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By Sharon K. Reamer, Klaus G. Hinzen, Brian W. Stump

"This study investigates seismic wave propagation from two production shots in a limestone quarry. Our motivation is to investigate the efficiency of two superpositioning techniques. The production shots consisted of an 18 and 20 hole explosive array detonated in a single row with constant delay times of 32 and 20 ms, respectively. A single shot was fired on a neighboring part of the quarry bench. The experiments were instrumented with 20 three component seismometers (35-120 m range). The computer-controlled electronic firing system resulted in firing time deviations of less than 1.4% of desired fired times. Linear superpositioning with the observed single shot data produces seismograms which adequately reproduce temporal effects of the multiple explosions; however, spatial effects due to the extended source length (68-76 m) are not modeled with this method. Linear superpositioning with individual half-space Green's functions for each explosion in thearray convolved with a calculated Mueller-Murphy source produces seismograms which match the time duration of the observed production shot seismograms and differ in absolute peak amplitude by less than a factor of three. Parameter estimation for the source is taken from chemical explosion study results. The single source model differs in amplitude from the observed single source seismograms by a factor of 2.3."

Jan 1, 1991

By U Nyberg

Peak particle velocity (PPV) and distance measurements from a single-charge blast test conducted by Swedish researchers in iron ore at the Kiruna Mine in northern Sweden are presented. They are used along with theoretical PPVs calculated using an equation based on hydrodynamics to determine a damage distance range caused by a single charge. This equation, which relates PPV to explosive properties, charge geometry, and distance from a charge, was then applied to a charge of different geometry that was used in drift rounds. A comparison between calculated and measured PPVs suggests that the stoping holes likely damage the easer hole locations, and the easer holes produce damage to the perimeter hole locations. The practical effect is that typical damage limit predictions based on measurements conducted in fresh or undamaged rock are conservative. This suggests that even when perimeter control is not exercised in drifting (i.e., the perimeter holes are fully loaded), the resulting damage may be less than normally expected due to the wave damping effect of the pre-damaged rock. Due to the damping effect, poor perimeter blasting practices are somewhat self correcting. However, it must be strongly emphasized that well-engineered blast designs with perimeter control are highly beneficial in relation to both economic and safety aspects.

Jan 1, 2011

By Cam B. Grundstrom

This paper will describe blast design modifications that have been made at the Island Copper Mine, near Port Hardy, British Columbia. To date, two additional designs have been implemented in an effort to reduce final wall damage and increase productivity. The typical blast patterns in use at Island Copper were monitored in an effort to build up data to which new designs could be compared.

Jan 1, 1994

By Conny Postupack, Jim Petrunyak, John Loope

The authors discuss the concepts, engineering considerations, and cost relationships involved in the use of drilling and blasting to accomplish backfilling and reclamation with minimum use of mechanical equipment. The four methods of reclamation now in use are reviewed, and their advantages and disadvantages are noted. Guidelines for selecting a particular method are offered in terms of applicability under varying geologic, economic, and technological conditions.

Jan 1, 1987

By J Lyall Workman, Peter N. Calder

Large hole rotary drilling is one of the most common methods of producing blastholes in open pit mining. Large hole drilling generally refers to diameters from 9 to 17 inch (229 to 432 mm), however a considerable amount of rotary drilling is done in diameters from 6½ to 9 inch (165 to 229 mm). These smaller diameters are especially prevalent in gold mining and quarrying.

Jan 1, 1996

By Vaughn Bowns, Allen Stanley, Brian Redeker

"Running casing in drilling operations is often complicated by boulders or large cobbles.Past practices of dealing with these have included use of drop hammers, attempts to drillthrough or around the boulder, contact explosive charges and even pulling the casing andrepositioning the hole. All these methods are time consuming, expensive and offer noguarantee of success. In this paper a different method of dealing with these boulders ispresented that promises to be faster and less expensive with a much higher success rate.This involves using a light plastic conduit pipe to place a shaped explosive against theboulder. It requires no special tools or techniques not commonly in use in the drilling andblasting industry."

