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By Scott Scovira

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009, one NA Quarry and Construction Business experienced a series of flyrock incidents. In the Spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By L C. Taylor, H U. Lesiste

This paper provides a preliminary description of the properties of the output pressure (shock) wave of an end initiated, cylindrical charge of low height to diameter ratio in saturated sand. The properties of primary interest are the pressure wave velocity, peak pressure and rate of rise of peak pressure to within 1.4 charge diameters from the output end of the charge. The behavior of these properties is seen to be quite different from their behavior at more customary ranges in water.

Jan 1, 2013

By Dirk Voogt, Quentin Steyl, D. Scott Scovira

A South Africa iron ore mine reported a decline in blast performance and ore and waste fragmentation. Preliminary investigation by the explosives services company found that the straight gassed bulk emulsion was breaking down and collapsing inside of some loaded slept blastholes. The bulk emulsion loaded at the subject site was manufactured in country and shipped to various clients throughout the region, with normal function in blasts at other sites. Historically, the bulk formulation emulsion being used at the subject mine site also performed well and without issue. This raised the question, “why is this bulk emulsion now breaking down and not firing in blastholes?”. Iron ore mines are not typically associated with reactive or acidic ground, and ground sample reactivity testing against the emulsion confirmed this. So, if not reactive ground or acidic water, then what is causing the emulsion to breakdown?

Feb 6, 2023

By C. Morel, P. Fredes, L. Rojas

This article presents a comprehensive study on the development and application of the specific module called "Exclusion Zone" created by Orica to determine blast evacuation exclusion zones. This module, integrated into the "SHOTPlus™ (blast design software)" software, has been used in the context of optimizing equipment evacuation exclusion zones in a northern Chile mine. The main objective has been to reduce the travel times of extraction equipment without compromising the safety of individuals. The module considers various factors such as the explosive charges used, stemming, sector topography, and detonation sequence to determine the rock projection generated by the blast. Furthermore, it utilizes information collected by drones and support tools such as Groundprobe and BlastVision™. The results obtained demonstrate that the use of this technology has allowed the optimization of blast evacuation distances in the northern Chile mine, generating significant economic benefits for the client.

Jan 1, 2024

By Michael Twomey, Alastair Torrance, Alan Twomey

Low density explosives have been available in various forms for nearly 20 years. These initially consisted of various diluted forms of ANFO formulated to slow the rate of reaction. One such product that was developed was a blend of ammonium nitrate and rubber. This product uses a coarse fuel provided by granulated rubber to slow the reaction rate of the explosive rather than being a diluted form of ANFO. There has always been a technical difficulty in blending two dissimilar materials without subsequent segregation.

Jan 1, 2011

By Shazad Hosein, William J. Birch, Robert Farnfield, David Jameson, Catherine E. Johnson

The current and consented quarry workings at a slate quarry in North Wales {UK} intersect old long abandoned underground slate mine workings. The old underground slate mine contains the remains of World War II buildings used to house artworks to protect them from war damage. Over the past 20 years, there have been a number of roof falls in the old underground slate mine, which have damaged the buildings and make general access unsafe. From observation of the timing of these falls, they occurred in the mid 2000’s. The purpose of the exercise was to determine the possible relationship between blast vibrations experienced on the surface and those experienced on the roof of the abandoned mine caverns. Thus preventing the need to regularly monitor in the old mine workings. In order to achieve this, a rigorous geotechnical assessment of the stability of the caverns was undertaken by a fully qualified Geotechnical Engineer. Once it had been determined that it was safe to do so, 3 “MEMs based” blasting seismographs were attached to the roof, in accordance with the instruction of the geotechnical engineer. In addition, 8 “MEMs based” blasting seismographs were deployed at various locations on the surface. The trial blast comprised of 51 blastholes, with charges varying between 46kg [101lbs] and 124kg [273lbs] of bulk emulsion explosive. The blastholes were in 4 rows of holes. The blast was connected using shock tube 25ms, 33ms and 65ms delay period relay detonators. The minimum distances from the blast to the surface and underground monitoring points were 78.1m [256 ft] and 114 m [374 ft] respectively. The results from the three underground monitoring locations in terms of resultant peak particle velocity was 4.42 mm/s [0.174in/s], 3.47 mm/s [0.137in/s], and 4.69 mm/s [0.185in/s]. In line with previous research, it was determined that the underground results [when compared on a “like for like” basis in terms of scaled distance] were lower in amplitude than the surface results. In this case by a factor between 0.47 and 0.87, averaging 0.68.

