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By Bruce B. Redpath, Thomas E. Ricketts

Scaling laws commonly used for describing or predicting blast motions generated by conventional arrays of blastholes are dimensionally incorrect. The scaling of distance by the cube root of charge weight is correct only for spherical charges, and scaling by the square root of charge weight is incorrect for any charge configuration, although both approaches may result in empirically useful formulas for a limited range of charge sizes. Analysis of motions generated by a large set of underground blasts shows that scaling distance by the square root of the linear charge density, which is dimensionally correct for a cylindrical borehole, yields much more consistent results than the traditional scaling rules. Further, this scaling law is valid right up to the free face of the burden. A significant result of this work is that the peak particle velocity for an array of blastholes is primarily dependent on blasthole diameter and not on total charge weight or maximum explosive weight per delay, which are the commonly used parameters for scaling seismic amplitudes generated by conventional blasting arrays.

Jan 1, 1987

By D T. Froedge

The state of Kentucky is making some changes in it's blasting program namely instituting a training program for blasters and instituting a new classification of blaster titled "Class A Kentucky Blaster". These changes will take place within the next year and are felt to be of great interest and benefit to those in the blasting industry.

Jan 1, 1978

By J T. Schamaun

Recent applications of explosives and blasting agents to rubble rock have led to requirements for more elaborate design and analysis methods. In most blasting uses, it is necessary not only to fracture the rock, but also to move the broken rubble in a predictable manner. Many in situ extraction techniques require; rubblization to take place in a confined region where rock motion is a predominate factor in creating a permeable broken bed. In this paper, an engineering model is presented which describes the large rubble motion during blasting. This model is intended to provide the blast designer with a tool for evaluation and further refinement of blasting patterns and timing sequences.

Jan 1, 1983

By Dave Proudfoot, Mike van Wyk

"There has akvays been plenty of discussion around the ‘accuracy of pyrotechnic detonators withmost recognised manufacturers claiming a variability of arourid 1% or less for their ‘superaccurate’ pyrotechnic based detonators. It is only now being understood that this 1% variabilitycan have serious adverse effects on blast performance. For example a 1% accurate 500millisecond shock tube detonator can fire anywhere between 485ms and 515ms. When wecouple these rather inaccurate ‘accurate’ detonators with short delays on surface, such as a 17millisecond connector, the probability of delay crowding and even out of sequence firing is quitehigh."

Jan 1, 1998

By Jim Petrunyak, Conny Postpack

The authors describe in this paper a systematic approach toward reducing coal production costs up to 35% through the use of explosives energy for overburden removal. In this system, explosives are employed to blast as much as 65% of the overburden instantly from highwall to spoil pile, with only the lesser portion requiring removal by dragline, shovel, or loader.

Jan 1, 1983

By Paul Worsey, Attila Szucs, Mark F. C. Schmidt

The use of water stemming with small explosive charges has been successfully developed at the University of Missouri-Rolla. Further study has been started to explore additional applications and uses for water stemming. Work has been focused in the areas of rock excavation and perimeter blasting techniques. This ongoing work is being conducted internally as graduate and undergraduate level research. A paper describing the general technique for use with boulder fragmentation was published in last year’s proceedings. The excavation work took place in the form of both small bench and trench shots while pre-split and trim shots comprised the perimeter-blasting portion. The excavation work was located in both the Roubidoux sandstone formation and the Jefferson City dolomite formation. Hole diameters ranged in size from 1.5” to 3” diameter and powder factors ranged from l/l 0 to l/3 of the conventional charge weight. The water was used to both couple the explosive charge with the surrounding borehole, as well as stemming. No other stemming material or products were used. The method of using water stemming in perimeter blasting was found to work well. However, when used for excavation purposes, adequate rock movement was not obtained. The rock was often split, but not fragmented. The airblast was surprisingly low, but the ground vibrations were excessive. This is not the case with trim shots, and therefore this method appears ideal for splitting purposes, especially in areas where people do not like to stem the tops of the holes, and where airblast and vibrations are of concern. Water coupling dramatically increases splitting and fracturing. However, fragmentation is not only fracturing but also the movement and swelling of the material. As the charge weights are reduced with this method, sufficient gas volume is not created to cause this necessary movement and swell, which is critical in rock excavation. This explains why its successful application was limited to perimeter blasting applications.

