Search Documents

By William E. Hill

The blasting program at the Valdez Creek Placer Mine must deal with challenging situations throughout the year. During the short summer, extreme water conditions must be confronted, while the winter months present problems of a different nature, where the overburden freezes to a depth of up to 18 feet. These obstacles require techniques borrowed from hardrock blasting combined with creative experimentation to overcome.

Jan 1, 1994

By Syed M. Tariq, John W. Wilson, Paul N. Worsey

The position of a major joint in relation to a blasthole has a significant effect in presplitting. Broad research into the combined effects of firing two decoupled blastholes has been performed in the past. The effects of joints simulated between two blastholes has also been evaluated. However, no attempt has been made to investigate the splitting effects produced by firing a single decoupled blasthole. This paper presents the results of such an investigation.

Jan 1, 1996

By R J. Roach, D Roy

After months of discussion on ways and means to improve productivity in the shaft sinking process, it was decided to look at those areas where, historically, methods have been stagnant for many years. These categories included drilling, hole diameter, drill patterns, explosive types, explosive loads, initiation techniques, cut design, wall control, fragmentation and heated magazines.

Jan 1, 1997

By Thomas P. Dowling

Since the 1950's, blasting practices have undergone many revolutionary changes. Some of the more radical departures have involved, in addition to high speed drilling equipment, a myriad of new explosives, blasting agents, boosters, initiators, initiating systems and delay devices. The introduction of ANFO in the mid 1950's as a blasting agent seems to have instigated a trend toward the development and use of less sensitive blasting agents. The evolution of slurries or water gels has produced dense, high strength, water resistant products which has further promoted this trend away from the more sensitive, conventional explosives.

Jan 1, 1975

By Jeff Wachendorf

Due to the competitive nature of the coal industry we are constantly challenged to reduce costs associated with day to day operations. Every facet of the mining operation is scrutinized for cost reduction and possible efficiency increases. This paper will discuss the pros and cons of two different blasting methods. Buffer blasting has been an institution for many years at Spring Creek Coal and very successful in its application. Cast blasting arrived on a trial basis in 1998 and has produced very encouraging results. This paper will describe the design, drilling, and blasting methods currently used, and a comparison of these two methods.

Jan 1, 2001

By Ken C. Pruss

Seismic studies have proven that the frequency with which shock or vibration waves are reacting on a structure, in correlation with the amplitude of those waves, has a definite affect of structural damage. Different structures will react to different frequencies. In the past few years, some major coal producers in the midwest United States have shown that with the use of highly accurate detonators and exotic timing patterns they have effectively been able to adjust frequencies and this has enabled the operators to continue their excavation of overburden in environmentally sensitive areas.

Jan 1, 1989

"In order to increase control over blasting, it is important to identify the imperative mechanismsand to quantify their participation during the rock fracturing process. The useful energyreleased by the detonation of an explosive is split into shock and gas energies. The relativeimportance of these two energies in the rock fracturing process is still an area of active debate."

Jan 1, 1999

By Michael D. Duffy, Martin W. Chenoweth

"Tenn Luttrell Company (TLC) is a major lime and limestone producer in the eastTennessee area. The property, which isreferred to as the Chesney Mine, has been mined from the surface and underground overthe past 20 years. The ore body consists of three major zones of chemical grade limestonewhich lay at a dip of 30 _ 65 degrees. In July of 1989, Tenn Luttrell Company made thedecision to reopen the underground operations which had been suspended during a time ofincreased surface mining."

Jan 1, 1993

By Francis O. Otuonye

An application of a time series and systems analysis modeling technique to blast vibration data is discussed. The vibration data was taken from a rock support structure and the surrounding rock mass at distances close (less than 15 feet) to a blast. The analysis technique provides quantitative information on the frequencies of ground motion as well as the frequencies and damping ratios of a near-field support structure.

Jan 1, 1994

By Anne Charline Sauvage

Blast designers and blasters need to know the rock mass influence on blast to increase explosive effi-ciency and to optimize costs, but also to succeed in limiting blast emissions (vibration, overpressure, flyrock) This paper presents an applied approach which makes it possible to structure the information con-cerning the rock mass and the blasting.

Jan 1, 2013

By Charles H. Dowding

This paper describes NUVIB, analytical software to digitize, analyze, display, and plot time histories generated by blasting and construction vibrations. It is available in conjunction with a new book on Construction Vibrations (Dowding, 1996) through internet procedures described at the end of the chapter on analytical software These internet based procedures eliminate the need for inclusion of disks in the book and take advantage of the growing electronic communications network. Perhaps more importantly this procedure allows the software to be updated more often than the book is reprinted.

