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By A T. Spathis, M G. Wheatly

Some preliminary dynamic pressure data were obtained from several charges detonated in a tunnel situated in massive granite rock. The context of the work is the potential for desensitisation of explosives, failure of detonators, and sympathetic detonation due to the close proximity of inter-hole and inter-deck explosive charges to each other. Dynamic pressures were measured using piezoelectric gauges in water-filled 45 mm diameter holes adjacent to the charges. Some of the first arrival peak pressures were noisy, and although not fully resolved, may be due to reflections and the physical arrangement of the transducers and their size with respect to the monitoring holes. The estimated peak pressures were between 0.1 to 8.7 MPa at approximate distances of 2.8 to 0.8 m, respectively. Further work is planned with gauges that are disposable, have a higher pressure range, and can be used within a few borehole diameters rather than the piezoelectric gauges used in the present work.

Jan 1, 2016

By Kenneth Eltschlager

Blasting represents the highest risk of any surface coal mining activity that could result in injury and/or property damage off the permit area. In addition, blasting related issues e.g. flyrock, vibrations, air blast, etc., are responsible for a large percentage of citizen complaints. Thorough and consistent regulation of individuals certified to conduct blasting by the Office of Surface Mining Reclamation and Enforcement in Federal Program states and on Indian Lands under Federal jurisdiction is vital, as it serves to: facilitate coal production to meet the nation’s energy needs; protect people and property on and adjacent to Federal mining permits; form a basis for states to grant reciprocity certificates to Federal blasters; and be a positive example to primacy states. OSM issues Federal blaster certificates for blasting on Federal surface coal mine permits. The certification program includes experience, training and testing components similar to many of the states. But where a state program may focus on the specific blasting applications within its boundary, the OSM certificate requires a very diverse test to cover all potential blasting applications and products across the nation. Therefore, the Federal certificate is a good surface mining credential for blasters anywhere in the United States.

Jan 1, 2010

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.

By DuPont Magazine

RBH Note: as stated many times in these articles, frozen dynamite was one of the greatest hazards facing the blaster. It wasn’t until the late 1920s that it was solved for good, with the introduction of nitrated ethylene glycol as a partial replacement for nitroglycerin in dynamites. The du Pont low freezing dynamites contained TNT, DNT, or nitro-substitution compounds of various sorts.

Jan 1, 2015

By Mark Bauckman

Discussion Topics • Market Needs • Technology Developments & Best Practices • Industry & Government Developments • Future Possibilities & Your Role

Jan 1, 2006

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 Joseph Kennedy

How do terrorists and other criminal bombers acquire explosives to be used in an attack against U.S property and/or citizens? The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) with nearly 40 years of investigating bombings and other explosives incidents, has learned that explosive materials intended to be used in criminal acts are obtained primarily by theft, clandestine manufacture or diversion.

Jan 1, 2010

By John Platt, Mark Stephens

"When blasting is required in critical areas and anticipated shot movement and quick cleanup areessential to the success of the project it is extremely important to use the best technology available to achieve the goals expected by the customer. Wampum Hardware was given such a challenge in 2014-2015 when the PA Turnpike and New Enterprise Stone and Lime hired the company to do presplit blasting along the PA Turnpike. The face height averaged 45 feet (13.72m) and the shots had to be controlled to stop within 60-75 feet (18.29-22.86m) of the face or in this situation before they entered the travel lanes on the PA turnpike. In many if not most blasting environments, it is essential in controlling the movement of a blast, to make certain that the face holes are drilled at exactly the right place, with the proper amount and type of burden in front of and to the sides of the borehole. Profiling is an important first step to insure that the holes are drilled at exactly the right place and showing us the correct amount of burden in front of each and every drill hole."

Jan 1, 2016

By Elliott A. Pood, Ron Gilbert

Recent advances in digital recording technology have allowed frame rate increases in video recording equipment that provide the capability for super slow motion playback of commercial explosives shots. Such slow motion playback allows for the analysis of shot patterns, cap scatter, pattern failures, etc. In addition, the availability of such materials on video tape enables commercial blasters to provide a means for training current and future staff.

Jan 1, 1996

By Wm. Reisz

There is no universal standard for Standard Operating Procedures (SOP’s). Every blasting operation has its own unique circumstances, its own methodologies and its own unique demands. It would be nearly impossible to create a one-size-fits-all document that would be totally appropriate for every blasting scenario. But there are universal objectives that should be adopted in any set of blasting SOP’s.

