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By Scott Scovira, Ruilin Yang

This paper presents a non-waveform blast vibration model for the near-fi eld. The model uses the concept of a dominant charge augmented by other contributing charges estimated using a scaled time window. The model accounts for the effect of broken ground created by earlier fi ring holes, amplitude attenuation, effects of signal broadening with travel distance from frequency attenuation, as well as asynchronous propagation of different wave types due to the wave velocity difference, the delay time effect, and non-linear superposition of near-fi eld vibration. The model uses an effective distance defi ned from the broken ground screening, and determines a dominant charge contributing to the PPV at a monitoring station. Then the model uses a time window for each individual charge to determine if it contributes to the PPV. The time window has a variable width to model the effects of the signal broadening with travel distance. For modeling the signal broadening, a generalized rock quality factor Qd is proposed. The time window includes a weighting function that diminishes the contribution for charges fi ring further from the dominant charge and this accounts for contribution arising from the timing difference between a contributing charge and the dominant charge. The model uses a non-linear charge weight superposition technique that scales the charge weights within the time window to the same distance of the dominant charge and superimposes the scaled charge weight. The case study demonstrates that the model provides useful predictions for near-fi eld blast vibrations.

Jan 1, 2008

By Y. Idrogo

Electronic delay detonators have been used in most types of blasting application with great success, with the accuracy and precision being used effectively to control negative environmental impacts like vibration. They have also provided consistent repeatable fragmentation and heave results. With the very wide choice in delay period and powerful timing design software, the choice of firing times to optimise blast results is not always clear to the designer. So the improved results achievable from the use of electronic delay detonators are often not optimally achieved.

Jan 1, 2018

By Joshua Hoffman, Braden Lusk, Kyle Perry

Despite its porous and lightweight characteristics, aluminum mesh is believed to have blast mitigation properties. The current use of the mesh includes fuel tanks for airplanes, boats, and fuel stations as well as light armored vehicles for the military. The mesh acts as an explosion suppressant by preventing fuel tanks from exploding when exposed to an ignition source. More recently, work has been performed to assess the ability of the mesh to mitigate blast pressures produced by high explosives.

Jan 1, 2009

By Juan Pablo Guevara, Victor Munoz, Rob Bush, Gonzalo Marias

Cerro Negro Mine, property of Goldcorp Inc., is in the process of developing four separate underground access ramps for the exploitation of high grade, narrow vein gold deposits with vertical to sub-vertical dips. The Mariana Central, Mariana Norte, and San Marcos accesses are primarily in the development stages, while the Eureka access began production stope blasting in April of 2013. Mariana Central will also begin production in May or June of 2014.

Jan 1, 2015

By Amund Bruland, Vegard Olsen

This paper presents analytical assessments around unintended misfire detonation, within rock debris drilling and bench top cleaning, primarily in the quarrying and mining industry. The main purpose of the work has been to see which operation has the lowest fatal accident probability. To be able to do this a risk analysis model is developed and the basics of the model are described first in the paper. Further a practical approach of the model use is presented. This includes a summary of general fatal injury statistical data, which is used to establish input parameters in the model. The result of the work shows that the rock debris drilling operation has at least half the probability of fatal injury compared to bench top cleaning. The result of the work should bring along rewriting of the Norwegian explosives regulation. The statistical data also shows that the blasting industry generally has a high fatal injury rate compared to other industries and basic risk reference levels. Risk reduction efforts concerning the examined operations are described.

Jan 1, 2008

By J. P. Remi Proulx, Juan Camilo Gonzalez T., Winston B. Wilches

Alabama USA based Drummond Ltd. operates two open pit mines in the Cesar Coal Basin of Northern Colombia. The mines produce a combined total of over 25 million tons (22.7 Mt) of thermal coal per year which is transported by rail to Puerto Drummond, a direct ship loading facility, where it is exported to over 15 countries. The company has proven and probable reserves in excess of one billion tons of thermal coal.

