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By Mathias Jern, Ruilin Yang

A blast vibration model has been developed that simulates effects of almost all blast design parameters on the blast vibration peak particle velocity (PPV) from a production blast with multiple blastholes at a given point of interest in the rock. The velocity of detonation (VoD), initiation points, explosive types (density, VoD, energy), charge decoupling, and decking in each blasthole are simulated along with other blast design parameters. The information from signature hole blast vibration and the blast design are the input to the model. The model can be used to assess blast damage in proximity of blastholes as well as far field vibration PPV.

Jan 1, 2019

By Ruilin Yang

This paper presents a fragmentation model for large production blasts. The model uses peak particle velocity (PPV) induced from the blast as a controlling parameter to predict the fragmentation size distribution. The PPV can be related to shock pressure or strain under a given rock condition. The fragmentation size is calculated at three-dimensional grid points within the blast volume. The grid size defines the calculation resolution of the model. The fragment size distribution is assumed to be in the same form as the crack distribution within a cube (of the size equals to the grid size) surrounding a grid point. The crack distribution in rock from impact is based on the finding from previous researchers (Seaman et al., 1976). The fines and oversized blocks are calculated explicitly. The summation of the size distribution at all calculation grid points over a specified volume of the blast yields an overall size distribution for the volume.

Jan 1, 2015

By Mark Spaniel

Computer 3D modeling to evaluate the potential underground blasting fragmentation performance based on rock within calculated damage radii along drillholes, as well as the burden distance from explosives along each drillhole. The results estimated from the 3D computer models closely predicted results found in the real world testing.

Feb 1, 2020

By Michael Laing

Blasting regulation and restrictions are tougher today than ever before. When blasting in population centers, strict limitations are often placed on the environmental effects caused by blasting, more specifically vibration and overpressure. Blast-induced vibration can be a tricky thing to manage at times, but there are a variety of options at our disposal to help optimize and manage vibration. This paper focuses on the application of rudimentary signature hole analysis to optimize blasting vibration in localized areas surrounding a mine.

Jan 1, 2017

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 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 B. A. Cheeseman, R. Skaggs, C. F. Yen, S. Wolf

Shallow buried explosives pose a significant threat to lightweight vehicles and their onboard personnel. To date, designers of lightweight vehicles are limited in their knowledge of what occurs during the blast. The high intensity, short term loading imparted by the explosion is enormously complex and can be significantly affected by a number of parameters including the size, shape, type, detonation point and depth of burial (DOB) of the explosive and the type, density and water content of the soil. Recent advancements in numerical simulations have enabled the complex blast event to be accurately modeled by coupling Eulerian and Lagrangian analyses: the former is well suited to modeling the blast and while the latter, the structural response. Further validation of the modeling technique is considered in the current paper, which details simulations performed utilizing the coupled Eulerian-Lagrangian analysis to the study the blast output of explosives buried in saturated sand. These experiments varied explosive charge size, its depth of burial, the target stand-off (SO) distance and target plate dimension. The investigation concludes with a discussion of the accuracy of the numerical simulations when compared with the experimental observations.

Jan 1, 2005

By Tapan Goswami, Lloyd Hain, Geoff Brent

For many years Ramp 24 at Ensham mine in Queensland, Australia has suffered substantial coal loss and damage due to the fragile nature of the coal and problematic geological conditions, which have proved very challenging. In the past various blasting techniques were applied in attempts to improve coal recovery. One approach was to use a shallow throw (cast) blast followed by a separate post-strip blast underneath. Another method was the introduction of the practice known as “baby decking” with the addition of a large buffer of material in front of the coal. However, despite increasing mining costs, none of these techniques adequately reduced coal edge loss and damage.

Jan 1, 2008

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 MacDonald B. Johnson, Douglass P. Bacon

With the advance of science, rise of public interest in environmental matters, and continuing erosion of air quality, Federal and state regulators are demanding an increasing complex array of data concerning emissions produced by burning and detonating energetic materials. The U.S. Department of Defense, one of the world's largest consumers of energetic materials, now must characterize combustion products resulting from open burning/open detonation disposal operations. The catch-all phrase "below detection limits" no longer satisfies the regulators who now want testing to delve into the ppt level for volatile organic compounds and ppt level for semivolatile organic compounds.

Jan 1, 1995

By Henry P. Jr Van Ormer

During any blast hole operation the first choice to be made is hole size - it seems simple, just calculate all the factors, spacing, burden, depth, rock characteristics, powder factor, etc. and you have it - Hole Size. But we all know that it is not that easy - the "hole size" is part of a system and many other situations can have great impact on the optimum production Blast Hole Size - such as crusher characteristics, hauling capability, mucking capability and - Drilling Capability!

Jan 1, 1983

By Angelina Anani, Seffit Aderuyi, Sylvester Avane, Joseph Wilson-Sey, Amatus Niminye

The Edikan mine in Ayamfuri, Ghana, faces economic challenges and community resistance due to its proximity to residential areas, particularly concerning blasting operations. Controlled blasting trials using air deck applications were conducted to address community concerns by minimizing environmental impacts and explosive costs. This method involves utilizing an air gap within blast holes to prolong the action of shock waves on the rock mass, enhancing crack formation and reducing rock movement. The trial project at the Edikan open pit gold mine aimed to evaluate the effectiveness of air deck blasting in reducing ground vibrations and overpressures, and to assess its impact on blast performance and economics in the prevailing geological conditions of meta-sediment and hard granite rocks. Results indicated lower Peak Particle Velocity (PPV) and Peak Sound Pressure Levels (PSPL) values in the air-decked blasts. Additionally, more uniform rock fragmentation and enhanced blast economics were achieved. Explosive costs were reduced by 20–24%, saving $0.97 to $2.24 per hole depending on the rock type. Overall blasting costs per volume decreased to $0.54 in granite and $0.48 in meta-sediment compared to conventional methods.

