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By Robert L. Chufo

This paper describes a general purpose imaging technology developed by the U.S. Bureau of Mines (USBM) that, when fully implemented, will solve the general problem of "seeing into the earth." A first generation radar coal thickness sensor, the RCTS-1, has been developed and field-tested in both underground and highwall mines. The noncontacting electromagnetic technique uses spatial modulation created by moving a simple sensor antenna in a direction along each axes to be measured while the complex reflection coefficient is measured at multiple frequencies over a two-to-one bandwidth. The antenna motion imparts spatial modulation to the data that enables signal processing to solve the problems of media, target and antenna dispersion. Knowledge of the dielectric constant of the media is not necessary because the electrical properties of the media are determined automatically along with the distance to the target and thickness of each layer of the target. The sensor was developed as a navigation guidance sensor to accurately detect the coal/noncoal interface required for the USBM computer-assisted mining machine program. Other mining applications include the location of rock fractures, water-filled voids, and abandoned gas wells. These hazards can be detected in advance of the mining operation. This initiating technology is being expanded into a full threedimensional (3-D) imaging system that will have applications in both the underground and surface environment.

By Joseph Cervik, Maurice Deul, Albert Sainato

This Bureau of Mines report deals with water infusion of coalbeds, which can control methane emission at face areas during developmental mining and which may sometimes suppress dust. Studies show that water infused into the coalbed flows through the fracture system and displaces the methane in the fractures and prevents migration from the solid coal. Displaced gas migrates away from the face area that has been water infused and enters the return ventilation airways. A gradual decrease in methane emission is observed from the start of infusion until the infused zone is mined through. Depending on the permeability of the coalbed, infusion pressures ranged from 300 to 2,200 lb/in2. Face emissions in the Upper Kittanning coalbed were reduced by 89 pct; reductions of 38 to 79 pct were measured in the Pittsburgh coalbed depending on the relationship between the face cleat direction and mining direction. Respirable dust levels were reduced by about 75 pct on a longwall section in the Pocahontas No. 3 coalbed and by about 50 pct on a development section in the Upper Kittanning coalbed, but no statistically reliable reduction was found in the respirable dust levels in the Pittsburgh coalbed.

Jan 1, 1977

To minimize support costs and to improve ground control by improving wood-crib design and utilization through the development of engineering methods that will match the placement and performance of the wood cribs to the load conditions imposed by the mine environment. Background While wood cribs are used extensively to stabilize mine openings, their utilization is often based on historical practice or trial-and-error rather than on engineering design. This has led to conservative crib utilization where more capacity than is necessary is employed or inadequate capacity is provided when mine conditions worsen. Critical design parameters, such as the stiffness of the support structure, are often ignored. Optimum crib design and employment is becoming increasingly important as the utilization of wood cribs increase due to the growth of longwall mining, and as the cost of wood continues to rise. A single longwall operation will spend as much as a million dollars per year on the support of the gate roads.

Jan 1, 1994

By Edward L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

By M. J. Dailey

This paper is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The property of the Silver King Coalition Mines Co. is situated in the western past of the Park City mining district, Utah, about 1 ½ miles southwest of the town of Park City, The elevation at the collar of the main shaft is 8,137 feet above sea-level.

Jan 1, 1930

By Kathleen M. Kowalski-Trakofler

This paper discusses human judgment and decision making under stress. The authors review selected recent literature across various disciplines and suggest a definition of stress within the context of decision making during the management of emergencies. They also discuss fieldwork by the Pittsburgh Research Laboratory, NIOSH, which explores traumatic incident stress, the relationship between previous training and performance under stressful conditions, and human behaviour in underground mine fires. The authors assert that stress is one of the factors that decision makers must contend with in most life-or-death situations. They suggest that a better understanding of individual judgment and decision making activities whilst under stress would yield a better understanding of how people reach the choices they make in emergencies. This enhanced understanding would be of enormous value to emergency managers, researchers and policymakers.

Jan 1, 2003

Provide a means to (1) rapidly disconnect a multifunctioning signal channel from a multichannel data collection system, (2) protect electronic devices from damage while causing the minimum amount of data collection disruption, and (3) operate electronic devices under gassy mine conditions. Background Data collection system instrumentation and cables are often located in hazardous areas of underground coal mines. As a result, frequent damage to the instrumentation cables occurs from roof falls, heavy equipment, and the relocation of air, water, and power lines. A similar problem exists in surface areas where cables and instrumentation can be damaged by animals and by vehicle traffic. Without a circuit-breaking feature, the damaged cables could cause instrumentation to be ruined, cause power supply failure, and otherwise disrupt data collection in some situations the lack of a circuit-breaking feature might cause an ignition in a methane atmosphere.

