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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

By Thomas E. Ricketts

Occidental Oil Shale, Inc. constructed two commercial-sized modified in situ (MIS) retorts, Retorts 7 and 8, at its Logan Wash Oil Shale Mine in February and April 1981, respectively. One of the primary objectives of this two-retort program was to examine large-scale blasting reproducibility for commercial-sized retorts. The blast design used 545 blastholes and 550,000 pounds of explosive in ANFO equivalent per retort. Each retort was blasted using millisecond delay blasting caps tied into a single round. The blasts resulted in rubble beds very close to one another and to predicted results obtained using newly developed limited void blasting technology. The heights of the remaining void rooms over the beds after blasting were within 0.3 feet of one another. This excellent reproducibility is brought into true perspective when compared to the scale of the rubble beds which were 230 feet high with volumes of over six million cubic feet each.

Jan 1, 1984

By Tyler Rockley, Cara Rosen

Blasting at a granite quarry in eastern Maryland produces elevated air blast readings that can fall into the cautionary zone for the state of Maryland environmental regulations on a semi-regular basis. When designing blast patterns in this quarry, challenging geology creates rough and uneven blast faces that can be difficult to capture with 2D laser profiling fully. Utilizing several methods known to manage high air blast results like pattern adjustments, decking, and timing changes have not achieved consistent outcomes.

Feb 1, 2020

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 Tyler Rockley, Cara Rosen

Blasting at a granite quarry in eastern Maryland produces elevated air blast readings that can fall into the cautionary zone for the state of Maryland environmental regulations on a semi-regular basis. When designing blast patterns in this quarry, challenging geology creates rough and uneven blast faces that can be difficult to capture with 2D laser profiling fully. Utilizing several methods known to manage high air blast results like pattern adjustments, decking, and timing changes have not achieved consistent outcomes. Accurately capturing and modeling this geology is the key to controlling high air blast. 3D modeling and profiling by drone is the solution to understanding accurate face profiles and real minimum burdens. Using 18 months of blasting data and air blast results to establish a baseline, the comparisons between blasts designed with 2D profiling and blasts designed with drone 3D profiling show improvement in air blast levels. Additionally, shots with completed drilling were drone profiled to understand precise amounts of burden for each borehole. This 'audit' of a blast allows for custom loading of explosives, accommodating the amount of burden present on the blast face. 3Dprofiling is not a new tool in the blasting industry, but a drone alleviates some of the restrictions ground systems face. Controlling and managing air blast, as it pertains to face burdens, requires an understanding of those burdens from all angles. A drone provides that distinct level of insight. The results of this study indicate that drone profiling is managing the customer's air blast readings, allowing the customer to maintain their license to operate within the community.

By Alejandro Ferrada Vergara, María Jesús Barros Godoy

The need for a basic method for selecting explosives based on rock mass or intact rock properties for mining and construction arises from the limited consideration given to these factors when choosing among products and also an implicit overestimation of the explosive power to fragment the rock. This study highlights the importance of evaluating different properties such as rock strength, deformation, fracturing, detonation velocity and energy release when selecting explosives. The concept of characteristic impedance, which considers rock strength against shock waves generated by explosive detonation, is introduced. Understanding this concept is crucial for assessing explosive behavior according to various rock types. The study concludes with a practical guide table that categorizes rock properties and provides recommendations for selecting explosives based on rock mass and rock properties. However, it is important to consider other relevant factors, such as the presence of water or nearby instabilities, which can influence the final choice of explosives.

Jan 21, 2025

By M. S. Dotto

The knowledge of the explosive/ rock mass interaction process is important in predicting blast performance. It includes understanding rock properties, energy usage, and attenuation in the rock mass. The paper proposes a method to quantify blast-induced rock mass damage from the field measurements and apply it to modeling blast fragmentation.

Feb 1, 2020

By Walt Meglasson

The Kaiser Aluminum Company Smelter, one of several in the Pacific Northwest, was built in 1942 and operated by the Olin Company during World War II and then purchased by Kaiser Aluminum after the war. At its height, the facility employed over 350 workers and was capable of producing 73,000 tons of aluminum per year. It was closed in 2000 through a combination of rising electrical and labor costs, and the inability to compete with more up-to-date foreign facilities.

Jan 1, 2008

By Robert A. Cummings, Francis S. Kendorski, Charles H. Dowding

During the summer of 1980, a field project was carried out to determine the stability of the beautiful and dramatic natural limestone pinnacles (locally termed "Hoodoos") at Bryce Canyon National Park, Utah, when subjected to ground motions and airblasts resulting from proposed strip coal mine blasting. The concern arose from environmental considerations associated with the proposed development of a large coal strip mine which would approach within 4 miles of the park. The pinnacles range up to 150 ft in height and are quite slender, producing a fragile appearance. The remoteness and ruggedness of the area required a field camp, and 4-wheel drive vehicles, helicopters, and snowcats for support. Portable magazines were necessary to store the more than 7 tons of blasting agents and explosives required. In conducting the blasting, great attention was paid to environmental impacts. In the field, a target pinnacle was selected and instrumented with mechanical strain gages, and research seismographs that required helicopter placement.

