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

Falls of ground remain a leading cause of fatalities and injuries in underground mines. In response to this situation, the Bureau of Mines conducted a series of experiments in the White Pine room-and-pillar copper mine which resulted in smoother, safer ribs due to a reduction in the amount of overbreak caused by blasting. The tests evaluated the effects of changes in the loading of the rib holes of the mine's 20- by 28-ft drift round driven in shale and sandstone. The relative integrity of the ribs remaining after the blasts was measured using both photographic and seismic refraction techniques.

Jan 1, 1989

Almost one half of Canada's total land surface is underlain by permafrost. This term describes the thermal condition of earth materials when their temperature remains below 0°C continuously for a number of years. The drilling and blasting of frozen materials requires more energy than the blasting of same in its unfrozen state. The cost of comminution could double in permafrost even with adequate organization, drilling equipment and proper explosives.

Jan 1, 1975

By Martin L. Smith, Robert L. Hautala

The objective of blast optimization can be approached either in a qualitative sense of designing a blast which will be "trouble free", or quantitatively in the sense of minimizing overall mining costs. Blast design simulators and fragmentation models have become an accepted tool in blasting over the last decade. Numeric simulators are very useful for solving quantitative problems, but are limited in their ability to address more qualitative problems such as post-blast bench condition. Also, current blasting models are limited by the complexity of site-specific blasting and are not functionally suited to mathematical optimization. As a result a great deal of expertise is still needed in optimizing a blast. The following describes the application of an expert system approach to integrating both a symbolic model of the expertise of the blasting engineer for attaining a trouble free blast, and a numeric optimization model relating fragmentation to unit operations from drilling to grinding. Research into this application of a coupled modeling approach to blast design is being carried out to develop a modeling methodology which will provide a suboptimal design for qualitative design goals as well as minimizing blast related costs.

Jan 1, 1991

By Dale Nies, David P. Childs

The open pit gold and silver mining operations in the State of Nevada have historically used simple row by row, echelon, or chevron delay patterns. Common practice has been to use detonating cord trunklines and either detonating cord downlines or nonelectric common in-hole delays in conjunction with surface delays. Several operations use a series of downhole nonelectric delays with an entire row loaded with the same delay to develop similar patterns.

Jan 1, 1991

By Raymond V. Adolphson

The introduction of a new explosive component in 1955-56, called ANFO, featured much safer, effective blasting characteristics when compared to dynamite, accompanied by a notable reduction in cost. These savings mounted as borehole diameter or depth was increased with ANFO volume subsequently enlarged.

Jan 1, 1983

By John W. Kopp, David E. Siskind

Over 4 billion pounds of commercial explosives are used by the U.S. mining industry every year with an excellent and improving safety record. However, accidents involving explosives are seldom minor. They produce a disproportionate amount of fatalities compared to other mining activities, as reflected in the relatively high severity rates. The U.S. Bureau of Mines (USBM) has been analyzing blasting accident data obtained from the Mine Safety and Health Administration (MSHA) to determine the most frequent causes of mine blasting accidents, examining trends in these accidents, and identifying areas of needed research. This paper is an update of three previous blasting accident studies conducted on 4-year intervals by the USBM and published in 1983, 1987, and 1991, and is based on a total of 869 blasting accidents.

Jan 1, 1995

By R J. Roach, D Roy

After months of discussion on ways and means to improve productivity in the shaft sinking process, it was decided to look at those areas where, historically, methods have been stagnant for many years. These categories included drilling, hole diameter, drill patterns, explosive types, explosive loads, initiation techniques, cut design, wall control, fragmentation and heated magazines.

Jan 1, 1997

By R E. Langston, S M. Gazioglu

A preconstruction inventory program was conducted to determine the existing conditions of residential, non-residential and all other structures within 2,000 feet of the blasting limits for a highway excavation site in Asheville, North Carolina. Prior to major production blasting, eleven test blasts were detonated to establish site specific propagation parameters in order to develop contours of maximum allowable explosive charge weights per delay. The method of scaling distance by the square root of charge weight per delay was utilized in developing the contours of allowable charge weights. The charge weight contours were revised during blasting operations as additional vibration data became available. The effects of blast induced vibrations on a nearby water storage reservoir, a nearby vehicular tunnel and other adjacent residential and non-residential structures were observed and monitored over a period of two years of blasting operations.

