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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 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

By Michael S. Wieland

This report discusses the U.S. Bureau of Mines research regarding the desensitization and malfunction of cap-sensitive explosives deployed in underground coal mines. Delay blasting in underground coal generates severe shock waves and rifting forces that fracture and heave coal. These dynamic interactions can damage other charges still remaining in the delay pattern. The debilitating impacts precipitate degrees of reduced charge performance ranging from misfires to weak detonations or out-of-sequence firings. Damaged charges react poorly, perform less useful work, and/or generate atypical fumes with higher toxicity.

Jan 1, 1993

Current research in comminution includes efforts to increase the efficiency of mineral processing systems and reduce the amount of electrical energy needed for size reduction. In most mining operations, comminution begins with blasting. Normally, blast design focuses on loosening material for excavation and sizing the product for efficient haulage. It is likely that blasting also results in internal damage to rock fragments within the blast pattern which may provide subsequent comminution benefits. If substantial comminution benefits exist, appropriate modification to blast pattern design may reduce the overall electrical energy needed for mineral liberation.

Jan 1, 1996

By Blair Jackson, Tjaart Louw

Martha Mine, owned by Newmont Mining, Australia appointed Macmahon Contractors (NZ) Ltd as the mining contractor to drill, blast, and crush and convey ore for processing, followed by construction of a tails dam facility from the waste material. The open pit is located 140km(90miles) south east of Auckland, New Zealand in the middle of the township of Waihi (the main street of the town with a population of 3,500 is 90m from the perimeter of the open pit mine). Mining must proceed at 325,000m3 (of which involves blasting approximately 11,000 holes per month, in order to ensure continued ore supply.

Jan 1, 2003

By T I. Jerman

The Du Pont "Detaline" nonelectric initiation system utilizes a low energy detonating cord. It is compatible with conventional detonating cords and shock tube downlines as well as nonelectric in-the-hole delay caps. "Detaline" millisecond surface and in-hole delays offer a great degree of flexibility in developing effective delay patterns for improved fragmentation and reduced vibration. All components are easily assembled in the field.

Jan 1, 1982

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 Shulin Nie

The detonability of a chemically gassed emulsion explosive has been studied in recent tests, after the study of three micro-balloon sensitized emulsion explosives. Blasting experiments in steel pipes and computer simulation have been carried out. This study showed that the gassed emulsion explosive and the micro-balloon sensitized emulsion explosives have different desensitization features. Namely, the gassed emulsion explosive can recover its detonability very rapidly after the pressure vanishes, in contrary to the micro-balloon sensitized explosives.

Jan 1, 1997

By R Yang, P D. Katsabanis, W F. Bawden

Understanding the mechanisms which are taking place during the propagation of a stress wave generated by an explosive charge is of high importance in the detection, characterization and prediction of blast induced damage to the rock. Vibrations caused by the detonation of an explosive are suspected to contribute significantly to the extension of the damage zone. Vibration monitoring close to a blasthole is a relatively new field of research, the hindrance being the scarcity of transducers capable of sustaining extreme accelerations without damage. This paper focuses on the vibration monitoring aspect of a blast induced damage study; the experiment took place at Queen's test site and was meant to record near-field vibration as close as 1 m from 100 mm diameter blastholes.

Jan 1, 1993

By Yang Ruilin

Bulk gassing technology is a growing trend in the commercial explosive industry. The gassed bulk products produced differ from microballooned bulk products or cartridged products. It is easy to know the loaded or in-hole density for microballooned bulk products or cartridged products, whereas it is not as straight forward to know the m-hole density for gassed bulk emulsions. The loaded density is one of the key parameters affecting explosive performance and therefore it is important to have a field technique to monitor the in-hole properties of gassed bulk products in order to accurately predict the blast performance and to ensure efficient use of the products.

Jan 1, 1999

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 R Fox, R Watt

On behalf of ICI's group of explosives companies around the world, a research programme is being undertaken to develop a new electrical shotfiring system which will have markedly improved safety features and operational advantages over existing initiating systems. The paper describes the development of the 'Magnadet' Electric Detonator and 'Magna' Primer and the field experience to date. It also indicates those areas where further work is being carried out on modification of the basic designs to meet specific application requirements.

Jan 1, 1981

In this work, is being described the developing of the study for the demolition by controlled blasting project of a building of reinforced concrete, in the center of a spanish city. Synthetically, it is being analyzed the timing of the fall of the parts of the structure. This documentation is completed with a group of four photographs of the falling sequence and a film about several demolitions and the particular one described in this paper.

Jan 1, 1977

By Alastair Torrance, George Boucher, Roger Keller

An investigative blast programme has been carried out to provide information on the best blasting methods to excavate Chek Lap Kok island in Hong Kong for the new airport. The objectives of the programme included the assessment of a range of blast design parameters and their influence on fragmentation. This has been evaluated by physical assessment, photo digitising of the muckpile and computer predictions. In addition, a model to predict the three dimensional muckpile shape has been successfully calibrated.

Jan 1, 1992

By R Ludeling, Klaus G. Hinzen, Ulrich Steiner, Friedrich Heinemeyer, Peter Roh

A method for hybrid modelling of blast vibrations in time domain is developed. Field seismograms of single shot experiments are combined with computer simulations. In this way firing times of blastholes in a pattern can be optimized due to diverse criteria like maximum velocity amplitude and frequency content of the vibrations.

Jan 1, 1987

By C A. "Hawk" Hanger

"The paper that will be presented is an in-depth study of sequential blasting using standardnon-electric shock tube down hole timing along with surface M.S. connector timing.Included also will be a discussion on the advantages in fragmentation, digability, oredilution' and ground vibration versus the common practice of row by row blasting. Alongwith the written presentation, several visual illustrations will be included. The visuals willrefine the actual direction and predicted movement of the shot involved."

Jan 1, 1993

By France Goupil, Richard Barabe

In 1987, a large company reopened its quarry located in a very dense urban area in Montreal-East. This reopening occurred after a long period of inactivity during which houses were built within 200 feet of the quarry. During the first year of operation, people in the vicinity reacted negatively which caused the City of Montreal to seriously consider closing down the quarry by expropriation. This expropriation would have resulted in millions of dollars of loss for the operator.

Jan 1, 1992

By Thomas C. Jones

The purpose of this paper is to disseminate new information for nonelectric blasting in trenching and construction work. The presentation is not designed or intended to discredit conventional electric detonators or use of MS connectors and cord. Its sole purpose is to inform the S.E.E. of new and exciting benefits realized by the use of the Hercudet non-electric system in the construction industry.

Jan 1, 1984

By Karl Kure, Anders M. Heltzen

Mixtures of prilled ANFO and 0,5 - 3 mm polystyrene balls are interesting substitutes to the tube charges or other types of reduced explosives or detonation fuses. Experiments have shown detonation ability even of a mixture of 95% bolt polystyrene balls and 5% ANFO. The gas and shock energy in the mixtures decrease proportional with the content of polystyrene. The detonation velocity shows higher values than expected for mixtures with more than 50% (vol.) ANFO.

Jan 1, 1980

By Edward J. Walter

An ancillary effect to every blasting operation is the generation of vibration Extensive research has been performed for the purpose of understanding, controlling, and predicting this vibration An examination of these studies clearly shows a variability in the resulting vibration effects It seems logical to expect that identical blasting procedures should produce identical vibration levels, but this is rarely the case. There is a distinct pattern of variation.

Jan 1, 1980