Jan 1, 2015

By Terry L. Cook

RAG Coal West, Inc., Belle Ayr Mine is located in the heart of Wyoming’s rich Powder River Basin coalfield. Belle Ayr utilizes an open pit, truck/shovel operation to strip the overburden off the 70’seam of sub bituminous coal. Our excavation capacities consist of a 301 Marion with a bucket size of 52 cubic yards, and a 4100 XPB P&H with a capacity of 76 cubic yards. Production levels on these machines are closely monitored utilizing the Modular Mining Dispatch system. RAG Coal West, Inc. is a coal mining business that utilizes the effectiveness of teams as one of their strategies. Technicians have a certain amount of control over their own Team Process. The Drilling & Blasting Team is an assortment of blasters with varying experience levels. We have been able to think outside of the box when it comes to certain “proven” methods of blasting.

Jan 1, 2004

By Martin Schrier

This paper is an overview of a granite quarry cleanup near Kirkland Lake, Ontario, Canada. A combination of local geology and previous subpar blasting techniques led to the quarry needing significant rehabilitation before it could proceed with general operation. Advanced technologies were implemented into the blasting process, including laser profiling, bore-hole tracking, and geometric timing. The contract consisted of two floor shots and two 25,000 tonne (27,558 US ton) production shots.

Jan 1, 2018

By Evan Jannoulakis, Wilfrid Comeau

Using the Scaled Distance (SD) and the vector sum Peak Particle Velocity (PPVvs) from a single delay, preferably single blasthole, in a shot, a number is derived which has shown itself to be consistently related to blasting efficiency, as experienced by one of the authors of this paper over the last thirty years. The numbers derived by this process range in value over one order of magnitude more or less. This variation, a function of distance, weight of explosive in the delay, blasthole diameter, blast design, powder factor and the geological environment, can be consistently related to two of these factors, powder factor and distance. In actual use the measured "BED" representing good blasting results should not vary by more than + 33 to + 50 percent of the estimated "BED" in non calibrated cases, and + 10 to 20 percent where previous experience is available. Relatively high "BED" values are indicative of poor blasting results while relatively low "BED" values may be precursors of poor blasting results in a shot. There are many variables in the geological environment which can affect the "BED". A case study is presented from a surface coal mining operation in eastern Canada. This case study tries to evaluate the reasons for the variability in "BED" values derived from multi-hole shots. A problem in using "Signature Vibrations" from a single-hole shot to predict blasting vibrations from multiple-hole production shots is identified.

Jan 1, 1998

Prepare ATF Report of Theft or Loss (ATF Form 5400.5). A Report of Theft or Loss - Explosives Materials must be prepared when it is discovered that explosive materials are missing from inventory. Submit the original to the U.S. Bomb Data Center and keep a copy for your records. The form can be obtained from the ATF Distribution Center or from www.atf.gov. Although the U.S. Bomb Data Center should be notified as soon as possible, Federal law requires notification within 24 hours of the discovery. A full inventory check is also highly recommended (but not required) to locate missing explosives and to prevent future losses.

Jan 1, 2008

By Brian Hawkins, David Bradley, Rachel Gooding, Lucas Rodriguez, Patrick Wilson, Kevin Wegman, Dhruv Mittal

To better protect the nation and inform difficult defense and preparedness decisions, the Department of Homeland Security (DHS) is performing a probabilistic risk assessment of explosive terrorism risk to the US homeland. After assessing existing models against requirements, well-developed mathematical descriptions and algorithms associated with explosives hazards were combined with probabilistic modeling techniques used in DHS chemical, biological, radiological, and nuclear (CBRN) terrorism risk assessments to create a suitable interior explosive consequence model for assessing the impact to human health.

Jan 1, 2018

By David Hersey

The Paseo Bridge was located at the I-29/I-35/US-71 Missouri River Highway Crossing. It was built between 1952 and 1954 by Massman Construction Company. The 1,232 foot long, self-anchored suspension bridge was the longest of its type when built. On Jan. 22, 2003, a connector pin designed to allow the bridge to expand and contract during temperature cycles seized and caused a portion of the bridge deck to raise up and block traffic. This marked the beginning of the end for the old Paseo Bridge.