Jan 1, 1980

By Jack Elorenta

A recent forum of mine operators revealed a continuing strong interest in alternative methods of freeing rock. A Rand Corporation report lists a continuous mechanical machine that would replace drilling and blasting as a priority for mine operators. Meanwhile, mounting evidence documents a dramatic cost benefit in processing where increased blast energy is available. The reasons for this dichotomy may be due to a number of factors.

Jan 1, 2002

By Ivan Kovac, Pero Marjanovic, Branko Bozic

"The paper deals with results of geophysical survey of the rock masses, and the blasting parameterswhich have effect on the fragmentation in quarries . A relationship between the burden, which is the distance between the charged borehole and the free rock surface, and the velocity of longitudinal waves in the rock mass is established based on measured values for different quarries. It is shown that the drilling geometry can also be detemrined from this relationship."

Jan 1, 1999

By Scott Giltner, Allan Koski

Blasting is one of the lowest cost yet most critical parts of the mining cycle. This paper discusses the findings of an audit conducted on the blasting operation at an iron ore mine. The purpose of the audit was to review current blasting practices in order to identify opportunities for production/cost improvements. The approach taken in the audit was to observe general blasting practices, their related downstream effects and to compare current procedures to established best practices.

Jan 1, 2009

By Steve Dillingham

With the millennium fever all but faded, we look to a new century filled with awe and excitement. We step forward in time, marveling over the achievements of the 20th century and wondering what the next 100 years could possibly bring. Will there ever be another time that produces such technological advances, economic progress or social changes? Keeping pace with the awesome accomplishments of the past century has not been an easy task and we must prepare ourselves for the possibilities of the future. Take, blasting safety for instance. We all know that safety is personal - a culture - promulgated not only by the company by which you are employed, but, by a sense of your own personal responsibility that must constantly be reinforced through awareness, training, and discipline. Great strides have been made in blasting safety since its crude beginnings, however, safety consciousness becomes even more important as technological advances and scientific progress are made in the coming years. It all begins with a positive safety attitude where every employee habitually examines each situation encountered, identifies potential hazards, and takes precautions to avoid those hazards.

Jan 1, 2002

By S B. Richardson, R E. Danell, D Mead, N T. Moxon

Explosives provide a very concentrated source of energy which is often well in excess of that required to adequately fragment the surrounding material. Blast design, environmental requirements, production requirements and the lack of detailed insitu geological data generally limits the degree to which the explosive energy distribution within the blasthole can be significantly altered using, for example, different explosive formulations or variable loading techniques. However, increased flexibility can often be exercised over a blast through the use of air-decks.

Jan 1, 1993

By R L. Calhoun

A paper on High Pressure Air must start with the industry accepted definition of High Pressure Air and, for the reader who is unfamiliar with High Pressure Air systems, include basic information on which type of Drilling Rigs can benefit from the use of High Pressure Air. The operation of a modern Downhole Drill must also be reviewed.

Jan 1, 1976

By P D. Katsabanis

Explosives malfunction due to shock waves is a serious concern for successful blasting results. Malfunction includes sympathetic detonation and desensitization of explosive charges as well as the modification of firing times of conventional pyrotechnic detonators.

Jan 1, 1995

By J Lyall Workman, Peter N. Calder

Flyrock can be a serious hazard associated with blasting. Many surface blasting accidents involving injury result from excessive flyrock beyond the protected blast zone. Numerous cases of equipment damage at the mine, quarry or construction site have resulted from flyrock. Fragments propelled beyond the property limits of the operation have also caused injury and damage.