Jan 1, 1997

By David A. Smith, B L. Jr Lindsey

Arkansas bauxite varies enormously in its consistency and composition which makes blasting a very difficult operation. Blasting rounds have to be designed based on each particular mine's ore characteristics. The variances are so great in some mines that blasting procedures have to be changed almost daily.

Jan 1, 1979

By K Ramachandra Rao

This paper explains the methodology for assessing the efficiency of rockmass fragmentation by explosive blasting, from ground vibration frequency spectrum analysis of the blast event. Explosives are used in the mining, quarrying and construction industries for fragmenting rockmass to a suitable size. When an explosive charge is detonated, in addition to fragmenting the rockmass, it will also generate ground vibration and air vibrations. Efficiency of a blast depend upon percentage of blast energy wasted in generating ground vibrations and air vibrations.

Jan 1, 1994

By Wang Xuguang Shen Yingfeng

Structure is the main aspect affecting the performance of emulsion explosive. Calculation of such structure parameters as osmosis pressure, interface area per unit volume etc. must be helpful to the understanding of the structure of emulsion explosive. This paper has solved the Laplace-Young Equation for simplified monodisperse emulsion system by Galerkin method, and gained the relationship between mean curvature, contact angle, volume fraction, fractional film area and interface area per unit volume. The paper also presents a new expression of osmosis pressure at non zero contact angle.

Jan 1, 1998

By Harnish Miller, Scott G. Giltner

One of the concerns with locating radioactive waste storage sites in salt deposits is how to permanently seal the underground storage areas once they have reached their storage capacity. The compaction of salt using explosives has been identified as a potential method of producing permanent seals in both entryways and shafts to storage areas. This paper describes the test procedure and results of a preliminary investigation to determine the feasibility of utilizing explosives in the compaction of salt. Three simple tests were carried out to measure the degree to which loose salt could be compacted.

Jan 1, 1996

By Braden Lusk, Kyle Perry

Recent events and MSHA actions have resulted in discussion and reevaluation of the practice of sealing abandoned coal mine workings. In the past, MSHA has approved alternative seals based on a pass/fail system that required minimal engineering. Disasters involving fatalities led MSHA to impose higher seal pressure requirements based on research and experiments. Impending new MSHA seal regulations will force manufacturers and industry to obtain a high level of engineering expertise. The expertise necessary is in the field of blast resistant design, which is not easily accessible due to the limited number of experienced individuals within the mining industry.

Jan 1, 2008

By Kenneth K. Eltschlager, Richard R. Brochu

At the International Society of Explosives Engineers Annual Conference held in Nashville, Tennessee in February 1995, a Seismograph Standards Committee was established. The purpose of this committee was to develop objective performance specifications for vibration measurement instrumentation and field use practices. It was also understood that due to geology, temperature, and moisture in the soils, it is not possible to design and build an instrument to give results which are absolutely comparable for ground vibration. It was, however, considered essential to standardize instrumentation by which vibration can be measured under closely defined conditions so that results obtained by users of seismographs are always the same within stated tolerances.

Jan 1, 1999

By Sung Su, Jui-Lin Chang

A new technique of dimensional stones blasting for achieving directional rock cutting by conical shaped charges is proposed in this study. This technique has many advantages like precisely controlling numbers and propagation directions of cracks under blasting, having a complete rock excavation face, and maintaining surrounding rock and slope’s stability. So it can be applied to quarrying, underground excavation, tunneling, rock slope blasting, bench blasting and dimensional stone blasting.

Jan 1, 2006

By Kenneth Eltschlager

Post-blast assessment techniques using off-site data which includes location, seismograph and photographic data were discussed during the Blaster’s Weekend at this year’s ISEE Conference. Blast and property locations with commonly available GPS units allow for the spatial relationships surrounding the blasting to be documented. When distances are coupled with the charge weight per delay, the scaled distance can be calculated to any structure for either compliance with the rules, or to project limitations. When blasting seismograph data is obtained, the scaled distances are then able to be plotted against ground and air vibration levels for post-blast assessment purposes.

Jan 1, 2007

By Quian Liu

The problem of cross-hole explosive malfunctioning in rock blasting (including sympathetic detonation, desensitization and cut-offs) is a function of delay and spacing in a blast which should be designed to avoid such occurrences. On a delay-spacing chart, the phenomenon of explosive malfunctioning is explained by dividing the chart into different regions, while the shape and size of each region could vary from one explosive to the other. Over seventy blasts have been carried out at the CANMET Experimental Mine to identify the malfunctioning characteristics of specific emulsion, water-gel and dynamite explosives. In each experiment, two parallel blastholes, 32 mm in diameter and 1.7 m deep, were drilled downwards in an underground drift.

Jan 1, 1994