Jan 1, 2013

By John Floyd, Larry Wardrip

A series of tests were conducted to evaluate the performance of a high density, high velocity cartridged explosive. The tests included two production blasts in a limestone quarry and two production blasts in a granite quarry. To quantify blast and product performance, each blast was monitored with the following equipment: l Two (16mm (Lo Cam) high speed cameras (500 images per second) l Velocity of detonation recorder (I million samples per second) l Four face motion accelerometers (1 million samples per second) l Digital seismograph The fragmentation distribution produced by each blast was quantified with digital image analysis The benefits of the use of high velocity, high density toe loading was quantified in terms of: l Vibration reduction l Fragmentation improvement l Excavator performance In addition to the field tests, a comprehensive evaluation was performed to determine the cost/benefit relationship of the use of the toe load. This paper will include the findings of the study along with guidelines for use in other quarry operations.

Jan 1, 2002

By P. N. Worsey, M. Schmidt

Many advanced military systems and civilian power generation concepts postulate the availability of compact sources of electrical power capable of delivering gigawatts over microsecond time scales. For example, such a compact power source is essential for future practical pulsed high-powered microwave sources. An explosive-driven flux-compression power generator (EDPG) could fill this requirement. A basic strength of this concept capitalizes on the inherent high energy density storage capacity of modern chemical explosives. It relies on the physics of magnetic flux compression to convert that stored chemical energy into very large amounts of electrical power over short time scales. The generator also has the additional advantage of employing the same types of explosives that are already routinely used in conventional munitions. However, the self-destructive nature of this type of power generator places serious limitations on power pulse-lengths and ranges of applications. This paper describes how a multi-disciplinary team led by researchers from the University of Missouri-Rolla (UMR), Texas Tech University (TTU), and Texas A&M University was awarded a grant by the U.S. Air Force Office of Scientific Research to perform basic research to resolve several fundamental EDPG problem areas. Described are the utilization of UMR’s extensive explosives research expertise and facilities to investigate questions of energy conversion efficiency and the mechanics of energy production. Also, UMR explosives researchers will provide inputs to improved dynamic computer models of the complex, intertwined physics and chemistry operative in these devices. In addition to explosives expertise, UMR provides facilities for basic explosives material research, as well as the storage, machining, and formulation of explosives. UMR researchers are also using test facilities and data collection equipment at the Rock Mechanics and Explosives Research Center and at the UMR Experimental Mine to perform “proof of principle” and subscale tests of explosive-driven flux-compression power generator components. An integral part of the paper is a description of the development of an extreme intensity flash system by UMR and TTU to allow for the high-speed photography of EDPGs in operation. This multi disciplinary research program offers major advances regarding the size, weight, and electrical characteristics of compact EPDGs. Such breakthroughs could dramatically accelerate the practical realization of systems currently under study. Also, these power sources may have far reaching relevance to other Department of Defense and certain commercial compact power applications.

Jan 1, 2000

By Bryan J. Lane, Paul N. Worsey

The recommended maximum explosive weight for boulder blasting using internal charges is 0.1 O-kg/m” (3.5 oz./yd) (Olofsson, 1988). Normally this charge results in excessive scattering and flyrock, creating increased liability for the operator, especially in congested areas. An alternative technique using smaller explosive charges is being developed at the University of Missouri - Rolla. It is designed to reduce boulder scatter, flyrock and fumes and allows shooting in close proximity, using common blasting products.