Jan 21, 2025

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 Italo Onederra, Miguel Araos

"Most of the current explosives for mining blasting activities are based on ammonium nitrate (ANFO, emulsions and watergels). AN-based explosives’ detonating properties were discovered in the 50’s and since then they have proven to be reliable, safe and cost effective. However, there is no current alternative raw material to replace AN. As part of a program of research initially funded by the Australian Coal Association Research Program (ACARP), Mining3 and the University of Queensland engaged in the search for potential oxidizing agent alternatives that could replace AN in the manufacture of mining explosives. Candidates included those that are produced in large quantities and that can be cost competitive with ammonium nitrate. The initial work identified hydrogen peroxide (HP), calcium ammonium nitrate (CAN) and sodium nitrate (SN). Explosives mixtures were prepared and sensitized using void sensitization techniques. The detonation properties results showed that explosives based onmixtures of HP/CN and HP/SN as the oxidizer were able to detonate in a range of 2000 – 5000 m/s, indiameters 50 and 102 mm, and densities in the range of 0.50 – 1.40 g/ml. Although more studies need to be conducted to fully understand these explosives, if successful, these explosives would be able to offer an alternative to the AN-based explosives in the mining industry."

Jan 1, 2017

By Denard Brandt, Isidro Martinez, Greg Baker, Laura Slattery, Teddy French

The Dos Pobres Mine is a copper oxide heap-leach mine located near Safford, Arizona. Mine production is 180,000 tons (163,293 tonnes) per day with a stripping ratio of 2:1. During the startup phase of the mine, the required fragmentation size was easy to achieve as the ore was highly weathered and fractured near the surface. As the mine depth increased, the proper fragmentation size became harder to achieve due to less weathering and different rock types. Because copper recovery increases as crusher product size decreases, achieving the appropriate product size at the crusher is the operating priority.

Jan 1, 2010

Electronic detonators are receiving increasing acceptance in the blasting industry. Electronic detonators offer several distinctive features over electric and non-el (shock tube) detonators including better timing accuracy resulting in excellent fragmentation and vibration control, field programmability and digital safety means. Several electronic detonator systems are available commercially today serving the surface, underground and seismic needs.

Jan 1, 2010

By D. Scott Scovira, Thomas Gustavsson

The potential of hydrogen peroxide explosives was introduced to Thomas Gustavsson and Robert Håkland by Dr Miguel Araos through his development of hydrogen peroxide gel compositions (HPG). In 2020, Thomas and Robert developed a concept project with Boliden Minerals and received Swedish government funding to evaluate HPG technology in a mine environment. The project showed HPG reacted violently with mine mineralization and concluded that HPGs did not offer a commercial solution due to safety concerns. Thomas and Robert engaged with Stefan Nilsson to develop hydrogen peroxide emulsion (HPE) compositions and the process techniques to manufacture them. In 2021, laboratory work produced a promising low carbon intensity, nitrate free, ammonia free, emulsion formulation based on industrial grade hydrogen peroxide and a fuel-emulsifier phase. Design and construction of an HPE pilot plant and underground charging unit commenced. The manufacture of hydrogen peroxide emulsion shares several similarities with the production of nitrate-based emulsions in that the plant is a facility to blend a strong oxidizer solution with a liquid fuel phase into a finished emulsion. A key differentiator between HPE and nitrate-based emulsion is that the manufacture of HPE is a cold production technology in that neither the oxidizer phase (HP) nor the fuel-emulsifier phase requires high temperature heating to prepare raw materials. A successful proof-of-concept HPE evaluation ran from April 2022 to October 2022 at Boliden’s Kankberg underground mine in Sweden. This evaluation demonstrated HPE technology's safety, performance, production, handling, and indicative environmental benefits.

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 Rolf Schillinger

Transport of Small Quantities of Explosives Material on Public Roads The transport of dangerous goods on public roads is extensively regulated by EU and national law. The transport of explosive material is not only done by forwarders but also by small companies and private persons with the goal of their own use. The following article tries to explain what is allowed and what is not.

Jan 1, 2010

By Michael Milstein

Northwest Research Station said as more and more older dams are removed to benefit fish, it’s become clearer that rivers rework themselves quickly.“Where the dam is relatively small, it’s a quick response,” he said. “The river quickly forgets.”