Jan 21, 2025

By Alejandro Rosario, Ricardo Dumuihual, Guillermo Silva, be nito Danial Valde, Carlos Scherpenisse

A monitoring campaign to record dynamic pressures generated by detonation of a single blasthole was implemented at Barrick Gold´s Pueblo Viejo Open Pit mine (PVDC), located in the Dominican Republic. Pressure amplitudes beyond the dynamic compressive strength of the electronic detonator´s capsules have the potential to damage these electronic devices, generating misfires along with all the associated risks and entailed safety implications. In most instances, misfires generated from high dynamic pressures are a direct consequence of drilling deviations resulting in blasthole distances smaller than originally designed. Tourmaline Crystal Sensors specifically designed for high dynamic pressure measurements in aqueous media were selected to address the challenge. These sensors are custom-made and require additional instrumentation for proper operation, including signal conditioners and recording equipment capable of capturing simultaneous events, both in their amplitude and frequency components. Field-testing comprised detonation of a single blasthole using current explosive loading practices along with an arrangement of sensors positioned within water-filled drillholes in a spiral configuration. Distances, explosive weights and all 23 dynamic pressure record amplitudes are included along with additional data regarding arrival time and P-Wave velocity estimations. As with typical vibration models, the Scaled Distance concept (D/W1/2) was used to construct an attenuation model relating Dynamic Pressure as a function of Distance (D) and explosive Weight (W). The resulting model, adjusted to a 95% statistical confidence limit (covering 100% of the recorded data) was used to generate a series of curves (Abacus) estimating dynamic pressure as a function of distance for different explosive charges. These curves, in association with permissible pressure limits defined at 50% (FOS = 2) of the dynamic pressure strength reported by manufacturers for both, the 1000bar (Al) and the 1400bar (Cu) capsules; allow for the determination of critical (safe) distances between blastholes. Tests were implemented to cover a variety of field scenarios, accounting for different rock mass types, qualities and water conditions; however, preliminary analysis indicate the convenience of developing a unique trend that considers said variability. This approach allowed construction of a single, simple, unambiguous and operationally applicable design tool to address entailed safety issues.

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 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 G Mendoza, L Taddei, C Robertson

It is a well-known industry fact that many mine sites around the globe experience blast holes that have elevated temperatures due to reactive ground, geochemical reactions, geomorphic reactions, sub level open fires, etc. It has been reported in many previous industry publications (White, Saputra et al) that elevated blast hole temperatures are a norm at many mine sites and are dealt with on an ongoing basis while the drill and blast process continues under elevated states of alert. The choice of explosives products including the type of detonator, primer, accessory, and bulk product all must be taken into consideration when loading blast holes where there is a known potential for elevated temperature conditions. It should also be noted that these elevated temperatures inside blast holes can be consistent throughout the blast hole length or vary in position within the blast hole depending on the mine conditions mentioned in the opening statement above. The risks associated with the loading of primers and bulk explosives in holes where elevated temperatures are present include: the ejection of the bulk explosives product, deflagration of the explosives during initiation of the blast or premature and uncontrolled initiation of a blast hole(s). This paper describes a unique and novel approach to the active monitoring of the temperature within blast holes with the application of electronic detonators with integrated temperature measuring (ITM) capabilities, deployed and demonstrated at a mine site in Mexico during January 2023 to March 2023. The deployment of ITM capable electronic detonators allows a user to monitor and record the real time temperature at multiple locations (e.g., toe, middle and collar) at each electronic detonator’s position within the blast hole, with the ability to react instantaneously to elevations in temperature reported. The measurement of the temperature can be for a single ITM electronic detonator, or simultaneous for an array of ITM electronic detonators, allowing for the potential for the data to be represented by a time/temperature/hole depth three-dimensional heat map. Changes in temperature at different borehole positions can vary, however, often the collar position is expected to be the most reactive due the combination of bulk explosive product and oxygen exposure, which can be confirmed with the application of the ITM electronic detonators. A mine site’s reaction to a measured elevated temperature within a blast hole can vary depending on the temperature measured and the change in temperature from the last measurement made. The study was found to produce real-time in-hole temperature information which was previously unobtainable without the introduction of another device. New and adaptive elevated temperature hole policies can be created and adapted proactively as real time information is received, leading to a safer mining operation.

Jan 21, 2025

By Robert Hopler

Torpedoing Wells. – On the completion of the drilling, or when the production is found to decrease, it is usual to “torpedo” the well to increase the flow. This process was patented in 1862 by Colonel Roberts, who believed, with many others, that the oil was contained in crevices in the rock, which might not have been tapped by the bore-hole. He therefore proposed the use of nitroglycerine, gunpowder, or other explosive, to break up the rock at the bottom of the well, so that these rich “pockets” might be brought into communication with the well.

Jan 1, 2007

By Zong-Xian Zhang

In sublevel caving mines, serious eyebrow break usually gives rise to lower ore recovery, higher dilution, and worse safety for the people working in the field. For example, chargers must go near the caving region and stand under the damaged eyebrow where a hanging stone may suddenly fall down or rock fragments may quickly roll down.

Jan 1, 2011

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 Gustavo Huerta Valer, Jorge Cárdenas Miranda, Johan Salas Flores

One of the challenges of mining is the optimization of the blasting process, which has an important impact downstream in the processing of crushed ore in the plant, that is why mining companies ensure the results of granulometry obtained from the blasting process through a joint work with companies specialized in the process of loading with explosives.

Feb 6, 2023