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By B. Winterberg, C. Lewis, M. Starkel, C. Johnson

Non-electric systems, specifically shock tube, have become the pyrotechnic detonator of choice over electric due to their safety regarding accidental initiation from stray radio signals. Typically, the best practice when hooking up shock tube systems is to have direct contact to ensure initiation. When gaps are introduced to the explosives chain, there is potential for detonation to come to a halt. It is understood that direct coupling is required between the various elements in the explosive chain to ensure detonation. This holds true whether tying in non-electric detonators, loading holes in a mining related blast, or priming a block of C-4. Poor contact and gaps in the explosives chain can lead to detonators firing out sequence, leading to increased vibration, air overpressure, and other undesirable blast results. Furthering work conducted in previous experimentation, a new study was conducted at the Missouri University of Science and Technology’s Experimental Mine in Rolla, Missouri to observe the initiation potential of an air gap and fragmentation on non-electric shock tube. A series of small test blasts were conducted using 50 grain detonating cord and fragments from a blasting cap to initiate a non-electric shock tube across an air gap of varying distances. The data collected in the high-speed imagery was used to analyze the velocity of the pressure fronts and blasting cap fragments used to initiate non-electric shock tubes across an air gap. It was found that the shock tube was sensitive to 50 grain det cord at a 5cm (1.97in) distance while parallel and 10cm (3.94in) when perpendicular as well as sensitive to frag from the electric cap out to 2.4m (7.87ft).

Jan 1, 2024

By Ethan Steward, Robert Eades, Kyle Perry

Shock tubes, either gas or explosively driven, are often used for physical modeling of free field explosions or arena testing. The use of shock tubes often requires less setup time of subjects and smaller driving forces to create pressure versus time waveforms similar to that of arena testing. However, the effects of the shock tube cross sectional geometry on waveform properties is uncertain while free field explosion wave propagation and estimation is well studied.

Jan 1, 2018

By Joshua Calnan, Braden Lusk, Kyle Perry

This paper presents detailed information and data regarding the load transfer characteristics of Blast Resistant Glazing Systems utilizing two different thicknesses of polycarbonate. A series of triaxial load cells, along with surrogates of identical stiffness characteristics, were placed around the glazing perimeter to directly measure the load transferred to the support system from explosions of varying degrees. The blast loads were developed using an explosive driven shock tube administered by the University of Kentucky Explosives Research Team (UKERT) in Georgetown, KY. Results presented include distribution of loading, maximum load transferred to connections, blast pressure-time data, glazing system deflection-time data, and final performance results of each system. The two glazing systems respond differently to the applied blast loading. Differences and similarities in the load transfer characteristics are discussed. The experimental results are then compared to a commonly used blast resistant glazing system analysis software tool utilizing a Single Degree of Freedom (SDOF) method of analysis for each system. Preliminary results show that currently used models do not correspond well with experimental data.

Jan 1, 2014

By Martti Hagfors, Jussi Saavalainen

The underwater explosions has been used as a test method for the determination energy content of explosives. The test method is suitable for all kind of explosives; homogeneous, heterogeneous, wa-ter-resistant, no-water resistant, cap sensitive, booster sensitive, explosives with hard confinement, explosives without confinement etc. It is also the only test method by which shock, gas heave and to-tal energy values of the explosives can be measured separately. This feature makes it possible to use the test method to develop the explosives for different purposes; the military high explosives need more shock energy where as the gas heave energy is very important feature for the blasting and sea mine explosives.

Jan 1, 2010

By K. M. Kim, J. B. Kemeny

A case study was conducted with 5 shots with varying pre-blast block sizes and explosive energies. From this case study a site-specific predictive fragmentation model was developed. There are two main innovations in this study. One is using an image analysis program (Split-Desktop 3.0) on the bench face to obtain the pre-blast block size (F80) quickly and consistently. Another innovation is to utilize the Schmidt Hammer Hardness (SHH) to estimate intact rock strength.

Jan 1, 2011

By Ken Schei, Martin Reed, Samuel Bowser, John Wright

From October 18 through October 21, 2001, United States Antarctic Program blasters opened ten access holes for research divers in 11-ft. thick sea ice at Explorers Cove, McMurdo Sound, Antarctica. During this project, a blasting seismograph with a hydrophone accessory was used to monitor the underwater shock waves associated with the blasting technique. Shock wave values averaged 42.3 psi for initial (cratering) shots and 5.9 for subsequent clearing shots, indicating that the ice absorbs most of the shock wave. The results also provide data for refining safety protocols for divers and for the protection of marine biota.

