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By B Mohanty, M Alam, F Gauthuer

A series of eleven full-scale production blasts has been earned out in a limestone quarry to study the effect of delay interval and its precision on overall blasting performance. The quarry employed ANFO and cartridged aluminized emulsion in 75 mm diameter boreholes with 2.6 m burden and 2.9 m spacing on a 6.7 m bench. Both V-cut and echelon designs were studied. The types of detonators tested were regular short period electric detonators with expanding delay intervals, a more precise pyrotechnic-based electric detonator (EXADET) with a fixed (25 ms) delay interval, and the ultra-high precision electronic delay detonator (EDD) with constant (but site-selectable) delay interval. The various techniques employed to assess the blast results are described, and the performance of the three types of detonators compared. The use of both EXADET and EDD lead to improved blast results in echelon design. Of the three delay intervals (25 ms, 38 ms, and 50 ms) studied, the best results were obtained with EDD with a 38 ms delay interval, which translates into a delay of 38 ms/m of effective burden. The results also show the need for modification of current V-cut delay designs to derive full benefits from these high precision detonators.

Jan 1, 1991

By Ron Stewart, Richard Youmaran, Andy Adler

In the current context of heightened concerns with explosives security, there is significant interest in technological controls to improve security. It is important to be able to control what is fired, by whom, where and when. This paper describes research Orica has performed to investigate and test biometric systems to address the question of "by whom". The goal of this research is to incorporate the most suitable biometric system onto the 'blaster' unit of an electronic initiation system. This approach will ensure that only authorized personnel can initiate a blast involving electronic detonators. Requirements analysis: we initially explored many different biometric technologies to evaluate them against the requirements, including security, usability, ruggedness, size, form factor, privacy, and operational temperature range, This analysis identified chip based fingerprint sensors as the best candidate. Development of prototype units: in order to test the identified sensors, we modified standard, commercially-available, electronic blast initiation units ("blaster") to incorporate a fingerprint reader. Testing and evaluation: Biometric We conducted a biometric scenario evaluation in order to determine: 1) security level (measured by false accept rate (FAR)); 2) usability (measured by failure to enroll (FTE) and false reject rates (FRR)), and to 3) discover environment specific issues and challenges (such as temperature, humidity, dirt, or those related to the usage patterns of the user group). Tests were conducted at quarry sites in eastern Ontario, Canada. Results show rates of: FAR= 0%, FTE= 1.67%, FRR= 28.81%. Overall, these results suggest that this fingerprint biometric technology has a good level of usability in this application of electronic blast initiation control.

Jan 1, 2007

By R. Hazael, R. Alford, R. Critchley

The ability to compare explosives is fundamental. Numerous methods are used and while simple conversion factors are often used, the use of TNT Equivalency (TNTe) is not a simple subject as explosives exhibit very different equivalencies depending on whether the pressure or impulse are being considered as well as other conditions. The scaled distance has been found to have a significant effect on the TNTe but due to the difficulty of taking measurements at very close ranges, no TNTe have been quoted for charges in direct contact (Z=0). This paper describes the use of a ballistic pendulum to measure the impulse from contact charges and presents some surprising results that require a two-stage propulsion, as originally described by Backofen, to be explained.

Jan 1, 2024

By Duncan Chalmers, Rob Nowell, Miguel Araos

Australian underground mines produce in excess of 60 mtpa of coal. Most of these use the longwall method, and they require the use permitted explosives (which are called “permissible” in other countries) for challenges that appear during the day-to-day activities. To obtain the approval for these explosives, they should pass Testing Memorandum #2 (TM-2), which sets out the test required for each category of permitted explosive. These categories are P1, P3, and P5. With P5 being unrestricted use and P3 and P1 have conditional use in underground mines. The TM-2 test was originally set up for NG-based permitted products around 1900. With the closing of NG plants around the world, ammonium nitrate explosives were the natural replacement, and therefore these explosives need to pass the TM2. Australia does have a P1-emulsion based explosive available. For high-risk scenarios (like blasting coal), no P5 explosives are available. The lack of P5 explosives has been prolonged for more than 25 years, since the phasing out of nitroglycerine-based permitted explosive products around the world. The main problem has been that when emulsion based permitted products are tested in the deflagration cannon, the results obtained were not considered in the TM2 criteria and therefore the tests were invalid. A research work on permitted explosives began in 2005 funded by the Australian Coal Association Research Program (ACARP). The aim of the project was to address the lack of P5-type permitted explosive (and, potentially develop them further, i.e., develop safer explosives) and understand the behaviour of emulsion explosive and the results they presented in the tests. Both bureaucratic and technical barriers appeared along the way. On the bureaucracy side, the facility was shut down, reopened, and shut down again. In view of these difficulties, assistance was sought overseas. On the technical side, from the very start the results of the tests when using emulsion-based permitted explosives were not established in the criteria, ignitions occurred for trial samples that were expected to be P5-type, etc. The aim of this document is to present the painful journey in the Australian industry to have a P5-type emulsion-based permitted explosive, for use in UG coal. Also, the technical learning acquired about emulsion explosives and the ignition path of mixtures methane / air will be shown.

