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By D O. Tan Sky

This paper will describe the mechanisms involved in delay blasting and how they are applied with the use of D.S.B. It will examine the control of potential damage resulting from detonations, and show how good fragmentation and efficient recovery of this material blasted can be achieved.

Jan 1, 1980

Previous approaches to pre-split blasting theory have tended to concentrate on the mathematics of dynamic stress wave interaction, whilst only recognizing some interaction with quasi-static stresses induced by expanding gases in the boreholes. However the decoupling used in pre-splitting is specifically designed to reduce dynamic effects to a level that a small degree of radial fracturing is created around the borehole which is emphasized and extended by quasi-static gas effects. It can thus be argued that the process has more in common with hydrofracture than with more conventional use of explosives.

Jan 1, 1984

By U Nyberg

Peak particle velocity (PPV) and distance measurements from a single-charge blast test conducted by Swedish researchers in iron ore at the Kiruna Mine in northern Sweden are presented. They are used along with theoretical PPVs calculated using an equation based on hydrodynamics to determine a damage distance range caused by a single charge. This equation, which relates PPV to explosive properties, charge geometry, and distance from a charge, was then applied to a charge of different geometry that was used in drift rounds. A comparison between calculated and measured PPVs suggests that the stoping holes likely damage the easer hole locations, and the easer holes produce damage to the perimeter hole locations. The practical effect is that typical damage limit predictions based on measurements conducted in fresh or undamaged rock are conservative. This suggests that even when perimeter control is not exercised in drifting (i.e., the perimeter holes are fully loaded), the resulting damage may be less than normally expected due to the wave damping effect of the pre-damaged rock. Due to the damping effect, poor perimeter blasting practices are somewhat self correcting. However, it must be strongly emphasized that well-engineered blast designs with perimeter control are highly beneficial in relation to both economic and safety aspects.

Jan 1, 2011

By V R. Sastry, D P. Singh, N R. Thote

Rock parameters which are uncontrollable impose restrictions on the procurement of desirable fragmentation. Blast design parameters which are controllable prove to be important tool in blasting operations. An attempt was made by the authors to investigate parameters which causes big oversize boulders in overburden blasting. A case study of coal mine is discussed in this paper.

Jan 1, 1995

By D. Goodings, W. L. Fourney, Bonenberger, R., Uli Leiste

The problem of the maximum depth at which a mine buried in the surf zone or beach zone is a threat to landing vehicles is being studied by Naval Surface Warfare Center (NSWC), Indian Head Division, Naval Research Laboratory (NRL), and The University of Maryland Dynamic Effects Laboratory. The problem was divided into two parts: The first part involves determining how deep a pressure plate mine can be and still detect a vehicle passing over it. This requires determining the distribution of stress within dry and saturated sand when a vehicle passes over a buried mine. The results obtained from that study are presented in a related paper (1). This paper will cover the second part, which entails determining the impulse delivered to the vehicle. This is equivalent to determining the impulse delivered to a plate suspended above the detonating explosive charge and includes an investigation of the distribution of the impulse over the plate. The purpose of the research is to develop a scaling law and/or computational capability which will permit predicting impulse to be expected in the field from tests conducted in the lab. The computational effort is aimed at the development of and confidence in computer codes that can be used to predict stresses and strains in plates due to the detonation of buried mines.

Jan 1, 2004

By Leslie C. Taylor, Anthony L. Kee

Computational modeling of explosively loaded saturated sand on a suspended plate is an inherently complex problem. In this study a computational method is used to predict the dynamic pressure load/impulse from a buried charge. A fully coupled code modeling the explosive charge, sand and air with a Eulerian mesh and the plate structure with Lagrange elements, such as Gemini-Dyna, is an appropriate computational tool. In water-saturated sand, the loadings are soil and water-transmitted shock and bubble or blast effects depending on the depth and the charge size. The computations provide the capability to determine the total impulse load placed on a horizontal plate on or above the soil due to an explosion in the saturated sand for different burial depths in saturated sand and different plate stand off distances. The following test case will be presented: (a) 4.5 Kg (10 lbs) TNT, 10.16 cm (4 in) depth of burial to top of charge, and 20.32 cm (8 inch) stand off distance (Test 4).

Jan 1, 2005

By Claude Cunningham

AEL’s Electronic Delay Detonators are in routine use and growing in both volume and breadth of application in Africa. This trend will continue and grow internationally owing to increasing pressure on rockbreaking operations to conform to sustainable development principles. A fundamental breakthrough has been achieved, bringing production blasting into line with technologies, which leverage performance through tight monitoring and control. When moving from pyrotechnic systems, benefits are normally realized without having to adopt different timing patterns, but significant additional benefits are realisable by using the flexibility and precision of the electronic units to enter windows of timing previously closed. The higher price and increased care needed are a worthwhile investment, enabling operations to cross the chasm to stronger revenues, but the system must be robust and suited to the application and personnel. Economic models are vital for keeping track of the potential and achieved benefits of these systems. Some resistance can be expected from those who stand to lose income as a result of the improved efficiencies.