Jan 1, 2003

By Daniel Scott

Mines have used explosives for economical fragmentation for many years. It can therefore be expected that the mining industry has thoroughly researched how to achieve the most efficient blast. However, there is still a large amount of iteration that must be undertaken before blasting at a mine site can be refined enough to allow for consecutively successful blast results. And then the geology changes. This paper will present an approach to blast design that considers production goals, geology, budget, and safety, and will contrast the proposed method with well established blasting theory.

Jan 1, 2012

By Lon Santis

This paper analyzes 110 serious accidents that occurred during the use of commercial explosives in mining, construction, and other industries since 1992. Data from the Mine Safety and Health Administration (MSHA), the Institute of Makers of Explosives (IME) members’ reports, and media reports were used. Only accidents that resulted in a fatality, significant lost work time, or injury to the public were considered in this analysis. The accident data were analyzed for trends in frequency, type of industry, cause, type of individual harmed, and geographical region. Although the data showed that explosives accidents are decreasing in frequency, still, 29 people were killed and 134 injured. Eightyfive of the accidents occurred in mining, 17 occurred in construction, and 8 occurred in other industries including oil recovery, seismic exploration, agriculture, logging, boiler cleaning, and avalanche blasting. As other studies have shown, flyrock and failure of blast area security caused over half of the accidents. Mishandling, misfires, or fumes caused just over one-third of the accidents. Lightning and drilling into explosives were responsible for the remainder of accidents.

Jan 1, 2003

By Sayantan Chakraborty, Kaushik Dey, SaKaushik Dey tyabrata Behera

Drilling and blasting is a popular excavation technique in the drift of underground mine. Faster completion of drift reduces the gestation period and thus longer blast pulls are attempted with longer drill holes. This compels the blasters to initiate higher charge quantity with higher confinements and ultimately results into blast-induced cracks beyond the desired periphery line of excavation. Assessment of the extent of these crack networks is difficult and often neglected. Near-field ground vibration models are often used as damage predictors (Dey, 2007, Yang et.al 1993, Holmberg et. Al 1979) but not necessarily deals with the positions of the cracks. Qualitative measurement of actual damage extent often measured using some geophysical tools, namely, P-wave velocity (Tezuka, 1995), seismic imaging (Dey, 2011), bore hole pressure monitoring (Brent and Smith, 1996), electrical resistivity (Grady and Kipp, 1993), GPR (Adams et.al, 1993) etc. Ground Penetrating Radar (GPR) is a similar geo-physical tool, which uses Electro-magnetic (EM) pulse for characterizing the medium. Similar to other geo-physical tools, GPR also comprises of a transmitter and one/multiple receivers to generate the EM pulse and receive the same after reflection/refraction from the medium(s) respectively. After its development in 1970s, GPR gained increased popularity due to its application in many important fields, namely, identification of buried objects, geological characterization, identification of geological disturbances etc. Thus, it is felt that GPR technique can be used to detect the invisible cracks inside the rockmass from the rock surface (wall and roof) itself. Understanding the same, field experimentations are carried out in an underground manganese mine in Central India, which operates on the ‘cut and fill’ method of mining at a depth of around 300m from the surface. Wedge cut blasting is carried out in the horizontal drifts of the mine using suitable blast design. A 1.6 GHz antenna was used for the GPR scanning, in which GPR transmitter transmits signals predominantly of the said frequencies. The signals get reflected back from any type of interfaces between materials in the target area, with different dielectric properties and is received by the receiver part of the ‘trans-receiver’ antenna and memorized in the Data Acquisition Unit (DAU). The data acquired is processed using a software. Ground vibration monitoring of the blasts are also carried out to develop a vibration predictor. The numerical analysis of near-field vibration predictor model results into the estimated vibration levels at the point of identified cracks. Introduction

Jan 1, 2019

By Lon Santis, Michael Swisdak, David Leidel, John Tatom

The Institute of Makers of Explosives (IME) and A-P-T Research, Inc (APT) have developed and released a quantitative risk management tool, IMESAFR (IME Safety Analysis For Risk), for the commercial explosives industry. Consequence algorithms in IMESAFR are considered state-of-the-art. Generally, they mirror those in SAFER (US Department of Defense Explosives Safety Board quantitative risk management software). The science behind the software has now been assessed for its maturity. Results have identified areas where additional test consequence data could improve predictions. To address these areas, full-scale testing programs to provide the needed data have been formulated. Proposed testing efforts include work to: (1) improve characterization of explosive articles now absent from SAFER, and (2) refine modeling of the Potential Explosion Site (PES) types, particularly small metal structures, also not found in SAFER. Goals of each program as well as requirements for conducting the tests have been established. Testing results are to be used to improve the algorithms and to further the state-of-the-art in risk-based explosives safety.

Jan 1, 2012

By B. Papilon

Dynamic pressures during blasting can affect performances of both electronic and non-electronic detonators. Boreholes can develop tremendous amount of pressures during blasting. The effect of such elevated pressure especially during electronic delay countdown is probably more acute in electronic detonators. Measuring the pressures during blasting can aid to understand the relationship between magnitude of the pressure developed and the multitude of blasting conditions.