Jan 1, 1993

By Paul Worsey, Attila Szucs, Mark F. C. Schmidt

The use of water stemming with small explosive charges has been successfully developed at the University of Missouri-Rolla. Further study has been started to explore additional applications and uses for water stemming. Work has been focused in the areas of rock excavation and perimeter blasting techniques. This ongoing work is being conducted internally as graduate and undergraduate level research. A paper describing the general technique for use with boulder fragmentation was published in last year’s proceedings. The excavation work took place in the form of both small bench and trench shots while pre-split and trim shots comprised the perimeter-blasting portion. The excavation work was located in both the Roubidoux sandstone formation and the Jefferson City dolomite formation. Hole diameters ranged in size from 1.5” to 3” diameter and powder factors ranged from l/l 0 to l/3 of the conventional charge weight. The water was used to both couple the explosive charge with the surrounding borehole, as well as stemming. No other stemming material or products were used. The method of using water stemming in perimeter blasting was found to work well. However, when used for excavation purposes, adequate rock movement was not obtained. The rock was often split, but not fragmented. The airblast was surprisingly low, but the ground vibrations were excessive. This is not the case with trim shots, and therefore this method appears ideal for splitting purposes, especially in areas where people do not like to stem the tops of the holes, and where airblast and vibrations are of concern. Water coupling dramatically increases splitting and fracturing. However, fragmentation is not only fracturing but also the movement and swelling of the material. As the charge weights are reduced with this method, sufficient gas volume is not created to cause this necessary movement and swell, which is critical in rock excavation. This explains why its successful application was limited to perimeter blasting applications.

Jan 1, 2000

By George E. Jackson

ANFO, as a blasting agent, is used in large quantities in coal surface mines. It can be purchased on the open market or through reliable suppliers. The blaster in the field must assume that his ANFO is homogeneous, consistent, and nearly identical on a daily basis. A quality control program will enable him to be assured of the correct product. Therefore, the material cost and operational efficiency can be better controlled.

Jan 1, 1978

By Lon Santis

Although unproven, it is suspected that there have been eleven locations since 1988 where explosive generated carbon monoxide (CO) gas moved through the earth and accumulated in nearby underground enclosed spaces. This paper summarizes the incidents, which involved about 30 suspected or medically verified CO poisonings and 1 fatality. Ten incidents occurred in residences and one occurred in a manhole. Although practically nothing is known about the mechanism behind the suspected gas migration, review of the incidents and available information indicates there are certain warning signs and a successful remediation technique available. In each case, overburden heavily confined the explosive in the blasts, preventing release of explosive-generated gases to the atmosphere. All the blasts were in residential areas, and none were excavated immediately. Where the distance from the blast was recorded, 5 of the blasts were within 20 to 50 feet (ft) (6 to 15 meters [m]) of the underground enclosed spaces, 3 were 100 to 150 ft (30 to 46 m) away, and 1 was 400 to 500 ft (120 to 150 m) away. Investigators often identified suspected pathways from the blast site into the underground enclosed spaces. One technique appeared successful at quickly correcting an existing condition. This technique involved applying negative pressure to the earth and removing the CO from the ground surrounding the underground enclosed space.

Jan 1, 2001

By Duane Skidmore, Calvin Konya

The supply crunch and cost rise for ammonium nitrate (AN) over the past year have been influenced by a number of factors. These include a general inflationary tendency, particularly great cost rises in fuel, and by a market condition in which demand for ammonium nitrate is great and supply is limited. Demand is largely confined to agricultural and explosives uses with explosives subdivided into mining, construction, and quarrying. The projections show that demand may be expected to increase markedly for the indefinite future in the agricultural and mining sectors of the ammonium nitrate market while fluctuating with indicators of economic activity for the construction and the quarrying sectors. Supply is projected to increase with plants being designed and built due to high need levels and commensurately high profit potential but not enough are planned to provide an equilibrium market. Constraints upon supply increases to match demand increases include shortages in the raw material, natural gas, high cost of investment capital, high equipment costs and long construction delays. The result should be, even under optimistic conditions, considerable shortage and resultant pressure for higher prices through 1979 for ammonium nitrate. The best hope for relief in the intervening years appears to be conservation. In blasting operations, the earliest and best proven route to conservation seems to be improved utilization available from application of highest available technology and most efficient current blasting practice.

Jan 1, 1975

By Othmar Mueller

Cable charges are theoretically endless. Practically,they are composed of very long sausage like explosive charges. They are primarily used for excavating ditches in soils. Blasted ditches are necessary in agriculture for irrigation purposes and for canals. Horizontal cable charges can be made by using a single or double strand of detonating cord. They can be placed into the mud at the bottom of ditches and used to clean or deepen the already existing ditch. They can also be used for soil compaction. Cable charges have been used for blasting soil in the Soviet Union, Czechoslovakia, Poland, the German Democratic Republic and Hungary. Their use was first mentioned in the first edition of Weichelt's handbook on blasting (German Democratic Republic, 1949).

Jan 1, 1976

By Tamara Wiseman, David Stewart

"A Quarry located in Georgia is a green-field site established in 2011. The quarry lies in the eastern part of the Georgia Piedmont area. It is within a distinctive, northeast-trending belt of relatively high-rank metamorphic rocks known as the Kiokee Belt, a poorly mapped sequence of units that largely consists ofamphibolite and various schists and gneiss that are host for relatively young granite bodies andassociated pegmatite and aplite dikes."