Jan 1, 2010

By Vitor Barcelos, Eduardo Elói, Gabriella Vaz, Davi Oliveira, Leandro Silveira

Following a routine production blast at Vale S.A.'s Itabira Mine in the Quadrilátero Ferrífero region of Minas Gerais, Brazil, nearby residents registered complaints about blast-induced vibrations. Analysis of the blast footage revealed that multiple blastholes were detonated simultaneously, resulting in a higher-than-expected charge per delay, ground vibration and cratering even though the electronic delay timing was configured correctly. Subsequent blasts within the mine's soft schist region confirmed the occurrence of sympathetic detonation. Mitigating or eliminating this phenomenon is critical for the mine's operation. Two dynamic pressure tests were conducted using carbon resistors together with typical VOD monitor maintaining the standard booster, electronic detonator, and a blend of 70% emulsion with 30% ammonium nitrate explosive. The tests involved increasing the distance between the central hole (detonated first) and the four surrounding holes in a five-hole sequence. Unfortunately, sympathetic detonation occurred in all these tests. To address this issue, a new explosive with a lower density and detonation velocity was tested. This approach proved promising, as no sympathetic detonation occurred. By leveraging the data obtained from this study, engineers can now identify situations at risk of sympathetic detonation and implement preventive measures, such as selecting the appropriate explosive and recommending safe minimum burden and spacing settings as well as confinement level for each blast while maintaining the desired level of rock fragmentation.

Jan 21, 2025

By Douglas Bartley

As the economy continues to slowly recover, our industry continues to finds ways to increase productivity while being forced to cut costs. The drilling and blasting process is the starting point of any aggregate or mining process. Many people refer to it as the “Primary Crusher” as it will always be more efficient to crush rock with explosives energy than it will be mechanical energy. It is the more efficient use of this energy that is addressed in this paper.

Jan 1, 2012

By Dennis Wilzbacher, John Wiegand

In an effort to reduce the cost of bulk explosives, Vigo Coal Company found that the addition of coal mined at their Friendsville Mine, not only reduced explosive costs, but also appeared to actually enhance blasting performance. The Friendsville Coal lies at the base of the Mattoon geologic formation within the Mcleansboro Group of the Missourian Series of the Pennsylvanian Geologic System in Southern Illinois. Vigo Coal Company commissioned VIBRONICS, INC., an independent blasting consulting company to quantify actual blasting performance. Insitu sonic velocity testing of overburden was conducted to determine the P-wave velocity of the sandstone present at Vigo’s Cypress Creek Mine, where the initial testing was conducted. Numerous VOD (velocity of detonation) recordings were obtained for varying blends of ANFO/Coal (now named Carbo*Prill). Cast blast percentages were determined for both Carbo*Prill and non coal blended bulk explosive blasts. The VOD of the coal blended product was intentionally reduced so as to more closely match the P-wave velocity of the sandstone overburden. Explosive blends containing as much as 40-50 percent coal were tested. Explosive blends containing greater than 30 percent coal, have been used in Cypress Creek Mine overburden production blasts. The coal blends appear to produce better fragmentation and yield excellent cast blast performance. Safer mining conditions were also observed. Flyrock potential was reduced. The blasts produced less back break, producing a safer highwall. Stripping dozer and shovel production rose during the testing period and equipment repair costs were lowered due to an increase in overburden fragmentation. Blasting vibrations were reduced, in part due to the lowered detonation velocity of the ANFO/Coal mixture. The Friendsville Coal Seam appears to contain inherent chemical and physical properties that enhance blasting performance. The use of Carbo*Prill has been approved by MSHA, BATF, the State of Illinois, and the State of Indiana. This paper will provide details concerning testing procedures, blast performance analysis, recommendations and conclusions for using this alternative blasting mixture.

Jan 1, 2007

By Brian Lewis, Reinhold Daykin Schnell

Blasting is the primary and most effective method for breaking and moving material at most mine sites. The blast design is often adjusted in efforts to optimize the effectiveness of the blasts’ explosive energy while minimizing costs. When adjusting blast design parameters, it is important to adjust one parameter at a time, observing and analyzing the potential effects of the change on the overall blast performance.

Feb 6, 2023

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

Hello, everyone. Way back in 1965, Devine and others at the US Bureau of Mines showed that a presplit fracture plane did not affect vibration levels transmitted across the plane (RI 6695).

Jan 1, 2010