high equipment costs and long construction delays. The result should be, even under optimistic conditions, considerable shortage and resultant pressure for higher prices through 1979 for ammonium nitrate. The best hope for relief in the intervening years appears to be conservation. In blasting operations, the earliest and best proven route to conservation seems to be improved utilization available from application of highest available technology and most efficient current blasting practice.

Jan 1, 1975

By Joseph L. Uraco, Harry C. Verakis

The use of explosives in underground coal mines presents a potential risk for serious injuries and death to miners. Widespread disasters have occurred from the explosion of methane and/or coal dust initiated by blasting with explosives. Many of these disasters took place in the early 1900's when the use of black powder for blasting was prevalent. Historically, the investigations in the U.S.A. to develop and test safer explosives for blasting coal began in 1908 when a testing station was established in Pittsburgh, Pennsylvania. Since that time, great strides have been taken in the development of safer explosives. The use of safer explosives has significantly reduced blasting accidents in coal mines. Enactment of legislation, such as the Federal Coal Mine Health and Safety Act of 1969 and enforcement of regulations has also improved blasting safety. More recently, MSHA began a major revision of its regulations for blasting in coal mines. In 1988, MSHA published final rules for the approval and use of permissible explosives in coal mines. The approval requirements for explosives address testing and evaluation. The requirements include tests for sheathed explosives which represent a new technology. The use regulations provide increased safety protection for miners by including standards to address identified hazards. Major aspects of these standards, such as qualifications for blasters, multiple-shot blasting and the use of sheathed explosives are discussed.

Jan 1, 1992

By V Krishna Mohan, J Edmund Hay

This paper discusses the results of the gap sensitivity measurements made on water-gel explosives, sensitized by monomethylamine nitrate (MMAN) and flake aluminium, and one emulsion explosive. This study specifically deals with the effect of the mode of initiation, end or center, on the measured L50 values with air gap and coal dust gap for the above explosives. Similar measurements have also been carried out on a nitroglycerine (NG) - based explosive. The results show that the mode of initiation plays an important role in determining the air-gap sensitivity of these explosives. However, in tests carried out with the coal dust gap, the L50 ( grams of coal dust ) values for these explosives are close in both the types of initiation. The results indicate that the sensitivities of these explosives may be ordered in the following manner: NG-explosive>> Aluminized explosive ~ MMAN-explosive > Emulsion explosive

Jan 1, 1982

By Shazad Hosein, Rob Farnfield, Bill Birch, Liam Bermingham

The propagation of a shock wave through air as a result of quarry blasting consists only of one type of wave, the compression wave. This is in marked contrast to seismic waves where a number of different types of wave are generated by the one blasting event. Even so the interaction of the burn time of a single hole and the resulting air overpressure is still too complicated to be able to be accurately modelled from first principles. It is considered that the best way forward is to monitor an individual single hole to obtain a signature wave form that has resulted from this complex interaction. Once this wave form is known, the variation in geometry of a mutli-hole blast and the timings of the successive detonations can be modelled to give a sufficient degree of accuracy to recreate the likely magnitude, duration and wave form of a multi-hole quarry type blast. This can then be directly compared with actual air overpressure wave forms from quarry blast to verify the model.

Jan 1, 2012

Computational techniques in determining particle size distributions after blasting is getting wide acceptance. A well known approach to extract this kind of information from digital images is edge detection. The number of edge points on a given image increase proportional to the increase of the particles on the image. By selecting a conveniently smooth threshold, counting the signed edge pixels may be a suitable metric further used to quantify the number of particles in the image. Here we propose an image processing algorithm together with Adaptive Neuro Fuzzy Inference System (ANFIS) to efficiently count the rock particles with various sizes on a given surface. To determine a suitable approximation for a mapping between the number of edge pixels and the number of particles, ANFIS is a suitable tool. As a trainable classifier ANFIS proved itself as being better efficient approach than other well known multilayer perceptron classifiers. ANFIS is trained by using convenient training data pairs previously experienced from empirically counted sample images. When given a new image containing the particle information of selected surface, the hybrid neuro fuzzy image processing approach provides satisfying performance on counting the correct number of particles up to the given scale of sizes. In this paper an experimantal study for assessment of particle size using ANFIS is presented.

