Search Documents

By D Schneider, H Elliott

The advantages and disadvantages of using inclined boreholes in blasting has been under discussion for a long time. Some recognized disadvantages are that drilling costs, both operating and capital costs, are higher for inclined holes than for vertical ones, and that drilling accuracy is more difficult to maintain. People who have used angled holes in practice, on the other hand, have claimed that the quality of blast results was improved. In fact, their popularity has increased, especially in Australia.

Jan 1, 1988

By Jack Eloranta

This paper documents the relationship between material handling and processing costs compared to blasting cost. The old adage, "The cheapest crushing is done in the pit", appears accurate in this case study. Comparison of the accumulated cost of: powder, selected wear materials and electricity; indicate a strong, inverse correlation with powder factor (lbs powder/long ton of rock). In this case, the increased powder cost is more than offset by electrical savings alone.

Jan 1, 1995

By Rahim G. Haghighi, Calvin J. Konya

Fragmentation is the fundamental concern of rock blasting, serving as a measure of blasting effectiveness. Fragmentation is sensitive to the inter-relationship among the design variables which define pattern geometry. Therefore, the objective of this study was to develop a model which represented a confined bench blast and to investigate the movement of burden-rock as the length to burden (L/B) ratio was varied.

Jan 1, 1985

By Chang-Ha Ryu, Hyung Yang, Hyung-Sik Yang

Ground vibration by rock blasting causes many environmental problems to adjacent structures and human bodies. Growing concerns have been given to the effects of dynamic loading induced by blasting works near safety-related structure like nuclear power plant, hospital, broadcasting station, research institute and tish farm, etc. In order to ensure the safety, rational safe criterion should be established. It requires development of a model to predict the design parameters through more systematic measurement and analysis. Primary estimation by adequate model with general parameters will be very useful for safe design and understanding the possible hazards in advance.

Jan 1, 2001

By Dale S. Preece, Stephen H. Chung

"In bench blasting, the distribution of loaded explosives with respect to the burden rock has strong effects on digging especially at the toe area. Blast design often focuses on other results such as percent-cast or fragmentation, sometimes leaving a diggability problem at the toe of the blast that is not discovered until excavation. A method for assessing the influence of blast design on diggability has been developed. This method relates the kinetic energy and rock displacement experienced by the material in the muckpile to its diggability. Simulation of the blast along with the calculation of kinetic energy and diggability is done with the discrete element computer program DMC_BLAST(DMC: Distinct Motion Code)."

Jan 1, 1999

Increasingly specialized blasting needs require that the explosive energy available in a borehole be reliably known for representative blasting conditions. The underwater test, when properly performed, can yield such information and thus provide a reliable rating of explosives in terms of energy release. This paper reiterates the stringent experimental conditions to be satisfied, and data analysis and interpretation techniques to be followed to achieve this. This is supported by detailed experimental studies involving select parameters in both detonator and booster sensitive explosive compositions. The paper also illustrates the inadvisability of equating blasting performance with the commonly calculated energy values.

Jan 1, 2000

By Lewis L. Oriard

This paper describes the process of developing blasting specifications for 850 miles of new pipe trench running parallel to an existing high-pressure gas pipeline, often with as little as 14 ft to the existing pipeline trench. The primary method of preventing damage to the existing pipeline was the use of fracture (overbreak) control.

Jan 1, 1994

The most common method for identifying the potential for blast damage is the peak particle velocity. But this can depend on many factors such as the type of blast, explosive, confinement, timing and the rock mass. The value must then be used to estimate damage. But the amount of damage will depend on the rock mass quality and the excavation size and shape. The amount of damage that can be accepted will depend on the purpose of the excavation. This paper presents a logical, but very approximate, procedure that the mining engineer can follow in order to assess the potential for damage in the control of that blasting.

Jan 1, 1987

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in 2-D. DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993).

Jan 1, 1997

By Shih Wen Wang, Ronald R. Rollins

A blast casting model is proposed to predict the burden velocity in bench blasting. This blast casting model is the first theoretical model that 1) explains the throwing procedures and mechanisms, 2) uses the explosion pressure as the primary source in throwing rock fragments, 3) applies them to field conditions successfully. Also the predicted burden velocities are based on the rock properties, the explosive properties, and the drilling and initiation patterns. This blast casting model is programmed into a computer software "ROCKFRAG". The comparisons between "ROCKFRAG" predicted values and two field test data are in good agreement.