Jan 1, 2017

By R DeLon Hunsaker

In the past, quarrying and other small operations have not been able to take advantage of the lower cost, convenience and better performance of bulk slurries. However, with the introduction of repumpable emulsion slurries and their ability to be stored in containers as blasting agents, bulk slurries are now available for small operations with small diameter boreholes and are producing excellent results. This same concept is being used successfully in larger underground operations.

Jan 1, 1984

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 Jeffrey E. Loney, Andrew F. McKnown

Recovery of contaminated groundwater migrating through bedrock can be very difficult due to the low transmissivity of many bedrock fracture systems. To overcome these difficulties, a system of controlled "trench" blasting has been used on several projects to assist in cutting off and collecting groundwater plumes in bedrock. By using a combination of trench blasting and presplitting techniques, linear "fracture" zones are created in appropriate locations to significantly increase flow into recovery wells and control plume migration.

Jan 1, 1995

By Justus Deen, Paul V. Sterk

Through the 119 year history of the Homestake Mine various methods of raise mining have been used, these include conventional, bored, and drop raises. These raises provide passage for men and supplies, provide ventilation, transfer broken rock from level to level, and serve as emergency escapeways. As the 1980s came to a close, many of the larger ore bodies in the mine had been mined out. This has resulted in many crown pillar situations that required a method to mine them. In addition, the Homestake ore body also contains numerous ore reserves that have short vertical height. The ore itself can be from vertical to 50 degrees in dip. Due to the high cost of drift and ramp development many of these ore bodies are sub-economic using conventional mechanized cut and fill mining.

Jan 1, 1996

By Edward J. Walter

A vibration record is a complex of motions resulting from a combination of direct, reflected and refracted seismic energy that originated at a blast source. Multiple hole blasting using delays further complicates the motion in that overlapping of seismic wave trains may occur when delays do not fire in the programed sequence. This can result in variations in amplitude, frequency and wave-1ength of the vibration. Amplitude may be doubled, frequency may oscillate between the highest and lowest frequencies present and wave-length may approach doubling of the longest wave-length present. These effects can present serious problems to conducting a safe blasting program since increased amplitudes and lower frequencies present higher damage potentials for structures. The development of these effects is described and illustrated graphically to show how these effects can occur.

Jan 1, 1989

By Petr Mostak, Miroslav Horacek, Miroslav Stancl

Detection of plastic explosives is an important task in the security measures against criminal misuses of this type of explosive. Particles and vapour detectors are basic instruments in this detection. Colour reactions and dogs are also used. Marking system in accordance with requirements of Montreal Convention was developed and applied in full scale production of plastic explosives including Semtex since 199 1. The influence of marking on technology, performance and other properties of plastic explosives is discussed. 2,3 dimethyl 2,3 dinitrobutan is the most popular marking agent which is broadly used. The detectability of this compound is not optimum by some detectors. The substantial effort has been given to development of plastic explosives with controlled shelflife. Some results of this work are presented. Technical and economic aspects of identification marking are discussed.

Jan 1, 2001

By M S. Sandhu

Singrauli area of Madhya Pradesh in India has been developed as the power capital expected to produce around 11000 MW in near future requiring 65 million tonnes of Coal per annum. Thermal power plants were installed considering the vicinity of coal reserves which are minable by open cast mining methods. Crisis of oil in seventies further expedited the process of planning big open-cast projects in the area varying from capacity of 3 million tonnes of coal to 14 million tonnes per annum. A separate company - Northern Coalfields Ltd. was formed to ensure meeting the rising demand of coal required for energy production. Northern Coalfields at present is producing 35 million tonnes of coal and will reach the capacity of peak demand of 65 million tonnes by the turn of the century.

Jan 1, 1998

By P Wapner, C Lo Edwards, S CO Schmidt, J N. Johnson, R Oliver

Shale oil recovery rates that can be achieved in underground in situ retorts can be strongly influenced by the shale breakage and fragment-size distribution achieved during rubblization. Since the fragmentation pattern in the retort is a direct result of the blast design used for rubblization, the characterizing blast parameters should be carefully selected. Explosives should be matched to the host material and blast geometries properly chosen so that the required fragmentation results are achieved at optimum costs. Special attention must be directed to selecting blast parameters that produce uniform bed permeability, suppression of fines, proper fragment size distribution, and minimal damage to the retort walls and ceiling. The influence of joints and natural fractures should also be known. In instances where the requisite blasting parameters are unknown, they should be determined from test blasts.

Jan 1, 1979