Jan 1, 2010

By Nadya Michel, Daniel Gros-Jean

This is a true story. Names have been changed to illustrate the importance and impact of carbon monoxide risk management in explosive blast projects and the community « Honey I’m not feeling good…” “What is going on Michael?” – – Michael was not answering so Julia, who was on the third level of the magnificent house, hurried down the stairs to check up on him in the basement. Today was day 2 of the construction work of the bathroom, yesterday they had excavated all the space for the shower. She started to breathe heavily as she was approaching the bathroom and saw Michael unconscious on the floor. “Michael!” – Julia immediately dialed 911. She opened a window since the air was heavy and went by Michael to hear him breathe and take his pulse. The paramedics took Michael on a stretcher and rushed him to the hospital. “I’m feeling dizzy” she thought to herself a couple of hours after the incident, and heard Matthew say: “Mom, I’m feeling sick”. Suddenly, she felt like she would pass out and felt in danger but couldn’t move. She desperately searched for her cellphone and dialed 911 but couldn’t speak. The dispatcher sent the firefighters and paramedics to the GPS location that was appearing on the screen and the emergency team was alerted that it was a second call in hours at the same address. When the firefighters arrived, they had to force the door to enter and found Julia in her bedroom on the third floor and Anette and Matthew also unconscious in their bedroom, lying on their respective bed. There was no smoke but on their multigas meter, carbon monoxide (CO) peaked at 1500 ppm on every level of the house, which is abnormally high.

Feb 6, 2023

By Lynn Long

We have seen many new developments in the explosive and blasting accessory category, but one of the most useful items is the blast control plug. Blast control plugs are cone shaped units that are placed in the stemming just above the explosive load. They are placed about 8 to 12 inches up into the stemming material.

Jan 1, 1996

By Francisco Sena Leite, Raquel Sobral, Vinicius Gouveia de Miranda, Céu Jesus

"The urgent need for improvements in the control and mitigation of environmental and social conditions associated with the extraction and processing of raw materials is increasingly a demand imposed by legal entities and institutions. Therefore, this present article proposes an improvement of the estimation in the magnitude of the vibrations resulting from rock blasting methodologies in the surrounding areas,incorporating the heterogeneity caused by uncontrollable parameters, such as geological andgeotechnical characteristics. This methodology combines the use of empirical vibration attenuation lawscommonly known and with terrain discretization techniques using Voronoi’s decomposition. For thevalidation assessment of this methodology, the data set collected and compiled is composed by 87 vibration measures collected in 16 sample points in one area of study of which 2/3 of the samples were used to create the model and 1/3 for the validation. Using normality tests for statistical residue analysis,it is possible to infer that this present model has null residual mean, as well as a smaller sum of residualerrors. Comparing the methodology present in this paper with the procedures executed nowadays, areduction of the errors associated with the estimation is obvious, highlighting a better characterization of the behavior of the vibrations associated with rock blasting."

Jan 1, 2017

By L D. Lawrence

Certain blasting applications are more prone to the generation of significant levels of nitrogen dioxide post blast fumes, more commonly referred to as after blast smoke, generally ranging in color from dark yellow to bright red. This paper reviews basic background chemistry defining the observed fumes and attempts to correlate geology, blast design, and explosive composition effects on the level of nitrogen dioxide that can be observed in various blasting conditions. Additionally, a test setting for evaluating the generation of post blast fumes is presented with pertinent test data detailing generic explosive formulation modifications which effect the overall level of post detonation generation of nitrogen dioxide.

Jan 1, 1996

By Joshua Hoffman, Braden Lusk, Kyle Perry

Shock tubes are used to simulate large-scale arena explosions without the use of full-scale arena sites that utilize large quantities of explosives. Instead, small explosive charges can be used to drive shock tubes. When this is done, the geometries of the explosive charges can alter the resulting pressure time curve. A common geometry chosen for the explosive charge is a sphere in order to be congruent with the spherical shockwave that emanates symmetrically in three dimensions from the detonation point. This paper reports on the findings from experiments that study the effects of altering the charge geometries and explosive types while keeping the TNT equivalency constant. Peak pressures and durations were affected by these changes. Directional phenomena are exaggerated by the use of certain charge shapes and detonation points. The speed of the detonation front in the explosive being greater than the speed of the shockwave in air played a critical role in the resulting pressure time waveforms. Waveform manipulation can be used to generate job specific waveforms that ultimately benefit the shock tube operators and their clients.

Jan 1, 2010

By Chanhwi Shin, Hyeongmin Kang

Mine optimization is a key strategy in the mining industry that focuses on improving the efficiency, productivity, and sustainability of mining operations. To achieve mine optimization, digitalization is essential for modernizing mining operations and attaining optimal performance. Due to the importance of mine digitalization, various software and platforms have been released to support this effort. Furthermore, by integrating these advanced technologies, mines can enhance processes, leading to significant economic and operational benefits. However, integrating data from various sources and collaborating across different platforms remains a significant challenge in the mining industry. Generally, data for mine optimization, such as mapping, smart drilling, FMS (Fleet Management Systems), fragmentation analysis, or vibration analysis, are collected and analyzed separately on different platforms. This separation makes it difficult to aggregate and utilize data comprehensively for overall mining process optimization. During the digitalization process, obstacles arise due to these complexity, variability, and sharing issues of data across different maker, sources, and methods. These challenges highlight the need for seamless integration to achieve optimal mining operations. Thus, this study applied a total solution that can cover the entire Drilling and Blasting (D&B) processes. The blast design was performed using actual terrain mapping data, and drilling and charging were conducted following a guide based on the blast design plan. After blasting, loading and hauling distances and fuel consumption were measured, and fragmentation for each blast was evaluated. All measurement tasks were automated to minimize human error. By collecting all data in one server, it became possible to perform an overall evaluation for each blast, allowing the identification of optimal values. In conclusion, to evaluate the optimization effects for each mining process, one month of integrated data collected on a single server was used. Compared to the period before the Total solution was implemented, there were notable improvements: a 25% enhancement in hole spacing, a 60% improvement in floor flatness, a 23% reduction in average fragment size, and a 19% improvement in fragment uniformity. Regarding cost savings per blasting volume, the improvements were 11.7% in drilling, 9.3% in explosives, 7.6% in loading, and 17.5% in hauling.