Jan 1, 2013

By Benoît Pinier, Jason Furtney, Gustavo Sampaio Lopes, Jorge Valencia, Johan Hawinkel

This paper describes a numerical modeling study on the effect of airdecking on vibrations, fragmentation, and movement in mining-related rock blasting. Practice has shown that air gaps reduce blast vibrations and damage while maintaining the required fragmentation and movement, yielding similar blast outcomes with less explosive mass per hole. Given that the premise of “replacing explosives with air” for better blast results is counterintuitive, this paper aims to shed light on the physical mechanisms and processes occurring in a blast with airdecks. It is hypothesized that airdecks are effective and beneficial because they load the rock at pressures lower than what is required to crush the rock. In the airdeck, the explosive gasses directly fracture rock and avoid energy loss due to crushing. In essence, the airgap allows similar outcomes in fragmentation and throw with less total explosive product, as the lower pressure gasses in the airdeck are still effective at breaking and moving the rock. This is distinct from only having less explosive and more stemming, as the stemming reduces the pressure more than an airdeck at the same position. This study uses the blastFoam software (for modeling of single and multiphase flows) to accurately calculate the pressure history throughout a blasthole and air gap. The pressure and gas loading are coupled to numerical models of vibration, fragmentation, and blast movement. Using this modeling technique, a suite of blast scenarios for typical configurations in a range of commodities is assessed with and without airdecks. Rock blasting practitioners have a responsibility to protect communities, infrastructure, and heritage — demystifying airdecks through a better understanding of the physics provides another tool in the blasting engineering toolkit to serve this goal.

Jan 21, 2025

By Jeffrey Meissner, Mike Waldron, Charles Dowding

Most studies of crack response have focused on opening and closing of a crack in the plane of the wall in which the crack occurs. Crack movement also occurs perpendicular or normal to the plane of the wall. This paper will examine and compare the in-plane and out-of-plane (normal) response of cracks in two different residences near limestone quarries. In two locations, sensors that measure in-plane and normal displacement were installed side-by-side on the same crack, allowing direct comparison of the two modes of response. In a third location, a perpendicular pair of displacement sensors was installed in a corner of a room to observe the bidirectional response of the structure at a corner. Both long-term and dynamic data were recorded with the same sensors; temperature, humidity, and air over pressures were also recorded to compare blast and weather effects. Measurements show that ratios of out of plane to in plane response to dynamic events can vary. However, the ratios of out of plane (normal) response to vibratory events to that of climatological change is still as small as the ratio for in plane crack responses.

Jan 1, 2010

By Brandon Fryman, Josh Hoffman, Rhys Baker

A post-detonation debris collection project was led in conjunction with a large ammonium nitrate (AN) railcar detonation conducted by the Department of Homeland Security-Transportation Security Administration, Department of Defense-Combating Terrorism Technical Support Office, Sandia National Laboratories, and the U.S. Army Dugway Proving Grounds. This important work will aid in underpinning algorithms used in a Quantitative Risk Assessment (QRA) tool.

Feb 1, 2020

By William McFerren, Pragasen Moodley

In contrast to global trends, African, especially South African, surface mining operations have shown a significant rate of adoption of Electronic Detonators (ED’s) over the last few years. Proven benefits of converting to ED’s from pyrotechnic initiation systems have aided this market conversion. These benefits are experienced throughout the mining operation. Benchmarking exercises, prior to the introduction of ED’s, form part of the conversion process and allow for quantifying improvements. Extensive work has been done on quantifying the benefits of converting to ED’s and have shown that results can be reproducible. Improvements have been experienced in many applications and include environmental impact control, improved mining efficiencies, increased cast benefit and improved size distribution. These step changes in blasting results, in conjunction with the adoption of ED technology have aided the rapid conversion of the African surface market.

Jan 1, 2004

By Jeffrey W. Lin, Larry B. Weston, Jonathan D. Abbott, Jordan L. Arthur

Hydrocarbon fuel oils are one of the main components of ammonium nitrate-based explosives, including ANFO (Ammonium Nitrate-Fuel Oil) and emulsions. While a wide variety of fuels can, and have, been used in the manufacture of ANFO and emulsion products, No. 2 diesel, particularly dyed, off-road diesel, is widely used due to its ready availability and use in fueling mining equipment. However, a number of alternatives to standard diesel have been introduced over recent years, namely, biofuels, ‘high-performance’ diesels, and renewable diesels. The pressure to adopt these alternative fuels come from a variety of sources, such as initiatives to reduce carbon footprints, increased lifetime of equipment, and cost-advantages from tax credits. While these factors may provide a very real benefit to the mine site, a consideration that is often missed is how the use of these fuels can impact the formulation and characteristics of the ammonium nitrate-based explosives. Herein will be presented a discussion of these alternative fuels from a chemical perspective as well as the results of several studies focused on how the inclusion of various alternative diesels influences the production and performance of ammonium nitrate explosives. ANFO and emulsion were manufactured using representative fuel sources and studying in terms of the manufacturing parameters, shelf-life, interaction with other chemicals using in mining explosives. Detonation data was then collected for these products and compared to the behavior of products made with standard diesel fuels.