Jan 21, 2025

By Mohammed Alkazimi, Katie Grantham

The purpose of this paper is to quantify the risk to both the environment and surrounding infrastructure from a pipe sealing implosion. Both accuracy and the precision in determining how a submerged infrastructure damaged by underwater explosions performs provide better decision-making capabilities for managers facing impending oil spills. This determination is vital, especially for both emergency and crisis management teams, as categorized consequences based on both the nature of the structural layout and the surrounding marine environment assist in identifying whether or not the utilization of this technique is applicable. Thus, the decision maker’s aim, in a crisis, is to minimize any associated risk that might result in aggravating the situation by endangering both the infrastructure and marine life. Therefore, the resulting risk matrices will enable technical personnel who are not experts in explosive technologies to be armed with the information necessary to determine if this mitigation technique is applicable to their situation.

Jan 1, 2013

By Kerina Taylor

Due to their high amount of stored energy, explosives have been the cause of many serious injuries and fatalities over the last centuries. Despite safety advances and awareness in the last decades, injuries and fatalities continue to occur at mining operations due to blasting. According to the National Institute for Occupational Safety and Health, from 1978 to 2001, blasting incidents claimed 106 lives and were responsible for over 1000 injuries in mines in the US. The main causes of incidents found today are flyrock, blast area security and premature detonations. The concerted efforts of the mining and explosives industries and labour and government agencies have greatly improved the safety record of blasting in mines.

Jan 1, 2011

By Diogo Fonseca, José Manuel, Nuno Fernandes, Blessing Taiwo

This research focuses on enhancing the synergy between blasting and primary crushing operations in quarries. A blast operation at dstgroup aggregate quarry in northern Portugal was simulated to fine-tune blasting techniques aimed at optimizing fragmentation indicators. The methodology involves conducting precise blast drill hole surveys, generating detailed terrain 3D models, and integrating these models into blast simulation software to enhance accuracy and optimize production efficiency. The study applies these simulations to test blasts, evaluating improvements in cost-effectiveness, crusher power consumption, and fragmentation efficiency using both aerial and terrestrial image analysis technology. The quarry key performance indicators (KPIs) guide the blast design simulations, ensuring practicality and relevance. The case study blast revealed that implementing optimum blasting techniques can enhance crusher throughput, reduce operational costs, and improve safety. This paper is part one of a three-part technical series where we aim to create a sampling procedure and establish a reliable baseline for the current state of operation. This baseline will be used in subsequent follow-up technical papers to make recommendations and improvements. The outcome of this study provides a framework for quarry operations seeking to enhance their efficiency.

Jan 21, 2025

By Bill Loviza, Jimmy Sanders

This report is not everything we would like it to be. Access to information concerning unresolved legal actions is a sensitive matter. Obtaining the information presented in this report was a challenge alone. The Tennessee Department of Commerce and Insurance, Division of Fire Prevention, the firms and individuals that elected to share information did so with various assurances of nondisclosure, confidentiality or anonymity. All those providing information did so with the expectation that the industry and ultimately the public would benefit from this effort. We offer special thanks to Assistant Commissioner, Fire Prevention, Emmett Turner, recently retired Director, Bomb and Arson, Dick Gardner and Director, Codes Enforcement, Randy Safer for support that made this endeavor possible. We make no claim with regard to being a scientific study. We did the best we could with available information. Our task was one of assembly, sorting and reporting. Where collateral information was available we used it.

Jan 1, 2004

By ISEE

Micrometer Crack Response to Vibration and Weather, by Prof. Charles H. Dowding of Northwestern University, adds to Prof. Dowding’s already important contributions to the industry with his “Construction Vibrations” books. This new book reports and interprets important data on crack response that are essential for differentiating the unseen effect of weather on structural cracking from the usually much smaller effect of vibration. In addition, the book contains detailed descriptions of data collection methodology.

Jan 1, 2010

By Jeff Hiedeman, Clint Sestrich, Christopher Hyle

Westslope Cutthroat trout have declined in distribution and abundance across their range and currently occupy about 59% of their historic habitat. Due to hybridization with non-native species such as rainbow trout, genetically pure populations persist in only 10% of that range. A westslope cutthroat trout population with relatively high genetic purity (97%) and conservation importance persists in less than two linear stream miles in the headwaters of the South Fork Madison River in southwest Montana. The relative purity of this population has been maintained through the presence of a downstream intermittent reach. However, spring flows fill the intermittent reach, creating a connection between occupied westslope cutthroat trout habitat in the headwaters and the habitat of competing trout species downstream.

