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By Scott Scovira, Ruilin Yang

This paper presents a non-waveform blast vibration model for the near-fi eld. The model uses the concept of a dominant charge augmented by other contributing charges estimated using a scaled time window. The model accounts for the effect of broken ground created by earlier fi ring holes, amplitude attenuation, effects of signal broadening with travel distance from frequency attenuation, as well as asynchronous propagation of different wave types due to the wave velocity difference, the delay time effect, and non-linear superposition of near-fi eld vibration. The model uses an effective distance defi ned from the broken ground screening, and determines a dominant charge contributing to the PPV at a monitoring station. Then the model uses a time window for each individual charge to determine if it contributes to the PPV. The time window has a variable width to model the effects of the signal broadening with travel distance. For modeling the signal broadening, a generalized rock quality factor Qd is proposed. The time window includes a weighting function that diminishes the contribution for charges fi ring further from the dominant charge and this accounts for contribution arising from the timing difference between a contributing charge and the dominant charge. The model uses a non-linear charge weight superposition technique that scales the charge weights within the time window to the same distance of the dominant charge and superimposes the scaled charge weight. The case study demonstrates that the model provides useful predictions for near-fi eld blast vibrations.

Jan 1, 2008

By P. N. Worsey, M. Schmidt

Many advanced military systems and civilian power generation concepts postulate the availability of compact sources of electrical power capable of delivering gigawatts over microsecond time scales. For example, such a compact power source is essential for future practical pulsed high-powered microwave sources. An explosive-driven flux-compression power generator (EDPG) could fill this requirement. A basic strength of this concept capitalizes on the inherent high energy density storage capacity of modern chemical explosives. It relies on the physics of magnetic flux compression to convert that stored chemical energy into very large amounts of electrical power over short time scales. The generator also has the additional advantage of employing the same types of explosives that are already routinely used in conventional munitions. However, the self-destructive nature of this type of power generator places serious limitations on power pulse-lengths and ranges of applications. This paper describes how a multi-disciplinary team led by researchers from the University of Missouri-Rolla (UMR), Texas Tech University (TTU), and Texas A&M University was awarded a grant by the U.S. Air Force Office of Scientific Research to perform basic research to resolve several fundamental EDPG problem areas. Described are the utilization of UMR’s extensive explosives research expertise and facilities to investigate questions of energy conversion efficiency and the mechanics of energy production. Also, UMR explosives researchers will provide inputs to improved dynamic computer models of the complex, intertwined physics and chemistry operative in these devices. In addition to explosives expertise, UMR provides facilities for basic explosives material research, as well as the storage, machining, and formulation of explosives. UMR researchers are also using test facilities and data collection equipment at the Rock Mechanics and Explosives Research Center and at the UMR Experimental Mine to perform “proof of principle” and subscale tests of explosive-driven flux-compression power generator components. An integral part of the paper is a description of the development of an extreme intensity flash system by UMR and TTU to allow for the high-speed photography of EDPGs in operation. This multi disciplinary research program offers major advances regarding the size, weight, and electrical characteristics of compact EPDGs. Such breakthroughs could dramatically accelerate the practical realization of systems currently under study. Also, these power sources may have far reaching relevance to other Department of Defense and certain commercial compact power applications.

Jan 1, 2000

By Elliott Giles

"Measuring a blast’s performance based on the bucket fill time or “diggability” has always been achallenge due to the subjectivity generally involved. The diggability of a blast is often based onopinions and speculation without the data to properly support the claim. This paper focuses howthe blast design can impact diggability and how it can be properly measured."

Jan 1, 2016

By Ruilin Yang

Based on large amounts of field data, this paper evaluates the validity of the above equations. During the evaluation, the different selections of the frequency in the equations were examined with field data. It is found that when they are used to estimate the vector sum values the above equations could result in large deviations from the values obtained directly from the field measurements or the waveform integration. The simple equations may be used to make rough estimations for single components of blast vibration provided that appropriate safety factors are taken into account. For single component vibration, the principal frequency (from ‘zero-crossing’) seems more effective to describe the blast vibration than the dominant frequency (fron FFT) for vibration peak value estimation using the simple equations.

Jan 1, 2012

By Benedict C. Di Duca

In the underground construction industry. when bidding work, not only is the contractor faced with determining if rock: is in existence within the parameters of his work. he must also estimate the quantity and the most efficient method of removal.

