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By Bengt Niklasson

"A test stope at the Luossavaara Research Mine in Kiruna, Sweden,was divided into four different modules in which various hole patterns and explosives were tested in order to evaluate:1. The optimum combination of explosive and hole pattern2. The resulting fragmentation3. The damage to the surrounding rock4. The application techniques of the VCR mining method"

Jan 1, 1985

By E Emery Jr Gray

A need for more delay periods other than those normally manufactured throughout the explosives industry rarely occurs. This paper will discuss one such incident from an analytical view through practical application.

Jan 1, 1976

By Oldrich Machacek

Seismic explosives are very important tools in the search for oil and gas. Changes and new techniques in seismic exploration methods are also demanding new developments in seismic explosives. This article concentrates on three problems, characteristics of surface seismic explosives,causes of fires in application of surface seismic explosives and new developments in downhole seismic explosives.

Jan 1, 1985

This paper describes experience in designing and implementing casting blasts over the past fifteen years. Important design parameters such as powder factor, burden and spacing, blast pattern geometry, front row burden and toe distance, pit width versus height, blast length, explosive selection, millisecond delay timing and tie-in types are discussed.

Jan 1, 1995

By Joseph W. Hejny, Marlyn G. King

Coal mining in the Powder River Basin has changed in recent years to accommodate the large quantity of coal produced. With strip ratios of one to one and up to three to one, extensive amounts of overburden have to be removed to get to the large thick seams of coal. Larger shovels and trucks have been implemented in the removal of this overburden. The addition of draglines and continuous miners have been added to increase the production of coal. Drills used today are capable of drilling up to 13.5 inch blast holes.

Jan 1, 1994

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 Maja Franjic, Ian Tolliday, Chris Collins, James Wiltshire

Ammonium Nitrate Emulsions (ANE) are a large segment of the explosives market for the mining industry. These emulsions are generally designed to be very stable but when breakdown does occur, removal of the resulting thick, crystallized material can be difficult, hazardous, time consuming and costly. A heavily crystallized emulsion cannot be pumped, so manual removal often becomes necessary. Buildup of semi-solid layers of crystallized emulsion can occur in bulk storage tanks or in truck compartments. In these situations, a manual cleanup involving hazardous confined-space entry and a significant amount of downtime is usually required. Once the crystallized emulsion is removed from the equipment, there is very expensive disposal of the resultant waste via a licensed trade-waste company. A much more desirable solution for dealing with waste emulsion is to completely break the emulsion, allowing the oxidizer and fuel phases to separate into two distinct layers. These layers would then be readily pumpable and could be disposed of much more economically. It may even be possible that the separated oxidizer phase could be repurposed as fertilizer and the fuel phase could be used to manufacture granular ANFO explosives. There are some existing products on the market for breaking emulsion explosives, but these generally need a high degree of mixing into the emulsion to achieve adequate breakdown. The aim of this study was to identify surfactants systems (demulsifiers) capable of effectively breaking a range of waste emulsions with minimized agitation. This paper describes the development and performance testing of novel demulsifier products. The test work involved a comprehensive series of laboratory screening tests, where the demulsifier formulations were optimized. A highly efficient formulation was identified, and field trials were conducted on real world, full-scale waste emulsions. Results will be presented that demonstrate a viable solution for the disposal, and potential re-use, of waste ANE in the explosives industry.

Jan 21, 2025

By J J. F Smith

The application of pneumatically loaded ANFO for underground mining has continued to increase year by year since the technique was first developed and introduced underground during the early 1960's. Improvements in the manufacturing process for explosives grade prills, the design and construction of more efficient AN prill-fuel oil blending equipment, and the introduction of more durable and reliable pneumatic loaders have promoted the wide application of the relatively low cost blasting agent, ANFO.

Jan 1, 1982

By Michael McDougall

"Suncor Inc. Oilsands Group, Mining Operation in Northern Alberta, Canada, has beenblasting to loosen the oilsands to increase production and decrease maintenance of the hugebucketwheel excavators for over twenty years. In 1991 an area of the mine wasencountered which had a working face in excess of 130 feet. In order to maintain theproduction objective, the blasting department took on the task of providing as much of ablasted face to work with as possible. In doing this Suncor has exceeded several knownrecords in production blasting."