Jan 1, 2004

By Pharis E. Williams

The ability of voids, microballoons, and even solids to sensitize explosives has been known and used for many years. This phenomenon has generally been studied and reported under the terminology of "hot spots" because of the increase in local pressure and temperature when a shock wave encounters such sensitizers. A method for treating this phenomenon in detonation theory or in a detonation model has been studied for almost the same length of time. Perhaps because of the complexity and non-linearity of the void, or microballoon collapse, several of these studies have used the expediency of including additional terms in the burn rate law to account for the influence of hot spots. The detonation model proposed here considers the sensitization due to discontinuities in the shock impedance to be a mechanical phenomenon to be accounted for in the mechanical equations governing the detonation and not in the burn rate law. While this is not a new contention, the method for handling this non-linear phenomenon within the proposed model is new. The model also includes a method which accounts for the manufacturing variables of emulsion matrix cell size, microballoon size and type, as well as energetic additives.

Jan 1, 1992

By Lina Lopez, Jose Sanchidrian, Jean Du Mouza, Essaieb Hamdi

This paper evaluates the actual energy delivered by the explosives used in the fragmentation of rock during blasting vs. the available theoretical explosive energy. The evaluation of the fragmentation energy of the blast is first done. Fragmentation by blasting can be seen as a process in which creation of new surfaces within the rock mass is made by generation of new cracks or extension of pre-existing ones. From this idea, the fragmentation blast efficiency can be assessed as the fraction of the available explosive energy used for creation of new surfaces. The evaluation of new cracks area created by the blast is based on the SIMBLOC methodology and the corresponding fragmentation energy is then obtained by the Griffith theory. Secondly, the amount of energy delivered down to a certain pressure or volume along the detonation product expansion process, given by the useful work, is calculated. This is done by first determining the CJ state of the reacted explosive and subsequently performing an adiabatic expansion calculation of the detonation products from that state. W-Detcom code has been used for the calculations using the BKW equation of state with the Sandia parameter set. The fragmentation energy and the useful work are calculated for blasts performed in two mines in Spain. Multiple regression is applied to the results in order to give an assessment of the better description of the explosive energy .

Jan 1, 2002

By L D. Lawrence, R S. Day, Gordon Coleman

Commercial emulsion explosives are typically characterized by their relatively high detonation velocities due to the intimacy of oxidizer and fuel and to their sensitization with glass microballoons. However, numerous blasting operations in softer, more porous rock formations are better fragmented with slower shooting explosives. Although mixtures of emulsions with large amounts of ANFO (60-80%) can considerably reduce the high velocities, little water resistance is achieved with low levels of emulsion blended with ANFO. "Water proof" blends containing typically 50 percent of emulsion become quite costly due to escalating powder factors in ANFO patterns. Blends of sensitized emulsions with 20-30 percent ANFO retain the high velocity characteristics of the emulsions as well as increased densities which can also adversely affect blasting results in softer rock formations. The introduction of a reliable and predictable on-site gassing process for sensitization and density control of repumpable emulsions, with or without added ANFO, offers the end user the option of supplying a final product more suited to his blasting needs. The capability to widely vary final product loading densities and consequently product detonation rates better tailors the final explosive to different rock characteristics. The beneficial advantages of this system in softer rock formations have been well documented. Overall comparison between these variable density products with typical repump emulsions containing solid density control will be reviewed. Besides the obvious cost advantages and safety advantages of these systems the end user is provided more definitive control of his blasting operation.

Jan 1, 1990

By W. J. Birch

The dedicated documenting of blast design and vibration monitoring results forms part of the best practice methodology for today’s blasting operators. This allows regression curves to be constantly updated and in turn compatible charge weight determinations are based upon the most current data. The point can arise however when so much data becomes agglomerated that variations in blast design, geology or monitoring location response and their effects can pass unobserved and start to have an adverse effect on the forecasting capability of the regression due to a deterioration of the standard error statistic. The simple solution would be to only compile like-for-like blasting returns, but this prospect can quickly become unworkable due to the number of potential variables. In addition it is very difficult to spot subtle variations by simply examining a standard scaled-distance curve mainly due to the intrinsic data scatter that is always present together with the logarithmic nature of the regression curve. If indeed a variation is thought to be apparent, how can the degree and magnitude of its influence to be quantified? The Likelihood Ratio Test when applied to regression data can diagnose subtle variations between data sub-sets and provides a comparative statistic as to the degree of variation. By analysing datasets in such a way, levels of compatibility are obtained, indicating which sets can be combined in order to increase prediction capability.