Jan 1, 1999

By Kevin Tallent

The use of military-type energetic materials in commercial explosive products is not a new concept. In the United States, the techniques for utilizing significant quantities of surplus military explosive materials by commercial explosive manufacturers dates back to the 1950’s. At times, explosive companies have found surplus military high explosives and propellant materials to be suitable ingredients for their commercial explosive products. The availability of these military-type energetic materials has varied over the past 50 years, as a function of the military’s strategic defense needs and the advances in modern weapon technology. For the most part, the commercial explosives industry has been able to implement methods for safely incorporating military-type high explosives and propellant materials, whenever these surplus materials become available. During the past 5-6 year period, a large amount of military-type energetic materials have once again become available for recycling into commercial explosives. This situation can be attributed to a number of factors, such as the political changes in Europe, the development of more sophisticated weapons systems, and the increased EPA pressures on the U.S. Department of Defense for disposing of surplus energetic materials. As in the past, U.S. commercial explosive manufacturers have made efforts to recycle these surplus materials into their explosive products. This paper describes some of the commercial explosive products that are currently on the U.S. market, which contain rocket and gun propellants as energetic ingredients. Some U.S. explosive companies, such as DYNO NOBEL, ORICA and Slurry Explosive Corporation, have been able to recycle significant quantities of surplus smokeless powder and composite propellants as energetic ingredients into their commercial Blasting Agents. The successes enjoyed by these companies have once again shown recycling into commercial explosive products to be an economically and environmentally sound method for disposing of surplus military-type energetic materials.

Jan 1, 2000

By Yeon-Ho Jin, Eui-Haeng Heo, Yun-Seok Park, Sung-Oong Choi, Hyung-Dong Min, Min-Su Jeong, Seung-Joong Lee

As rock fragmentation in bench blasting can affect the following process such as loading, hauling and crushing, its good control is essential for assessment of blasting efficiency and production cost.

Jan 1, 2015

By Ashwani Jain, D K. Soni

Compressive strength of rocks is often required by mining engineers and quarrying authorities for blasting operations. Uniaxial compressive strength of rocks can be predicted with reasonable accuracy with the help of point load strength tests which can be easily conducted at site by the field staff, simultaneously as the cores are recovered from drilling operations. A number of diametral point load tests and uniaxial compressive strength tests have been conducted on the specimens of different rock types under air dried, and saturated condition as well to study the effect of ground water saturation on strength. It has been observed that due to saturation uniaxial compressive strength and point load strength get reduced to a maximum of 32 and 29 per cent respectively. It has also been observed that uniaxial strength is sixteen times the point load strength in air dried as well as saturated condition. However, this factor used for calculating uniaxial compressive strength may be reduced to a lower value for the safety of miners in field blasting operations.

Jan 1, 1994

By Mark S. Stagg, Rolfe E. Otterness, Farrokh Djahanguiri

The U.S. Bureau of Mines (USBM) evaluated empirical equations that predict fragmentation from underground stope rounds. Controlled blasting is necessary for creating leaching stopes that maximize the recovery and minimize backbreak of the perimeter wall. This paper presents the fragmentation results from one of the three drop-raise blasts used to develop a reduced-scale cylindrical stope, 1.8 m in diameter and 6 m in height. The stope is located in the Colorado School of Mines Experimental Mine (Edgar Mine) in Idaho Springs, Colorado. This stope is part of a USBM research effort to determine the feasibility of incorporating in situ leaching of rubblized stopes into active underground metal and nonmetal mines.

Jan 1, 1994

By Robert Cefalo

Drill and Blast Engineer Abstract In 2019, the Bingham Canyon Mine, owned by Rio Tinto Kennecott Utah Copper Company, mined through the active underground that dewaters the pit. The active underground required the limitation of vibrations to avoid catastrophic damage or damage that would require work to the shotcrete and additional roof support. The surface design of the current sector next to and through portions of the active underground. The drill and blast group was required to test site law vibration parameters to ensure that vibration limitations were lower than limits set by the underground management team. Seismographs were used to validate the vibration prediction model and check performance of blast in areas of the underground. The bench conditions and limited pounds-per-delay created large obstacles for the blasting team, making it difficult for them to accurately load the pattern with the number of decks in the blast. Methods were used to improve the loading instructions and ensure that each hole achieved pound requirements based off of the distance to the underground that it was designed to protect. The project evolved from start to finish, and the process to estimate distances and loading improved to make the blast a more repeatable process for the size of the project.