Search Documents

By Gerald G. Schmitt, Richard D. Dick

Continuous Reflectometry for Radius vs Time Experiments (CORRTEX) was used to monitor several conditions of blasts such as the detonation velocity of the explosive column, the functioning of different types of initiators and initiation schemes, and the behavior of the stemming column confining the explosive. The CORRTEX data were also used to deduce the occurrence of dead pressing of ANFO slurry. Measurements of propagation speeds of shock waves in the stem column with various cables allowed some conclusions concerning bridging, stem failure, and stress levels in the stem.

Jan 1, 1985

By Roger Holmberg, Dick Salomonsson

Nitro Nobel (the company was acquired by Dyno Nobel in 1986) originally developed non-electric initiation systems. These system were based on the 1967 invention of the shock tube fuse by Per-Anders Persson. Through licensees CIL and EB production and sales also started in Canada and the US. Early on, some accidental initiations of the tube occurred in production. It was found that static electricity was involved. After corrective action was taken - by changing the aluminium content in the tube core load - no further accidental initiations were reported until 1991.

Jan 1, 2002

By G Dean Barrett

Just one year ago at the 1986 Annual Meeting of the Society of Explosives Engineers, Dr. Calvin J. Konya presented a paper entitled "Presplitting Granite Using Pyrodex, A Propellant.'' Since that time more evidence has been developed to support the concept that "...gas energy can be the principal splitting force and that the stress wave or shock wave is not necessary to cause the presplitting action to occur." Work done in Vermont and Georgia is presented, and the ability to split granite without causing radial cracking of the bore holes is demonstrated.

Jan 1, 1987

By Dale S. Preece

A discrete element computer program, DMC (Distinct Motion Code), has been used for several years to simulate blasting-induced rock motion. Recent enhancements of DMC's capabilities have included addition of an algorithm that couples together rock motion and gas flow. This allows the user to specify a particular explosive which also specifies equation-of-state and other parameters necessary to model explosive gas flow from the blastwell. Rock loading by the flowing gas is calculated automatically. The mechanism for calculating the rock loading is the subject of this paper. The rock motion effects the gas flow calculation by changing the porosity. DMC is currently being used on a SUN SPARCstation 2 computer workstation.

Jan 1, 1993

By D T. Froedge

To preface these remarks, it is not intended that this paper be a criticism of anyone or any organization involved in drafting the current regulations, for it appears that everyone involved in the process has made an extreme effort to be safe. We wish to show that in this case by making huge safety margins, we have created an unsafe condition in another area. That is by creating vast safety margins in the area of mobile transmitter intensity versus distance scales we have caused a severe handicap in the use of the mobile transmitter in securing blasting areas. The use of these mobile transmitters, which are absolutely essential in clearing areas where there are woods, mountains, or urban structures is virtually eliminated because of the safety factors prescribed in the regulations. We wish to show that these mobile transmitter safety factors are much too great, and can be traded off to increase the margin of safety in the ability to clear blasting areas.

Jan 1, 1975

By Justus Deen, Paul V. Sterk

Through the 119 year history of the Homestake Mine various methods of raise mining have been used, these include conventional, bored, and drop raises. These raises provide passage for men and supplies, provide ventilation, transfer broken rock from level to level, and serve as emergency escapeways. As the 1980’s came to a close, many of the larger ore bodies in the mine had been mined out. This has resulted in many crown pillar situations that required a method to mine them. In addition, the Homestake ore body also contains numerous ore reserves that have short vertical height. The ore itself can be from vertical to 50 degrees in dip. Due to the high cost of drift and ramp development many of these ore bodies are subeconomic using conventional mechanized cut and fill mining.