Jan 1, 2004

BLASPA is the name for a computer code which can assist in the rapid optimisation of blasting procedures in an open-pit mine. BLASPA is based on a mathematical model of the blasting process, a model which has been developing since 1963 as a result of blasting research carried out at the College Militaire Royal de Saint-Jean under sponsorship of the Defence Research Board, and in co-operation with the mining and explosives industry. The model presently includes the following aspects: (1) Geometry, i.e. spacing, burden, bench height, collar, sub-grade drilling; (2) Explosives, i.e. types and grades of explosives, distribution into bottom and top load or decking, size of hole and coupling; (3) Hookup, i.e. parallel or angled firing, delays, location of primers. Computer costs are very small, by comparison with purely spherical AEC codes, so that any number of simulations can be carried out very efficiently. The system has already been used to carry out thousands of simulations for over 40 mines in Canada and abroad. It will be explained how such simulations become a useful guide for a mine's blasting engineer who wishes to optimize his blasting and drilling costs.

Jan 1, 1980

By Thomas Barkley

Mining tradition holds that a parallel round underground can not be any deeper than it’s smallest face dimension. ln other words, a mine using a 12’ (3.7 m) high by 24’ (7.3 m) wide room and pillar mine, the deepest pull that can be achieved is plus or minus 12’ (3.7 m). After experience with decking of rounds in a 12’ (3.7 m) diameter shaft to achieve more than 12’ (3.7 m) advance per round, the concept of deepening the pull on horizontal parallel rounds seemed to be a feasible concept. Tests were conducted in a conventional room and pillar metal mine with a round size of 12’ (3.7 m) high by 24’(7.3 m) wide. Standard rounds were drilled with a 16’ (4.9 m) steel as parallel rounds to an average depth of 14.5’ (4.4 m). The average depth of pull on these rounds was about 13’ (4.0 m). Using the available drilling equipment, 20’ (6.1 m) drill steel was used to drill holes to an average depth of 18’ (5.5 m). Five rounds were drilled and shot with a resulting aven$e pull of 16.2’ (4.9 m) or 90 % of drilled depth. Rounds were designed with decked bum cuts to maximize depth of pull in the cut area An innovative method of de&mining drilling accuraq was used to estimate it’s effect on depth of pull in the rounds. This method used a standard automatic 35-mm camera and scaling to determine the average drill deviation for many of the holes in the rounds.

Jan 1, 2000

By Joseph Meyers

Explosives techniques and technology are constantly evolving and improving, yet basic communication and business skills are not being used regularly. Many potential blasting projects never occur due to simplistic, basic factors, such as a lack of communication. Articulate communication is the key component in the blast approval process, which has changed remarkably from how business was conducted fifty years ago. Imperative to the approval process is communication outlining the safety and benefits of the blasting project. Information and transparency with the stakeholders and the Authority Having Jurisdiction (AHJ) will greatly improve the chances of having a blasting project approved. This open communication starts at the inception of the project when the memorandum of understanding (MOU) is obtained, and involves the AHJ through all steps of the approval process. The blasting industry and regulators must work collaboratively to improve safety, security, regulations and licensing. Implementing state of the art blasting techniques, security, safety measures, vibration monitoring and strict licensing allows the AHJ and all stakeholders to remain integrated and informed, contributing to process approval. Regulatory operators should strive to achieve success thru communication, cooperation and compliance which is accomplished thru continued education and transparency. These steps, combined with regular meetings, has proven to be a benefit to both industry and regulators. Relationships are built through trust, teamwork, transparency and communication –including the take holders and AHJ in the approval process from the inception solidifies these relationships and improves teamwork

By D VanDoorselaere

"Image analysis techniques are widely used for blast fragmentation measurement, and various commercial packages are available for this purpose. These packages are very versatile and serve as a useful tool for optimization of blasting practice. But many times, the results provided by image analysis techniques do not match with sieved and predicted data. This leads to the suggestion that understanding the limitations of this technology is as important as understanding its usefulness and versatility.A study was conducted in two stages:(a) Comparison between the results of image analysis and screened data using laboratory scale muck piles.(b) Comparison between predicted (Kuz-Ram) and measured (Image analysis) blast fragmentation results for several bench blasts.During laboratory work, muck piles with known size distributions were analyzed with the help of image analysis technique. A disparity was observed between the sieved and measured results because the image analysis techniques cannot accurately determine the % of fi nes in the muck. During fi eld work about fourteen blasts were monitored. It was observed that predicted (Kuz-Ram) results rarely matched with measured (Image analysis) results. The Kuz-Ram curves were modifi ed by changing the rock factor so that the Kuz-Ram and Image analysis curves match in the vicinity of the 50% passing size. The pairs of curves (modifi ed Kuz-Ram and Image analysis) were divided into three categories depending upon their differences in the coarse and fi nes ranges. The blast design parameters affecting the difference between the pair of curves have been outlined. The suggestions have been made to better utilize the image analysis system."

Jan 1, 2007