Jan 1, 2011

By Langdon T. Mitchell, Karl Ingmarsson

The title is not referring to jewelry; nor is it about diamond core drilling. This article is instead about an emerging application for diamonds, hard rock percussive drilling with diamond drill bits. Diamond’s outstanding wear resistance has long been taken advantage of in core drilling. However, until now diamond has been less successful in hard rock production drilling in the mining and quarry industry.

Jan 1, 1999

By Mark Bosse

This is a paper demonstrating the use of a fixed wire and trolley system to deliver 2 or 5 lb cast primers (with 2 meter cap/fuse assemblies) deep into avalanche terrain. This avalanche terrain is mitigated using explosives prior to being opened to guests.

Feb 1, 2020

By Robert Hopler

THE work that is being done by the Government to reduce the dangers of mining was brought out strikingly in the First National Mine-Safety Demonstration which occurred at Pittsburgh, Pa., on October 30th and 31st, under the auspices of the United States Bureau of Mines with the assistance of the American National Red Cross Society and the Pittsburgh Coal Operators’ Association.

Jan 1, 2012

By B S. Petri, N T. Rouse

Underground limestone mines generally lack air pressure monitoring procedures and instrumentation guidelines. The blasting industry also lacks an applicable source for air overpressure levels that are produced by blasting operations in underground mines. This became apparent during the development of a new underground limestone mine, where overpressure levels from production blasting needed to be estimated. During the development phase of the mine, it was imperative that newly constructed underground structures be capable of withstanding the overpressure produced by blasting. Therefore, a study was conducted to (1) identify and review any published studies for data that may be applicable, (2) identify the appropriate equipment required to record the overpressure levels, (3) determine the proper procedures for setting up the equipment and recording overpressure, and (4) provide an understanding of the nature of the air overpressure in a developing mine.

Jan 1, 2014

By John Norman

This paper will cover blasting techniques that are applicable to underground and other rescue that involves removing obstacles and breaking rock in close proximity to rescuers and subjects.

Feb 1, 2020

This paper will review some of the work conducted in the past at the Dynamic Effects Laboratory to examine the use of stress waves and fracture mechanics in understanding dynamic fracture and fragmentation in blasting applications. Along the way, we will use photoelasticity and high speed photography to better understand the mechanisms of fracture and fragmentation.

Jan 1, 2015

By Keith Henderson

An open pit quarry operation in West Central Illinois provided a challenging proposition regarding the removal of a rock wall that once separated two pits, but was now in the middle of the north wall of the combined pit. Their mining plan included the development of a new ramp into the quarry pit in order to lessen the slope and to shorten haul truck cycle time. The task would be to remove a section of rock left behind from mining operations more than 20 years ago that was at or near the bottom of the designed ramp.

Jan 1, 2012

By Clarence Hall, Charles E. Monroe

Squibs, Fuse, and Detonators It has been made clear in the discussion of combustion and explosion and the description of various explosives that they can be caused to explode by various means. All of them can, under some circumstances, be made to explode by fire. Some of them can be caused to undergo a detonating explosion by setting off a detonator in contact with them. In blasting use is made of both these means for setting off explosives, the means used being determined by circumstances.

Jan 1, 2010

By Robert Hopler

Although electrical instruments were being widely introduced into the study of seismic tremors, attempts to understand and quantify shocks from blasting continued to use rather primitive methods well into the 19th century.

Jan 1, 2007

By Ethan Steward, Kyle Perry

Underground coal mines have several dangers, one the most hazardous of which is the possibility of an explosion caused by the ignition of methane gas. To reduce ventilation costs, coal mines have the option to close off abandoned areas that are no longer active with structural seals to keep an explosion from propagating into working areas of the mine. These seals must be designed to withstand different pressure levels based on the potential of the atmosphere behind the seal to become explosive, either 50 psi (345 kPa) for inert atmospheres, 120 psi (827 kPa) for non-inert, and over 120 psi (827 kPa) for special cases. Though seals have been designed to resist the overpressure, none have been evaluated for their resistance to the impact of heavy objects. Underground explosions produce high velocity gasses that, traveling through mine openings, may propel objects in the mine at a high velocity causing them to impact and damage the mine seals. Seals damaged in this manner may no longer hold the pressure they were originally rated for and may fail during subsequent explosions or leak explosive gasses into active workings. To test the effects of impact on mine seals, a projectile generator and two seals have been constructed. The projectile generator is a 12-inch (30.5 cm) inner diameter steel pipe with a 4-inch (10 cm) wall, is 8.5 feet (2.6 m) in length, and sealed on one end. Projectiles are propelled by a charge of black powder with a wooden wad and are held in place by foam sabots in the bore. This system, combined with the large bore, allows firing of many different potential projectiles that may be found in an underground mine at a high velocity into the seals. The velocity of each projectile is measured by an infrared chronometer which can later be used to determine its impact energy. Impact effects on the seals are measured using strain gauges, LIDAR scans before and after impact, high speed cameras, and visual inspection. The focus of this paper is on the projectile generator design and initial testing.