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By Gerald R. Coonan

Laboratory research is being conducted to substantiate suggested levels for voluntary standards on human response to transient vibration. The application of those findings to actual field conditions, however, will be limited because they will not include social and psychological factors existent in the real world. It is necessary, therefore, to examine available empirical information on complaints in an attempt to define the influence social and psychological factors might have on the laboratory results.

Jan 1, 1982

By David W. Zeeb

The use of an ordinary VHS video camera and a four-head player can be an effective tool to analyze surface blasting. The necessary equipment can be purchased for under $1,300 and will allow frame by frame or slow motion viewing of a blast in 33.33 millisecond increments. Rock breakage, movement, and timing can be studied in high quality slow motion. These studies can result in improved blasts by showing things that the eye can miss in real time.

Jan 1, 1992

Coal strip mine operators in Western Canada often mine steeply-dipping multiple coal seams in mountainous terrain. The ability to fragment the rock waste layers above and below these seams with minimum disruption of the seams in large blasts normally involves decked charges in large rotary boreholes. Mining these seams may take two or more separate blasts to break the waste wedges above and below the coal, but these wedges can be blasted in a single shot for better mining efficiency.

Jan 1, 1985

By E Emery Jr Gray

The City of Richmond, in an effort to improve sewage treatment facilities, designed an invert syphon to cross the James River at Fulton Bottom. The design criteria called for installation of two 36-inch pipe' lines at an elevation of -35 with the mean water level being at elevation 00. This paper discusses the actual method of construction used to blast the river bottom. Choice of excavation equipment, nature of the river, as well as the geological structure, were taken into consideration.

Jan 1, 1979

By Calvin L. Cumerlato, David E. Siskind

The Bureau of Mines has monitored structural responses to airblast overpressure produced by munitions disposal at the McAlester Army Ammunition Plant. The Purpose of this study was to determine if the blasting caused vibrations, airblasts or structural responses that could possibly be responsible for cracking or other damage observed in nearby residences. Monitoring took place during a 3-month period at 10 selected residences surrounding the plant. By the end of the monitoring period, nearly 2300 blast-related events had been recorded.

Jan 1, 1994

By Janos Foldesi, Calvin J. Konya

The determination of the number of primers necessary to efficiently initiate an explosive column charge is essential to good blasting. If the number of primer is insufficient, the total energy stored in the main charge will not be released. On the other hand, the use of too many primers will be counterproductive and raise the blasting cost. Tests were conducted by the authors to determine the correct priming procedure for a basalt quarry. This paper describes the results of those tests.

Jan 1, 1976

By Andrew Drake, Mark Burchard, Peter Bellairs

The Astec Bluerock Quarry is excavating an extremely difficult to blast rock type due to its highly variable jointing density that leads to excessive oversize. A drill and blast benchmarking exercise led to eight recommendations to minimise this problem. Quarry personnel instigated a continuous improvement blasting program, that has implemented six out of eight recommendations, resulting in a large reduction in the oversize and increased crusher throughputs for a marginal 7% increase in drill and blast costs. Unit costs have reduced by an estimated 10%.

Jan 1, 1998

"Recently, an effort was made to calibrate the Riedel-Hiermaier-Thoma (RHT) material model to reproducethe behavior of granite under impact and explosive loading conditions. The study concluded that the materialmodel captured the phenomenon of compressional damage in granite due to such loading conditionsfairly well. The present work uses hydrodynamic modeling with the calibrated RHT model to estimate thefines generated around a blasthole. This can improve the calibration of different size-distribution empiricalmodels and enhance the prediction of fines."

Jan 1, 2012

Blasting is a very cost effective method of rock fragmentation but its uncontrolled application often results in excessive damage to the perimeter of an excavation. Several perimeter control techniques are available but tracer blasting is commonly used in Canadian underground mines for overbreak control. This involves tracing a column of Ammonium Nitrate-Fuel Oil (ANFO) with a detonating cord. In order to investigate the techno-economic effectiveness of tracer blasting in perimeter control, a field experimentation was conducted which involved blasting in sublevel caving and sublevel sloping operations, experimental drifting, benching and pipe tests.

Jan 1, 1997

By Dale Nies

In the past, cap and fuse has been the only economical and efficient initiation system capable of providing sequential timing, ease of loading and hookup, and unlimited borehole number for backstope rounds. Unfortunately, in spite of these advantages, several negative factors inherent to the system have always been noted. Due to the long, narrow nature of backstope rounds at the Sunshine Mine, the cap and fuse system results in very long, inaccurate delay times. The system was also occasionally unreliable under all the conditions encountered, which in turn could cause potential safety hazards.