Jan 1, 1992

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 R Holmberg, P A. Persson

Recent developments in the methods of measuring rock motion close to the contour at the moment of blasting have given an improved understanding of the extent of rock damage caused by different charge systems. The paper presents the new results and the methods of prediction of damage zones which are used in Sweden for the design of contour blasting rounds. A survey is given of the tools and the techniques for smooth blasting that are now used on a routine basis in Sweden.

Jan 1, 1978

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

By Tom McDonald, Rodney Burke

As mining progresses in the West, the depth of material has increased, making highwall stability a major factor in safety and production. The Jim Bridger Coal Mine has made highwall stability a priority, concentrating on safety as well as increasing and improving production. Overburden depths are increasing dramatically; the geological environment consists of medium to soft material, faulting, water, and current pit alignment not favorable to joint planes. Angle drilling the presplit at 20 degrees became necessary as vertical presplit drilling produced wall failures.

Jan 1, 1997

By John Watson

Overview: Intro and Product Use Trends ?? Packaged Explosives ?? Bulk Explosives ?? Initiation Systems – Conventional Initiation Systems – Electronic Detonators ??Q&A

Jan 1, 2006

By Ken Fiorentino, Gordon F. Revey

H3 Tunnelers recently excavated two conventional 48 foot diameter highway tunnels through the Halawa side of the Tran-Koolau Mountains on Oahu. The primary blast design challenge on this Job was minimizing overbreak In the alternating layers of pahoehoe and aa lava, clinker, end tuff. Two different excavation techniques were evaluated in the Halawa tunnels. The first method used drilling and blasting to excavate the tunnels to within one foot of their final perimeter. A roadheader, mounted on a backhoe, was then used to excavate the remaining foot of ground. The second method used conventional smoothwall blasting techniques, without any mechanical excavation. This paper describes the details and relative success of the two excavation methods tried in the Halawa tunnels.

Jan 1, 1993

By Terry Graf, Bill Thompson, John Guenther

SYNCRUDE CANADA LTD.. operates the largest synthetic crude oil production facility in the world. Over 60,000,000 Bank Cubic Metres of oil sand is mined each year from their open pit located in Fort McMurray, Alberta. Despite the extremely cold temperatures encountered during the winter months and the problems associated with frost buildup, SYNCRUDE has continued to operate on a 12 month per year basis. In 1989 SYNCRUDE mine management embarked on a comprehensive Frost Blasting program to improve mine production of their oil sand moving equipment. The following paper will discuss the development of their frost blasting program to its current status.

Jan 1, 1993

By J Lyall Workman, Peter N. Calder

The Manassas Quarry is a large industrial stone quarry in Northern Virginia owned and operated by Vulcan Materials Company. The quarry experienced instability in a portion of the north wall, which included toppling failure in a metasediment and movement on a major fault zone. It was necessary to take remedial measures to stabilize the wall and create good quality final pit walls.

Jan 1, 1992

By Virgil J. Stachura, Larry R. Fletcher, Paul V. Sterk, Matthew N. Plis

The large diameter blastholes now being used in underground mining have caused concern because of their increased potential for damaging openings and creating rockfall hazards. In response to this situation, the Bureau of Mines is conducting research to reduce the amount of overbreak and damage to the perimeter of underground openings. This paper presents the results of tests with decoupled charges in 6.5 inch diameter blastholes, and unloaded guide holes, in Vertical Crater Retreat (VCR) stope panels at the Homestake underground gold mine in Lead, SD.

Jan 1, 1991

By Tom Short, Bill Beam

Some of the weapons testing shafts at Mercury, Nevada require depths of 1000ft and diameters of 10 feet. The top 40 feet to 65 feet is drilled, blasted and excavated by Large caisson type augers in order to provide vertical working room for the placement of large, oil field type, drilling rigs and the required drill collar.

Jan 1, 1991