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By Hike Humphreys, Geoff Baldwin

A project aimed at blast optimisation for large open pit coal mines is utilising blast monitoring and analysis techniques, advanced dragline monitoring equipment, and blast simulation software, to assess the major controlling factors affecting both blast performance and subsequent dragline productivity. This has involved collaborative work between the explosives supplier, mine operator, monitoring equipment manufacturer, and a mining research organisation.

Jan 1, 1994

By Wang Zhong Qian, Liu Hui

The paper proposed a fractal and damage model for rock-breaking by blasting, which assumed that the process of rock-breaking results from intrincent fractal development and the accumulation of damage. Remarkably, the process is of fracture character. Based on the model, a computer program is compiled to calculate the 3-dimension damage distribution in blasting crater. Trial results agree well with the predicted results, showing the model set up in the paper is sound.

Jan 1, 1997

By J Edmund Hay, T S. Bajpayee

The Bureau of Mines is developing a test to determine the initiating strength of commercial detonators. Various tests of "detonator strength" are in use, but many of them do not correlate well with each other, and so far, there is little evidence that any of them correlates well with the ability of detonators to initiate detonation in an explosive. Therefore, the Bureau decided to attempt a measurement of the ability of detonators to initiate detonation. To this end, an explosive mixture of adjustable sensitivity was developed. This mixture was nitromethane sensitized with ethylene diamine, the sensitivity being "fine-tuned" by the addition of nitropropane.

Jan 1, 1992

By James G. Stuart

For precise control and timing of a blast, people use electric detonators. Most of these contain a fine metal “bridgewire,” that heats to the required burning temperature when electric current passes through it. Users should be careful. Stray voltage can fire these detonators. Some designs are particularly susceptible to electrostatic-discharge (ESD). We will discuss some of the accidents we have encountered in our forensic work. We will recommend specific safe procedures for handling and firing these devices.

Jan 1, 2005

By John J. Ridgeway

Habits take us where we were yesterday and attitudes tend to keep us there. Until recently, little had been accomplished to improve conventional explosive energy for use offshore. But with the special requirements of the Offshore Oil Industry, and particularly in the North Sea, most equipment, products and services must be specialized as well. Previous attempts to excavate a trench for a sealine in surf areas had been impossible to accomplish. But with the application of safe, controlled explosive energy, an impossible task to accomplish yesterday has now become a reality. Explosive energy, often overlooked as a convenient and economical offshore tool, excavated a clean trench underwater for a 40" sealine at Djeno in the African Congo recently.

Jan 1, 1977

By G. R. Adhikari

A major part of mineral production comes from surface mining and there has been a rapid growth in this sector with the deployment of high capacity equipment. The importance of blast design combining appropriately both theoretical methods and practical approach has been well recognized in the field of surface mining. It is known that blast design has a direct consequence on productivity, safety and economic viability of these mines. Blasting is the most common method of breaking rocks in mining, but it has to be cost-effective. In coal production, for instance, drilling and blasting account for 25 percent of the total procution cost. In hard rock mining, the cost of drilling and blasting is about 40 percent. Due to ever increasing concern for cost-effectiveness together with environmental consciousness, designing blasts for each application has now become a stringent requirement and indeed a challenging task as well.

Jan 1, 2002

By C De La Cruz

The use of a thin-film piezoelectric stress gauge to determine the pressure profile in a detonating explosive has been demonstrated. These PVDF gauges have measured, in the borehole, the Chapman-Jouget pressure and the release adiabat of the detonation products for several explosives including ANFO and ANFO/emulsion mixtures. The technique can provide: (1) a direct measure of the blasting stimulus, (2) a sensitive QA tool for the blaster, and (3) a means to examine the magnitude and effects of preshock from adjacent bore holes. The PVDF pressure gauge is self powered, can measure pressure from a few bars to 400 kbars, has high time resolution (0.05 µsec), and is easy and economical to use.

Jan 1, 1997

By H Y. Fang, H Sutherland, R M. Koerner

Due to the increased number of complaints by property owners to blasting related industries an apparent need for a clearer understanding of blasting-related damage is needed. We feel that direct structural crack monitoring during such blasts is the appropriate measurement technique. Instrumentation and interpretation of results for taking such measurements are described in this paper. Typical results from blasting and other environmental effects are also described which can eventually be related to Fracture Mechanics principles in the hope of clarifying such disputes in an equitable manner.

Jan 1, 1976

By H. Bilgin, Sedat Esen

In this paper, the ground vibrations induced by blasting for stripping work at Sekkoy Open Cast Coal Mine belonging to TKI Yenikoy Lignite Mine (YLI) are investigated and the procedures for monitoring and control of ground vibrations are presented. Ground vibration measurements are conducted in the direction of Turkish Electricity Authorities’ Yenikoy Establishment and social facilities because of the complaints and annoyance arising from this site. Forty ground vibration records are taken in this direction and the vibrations are measured in transverse, vertical, longitudinal components together with peak vector sum. After then the scaled distance relationship is determined at 95% confidence value. Further, Fast Fourier Transform analyses are carried out to determine dominant frequencies for both ground and the structures and amplification factors. When the records taken at four different structures together with the ground are evaluated, it is observed that one of the apartment buildings is amplified the amplitude of longitudinal component 4.3 times. The maximum allowable amount of explosive that can be fired safely at this mine is calculated and recommended on. In the determination of safe amount, 95% confidence line, USBM RI8507 and OSMRE criteria, the dominant frequencies of both ground and the structure, amplification factor and the human response are taken into account.