Jan 1, 1990

By Clarence Hall, Charles E. Munroe

In accidents resulting from the use of explosives in metal mines and quarries in the United States more than 130 men were killed and 250 seriously injured during the calendar year 1913. More- over, an unknown number of miners suffered from the effects of breathing the harmful fumes and gases given off by the burning or the incomplete explosion of some explosive. Consequently, the Fed- eral Bureau of Mines, which is endeavoring to increase safety in mines and to abolish conditions that tend to impair the health of miners, is studying the kinds of explosives used in mining and the conditions under which these explosives can be used with least danger to the miner. Information about the different explosives used in coal mining and the precautions to be taken in using those explosives has been printed in Bulletin 17 and other bureau reports, the names of which may be found at the end of this bulletin. The bureau has not been able to give much attention to explosives used in metal mines and quarries, but has published some information about these explosives in Bulletin 48, "The Selection of Explosives Used in Engineering and Mining Operations"; Technical Paper 17, "The Effect of Stemming on the Efficiency of Explosives"; and Miners' Circular 19, "The Prevention of Accidents from Explosives in Metal Mining." This bulletin aims to give the metal miner and the quarryman information similar to that given the coal miner in Bulletin 17. In- flammable gas or dust is seldom, if ever, found in quarries or metal mines, and the danger from using explosives there is less than in coal mines; but, as the figures show, the number of men killed and injured yearly in accidents caused by explosives proves the need of both miners and mine officials striving to see that none but proper explosives are used and that these are used properly.

Jan 1, 1915

Improve the safety and comfort of operators of large mining equipment. Approach Develop an improved driver restraint system that is easy to use, reliable, and cost-effective, while providing increased protection in the event of a collision or rollover. The Novel Restraint System There are several problems associated with conventional lap-belt type restraint systems. Among these are: restriction of movement, lack of comfort, and fear of entrapment. Standard seatbelts become dirty and oily from lying on the vehicle cab floor and can ruin a driver's clothes. Some haulage equipment may not even have seatbelts available to drivers since they are sometimes removed during maintenance activities or as a result of vandalism. Recognizing a need to address such problems by providing a more acceptable means of driver restraint, the Bureau of Mines designed and fabricated a novel vest-type restraint system. The vest is designed to be worn during a driver's 8-hour shift and would be issued much like safety glasses, hard hats and safety shoes, thus becoming part of the operator's individual protective equipment and assuring that each vehicle has a restraint system when in operation. The vest-

Jan 1, 1985

By Daniel D. Sweeney

The United States coal mining industry has traditionally experienced difficulty in controlling dust levels below the occupational exposure limit. While improvements in face ventilation and water spray nozzles have decreased dust exposures, approximately eight percent of experienced coal miners are still developing Coal Worker?s Pneumoconiosis. This investigation tested the feasibility of enhancing existing engineering dust controls by mounting a simple barrier on a longwall shearer that separated the operators from the cutting drums. The barrier was constructed and tested above ground at the National Institute for Occupational Safety and Health Pittsburgh Research Laboratory longwall gallery test facility. A 96-percent reduction of respirable dust occurred at the headgate sampling position when tested at 2.4 m/sec (480 ft/min). The average dust level decreased from 39 mg/m3 to 1.5 mg/m3 by utilizing the barrier.

Jan 1, 2009

By Foster Fraas

In the separation of a component from a mixture , two fractions are obtained , one containing a high - percentage composition of the component and the other a low - percentage composition . The high - percentage fraction is frequently called the concentrate and the low - percentage fraction the tailing . In many separation processes the recovery is not complete , and the composition of the concentrate decreases as the recovery of the component, which is concentrated , increases . It is this particular class of separations to which this paper is confined .

Oct 1, 1942

By Thomas E. Popplewell

This paper is one of a series being prepared for and published by the United States Bureau of Mines describing the mining and treatment methods and costs obtained in sand and gravel plants throughout the United States. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual operators as well as to the industry as a whole. On the other hand operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue.