Jan 21, 2025

By Joe Atalla, Jesse Desrochers, Rodrigo Hayashida, Joseph Mukendi Kabuya

The Mont-Wright mine stands as a prominent open-pit operation in Canada, renowned for its vast iron-ore reserves. However, the efficacy of its blasting operations, crucial for efficient production, has encountered challenges due to the diverse lithological compositions across multiple pits. This study presents a comprehensive approach to optimize blasting practices at Mont-Wright mine, tailored to the specific lithological characteristics of each rock domain. Through systematic analysis and experimentation, blasting guidelines were meticulously developed, aiming to enhance grindability and equipment productivity. The implementation of these guidelines promises significant improvements in operational efficiency and resource utilization, positioning Mont-Wright mine at the forefront of sustainable iron-ore extraction.

Jan 21, 2025

By Allen Kinney, P. T. Freeport

This paper presents the methodology for final wall-controlled blasting utilized at the Grasberg Mine. The resulting optimized slopes representa14%and17% increase to bench face angle (BFA) and inter-ramp slope angle (ISA), respectively. The corresponding increase in both copper and gold recovery was more than 40% greater than forecast for each material. The Grasberg open pit mine is located in the remote jungle province of West Papua Indonesia, at an elevation of 4,200 meters(13,780 ft).With a diameter of approximately 3.5km(2.2 mi), anddepthover1.2km(0.7 mi),P.T. Freeport Indonesia (PTFI)has mined billions of tons of rock from one of the world’s largest gold and copper deposits. Grasberg Operation and Engineering implemented a quality driven slope optimization program for the final pushback, with the goal to safely increase recoverable metal through steeper slopes, while utilizing existing infrastructure and equipment. This paper focuses on controlled blasting initiatives, blast monitoring, and as-built slope measurement tracking, although many groups contributed to the success of Grasberg slope optimization. The potential slope optimization area was divided into two sections based on geologic assessment: Area A at radial 200°-270° and Area B at radial 270°-360°. Original slope designs for areas A and B specified ISAs of 51° and 52°, respectively, with all BFAs in the pit at 70°. Through continuous development, collaboration and achievement, the Grasberg final pit accomplished a BFA increase to 80°for all areas, and an ISA increase from 51° to 56°in Area A, and 52°to 60° in Area B.

By Huang Daguang, Paulo Couceiro, Juan Navarro

Mining is typically conducted through a set of interdependent unit-operations, which commonly include drilling, blasting, digging and hauling, in order to deliver the required ore material into the comminution circuit and to remove waste rock with minimum impact in the operation. In such complex environment, the identification of critical paths, and respective interfaces between different unit-operations, are necessary to determine a sustainable long-term operational program. Facing this challenge, adaptive cost optimization strategies are required to increase productivity and revenue while minimizing potential environmental impacts. Since the overall mining efficiency can be strongly impacted by blasting outcomes, an operating method based on the searching of the ideal blast design is required in order to minimize the mine total cost of ownership. The implementation of a consistent continuous improvement program requires specific care in terms of design, control and execution of the different stages of blasting. For that, the application of the most advanced technologies for rock characterization, based on drill monitoring systems, and smart explosive products, allows the improvement and control of blast results by adapting the explosive energy distribution to the rock condition, so as to optimize the performance of downstream stages such as digging, hauling and comminution. This paper describes the application of a heuristic optimization approach, where blast parameters are used as decision variables to evaluate the potential impact of several blasting scenarios on subsequent unit operations, under the continuous ability of modelling, measuring and calibrating operational performances along of the mine cycle.

Feb 6, 2023

By Chris Vagasky

On July 10, 1926, lightning struck at Picatinny Arsenal, New Jersey, and caused the explosion of at least 600,000 pounds (272,000 kilograms) of ammunition, resulting in more than $600 million (2015 dollars) in damage, the destruction of 200 buildings, and 22 deaths. Fortunately, there has not been a major incident involving lightning and explosives in the US in some time, though lightning has destroyed fuel storage tanks in recent years, including in North Dakota, Texas, and Ohio. Lightning poses a significant hazard to the explosives industry. Carrying high currents and temperature, lightning can cause explosives to detonate, start fires near storage facilities, and injure or kill operators.

Jan 1, 2017