Jan 1, 2001

By J W. Edl, F C. Wu

In instrumented model rock blasting experiments in granite blocks, best fragmentation results were obtained when delays between holes were 1 to 2 milliseconds per ft. of burden and when a rectangular shothole pattern was used with spacings larger than the burden. Effective fragmentation in multiple hole blasts seemed to depend primarily on the full development of the crack network around each hole before the charge in the next hole was detonated. The test results showed that simultaneous or almost simultaneous initiation of shotholes in bench blasting resulted in poor fragmentation.

Jan 1, 1975

By Thomas L. Barkley, Michael A. Indihar

The new Cyprus Northshore Mining Co. has taken the previous blasting methods of Reserve Mining Co.'s mine in northern Minnesota and adapted them to a new competative Iron Ore Industry. Cyprus was challenged to develop new blasting methods to reduce costs and improve results over the previous mining operation. Many of the older procedures have been kept, but others have been changed in ways that bring the mine operation up to state of the art technology. In addition, unique ideas not previously tried in the North American Iron Ore Industry have been instituted. So far, this has reduced Cyprus's blasting costs by 70 percent.

Jan 1, 1991

By Mark S. Stagg, Rolfe E. Otterness, Stephen Rholl

The Bureau of Mines is engaged in research to develop and test high explosive fracturing and rubblization techniques that will enhance ore body permeability and thus increase recovery during in situ mining. The natural permeability of many ore bodies is too low to allow successful in-place leaching. These deposits could be profitably mined if flow rates of leach solutions could be increased. Blasting represents a potentially low-cost and effective permeability enhancement technique.

Jan 1, 1991

By Ettore Contestabile, Cameron Thomas

Implosive-type electrical/mechanical connectors such as XECONEX have been used extensively for joining electrical transmission lines. This implosive action of explosives has also been applied to other forms of high energy metal working with excellent results. However, as with many other products, the inherent blast energy of these units has caused some environmental concerns especially when used in proximity to inhabited areas.

Jan 1, 1995

By Gregory P. Lorsbach

Significant information about any blast is contained within the seismic signal generated by the blast. In this study, standard digital signal processing techniques are utilized to extract source parameter information from a seismic signal recorded at distances commonly used in compliance monitoring. Specifically, digital seismic data was analyzed using the cross-correladon and autocorrelation functions for the purpose of determining delay timing. The initial results are interpreted to indicate that: 1) Individual delays can be identified analytically but not visually for short delay periods and large source to receiver distances, 2) Delay timing can be resolved to a few milliseconds, and 3) Results can be obtained from data collected at a minimal number of locations.

Jan 1, 1991

By Hung Tran, Qian Liu, Patrick Andrieux, Dave Counter

Blast damage in open stope mining has been an important concern in controlling ore dilution. Severe damage to the surrounding rock mass can result in the caving of waste rock and/or backfill materials, as well as general instability of the ground. The blast damage study conducted at Kidd Mining Division in 1995 was aimed at measuring the damage zone around blastholes and at identifying other factors which influence the damage. An approach and methodology developed mainly by Blastronics, together with Noranda under a project with the Mining Research Directorate, was adopted for this project. The principle was to combine vibration measurement results with borehole camera observations to derive the blast damage criteria at the specific site. The Holmberg-Persson Equation was used for the regression of near-field vibration data. The damage criteria was examined with both borehole camera observation results and rock elastic and mechanical properties. Details of this methodology, including instrumentation, are reviewed in this paper and an implementation case study of the blast damage evaluation is presented.

Jan 1, 1998

By Robin L. Simmons

Mining in the Genesis open pit has been conducted above the active haulage and ventilation declines of the Deep Star underground mine. Production has continued in both mines. The Deep Star haulage and ventilation declines, the primary and secondary egresses respectively, had to remain open and safe for travel until the new haulage and ventilation accesses were completed. Eventually, the upper 350 feet in each decline will be removed. The declines are in relatively competent calc-silicate hornfels with several high-angle, northeast-striking, clay-filled or open-spaced fault zones that create localized areas of poor ground requiring steel sets. To maintain the integrity of the declines, blast-induced vibration levels and damage were monitored in both declines after each surface blast. Seven geophones were installed in the declines to monitor peak particle velocity and peak vibration frequency. These data helped design subsequent blasts and predict expected vibration and damage levels. Blast design modifications included reducing the pattern size, reducing the powder factor and limiting blasthole detonations per delay. While limiting blast-induced vibration, these blast design modifications had to allow effective surface mining to continue. Linear regression analysis of peak particle velocity and scaled distance was used to determine the scaled distance necessary to keep the peak particle velocity under 2 inches per second. To date, the new ventilation raise, which is also the secondary escapeway, has been established and safe conditions were maintained in the original ventilation decline. Data collection and conscientious blasting procedures continue above the haulage decline.

Jan 1, 1998

By Jerry R. Wallace

A systematic, team approach to pre-blast and on-going problem solving contributed to the successful completion of this indoor industrial construction blasting project.

Jan 1, 1995

By John Petty, John Loviza

Single sentence describing content-- "The best ally an Explosives Engineer can have in a court of law is a regulations enforcer stating all codes and standards were met on a jobsite".

Jan 1, 1996

By Mark Bauckman

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

Jan 1, 2006

By Eduardo Gonzalez Fernandez, Jaime Rios Vazquez

This report substantiates the connection that always exists between explosives and vibrations and draws attention to low frequency vibrations, which are the moat dangerous for the structures affected.

Jan 1, 1986