Jan 1, 1994

By Fumihiko Sumiya, Yuji Ogata, Masahiro Seto, Yukio Kato, Yuji Wada, Kunihisa Utsuyama, Yoshikazu Hirosaki

It is well known that emulsion explosives can be dead-pressed especially in underground blasting. Voids in emulsion explosives will affect such malfunction of explosives. To clarify the factors that affect the dead-pressing phenomena, the characteristics of the pressure wave propagation in emulsion explosives were investigated. Three types of microballoons .or microbubbles, glass microballoons(GMB), resin microballoons(RMB) and chemical gas bubbles, were used as sensitizers for emulsion explosives. The pressure profiles inside the explosives were measured to determine the effects of the microballoons or microbubbles contained. The underwater explosion test and the large-scale drop hammer test were carried out to load the explosives with a dynamic pressure and a quasi-dynamic pressure respectively. In the underwater explosion test, the pressure profiles in the emulsion explosives were measured by a piezo-electric pressure gauge inserted to the center of the explosive cartridge which had a diameter of 30mm. In the large-scale drop hammer test, the same type of pressure gauge was placed at the bottom of the explosives. From these experiments, the following results were obtained ; A) The pressure profiles in the sample explosives sensitized by RMB or chemical gases were sharp, while in the sample explosives sensitized by GMB the profile was broad. B) The peak pressure levels in the sample explosives sensitized by RMB or chemical gases were twice as high as that in the sample explosives sensitized by GMB in the underwater explosion test. However in the large-scale drop hammer test, the amplification of the peak pressure is low compared with in the underwater explosion test. C) The impulse value was independent of the types of the microballoons or microbubbles in both tests. It was concluded that the type of the microballoons or microbubbles significantly influenced the characteristics of the pressure wave propagation in emulsion explosives.

Jan 1, 2001

By Richard J. Mainiero, Marcia L. Harris, James H. Rowland

In the past several years, there have been a number of blasting-related carbon monoxide migration incidents. In each case, there have been some common factors that appear to be related to carbon monoxide migration. Geology, heavy confinement of the blast, close proximity to the affected structure, and open pathways into the affected structure are just a few. Prince William County, VA is an area undergoing a boom in suburban development. In the year 2001, more than 4,050 new homes were constructed within the county.1 In the new housing development located in Bristow, VA, trench blasting was utilized to excavate proposed sewage and utility lines. On November 8, 2002, a trench blast was conducted for the installation of utility lines. Later that evening a carbon monoxide detector alarmed in a nearby house. The gas company and fire department sampled for carbon monoxide and measured 100 ppm and more than 200 ppm on the first floor and in the basement respectively. Subsequent efforts to prevent migration of CO into the nearby homes met with mixed results. The only reliable technique for protecting neighbors from CO appears to be the placement of CO monitors in the homes. The events are presented and discussed.

Jan 1, 2004

By Peter Stamos

In the summer of 1989, Material Service Corporation (MSC) was expanding its Thornton limestone mining operation putting them in close proximity to two shopping centers in Homewood. In other communities, similar expansions had been met with community protests and lawsuits seeking injunctions to stop operations.

Jan 1, 1991

By Bengt Ljung

Manual charging of long upward drilled holes in mines is a heavy and risky job today. Mechanization of this work has been requested for some time by miners, their supervisors, industrial safety organizations and the trade unions, all of whom are interested in improving the working environment. This paper presents newly-developed charging systems intended primarily for charging in connection with sublevel caving and sloping. These systems have been field-tested during 1977 in the LKAB mines in northern Sweden. The results of these field tests and the results of laboratory work conducted to help eliminate the risks involved in charging explosives are also discussed. The equipment being tested (see fig. 1 and 2) consists of a charging vehicle with articulated steering, the PT-60, which has been equipped with a hose feed system mounted on the hydraulic extension boom. From a sheltered position, the operator brings the detonator and primer to the hole opening, after which the hose is pushed in mechanically to the end of the hole. Measuring equipment indicates when and if the end of the blasthole is reached. The operator then withdraws the hose mechanically as charging takes place.

Jan 1, 1978