Jan 1, 1996

By William H. Snyer

A relatively inexpensive, very fast response photo-optic/fiberoptic system has been conceived, constructed and employed by Denver Research Institute (DRI) to measure charge breakout uniformity on the surface of a very large ANFO detonation. The new equipment and technique was coined OWL (observation without leads). Its unique design provides the ability to monitor or measure detonation velocities and/or detonation breakout characteristics without fiberoptic or any other direct contact with the explosive. This system has proven to be versatile and has been used to measure surface breakout simultaneity on large ANFO detonations, munition case breakout times and velocity of detonation (VOD).

Jan 1, 1990

Case histories in blasting show that Livingston's cratering technology has been applied successfully to blast designs with explosives having a charge length to diameter ratio not larger than 6. But the evaluation of experimental results such as the crater volume is tedious and sometimes impractical. A key analysis presented in the study shows that the optimum scaled volume relates well with the optimum scaled rupture limit, and the latter can be determined by means of high speed photography without excavating the blasted material. Through the studies of harvesting gypsum from a dried up settling pond the high speed photography approach has demonstrated to be effective for determining the optimum design for blasting plastic material.

Jan 1, 1987

By Carlos Agreda

"It is widely accepted that the rock blasting results are a function of several stochastic variables given by: -The natural geological structure of the rock mass (joint spacings, discontinuities length orientation and characteristics, physical-mechanical properties, such as: ultimate strengths and elastic properties, etc.).-The detonation and explosion parameters of the explosive mixture (V.O.D., P2, T2, Q3, etc.).-The drilling and blasting pattern dimensions.-In this paper the most important stochastic variables regarding with the rock mass and the blast design dimensions before mentioned are identified, described and discussed.A non linear programming method to calculate the optimum burden Bo) is proposed and discussed.The great impact of the stochastic variable called burden (B) on the rock blasting results is emphasized. A comparison between burden theoretical calculations and some field blast results is also shown."

Jan 1, 1996

By Dennis J. Viscusi, James H. III Rowland, Lon D. Santis, Mark H. Weslowski

This paper describes the procedure for analysis of toxic fumes from the detonation of high explosives using the Large Chamber at the U.S. Bureau of Mines (USBM), Pittsburgh Research Center (PRC). This test is specified in 30 Code of Federal Regulations (CFR) Part 15.20 (g) as a requirement for the Mine Safety and Health Administration's (MSHA) approval of an explosive as permissible for use in underground coal mines. The Large Chamber replaced the Bichel gauge and CrawshawJones (C-J) apparatus in the 1989 revision of these regulations. To determine the safety of an explosive in terms of toxic gas production, the Large Chamber Test attempts to simulate mine conditions and miners' exposure to toxic gases from explosives.

Jan 1, 1995

By S Lukovic, Robert Briton, Calvin J. Konya

Investigators have reported that charges which are decoupled from the borehole wall produce different fragmentation then those which are fully coupled. The difference in effect could be as a result of energy doss during transmission across the air gap or it could be due to the change in detonation characteristics of the explosive as a result of the change in confinement on the charge during detonation. In order to better understand the phenomena of decoupling, a research project was conducted at the United States Bureau of Mines Station, near Pittsburgh, Pennsylvania. It was decided to use shock and bubble energy tests along with simultaneous velocity measurement to determine the mechanics of decoupling and energy transmission. Two explosives were selected for the test, one dynamite and one water gel. Test results indicated that decoupling could both boost the total energy output of the explosive and that further decoupling would drop the energy output.

Jan 1, 1987

By Hans Perlid

In the handling of emulsion explosives pumping is a key operation. A number of serious accidents has shown that pumping can be a risky operation and should be care&lIy considered and investigated. This is the background behind a series of pump tests carried out by NTTRO NOBEL.

Jan 1, 1996

By Rene A. "Moose" Morin, Craig Copping

Innovative concepts in drilling and blast design have been used to remove deteriorated concrete and have enabled contractors to reduce costs and time on St. Lawrence Seaway rehabilitation projects. Time is of the essence on these contracts since the Seaway system is only available for this work during the winter freeze up. Unique electrical sequential initiation systems and specially modified drilling equipment have been used to accurately remove a narrow slice from the 83 foot high lock walls. These new methods successfully reduced demolition time, minimized overbreak and adhered to strict vibration limits.

