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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 Calvin J. Konya

There have been many different brands of high precision caps introduced on the US market in the last five years. High precision timing definitely effects the performance of the blast. One should be able to optimize fragmentation and minimize environmental effects with the use of high precision caps and selection of the proper time period. The consumer who purchases the caps may not be fully aware of the tolerances in firing times of caps used in the field. This paper will discuss results of field tests of cap tolerances from an independent study conducted by Precision Blasting Services.

Jan 1, 1989

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 D E. Siskind

The Bureau of Mines performed a comparative study of nine sites at eight surface coal mines to determine if the presence of near-surfaced underground abandoned workings resulted in the generation of adverse long-duration, low-frequency blast vibrations. Six of the nine sites had underlying workings, and two had thick layers of low-velocity unconsolidated surface material.

Jan 1, 1990

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 Richard Arsenault

The production of oil & gas from wells requires method of flow from the producing formation into the well bore. Once the well is drilled it will have casing pipe installed to protect the integrity of the well formations and means of delivery to the surface. Once casing pipe is installed it will be cemented in by pumping cement through the annulus of the casing pipe down to the bottom of the well and allowed to flow outside the casing pipe up into the formation.

Jan 1, 2007

By William R. Adamson, Carlos R. Scherpenisse

The successful development of surface mining operations depends, amongst other factors, on the successful creation of final pit walls which offer long term structural stability. The achievement of such walls will be much more feasible if the mechanisms of rock mass deterioration in the mine are well understood, permitting the control and reduction of this deterioration (or damage). The role of drilling and blasting in causing damage is widely accepted but rarely fully quantified. It is also true that the dependence of rock mass damage on vibration levels is only incompletely understood and little accurate field measurement is routinely conducted in the mining industry.

Jan 1, 1998

By Kenneth Eltschlager, Steven V. Crum, David E. Siskind

The Bureau of Mines was funded by the Office of Surface Mining (OSM) to determine how blast vibrations from a local surface coal mine were affecting homes in the towns of Daylight and McCutchanville, located in southwestern Indiana near Evansville. Although Daylight was about two miles from the blasting and McCutchanville four to five miles away, many residents claimed that blast vibrations were damaging their homes. At least one citizen felt that the vibrations worsened at the time the mine began cast blasting.

Jan 1, 1992

By Raymond V. Adolphson

Use of explosives effectively and safely has come a long way since its discovery and early stages of development. The need to objectively and functionally train personnel in the safe and effective use of explosives became forcefully apparent in the early 1930's in Forest Service work at the start of the Civilian Conservation corps program.

Jan 1, 1978

By Sushil Bhandari

Presented here is the simplified process of fragmentation of homogeneous rocks by blasting based on experimental studies. Small scale single hole blasting experiments on jointed limestone are described. Results show that directions of joints overshadow the degree of fragmentation and also influence the remaining rock. The possible influence of joints on the process of fragmentation of non-homogeneous rock by blasting is also discussed.

Jan 1, 1983

By M Lemieux, R Mason

The SABREX blast modeling program was introduced to I.O.C.C.'s Carol Lake Iron Ore Project in December 1987. As part of CIL's Technical Services, SABREX was used to implement an optimization program designed to analyze and introduce various grades of MAGNAFRAC at a constant pattern while maintaining acceptable blast results.

Jan 1, 1989

By Charles E. Joachim, Christo V. Lunderman, Charles R. Wdch

The U.S. Army Engineer Waterways Experiment Station (WES) recently conducted a series of precision-scale water shock experiments which consisted of the detonation of several 8-gram, 10-gram, and 12-gram spherical explosive charges. The charges were fabricated from NAX 2000 Primasheet explosive and were center-detonated. Commercial tourmaline crystal water shock sensors were used to measure the induced pressure fields in the water. The measured water shock waveforms and related parameters from the precision-scale experiments were in general agreement with data from larger-scale experiments.

Jan 1, 1998

By Glenn Ludwig, Stephen H. Chung

Fragmentation has a direct impact on mine costs and productivity. Computer programs have been developed to calculate fragmentation using data on the properties of the explosive, the characteristics of the rock, the rock mass and the blast pattern. While computer models can yield good data, conclusions must be verified. Fragmentation assessment, muckpile surveys or high speed film analysis of rock mass movement are some of the techniques that have been used to confirm blast results. Digitizing photos of the muckpile is now the most common method to assess fragmentation. But it has some drawbacks. Although automatic electronic imaging equipment speeds up the process, the results depend on the photographs. Shadows will distort results. High resolution, black-and-white prints are essential.