Jan 1, 1993

By Earl C. Hutchison, Gene Smith

Extensive blasting was required to construct an underground tunnel for a 90 inch sewerage relief line. The tunnel and required excavation extended under an upper middle-class residential area in Atlanta, Georgia for more than a mile and a half and required the use of more than a half million pounds of explosives in the immediate vicinity of houses and residential apartments valued at more than 16 million dollars. Other houses and property valued at more than 80 million dollars were within range to claim blasting damages. An effective blasting damage control program was carried out which limited the number of blasting damage claims to less than 2-1/2% of the total number of potential claims. All but three of the small number of blasting damage claims which were made were effectively denied without any resulting legal actions and less than $3,800 was paid for settlement of the three claims.

Jan 1, 1981

By Stephen John Brace

Increasingly, electronic blast initiation systems are being made available to the mining and construction community, both in South Africa and internationally. Indeed, in some parts of the world, perhaps half a dozen electronic products are being used, with a choice also of shock tube, electric and fuse and igniter cord systems. As these developments have taken place, improvements have been made in safety, reliability and accuracy, so much so that high performances in all these areas are now expected. However, disadvantages often seen by customers, other than : higher price, are decreased user-friendliness and loss of flexibility.

Jan 1, 1998

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

The Bureau of Mines has developed computer software to study the effects of initiator scatter on all aspects of the blasting process. The software is useful because it is difficult to obtain actual initiator data, particularly the standard deviation which is needed to express initiator scatter. The new software is structured to allow blasters to answer the question: how precise must initiators be to insure a successful blast? Successful is defined statistically in terms of a confidence level. The software can be used with any possible design since there are no restrictions due to size or complexity.

Jan 1, 1992

By Christopher Smith

The critical nature of detonator function in blast design and its effects upon performance and safety of a blasting operation are well documented. Numerous laboratory and field studies have shown dynamic shock waves, generated by the detonating explosives in a shot, to be detrimental to the performance of the explosive columns in the adjacent boreholes. Laboratory tests conducted in Japan have explored the possible effects of dynamic precompression upon cartridges of emulsion explosives, which had been sensitized with different hotspot void producing methods. These tests uncovered significant differences in the magnitude of the dynamic shock wave pressures measured inside the different emulsion explosive cartridges, and demonstrated these pressure differences by crushing detonator shells inserted inside the emulsion cartridge. Basically, the results of these tests clearly showed the magnitude of the compressive force applied to the detonator inside the primed explosive cartridge to be a function of the mechanism that had been used to sensitize the emulsion (i.e., glass microspheres, plastic spheres, chemical gassing). The current study was designed to further explore the actual detonator failure mechanism in these dynamic precompression tests using live detonators inside the emulsion cartridge as opposed to empty detonator shells. The testing involved inserting commercial delay detonators inside emulsion charges, which had been sensitized with common hotspot void producing agents, and subjecting the primed explosive cartridge to the dynamic pressure wave generated by an underwater donor explosive charge. The effects of variations in the emulsion’s sensitization method upon the damage inflicted to the detonator were studied. Depending upon the degree of detonator damage, detonator crushing can lead to varying degrees of detonator malfunctions, ranging from sympathetic initiation of the detonator, to a reduction in delay time accuracy, to reduced detonator output, to complete detonator failure. Each of these malfunctions can have serious detrimental effects upon the performance and safety of a blasting operation.

Jan 1, 2006

By Robert B. Hopler

The Hercudet ? Nonelectric Delay Blasting Cap System has undergone significant changes since the last paper on the subject was presented at the 1978 S.E.E. Conference. The changes have been made to improve reliability of the blasting machine at low temperatures, and to improve efficiency and economy in usage in surface mining. The paper includes examples of the blast design process, details of use of the new in-hole connected cap, and delay patterns which have found use in quarrying and coal stripping.

Jan 1, 1980

By Shawn Kirkpatrick, Yang Ruilin, Tamara Whitaker

In order to manage blast vibration in soft ground containing large diameter holes and large charge weights, a number of issues must be considered. This paper describes techniques to control and reduce near-field blast vibrations absorbed by highwalls in soft ground. Sympathetic detonations need to be controlled. Sympathetic detonations can cause excessive vibration due to an unknown number of charge weights firing out of sequence. The excessive vibration can cause damage to the ground. Sympathetic detonations can be controlled through proper design of blast patterns and, in some cases, through the use of specialized electronic detonators.

