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By William C. Burkle

In this paper, the author has cited essential areas in which the explosives engineer can assist the mine manager in his planning of an entirely new operation or in a major expansion of an existing facility.

Jan 1, 1990

By Ian A. Niell, Alastair C. Torrance

A joint research programme conducted by BHP Central Research Laboratories and Du Pont Wesfarmers Pty Ltd examined the effect of the size of cast primers on the run up and steady state detonation velocities of ammonium nitrate based explosives as a function of blasthole diameter. Both continuous and point to point velocity of detonation measurement techniques were used. The field trials examined a number of the Du Pont HDP series of primers in conjunction with ANFO, emulsion and watergel explosives. Results indicate that the run up velocity of 187mm diameter ANFO charges is negligible using cast primers as small as 1509. However, emulsion and watergel explosives did exhibit run up in both 187 and 311mm diameter blastholes, independent of the size of primer. This could last from 7 to 10 blasthole diameters.

Jan 1, 1990

By L D. Lawrence, R S. Day, Gordon Coleman

Commercial emulsion explosives are typically characterized by their relatively high detonation velocities due to the intimacy of oxidizer and fuel and to their sensitization with glass microballoons. However, numerous blasting operations in softer, more porous rock formations are better fragmented with slower shooting explosives. Although mixtures of emulsions with large amounts of ANFO (60-80%) can considerably reduce the high velocities, little water resistance is achieved with low levels of emulsion blended with ANFO. "Water proof" blends containing typically 50 percent of emulsion become quite costly due to escalating powder factors in ANFO patterns. Blends of sensitized emulsions with 20-30 percent ANFO retain the high velocity characteristics of the emulsions as well as increased densities which can also adversely affect blasting results in softer rock formations. The introduction of a reliable and predictable on-site gassing process for sensitization and density control of repumpable emulsions, with or without added ANFO, offers the end user the option of supplying a final product more suited to his blasting needs. The capability to widely vary final product loading densities and consequently product detonation rates better tailors the final explosive to different rock characteristics. The beneficial advantages of this system in softer rock formations have been well documented. Overall comparison between these variable density products with typical repump emulsions containing solid density control will be reviewed. Besides the obvious cost advantages and safety advantages of these systems the end user is provided more definitive control of his blasting operation.

Jan 1, 1990

By Paul Worsey

A strong inverse relationship between rock face movement and stemming ejection is presented. Previously unpublished data from blast control plug research and development involving high speed video analysis, which was conducted between 1986 and 1988, is presented. Face and stemming ejection velocities were calculated for tests utilizing the same bench blasting configuration comprising; a 4 ft high bench in dolomite, 3 ft burden and single 1.75 in. holes loaded with 2 ft of small diameter cartridge emulsion. The singular difference between these tests was the stemming configuration. Varying lengths of stemming were used with the presence or absence of differing experimental configurations of blast control plug. The effectiveness of this plug has been published previously.

Jan 1, 1990

By John T. Watson, Jim Bailey

Increasing public awareness is probably the single most important challenge faced by any blasting contractor today. This increased awareness usually results in an outcry for tighter regulations and restrictions on those in the blasting industry. Those affected do not often understand the dynamics of blasting and are simply fearful of the unknown. This reaction very often results in more regulations and restrictions which frequently fail to address the real problems.

Jan 1, 1990

By Greg S. Williams, David L. McDorman, Richard W. Givens

This paper examines the effect of prill size consistency, internal particle density, and oil absorbency on Ammonium Nitrate Fuel Oil (ANFO)-emulsion blends. By analyzing these physical properties of prill and the nature of the blending process, a mathematical model has been developed to theoretically predict blend densities. Calculated densities can now be compared to actual field densities to give an operator a basis for comparing various manufacturers' emulsions and Ammonium Nitrate (AN) during bid solicitation. The lowest priced emulsion and/or AN may not be the most economical, due to the impact of specific physical characteristics. These factors dictate the blending mechanics and resulting density yields for various mixes. The research was driven from observed 'field' mixing relationships and data. Ultimately, such a model can be an effective tool in evaluating blends from a cost and performance basis.

Jan 1, 1990

By Roger Scarr, Richard A. Walker

Interactive video is the combination of computer and laser disc -technologies that allows for the storing of 54,000 single images or 30 minutes of video with the ability to access any segment or single image within a half a second. This capability combined with the use of a graphics overlay on the video and accessed through a keyboard or touchscreen creates a very powerful and versatile marketing or training tool.

Jan 1, 1990

By Calvin Konya, Theodore R. Myers, Robert Lundquist

The design of a single, large mass blast using ring drilling may take two to three months. This time requirement inhibits the evaluation of multiple designs. It also reduces the flexibility to redesign a blast when a parameter affecting the blast changes. Manual preparation exposes the design of a ring blast to a greater probability of human error. The use of Computer Aided Design (CAD) can help to overcome the shortcomings of manual design preparation. High speed electronic calculation, as well as programming, allow for many designs to be considered before blasting. Parametric programming allows single or multiple parameter changes to be introduced into an existing design, such as changes in drilling equipment, variations in ore density or changes in explosive. Exposure to human error is reduced by programming that performs calculations and produces graphical displays for review by the designing engineer. The goal of achieving desirable fragmentation for the minimum cost, when using ring blasting, is obtainable using blasting design techniques and CAD. Multiple designs can quickly be generated and costed, producing cost curves that indicate an optimum design with respect to cost.