Jan 1, 2000

By Ed O'Connor, Per-Anders Persson, Manhong Zhou

This chapter deals with the concepts of shock waves and detonation waves together, because a detonation wave is really a shock wave, supported by the explosive reaction that the shock wave ignites and propagates as it travels through the explosive material. In the context of rock blasting, furthermore, there is justification for treating shock waves and detonation waves together, because the mechanical effect of the detonation in an explosive in a drillhole in rock is propagated and its effects are spread throughout the surrounding rock by means of a shock wave. The overall performance of an explosive in rock blasting or any other application is of course dependent on how much thermal energy is released in the chemical reaction that occurs when the material detonates, and on how much useful mechanical work the reaction products can do as they expand. A major portion of this chapter deals with the prediction and measurement of explosive performance, a subject which is now still in a process of rapid development.

Jan 1, 1997

By Clarence Zink

The need for continual process improvement and innovation to reduce operating costs in the mining industry extends to the first significant encounter all production miners have with the rock: drilling blastholes. Material and design advances alone have greatly increased the productivity of today's tricone blasthole bit over bits used just a few years ago. Significant additional operating savings are being realized by utilizing improved air practices on blasthole drills, and by selecting drilling equipment designed to provide optimum air volume and pressure at the blasthole bit.

Jan 1, 1997

By Keith Pucalik

One of the more important duties of the vibration consultant is to evaluate allegations of blasting damage by neighboring property owners. Unfortunately, the consultant is generally faced with having never seen the project, or preparing for litigation three or more years after blasting was completed. Under these circumstances, he must rely totally on blaster's logs and other contemporaneous records to conduct a meaningful evaluation.

Jan 1, 1990

By C. Kosloski, E. McCullough, A. Fox, S. Reed

This paper serves as a reference guide for creating or strengthening student chapters of the International Society of Explosives Engineers. This includes chapters that are just starting, currently undergoing transition in leadership, or that are in the process of rebuilding. ISEE student chapters have great potential to increase student involvement and national membership, and can benefit from formalized strategies to help them do so. Several key strategies are introduced and should be employed to promote organizational participation throughout the university system.

Jan 1, 2016

By Stephen H. Chung

Direct visualization of rock movement during blasting is an important key to understanding the blasting process, as well as optimizing blast designs and explosives performance. To achieve this, a digital camera system (HSIS-500) has been built. It is a custom made high speed solid-state camera employing an advanced charge coupled device (CCD) and dynamic random access memory (DRAM) technologies. It handles like a regular video camera but requires no film or tape as the image is recorded in digital form on memory chips and transferred to the system hard disk for storage. The system consists of two components: the camera body and hardware, and the image processing unit.

Jan 1, 1996

By Doug Wathen, Philip M. E Thomas

The City of Fort Myers needed to replace a 40-year old 42-inch storm sewer line in downtown Fort Myers with a new 54-inch line to accommodate population growth. The old line had to be kept operational while a new line was installed. the contractor spent two months using a drop ball, a hoe ram, and large rippers trying to break the three to four feet of rock that needed to be removed to accommodate the new pipe. Mechanical trenching was considered but was proven to be overly expensive. On very short notice, Ireco of Florida was asked to design and execute a blasting procedure that would allow this project to proceed. Nearby buildings were over 80 years old, three of them containing antique shops specializing in glass antiquities with attorney offices above them. High water table compounded problems with a 20-year old steel water main and clay drainage pipe 15 feet from the new sewer line. Holes had to be drilled within six inches of the edge of the existing pipe to four feet below the pipe on either side of the pipe and blasted. No interruption in the sewer line flow was to be tolerated.

Jan 1, 1996

By Andrea Brickey, Ethan Marcoux

The South Dakota School of Mines and Technology (SD Mines), located in Rapid City, South Dakota, is one of only a few universities in the United States that offer a Bachelor of Science in Mining Engineering. The Department of Mining Engineering and Management (MEM) at SD Mines teaches courses that introduce students to concepts related to mining, including a course covering explosives engineering. Students are taught the basics of explosives theory and application in the mining and construction industry through a series of lectures and assignments. With limited field experience, many students find some topics difficult; these include: flyrock, ground vibration, timing, and others. Some US mining schools have an experimental mine in which they can simulate field conditions and conduct hands-on training, but not all universities have such facilities. For those without, teaching certain concepts can be more challenging in a pure classroom environment. To counteract the lack of an experimental mine, the mining department at SD Mines implemented Paradigm (Version 18.4.4984.0; McKenzie, 2017) a computerbased blast modeling software to improve the learning environment.