Jan 21, 2025

By Joseph Hoang, Nick Reed, Scott Wishart, Michael Lovitt

Marvel Loch Underground forms part of St Barbara Limited’s Southern Cross Operations which is located 360km (224 miles) east of Perth. Southern Cross Operations produces approximately 120,000 ounces of gold each year. Mining occurs in over 8 lodes using a variety of stoping methods including Uphole Benching, Long Hole Open Stoping, and Core and Shell.

Jan 1, 2012

By Guillermo Lazcano Ríos, Jorge Parvez Aguirre, Alejandro G. Díaz Berríos, Felipe Rodriguez Alveal

Codelco's Chuquicamata Underground Division (DCHS) faces issues due to collapses in its subsidence streets, which hinders the advancement of the subsidence front and leads to the loss of areas and reserves. To address these issues, DCHS and Orica have developed a new excavation methodology based on pre-loading explosives in high drawbell. This methodology involves creating a high drawbell extending from the floor of the production level to the ceiling of the subsidence level, divided into two phases: upper and lower. A resin stemming is used to separate these phases. The excavation strategy adjusts to variables such as reception volume, fluffing, and excavation geometry, involving vertical pre-loading of the explosive and the use of a separating element between the phases. The test aims to validate the new excavation methodology and the retaining element in the rock mass, evaluating aspects such as drawbell geometry, impact on the rock mass, damage to the retaining element, and fragmentation. Wireless electronic detonators are used in the upper phase to improve safety by eliminating the need for physical connections, while traditional electronic detonators are employed in the lower phase. Low-density bulk emulsion is applied to minimize the impact on the Crown pillar and extraction point, and higher-density explosives are used above the subsidence level to ensure good caving. Results showed that the blast achieved 86% conformity with the theoretical design. Resin stemming allowed for 100% effective detonation in the upper columns, and the fragmentation obtained was 5.44 inches, which was less than expected. No damage to the Crown pillar was observed, and the explosive quality met standards. This technique has proven to be effective and viable, suggesting the possibility of eliminating the subsidence level in future levels, resulting in savings, and providing greater stability to the rock mass.

Jan 21, 2025

By N. Skopak, C. Aimone-Martin, J. Redyke, B. O. Meins

PipeBlast is a spreadsheet-based calculator based on research conducted by Southwest Research Institute (SwRI), used by the pipeline industry to determine if proposed blasting planned near existing pipelines can be safely executed. The two factors determining “safe” are blast-induced pipe wall hoop stresses and predicted peak particle velocity (PPV) at the pipeline. Although methodology used to predict hoop stresses is somewhat sound, predicted PPV amplitudes are highly exaggerated based on inappropriate attenuation models developed using spherical explosive charges of limited charge weights, placed in soil adjacent to model pipelines that do not represent rock blasting. Hence, pipeline companies readily reject well-design blasts and limit scaled distances far beyond what is reasonable and cost-effective to pipeline owners. Full-scale trench blasting in rock was conducted near a 24in (711mm) diameter operating API 5L X70 grade steel pipeline in Texas to compare PipeBlast model predictions with a Ground Strain Model (GSM) based on field measurements of ground motions on the surface and at the pipeline springline. Results of the GSM were compared with pipeline strains measured using wire gauges mounted on the Springline. The comparative results showed that a site-specific velocity propagation model provided good estimates of ground strains that are replicated on the pipeline walls in terms of hoop and longitudinal strains. Trench blasting 28ft (8.5m) from the pipeline produced ground motions of 7.6in/s (193mm/s). At this ground motion amplitude, the factor of safety defined as the allowable stress divided by the combined operating and blasting hoop stresses was reduce from 3.04 in the absence of blasting to 2.98. This paper explains the research and findings on which PipeBlast is based and presents an alternative approach to predicting blast-induced pipe wall stresses based on site-specific velocity propagation measurements and a ground strain model.

Jan 1, 2024

By Robert Hopler

After the disbanding of the Gunpowder Trust Association in 1904, the Association of Independent Powder and Dynamite Manufacturers was formed, followed in May of 1906 by the formation of the Association of Manufacturers of Powder and High Explosives. Due to a lack of success in attracting all manufacturers to membership, these organizations did not survive.

Jan 1, 2014