Jan 1, 1990

By Y. Idrogo

Electronic delay detonators have been used in most types of blasting application with great success, with the accuracy and precision being used effectively to control negative environmental impacts like vibration. They have also provided consistent repeatable fragmentation and heave results. With the very wide choice in delay period and powerful timing design software, the choice of firing times to optimise blast results is not always clear to the designer. So the improved results achievable from the use of electronic delay detonators are often not optimally achieved.

Jan 1, 2018

By Hans-Peter Rossmanith

Fracture mechanics (Atkinson 1987, Broek 1988, Rossmanith 1978-2002, 1983, 1997, Kanninen & Popelar 1985) and wave propagation (Graf 1975, Rinehart 1975) form the main ingredients in the new electronic detonator based blasting technology. The full potential of using short delay initiation timing in bench and underground blasting can only be exploited if the underlying physical processes are properly understood. From a structural geology point of view, in many open pit mine operations, blasting is performed in incompetent and/or loose rock. Under such conditions the stress waves produced by blasting very quickly dissipate in the rock mass and often their energy cannot effectively be put to work. This contribution shows the effect of open and closed joints – and to some degree also faulting – on the blast wave field and shows the influence of structural geology on the blasting result. A simple engineering method which combines wave propagation and impact mechanics is developed in order to assist the non-scientifically trained blaster in understanding blasting in blocky rock formations. Extensive use will be made of the so-called Lagrange diagram which was introduced in detail in the author’s previous lecture at ISEE 2003 (Rossmanith 2003). This presentation can be considered a continuation of the 2003 presentation.

Jan 1, 2004

By A T. Spathis

Corrections are given for “A three parameter rock fragmentation distribution” by A.T. Spathis (Measurement and Analysis of Blast Fragmentation, Workshop hosted by 10th International Symposium on Rock Fragmentation by Blasting, New Delhi, India, November 25-29, 2012 pp. 73-86). Typographical errors in two equations for the uniformity index in the two versions of the original and modified Kuz-Ram model are corrected. It is noted that the modified equation in the original published paper of Cunningham also had the same typographical error. A corrected plot of the dependence of the uniformity index versus the burden to diameter ratio is given. These corrections do not affect the rest of the original published paper.

Jan 1, 2013

By R. Jacob

Mining has been around for a long time, and new deposits are being discovered continually but are becoming more complex for processing and typically sulfide in nature. Most of the large easy deposits with simplified and cheaper to process oxide material have been mined or the deposits are locked up with legal or social issues and may never be mined. It is common to see the mines today being evaluated to mine have little in oxides and have a sulfide component to the deposit. This creates a problem with explosives being selected for the mine because ANFO could cause a reactive ground issue. When evaluating the cost component of mining for future mines, ANFO is the go-to selected bulk explosive because of the cost and effectiveness. More work needs to be done by projects evaluating costs by properly testing the ground and water conditions to match the correct bulk explosive for the ground conditions of the mine. This will prevent a possible safety hazard and the best result for the mine.

Feb 6, 2023

By Kerina Taylor

Due to their high amount of stored energy, explosives have been the cause of many serious injuries and fatalities over the last centuries. Despite safety advances and awareness in the last decades, injuries and fatalities continue to occur at mining operations due to blasting. According to the National Institute for Occupational Safety and Health, from 1978 to 2001, blasting incidents claimed 106 lives and were responsible for over 1000 injuries in mines in the US. The main causes of incidents found today are flyrock, blast area security and premature detonations. The concerted efforts of the mining and explosives industries and labour and government agencies have greatly improved the safety record of blasting in mines.

Jan 1, 2011

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 Derek Morris, Vito Saccheri

In the monitoring of seismic exploration (whether by explosive or vibratory energy sources), the intensity of shaking at neighboring structures can now be measured quite accurately and comprehensively with portable equipment. However, the interpretation of the results is open to considerable debate and mis-interpretation. One conventional approach is simply to compare the maximum measured peak particle velocity (PPV) with a permissible standard – usually 0.5 inches/sec (1.3 cm/sec) because this is the value generally referred to in the U.S. Bureau of Mines standard. This can be very conservative, both for surface structures, and especially for buried structures like pipes, for which absolute reliance on PPV obscures the true complexity of field problems. Quite apart from the fact that the full Bureau of Mines standard is actually a reasonably complex function of frequency (for the simple reason that in differing parts of the frequency spectrum, damage may be displacement or acceleration controlled), the effects of spatial direction and orientation are often ignored.