Jan 1, 1989

By Gerald G. Schmitt, Richard D. Dick

Continuous Reflectometry for Radius vs Time Experiments (CORRTEX) was used to monitor several conditions of blasts such as the detonation velocity of the explosive column, the functioning of different types of initiators and initiation schemes, and the behavior of the stemming column confining the explosive. The CORRTEX data were also used to deduce the occurrence of dead pressing of ANFO slurry. Measurements of propagation speeds of shock waves in the stem column with various cables allowed some conclusions concerning bridging, stem failure, and stress levels in the stem.

Jan 1, 1985

By Phil N. Bradbury

"During a routine belt tightening of all cost centers, the management at the Martin County Coal Surface Mines, located in Martin County Kentucky felt that a thorough investigation of the drilling and blasting program could possibly pinpoint areas where the cost could be cut without sacrificing production. Upon close inspection of the drill benches it was noted that the actual layout of burden,spacing and stemming varied a bit from the actual blast design that the management had outlined for the blasters. This paper will outline the method of reducing the drilling and blasting cost at the Martin County Coal Operation."

Jan 1, 1986

By Marlyn G. King, Robert L. Martin

Blasting activities in all four pits at Thunder Basin Coal's Black Thunder Mine are focused on cast blasting. With widths varying from 190 feet to 265 feet and bench heights varying from 90 feet to 175 feet, casting efficiencies vary with different geometry's. For example, the percent cast to final in the 200 foot pit is on the average higher than the 270 foot pit. The powder factors are somewhat higher in the narrower pits, thus increasing the cost of blasting. This leads to a very detailed look at the actual benefit of cast blasting and the associated cost of these benefits.

Jan 1, 1995

By Karl E. Burgher

Accidental explosions occur throughout the world. They can happen at chemical plants, fireworks plants, grain depots, or as a result of collisions involving volatile or hazardous chemicals. It is interesting, as we know as blasters, that we can take two very harmless products and mix them under certain conditions and produce a violent explosion. It is often very difficult for the investigator to determine the magnitudes of blasts after the fact. However, an estimate must be made to settle vibration and airblast damage claims. The blasting consultant or technical representative is often called upon to act as an expert to mitigate these claims.

Jan 1, 1993

By S B. Richardson, N T. Moxon, A C. Torrance

In many mining situations the energy released by an explosive is far too high and results in over fragmentation and excessive damage to the surrounding strata. Laboratory experiments have demonstrated that the shock energy of an explosive can be significantly reduced by surrounding it with an attenuating material such as a foam. The effect of this reduction in shock energy on fragmentation has been determined using model materials. A four fold reduction in the amount of minus 8mm material relative to an air decoupled charge of the same weight was obtained for a foam attenuator.

Jan 1, 1989

By Keith Orgeron, Tibor Rozgonyi, Graham Mustoe, Vilem Petr

This paper presents the results of an experimental and numerical investigation of the shock wave energy transmission and reflection through boundary layers (joints, fractures) or between inhomogeneous geomedium with different physical properties. The conclusions drawn significantly clarify the dynamic failure mechanics because of shock wave energy transmission and reflection through different rock materials and their jointed interfaces. Thorough studies were performed to document the transient, two dimensional deformation characteristics, the normal and shear stress fields for inhomogeneous geomedium focusing on the influence of the internal geometrical shapes, relative density variations and packing of the grain boundaries.

Jan 1, 2002

By Robert E. Miller

Mass blasting of open stopes and pillars is a normal operating practice at Isa Mine. Three main parameters are used to classify the types of mass blasts. These are type of explosive used, blasthole diameter and system of initiation. Both electric and non-electric initiating systems are currently employed. The advantages gained by large firings are many. More efficient utilization of manpower, due to the concentrated and continuous charging, is achieved. There is no requirement for men to re-enter areas where localised ground conditions may have deteriorated and exposure of ringfirers to stope voids is reduced.

Jan 1, 1980

By P Cotton, N Cox

The Brisbane City Council has implemented a program of continual improvement at its Mount Coot-tha Quarry in the heart of Brisbane, Australia. The program has been underway for the past 6 years, and has resulted in very significant improvements in terms of both the cost effectiveness of its operation, and in terms of its environmental impact on nearby residents. The work has included a focus, amongst other things, on blasting efficiency, and has challenged conventional thinking in terms of the size of blasts fired, the frequency of firing, the diameter of blastholes, and the use of bulk emulsion or slurry explosives.

Jan 1, 1995

By T Guiliani, F Ottuonye

Explosives casting is gaining increasing popularity as an overburden removal method in strip mining because the coats of using explosives to cast a percentage of the overburden to the spoil are lower than the costs of using stripping shovels or draglines to do all the overburden removal. This is due to the rising capital and operating costs of draglines and shovels.

Jan 1, 1989

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