Jan 1, 2019

By Yessica Idrogo, Omar Gómez, Francisco Pérez, Eduardo Yrigoyen

Rock blasting is one of the most important operations in the mining cycle value chain, requiring optimized explosives mixtures to get good results. A new and better strategy, and that which is discussed herein, is to design a new emulsion explosive, which can provide improved characteristics and benefits over and above general types of emulsion explosives. It is therefore critical that this product is functional over a wide range of conditions

Jan 1, 2019

By Dale L. Ramsey

Blasters in the field for years have been faced with the task of plotting blast locations for future reference and calculating scaled distances or seismograph placement from maps,aerial photo's etc.'With the constellation fully operational, GPS provides a satellite signal transmitted to a ground receiver which will display the desired coordinate positioning worldwide, 24 hours a day in any kind of weather conditions. There are a variety of GPS receivers available with varying levels of accuracy. The field trials of a handheld navigational quality instrument for plotting blast and seismograph locations along with other necessary industry related data is the basis of this paper.

Jan 1, 1994

By Ray Heater, Qian Liu, Alan Bauer

The channel effect is a phenomenon that takes place with decoupling explosive charges; an air shock wave propagating ahead of the detonation wave in the annular space around the explosive charge compresses the charge so that the process of detonation is modified and even stopped. For commercial explosives, such as AN/FO slurries and emulsions, the channel effect causes partial detonation under certain conditions. To simulate and evaluate the phenomenon, a hydrodynamic model was developed based on the assumption that the pre-shock wave is produced by Mach reflection at the tube walls. Based on instrumented experimental studies with the above explosives in diameters ranging from 25 to 90 mm in pipe sizes ranging from 35 to 127 mm, it has been possible to demonstrate that a criterion for failure based on a critical impulse concept fits the experimental data well. Critical impulse values for the various explosives tested are presented along with the necessary correlations between charge and borehole diameter required to produce this.

Jan 1, 1988

By B Mohanty, R Deshaies

Initiation of small diameter explosives by sympathetic shock pressure in water has been investigated under controlled laboratory conditions. Changes either in the geometry of the donor explosive or its point of initiation can alter the essential characteristics (amplitude and duration) of the resulting shock pressure pulse. The pressure signatures from both spherical and cylindrical explosives donors have been studied, in water as well as in various explosive matrices. This paper summarizes the investigations carried out with both 'primed' and 'non-primed' slurry and emulsion explosive matrices with various types of voids. These measurements serve the basis for predicting distances in water for sympathetic initiation for both spherical and linear charges. It is shown that the explosive-detonator system in combination has a far greater probability of initiation due to sympathetic shock pressure than either the explosive or the detonator alone. Various explosive matrices with air bubbles and glass microballoons have been examined and the differing sensitivities to shock pressure explained on the basis of these measurements. It is also concluded that explosives containing air bubbles instead of microballoons would be significantly more prone to sympathetic initiation.

Jan 1, 1992

By Yang Ruilin

Bulk gassing technology is a growing trend in the commercial explosive industry. The gassed bulk products produced differ from microballooned bulk products or cartridged products. It is easy to know the loaded or in-hole density for microballooned bulk products or cartridged products, whereas it is not as straight forward to know the m-hole density for gassed bulk emulsions. The loaded density is one of the key parameters affecting explosive performance and therefore it is important to have a field technique to monitor the in-hole properties of gassed bulk products in order to accurately predict the blast performance and to ensure efficient use of the products.

Jan 1, 1999

By Philip H. Porter

Ammonium nitrate blasting agents continue to be the work-horse of the explosives industry. The versatile, low-cost, anfo products, whether packaged, poured, or bulk, continue to produce superior results for the explosive consumer who understands their limitations and capabilities.

Jan 1, 1984

By Frank Sames

Where applicable, high production benches can improve efficiency in quarrying. Quality control, geological, cost or other considerations might result in the development of quarry benches higher than 30 m (»100 ft) and sometimes up to 60 m (»200 ft).

Jan 1, 1996