Jan 1, 2004

By Thomas L. Linton

The results of an extensive literature review and field experiments regarding the effects detonation of high energy explosive have upon various aquatic organisms are reported. These results were used to modify regulatory permitting criteria in Texas. Three separate field experiments were conducted. In the first study, surface placed charges were used in a marine habitat. In the other two, the charges were placed in drilled holes. In one, which was in a freshwater environment, the drilled holes were filled with drilling mud after placement of the charges. In the second, which was in an estuarine environment the holes were allowed to sit for thirty days prior to detonation to permit natural back-filling to occur by water transported sediments. A variety of aquatic organisms held in wire cages were exposed to detonations. Immediate and long-term effects of the exposure were determined based on external and internal visual observations. Damage to aquatic organisms was found to be reduced by placing the explosives in drilled holes and back-filling the holes prior to detonation of the explosives.

Jan 1, 1997

By Alan Hooper

This paper and slide presentation is a brief rundown on what is probably the worst natural devastation I have ever witnessed. The epicenter of the quake that so violently shook Mexico City occurred 230 miles away near Mexico's west coast. The first calculation placed the quake at 7.8 on the Richter scale. This was later upgraded to 8.1. Each unit increase on the Richter scale indicates about a 30 fold increase in energy released. The quake was felt in much of Mexico and south Texas and damage occurred in many other Mexican cities. On the morning of September 19, 1985, at 7:18 A.M., the ground went into motion and shook for approximately 2 to 4 minutes. During this period most of the devastation occurred. At 7:38 P.M. the following day, the second quake hit and more buildings fell from this 7.5 quake. The ground in Mexico City moves like jello since it is a dry lake bed 7,350 feet above sea level.\

Jan 1, 1986

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 Douglas Bartley, Kevin Hachmeister, Rich Barry

The use of explosive energy as a tool in mining and construction is the most effective way to move large amounts of rock that is otherwise unable to be efficiently excavated. Since the early days of explosive engineering utilizing black powder initiated by cap and fuse to the present day diversity of specialty products and technologies the goal has always been to "Break and Move" as much rock for the least expense possible. It has primarily been the competitive nature of our economy that has driven the advancement of technological innovations and practice. However, the concept of removing rock is not specific to the mining and construction industry. Since the dawn of creation, man has used rock as a medium to express his creativity in the form of sculpture. Even though the process of sculpture requires the removal of rock, the final work is defined by the rock that remains intact. This typically necessitates the extreme care of the sculptor to painstakingly chip away the rock allowing the image to emerge from the original mass of stone. The famous sculptor Michelangelo once said, "I saw an angel in the marble and carved until I set him free."

Jan 1, 2004

By Atsuo Inoue, Toshihiro Ogata, Hideaki Sugihara

Generally in Japan, since ANFO has easy handling and low-price, it is most used as industrial explosives. However, ANFO is very easy to dissolve in water, it is difficult to use under existence of water and the consumer have desired water-resistant ANFO which has perfect water resistance. Then, we have developed the Water-Resistant Granular Explosive (It is written as following WRGE.) in which the surface of the explosive was covered by waterproof film, so that WRGE is able to use in hole with water. We ran various performance tests about the WRGE developed in the laboratory. Consequently, WRGE has water resistance of over 6 hours, and it has been checked that a performance and handleability were equivalent to the conventional ANFO. Then, we carried out the field test in the consumption site, and did performance evaluation on an on-site level. As compared with ANFO, fragmentation (size and volume) and handleability are almost equivalent. However, some problems which the WRGE is not settled out smoothly in hole with water and need more time for loading were also clarified. We are going to continue some advanced improvements through field tests.

Jan 1, 2005

By Mark William Withey

Blasting safety in surface mining is a necessary industrial goal. Proper techniques and disciplines exercised during the blasting process enhance the probability of achieving that goal.

Jan 1, 1995

Jan 1, 2002

By J Lyall Workman

This paper examines the comparative economics of cast blasting to alternative stripping techniques. There are several scenarios where a mine may consider introducing cast blasting. However, there are other alternatives such as adding dragline capacity or introducing a prestripping operation. The question becomes which alternative will be more economical.

Jan 1, 1998

By Ronald L. Sanders

The prevailing view of the coal mining industry by government officials is: "Tell everyone you're coming - Don't let anyone know you're there - And remove all evidence you have ever been there". Now the irony is that the government inspectors are just enforcing the law. The coal mine operators seem more interested in genuine reclamation than the inspectors.

Jan 1, 1979

By Michael D. McGill, John L. Turner, Don Sieger, Doyle Newhouse

Since its introduction by Atlas Powder Company in late 1986 as a means of highwall stabilization in surface coal mines (1), applications of the basic AirDek (2) blasting technique have multiplied rapidly.

Jan 1, 1991

By Rahim G. Haghighi, Calvin J. Konya

Fragmentation is the fundamental concern of rock blasting and it measures the effectiveness of blasting. Fragmentation is sensitive to not only the interrelationship among the design variables, but also is sensitive to local geology. Local geologic conditions have a significant impact on the success of a blasting operation.

Jan 1, 1986

By Fumihiko Sumiya, Koichi Kurokawa, Yukio Kato, Tetsuya Sawada

In some metal mines, it is a serious problem the decomposition of explosives which occurs suddenly by contact with ore containing pyrites under high temperature conditions. In the present paper, we investigated heat resistant properties of emulsion explosives and other industrial explosives by contact with ore containing pyrites under high temperature conditions.

Jan 1, 1992

By A T. Spathis, J J. Felice, W Klass

Cast blasting has become one of the most efficient ways to move waste rock in open cut coal mining. It is used at Mount Thorley Mine in conjunction with a dragline to move some of the overburden onto the spoil dump.

Jan 1, 1992