Jan 1, 1990

By Mark S. Stagg, Stephen A. Rholl

As part of its research program to evaluate efficient design criteria for improved blast fragmentation, the Bureau of Mines has developed two computer programs to facilitate data analysis. Results of these two programs are used to better understand the fundamental parameters of blasting for surface mine rock fragmentation.

Jan 1, 1990

By Oldrich Machacek, Gary R. Eck

The underwater detonation test method has been long recognized as a useful tool for the evaluation of the energy release and relative effectiveness of commercial explosives. In this study, underwater energy tests were performed for emulsion and watergel commercial explosives in comparison with ANFO. Heavy ANFO type blends based on emulsions and watergels were also investigated under and without confinement.

Jan 1, 1990

By Lyle Avey

For the purpose of this paper, testwork and general pre-splitting practice will be discussed for the Chimney Creek Mine.

Jan 1, 1990

By D Wilson, E Nagy, R A. Augsten, R R. Vandebeek, R L. Guilbeault

The Canadian Explosives Research Laboratory (CERL), is evaluating the status of the Schedule IV explosives container as it presently pertains to the industry. The Schedule IV container serves the same purpose in Canada as the IME 22 container does in the United States. That is, to transport detonators on the same vehicle which is carrying explosives.

Jan 1, 1990

By Carl Hendricks, Malcolm Scoble

There currently exists no viable means of obtaining continuous feedback on blast efficiency. This paper describes the adaptation of a loading shovel to serve as a diagnostic tool to evaluate the success of ground preparation. Work undertaken in a large western Canadian open pit involved microprocessor-based instrumentation for the performance monitoring of an electric mining shovel. The monitored shovel responses proved to be reliable indicators of variations in muckpile diggability. This approach is considered to provide a very comprehensive survey of post blast conditions since such a shovel interacts which every cubic yard of a blast.

Jan 1, 1990

By Roger Lucas, Dale Nies

The McLaughlin Mine is an open-pit disseminated gold mining operation. Homestake Mining Company's approach to solving some of the blasting problems inherent to this type of deposit provide an interesting case history. Geology, although unique and site specific, is overall similar to other mines within the Western United States over-thrust belt and demonstrates an excellent example of the blasting conditions and requirements common to most of these operations.

Jan 1, 1990

By Alan R. Cameron, Alastair C. Torrance

An explosives underwater test facility has been established and commissioned in the Hunter Valley, New South Wales, Australia which allows the measurement of the actual shock and gas energies of the explosive

Jan 1, 1990

By H Leonard Mangum, Victor C. Bryan, Dan McCutchen

Recently there has been an unprecedented marketing effort to promote the advantages of various non-electric initiation systems. This activity has probably been influenced by a major manufacturer's decision to discontinue electric detonator production. Subsequently, distributors of explosive materials, rather than introducing new electric detonator brands, are emphasizing the use of existing non-electric systems. In many cases, such methods fill the need of explosive users in the quarry industry. However, the use of any initiation system should be based on performance, rather than the bent of the market or convenience to the supplier. This analysis is an evaluation of the performance of non-electric systems with emphasis on double trunk line and loop (redundant), as compared to precise electric detonators in use by Martin Marietta. Redundant non-electric detonators, even though more costly, offer the most reliable method of non-electric initiation. However, state-of-the-art precise electric detonators give the best overall performance, except in an environment involving extraneous electricity.

Jan 1, 1990

By B R. Spencer

Using bulk repumpable water gel explosives in underwater shooting results in even more benefits to the user than a "dryland" customer. It is nearly impossible to reshoot underwater, so a bad shot causes tremendous problems. The huge expense of operating drill boats, dredging buckets and clamshells makes shot loading, hookup and digging cycle times critically important.

Jan 1, 1990

By Richard J. Mainiero, T S. Bajpayee

The U.S. Bureau of Mines (Bureau) has conducted research to evaluate the firing accuracy of electric delay detonators used in surface blasting operations. Over four billion pounds of explosives and blasting agents are used every year in surface blasting in coal, metal and non-metal mines. In a typical large-scale surface blast, several thousand pounds of explosives are fired in a timed sequence using delay detonators. The delayed firing of explosive charges allows time for the fragmented rock to move out before the next charge is fired.

Jan 1, 1990

By Thomas F. Mechtenberg, Michael S. Powell

In the past several years many coal operators and stone producers have reduced drilling and blasting cost by utilizing Bulk Emulsion/ANFO blends. For many operators the cost of equipment to handle blend products has been a major consideration in evaluating overall cost effectiveness of changing from packaged products or bulk ANFO to blends. This is especially true when the project length is short term or is uncertain.

Jan 1, 1990

By Malcolm Scoble, Yves Lizotte, Ajit Singh

Fragmentation size assessment faces difficult problems, traditionally involving tedious and time consuming procedures. Early work had been directed towards developing empirical methods of predicting rather than measuring fragmentation. More recent development of computer-based image processing techniques which derive size distributions by analysis of photographic or video images are reviewed. These are now being adapted by various workers to fragmentation analysis in mines. Results are presented from experimental work aimed to establish the accuracy and precision of photographic techniques for muckpile assessment. Reference is made to McGill fragmentation studies at surface and underground mines in Canada, relating to experience gained in photographic and image processing techniques. The various factors that affect such techniques as well as their limitations and strengths are discussed.

Jan 1, 1990