Jan 1, 2009

By Hung Tran, Denis Fleury, (Ken) Qian Liu

Pastefill technology has gained an increasing popularity over the past decade. The main advantages are: environmental performance (mainly in tailings disposal), low operation costs and ease of operation, as well as homogeneous properties. However, its weaker nature compared to other types of fill makes it more vulnerable to blast damage. In the last few years, Louvicourt Mine has experienced some cases of pastefill sloughage during the mining of secondary stopes. In order to reduce pastefill sloughage, some studies have been undertaken to investigate the causes and to find possible solutions by looking at stope design, extraction sequence, ground support and blast design. This paper presents the results of a blast damage study carried out at Louvicourt on the 860m level. The instrumentation included vibration monitors (using 6 sets of triaxial geophones grouted in the pastefill), a borehole camera to observe the damage in the pastefill, and a cavity monitoring system for three-dimensional surveys of the blasted stope. The test stope was mined out by four slot blasts and three mass blasts. Most of the damage was created by the mass blasts. It was found that the accumulation of ground vibration was mainly due to the low seismic velocities in the pastefill and the relatively tight delay between blastholes. In addition, there was a substantial difference between the critical PPV in the confined and unconfined pastefill. In practice, these findings have led to modifications of blast design to minimise the exposure time of pastefill walls to air. Such modifications included changes of blast sequence in secondary stopes and delay layout between heavily loaded blastholes. Over the paste two years, the implementation of new blast sequence has shown encouraging results in terms of reduced pastefill sloughage and dilution.

Jan 1, 2000

By Christodoulos Xiouris, Ali Reza, James Karnesky

A rocket parachute signal flare is often used to signal a maritime emergency. In the general operation of these devices, a solid rocket motor propels a metal body to an altitude of approximately 1000 ft (305 m). At the end of the rocket motor, a propelling charge drives a signal flare and parachute out of the metal body and ignites the flare, which then burns for approximately 40 seconds as it falls to earth. In this paper, we describe an engineering investigation of an accidental ignition of a rocket parachute signal flare, which caused injury to the user. T

Feb 1, 2020

By Robert Hopler

In use, blasting powder is exploded by a spark from fuse, electric squib or miner’s squib, or by a primer of some high explosive, the last being employed only in heavy charges on open work. In mining, and sometimes in light charges on open work, blasting powder is made into cartridges by means of a paper tube or cylinder sealed at one end, which is known as the Du Pont tamping bag. Sometimes the paper cylinder is made by the miner by coiling a section of heavy paper, known as blasting paper, around a wooden pin, called a cartridge pin, and securing it with what is called blasting soap. The removal of the pin leaves a cylindrical cartridge open at one end, into which the powder is poured and the top folded and sealed with blasting soap.

Jan 1, 2014

By Qi Jingyue, Wang Zhongquian, Yang Nianhua

Qinling Tunnel is the longest tunnel in China. The rock stratum is very hard rock - intact mixed gneiss. At the beginning of the construction, drift-pilot excavation is very costly due to the use of regular drill and blasting methods. After tests on the acoustic impedance match between rock and explosive, watergel explosive, which has a high velocity of detonation and high brisance, has been used for hard rock blasting. In addition, different cut plans have been compared. It was found that four-large-hole cut is the most effective. And the number of drillholes and specific charge cut down and the average advance reaches more than 94% of the blastholes depth. Thus, the difficult problem of hard rock blasting in drift pilot is successfully solved, while safe and quick construction is guaranteed.

Jan 1, 1998

By Satish R. Kate

Explosive is a chemical energy, which on detonation is released instantaneously with extremely high speed and under high pressure. It is used to meet the basic requirement for breaking of rocks. The productivity is the function of Drilling, Explosives and Fragmentation. Thus, the quality of explosives (energy content) is the key to get desired fragmentation. The variation in energy of explosives and volume of rock per hole have direct impact on fragmentation and cost of excavation (drilling and explosive costs). With the application of higher and higher energy content explosives, it is possible to expand the drilling patterns, i.e. volume in cum. per borehole. As such, higher drill productivity and higher production from the given number of holes can be achieved by adopting appropriate energy content in explosives, and suitable drill pattern for getting desired fragmentation.

Jan 1, 1998