Jan 1, 2009

By Randall M. Wheeler

Pre-blast surveys are used to document the condition of a structure prior to the commencement of blasting activities. They provide the best means of determining the pre-existence of visible cracking and deterioration in a structure before blasting is initiated. A small investment in a good pre-blast survey, coupled with good public relations, could mean a large cost savings for a company in the future.

Jan 1, 1992

By Yeon-Ho Jin, Eui-Haeng Heo, Yun-Seok Park, Sung-Oong Choi, Hyung-Dong Min, Min-Su Jeong, Seung-Joong Lee

As rock fragmentation in bench blasting can affect the following process such as loading, hauling and crushing, its good control is essential for assessment of blasting efficiency and production cost.

Jan 1, 2015

By Steve Collinsworth

Sometimes, for those of us in the right place at the right time with the right product, necessity creates opportunity. Such is my case at a West Virginia coal mine where a mine manager was desperately seeking a way to eliminate coal damage on cast shots while maintaining cast percentage without the expensive process of secondary drilling. This paper will focus on how bottom hole air decking is solving the problem.

Jan 1, 2000

By Z X. Zhang

If the iron ore loss is 15% in the process of mining, the total iron ore loss in the world will be about 461 million tons, this is equal to the total production of 230 iron ore mines each of which produces 2 million-tons of iron ore per year. Based on a series of blast tests in the Malmberget mine, this paper shows that ore recovery can be markedly increased by improving blasting technology such as choosing a correct primer position and making use of shock wave collision. The paper further suggests that a high ore recovery can not only reduce natural resource loss and mining cost but also prolong the life of a mine. In addition, the paper shows an example of reducing blast-caused rock damage in the roofs and walls of underground drifts (tunnels) by using new blasting methods in the Malmberget mine. Finally, the paper shows how the Malmberget mine has successfully reduced the ground vibrations, without adversely affecting fragmentation and ore recovery in sublevel caving mining.

Jan 1, 2014

By Bryan J. Lane, Paul N. Worsey

The recommended maximum explosive weight for boulder blasting using internal charges is 0.1 O-kg/m” (3.5 oz./yd) (Olofsson, 1988). Normally this charge results in excessive scattering and flyrock, creating increased liability for the operator, especially in congested areas. An alternative technique using smaller explosive charges is being developed at the University of Missouri - Rolla. It is designed to reduce boulder scatter, flyrock and fumes and allows shooting in close proximity, using common blasting products.

Jan 1, 1999

By J. P. Remi Proulx, Juan Camilo Gonzalez T., Winston B. Wilches

Alabama USA based Drummond Ltd. operates two open pit mines in the Cesar Coal Basin of Northern Colombia. The mines produce a combined total of over 25 million tons (22.7 Mt) of thermal coal per year which is transported by rail to Puerto Drummond, a direct ship loading facility, where it is exported to over 15 countries. The company has proven and probable reserves in excess of one billion tons of thermal coal.

Jan 1, 2015

By Romel Villanueva L.

"Peru does not produce ammonium nitrate; nevertheless it is a large consumer of both, porous prill (PP) and high-density (HD) varieties. Explosives cost is an important preoccupation in Peru, due tofluctuations of the imported ANFO grade Ammonium Nitrate (AN). The use of Gasified Emulsion (GE)-manufactured with much cheaper HDAN- has become an alternative to reduce such costs. However, some problems were reported in the application of pure GE, including explosive percolation in highly fractured rock and lack of sensitivity by the effect of hydrostatic pressure in very deep holes. It was, hence, proposed to have an explosive based on GE too, but more robust and capable to keep the shape of the explosive column into the blast hole, by minimizing the leakage into the cracks. This could be achieved by adding limited amounts of lower priced HDAN, at the same time of providing gas pressure benefits. Other alternative is to add a low-density material, such as polystyrene prills, into the GE, although it reduces the explosive energy. The chemical gassing controls the density of GE, thus it can be obtained a wide range of densities."

Jan 1, 2016

By Scott Stephenson

Making a tunnel through solid rock can sometimes be a dangerous task. Many things must be considered in order to complete such a task safely, and efficiently. Prior to starting things must be known such as, the type of rock, the purpose for the tunnel, the destination point, then angle of decent (or ascent). Once these things are known, the method to proceed must be considered. Factors such as cost, feasibility, and time to completion must be taken into account.

Jan 1, 2009