Jan 1, 1992

By Chantale Doucet, Yves Lizotte, Alan Cameron

A joint Federal Government-Industry research project on the effect of geology on the fragmentation of rock excavated by blasting in underground developments was conducted at the CANMET Experimental Mine, near Val d'Or, Québec. A total of thirteen (13) blasts were studied from November 1994 to February 1995. The analysis of each blast was divided into three stages: pre-blast characterization, including structural mapping, assessment of Rock Mass Ratings (RMR), Tunneling Quality Indices (Q), blast design documentation; blast characterization comprising blast vibration monitoring and analysis; and post-blast assessment comprising fragmentation assessment by digital photoanalysis, calculation of half cast factors and measurements of bootlegs.

Jan 1, 1996

By Jaki M. Wilson, Neville T. Moxon

The detonation pressure of ANFO can be significantly reduced by the addition of low density materials such as polystyrene, bagasse, sawdust or perlite. Laboratory and field test results have shown that homogeneous mixtures of these low density explosives can be produced in a bowl truck and loaded into a blasthole without segregation. The detonation pressure of the mixture can be altered to be more compatible with the material in which it is being used by varying the quantity of low density additive incorporated into the mixture. Field results have shown that these low density explosives can lead to significant cost savings without compromising fragmentation or production.

Jan 1, 1989

By John M. Bolger, Keith E. McMaster

Excessive salt fines are undesirable in underground salt mining as they are considered a costly waste by-product. This paper describes an extensive explosive application program conducted at The Canadian Salt Company Ltd, located in Pugwash, Nova Scotia, Canada. The prime objective of the program was to reduce the quantity of fines generated from this company's underground production blasts. The program was known as the "The Fines Reduction Program".

Jan 1, 1996

By Richard Scales, Giles Hellyer, Ian Travers, Dean French, Peter Bellairs

"The Mt Whaleback iron ore mine is located in the Hamersley Province situated about 1OOOkm to thenorth of Perth, the capital city of Western Australia. A small but significant portion of the waste in Mt Whaleback presents problems due to its ability to react with normal commercial bulk explosives resulting in premature detonations, two of which occurred at the mine in 1983 causing great consternation as well as disruption to the mining operation. The techniques and procedures developed to overcome this problem were based on the use of tough durable, acid and heat resistant liners to provide a physical barrier separating the explosive from the rock togetherwith the development of an accurate down the hole remote temperature logging technology. The liner technology was developed due to the inability to produce a reliable inhibited ANFO despite exhaustive mine based testwork."

Jan 1, 1999

By K Uenishi, H P. Rossmanith, N Kouzniak, A Daehnke

This contribution presents an introduction into that part of the field of elastic wave propagation which is relevant to blasting of boreholes and addresses briefly borehole breakdown and the formation of the fracture network around a borehole which ultimately leads to the disintegration of the rock mass. Phenomena of this kind are encountered in mining and quarrying. Numerical as well as experimental work referring to stress wave expansion from a detonating borehole is addressed.

Jan 1, 1998

By Kamal Wadhwa

Ever since the introduction of Liquid oxygen explosives in India in 1927, these explosives are being extensively used in the various mining industries such as coal, ironore, limestone, bauxite, magnesite etc. The earlier LOX compositions were based on cellulosic material of Weberlox series of French origin. They contained the basic ingredients of saw dust with an admixture of cork dust, some hydrocarbons and some metallic powders. However, there were some inherent defects in the soaking characteristics of these compositions, in as much as, absorption and retention of liquid oxygen in the cartridges were not properly regulated in the fine pores and in the inter-granular spaces inside the ingredients in a uniform manner.

Jan 1, 1989

By Donald J. Westmaas, Fred C. Drury

The factors affecting the selection and use of exploisves have changed radically in the past three decades. The objective of this paper is to point out considerations which should now be employed by the Explosives Engineer in his selection and use of modern chemical explosives.

Jan 1, 1978