Jan 1, 1982

By Italo Onederra, Jason Furtney, Ewan Sellers

The Hybrid Stress Blasting Model (HSBM) is a high level blast modelling research tool which provides results that can still be used implicitly for practical blast design. The code is being developed through an international collaborative research project funded by a consortium of companies which is comprised of explosive, equipment suppliers and major mining houses. A key component of the HSBM is the numerical code and user interface designated as Blo-Up 2.5. To date validation work has focussed on breakage, fragmentation and damage outcomes in controlled laboratory experiments and using large concrete cubes

Jan 1, 2012

By Bob de Raadt

After a review of the general principles for blasting stacks, the stagnations of two stack demolitions are investigated. The author concludes and demonstrates that MS-delay blasting can be risky under certain circumstances. How this initiation device can still be applied safely to the demolition of stacks is shown in an account of a blasting operation, in which two 106-m (350 ft) -high concrete stacks were involved. The recent discovery of a possible hazard of MS initiation in this field of blasting is an essential contribution to increased safety in blasting tall structures.

Jan 1, 1982

By Larry Ng, Keith McDonald

The benefits of controlled blasting techniques have gained increasing recognition by the mining industry in recent years. The utilization of an effective controlled blasting programme can result in a safe work environment with less loose rock and a reduced level of scaling and ground support.

Jan 1, 1994

By Raymond M. Dixon, Dale L. Ramsey

Upon being introduced to the MAGNETIC COUPLING concept,Balsinger,Inc. wanted to conduct field trials to explore the potential of Magnetic Coupling in the U.S.. Although the Magnetic Coupling Concept has been widely used, the U.S. proposed blasting criterion not previously addressed by the system. Modification to the system assembly and blasting accessories had to be made to make the system adaptable to our specific requirements. The field trials and system modifications are the basis of this paper.

Jan 1, 1990

By John Floyd, Maria Rocha, Benjamin Cebrian

Wall control blasting is needed in most metal mining operations in terms of increasing mineral reserves and assuring the safety of the operation. This type of blasting has the goal to achieve a clean, stable rock wall in the shortest distance from a well fragmented, easy to excavate, blasted rock mass. This can be done with a variety of blasting techniques, all of which decrease the explosive energy towards the final wall. Each technique needs to suit the geology: modified production blasting, buffer blasting, pre-split and line drilling of empty holes. Pre-split is the most expensive technique, and allows final steeper bench face angles while modified production blasting is the least expensive but needs wider berms.

Jan 1, 2018

By Francisco Sena Leite, Vincius Miranda, PhD Machado Leite, PhD Pinto, Raquel Carvalhinha, Alexandre Julio, Dorival de Carvalho

Rock blasting, in particularly the drilling process, is one of the first processes in the stage of rock fragmentation and plays a fundamental role by influencing all the following stages. Given its importance, some proposals to optimize this process have been presented over the last few years. These proposals, while having different approaches, aim (in a large part) to minimize the costs of drilling and blasting respecting the limits of fragmentation required by primary crushing. Reviewing some recent articles leads us to an enriching experience, since the authors of these articles clearly model the problem, but do not address the mathematical solution of these models, which in turn, given their non-linear nature, have no directly and easy solution. Simple and even robust optimizers present in the market show different results and often do not converge to a single solution. To address this problem, an adapted gradient heuristicbased model was developed to try to find optimum values. Heuristics search for values of stemming, subdrilling, burden and spacing that minimize the costs of blasting and drilling. This search, which by the nature of the heuristic moves the solution in the direction of the gradient with maximum decrease to find optimal solution, found values that in turn, when compared with values presented by market solutions not only equaled them as, in some situations, even improved the proposed solution. The algorithm was tested and validated on the field, and although the results have already been presented in papers published in the last year by the authors of this paper, it is now presented with its mathematical formulation and comparison with the other solutions. This approach is expected to be able to improve (and even demystify) the process of pattern expansion and be the basis for future work in the continuation of the optimization process.

Jan 1, 2019

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 B de Raadt

After discussing mechanisms of collapse for the explosive demolition of towers in general and cooling towers in particular, author comments upon a blasting operation in which four cooling towers were involved. The intention of this paper is to present reliable parameters, generally valid for the explosive demolition of reinforced concrete cooling towers.

Jan 1, 1978

By Bob de Raadt

For a long time industrial underwater blasting has stood in need of a calculation method, for the determination of shockwave-proof as well as shockwave-effective charge distances to objects in water. After a brief discussion of the physical background of the shockwave mechanism in water, the author discusses an empirical theoretical computing method based on the "Bubble boundary" concept. The practical application of this model is finally shown in an account of a few underwater blasting operations in which charge weights of c.1-1000 kg were involved.

Jan 1, 1980

By Jack Eloranta

"Unwanted, dynamic interaction of adjacent blastholes is a well-recognized phenomenon. Timingschemes and products are selected to minimize adverse effects. Large diameter, surface blasting is less prone to dead pressing and other disruptions which commonly plague underground and construction blasters. However, several lines of evidence suggest that fragmentation may be compromised as a result of powder column disruption in large diameter shooting as well."

Jan 1, 2016

By Bob de Raadt

The main problem in blasting a fly-over spanning a main road is the brief time available for blasting and the removal of the debris, in order to minimize the ensuing traffic disruption in the public highway below. The blasting plan is consequently based on an extreme "time is money" concept, in which speed and public safety are predominant factors. This paper discusses reliable blasting parameters for this type of demolition.

Jan 1, 1984