Jan 1, 1986

By Gungor Tuncer, Erhan Bakirci, Ali Kahriman, Atilla Ozmen, O. Nuri Ucan, Savas Gorgun

There are several methods for demolition of structures but most of them depend mostly on conventional ways of using machines for breaking and crushing structural elements. However the need for lots of work force, expense and extreme amount of time for demolition, made most of these methods non-popular nowadays. Therefore, trials to accomplish a more economic and less time taking method lasted with the use of blasting. By applying controlled blasting on a suitable structure, the structure can collapse and break down to pieces in very short period of time, with no extra work force and cost. In spite of advantages of explosive demolition, the potential danger of explosives and the damage that the blasting may cause to surrondings, if not controlled properly, made people timid to the method especially in urban areas. Therefore, the pre-assumption by computational analysis has become an essential matter in the process.

Jan 1, 2002

By Peter Bellairs, Anthony Bubb

The Porgera Gold Mine is located at an altitude of 3000m in the central highlands of Papua New Guinea some 600 km Northwest of Port Moresby the capital city. Access to the mine is via a five hour trip on an unsealed road from Mount Hagen the nearest regional centre or 40 minutes via air. The mine operates on a fly in - fly out basis and currently produces ore from both opencut and underground operations with the former providing the bulk of the mill feed. Opencut mining utilises conventional truck / shovel, drill and blast methods on both 10 metre and 14 metre bench heights with the larger benches being restricted to the stripping areas. This paper presents the strategy used and the results of a blast optimisation process in the opencut that was a joint effort between the mine personnel and the explosives manufacturer/supplier.

Jan 1, 1997

By E Castelli, M Fomaro, R Mancini, M Cardu

The economic return of rock blasting is not provided by brute volume of broken rock, rather by the amount of marketable product. That is the case of the porphyry quarries of Trento district, whose output is mainly absorbed by road paving and building facing elements production.

Jan 1, 1995

By R W. Givens

This paper presents blast casting design variables that have been developed and are currently being used at the High Power Energy mine in West Virginia. The shot specifications are summarized in Table I. The two active casting pits were designed with casting in mind and as a result are better designed and more efficient. About 55% of the overburden material is effectively cast and clean up is done by a bulldozer, front-end-loader, and trucks. This results in a 15X decrease in the cost of coal production.

Jan 1, 1988

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 Roy McKinstry, Mark Rantapaa, Thomas Bolles

In March of 2001 Barrick Goldstrike Mines, Inc. began evaluating the potential benefits of electronic detonators at the Betze Post open pit gold mine. The original evaluation focused on increased fragmentation, and excavator productivity. During the original evaluation there was an attempt to quantify mill throughput. Early tests indicated that there would be a benefit to mill throughput, however management was hesitant to take on the added cost of electronic detonators based on the initial evaluation. In early 2002 a decrease in mill throughput was being forecast as a result of harder ore being encountered. As a result of the initial electronic detonator evaluation a team of individuals from the Open Pit and Process areas worked closely on the Drill-to-Mill (D2M) Continuous Improvement initiative. This initiative was targeted at improving mill throughput as the harder ores were encountered. Batch tests were conducted to determine if adjustments to drilling and blasting in the open pit could increase mill throughput and justify a 50% increase in drilling and blasting costs for the harder ore material.

Jan 1, 2004

By Thomas J. Snyder

Modern quarry management should be alert to every opportunity to improve productivity and reduce operating costs. In this paper, the author outlines areas in which explosives suppliers should be encouraged to propose changes. He also supplies guidelines for evaluating these proposals, suggests yardsticks for measurement, and stresses the need to be open-minded when dealing with imaginative, innovative concepts.

Jan 1, 1988