Jan 1, 1932

By D. Harrington

An explosive may be defined as a substance (usually a mixture) that has the property of yielding, readily to combustion or oxidation upon application of flame or shock, the combustion or oxidation process being rapid and accompanied by formation of such relatively large quantities of gases that much violence and pressure are produced; these, in turn, react against their surroundings and cause what is termed an explosion. By their very nature their action is destructive and disruptive of adjunct materials; hence, all explosives axe potentially hazardous and every type of explosive, irrespective of its relative safety, should be handled, .stored, and used with utmost care at all times and under all conditions. It should always be remembered that any explosive can be rude safe only in certain of its features and under certain conditions and circumstance. If these facts (and they certainly are facts) are always kept in mind, most of the modern types of explosives can be utilized advantageously in our industrial life and with a considerable degree of safety. That commercial explosives can be handled. safely is borne out in part by the fact that in the past 15 years at least 3,000,000,000 pounds of the commercial explosive dynamite have been transported by railroads in the United State, without injury to any person, insofar as available records indicate.

Jan 1, 1939

By Alton B. Cook

Equipment has been designed and fabricated for study of the vaporization of oil during gas-cycling operations, A sand-packed steel tube, which can be rotated to minimize gravity drainage, is used as a model oil reservoir. A minute windowed cell at the discharge end of the tube through which the liquid-gas interface may be observed, makes possible the separate removal of produced free gas and gas-saturated oil. The operation of the model oil reservoir, and auxiliary equipment, are described by use of a schmatic flow diagram. Details of the specially designed equipment are illustrated by isometric and pictorial drawings, and a description of the experimental procedure is given.

Jan 1, 1959

By L. O. Bacon

This Bureau of Mines report summarizes the results of laboratory work in the design of instrumentation for obtaining the dynamic tensile strength of rock at minimum loading. Minimum loading is defined as the lowest tensile loading by pulse reflection to cause fracturing. The instrumentation for obtaining dynamic tensile strengths of rock cores evolved into the use of a compressed-air pellet gun to impact one end of a rock core, suspended by wires, at increasing increments of air pressure. Maximum strain was measured on most or all of the impacts, and the strain at fracture of the core was obtained by extrapolating the pellet velocity-strain curve to the pellet velocity at fracture. Stress at tensile fracture was obtained from the maximum s train, and the dynamic Young's modulus was calculated from the rod velocity by using simple rod theory.

Jan 1, 1962

By Kung-Lee Wang

The 1963 performance of the United States economy was impressive. The year was one of continued growth unmarred by a recession. By the end of 1963 the economy's expansion had already lasted almost as long as the 1954-57 upswing, and the net gain in output since the trough in activity in early 1961 compared favorably with most earlier postwar cyclical advances. There was no indication of any slow- down at yearend. Both gross national product (GNP) and national income in 1963 were 5 percent higher than in the previous year. GNP totaled $584 billion, a gain of $28 billion over 1962. Real output of goods and services rose 3.4 percent over the year. Price increases continued to be moderate. Production, employment, personal income, and corporate profits all registered new but unemployment continued high at 5.5 percent and the prospects for improvement remained poor. The economy again failed to use its full potential. Current value of mineral production kept pace with the economy. The constant dollar value of mineral production gained more than real GNP because of the relatively stable price of minerals. Mining production achieved a new high in 1963. Steel production totaled 110 million tons, 12 million tons above 1962, making 1963 the first 100- million-ton year since 1957 and lifting the steel-associated minerals group upward. The gain in ferrous metals mining was insufficient to compensate for the decline of nonferrous metals mining resulting in an insignificant decline in the metal mining total as a whole. The upsurge of construction material minerals output, with an assist from chemical and fertilizer minerals, accounted for peak production of

Jan 1, 1964

By H. D. Baylor

This paper, describing the operations of the Louisville Cement Co. in quarrying limestone for the manufacture of quicklime, is one of a series being prepared for and published by the United States Bureau of Mines on stone quarries throughout the United States. Those papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual operators as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. ACKNOWLEDGMENTS The author acknowledges the assistance of J. H. Lemmon, plant superintendent, Charles Taylor, plant engineer, and F. H. Compton, chief engineer, of the Louisville Cement Co. in the compilation and preparation of this paper.

Jan 1, 1932

By Wm. O. Vanderburg

This paper describing the mining practices at the Block P mine of the St. Joseph Lead Co. at Hughesville, Mont., is ore of a series of similar papers being prepared by the Bureau of Mines on mining practices, methods, and costs in the various miner of the United States. ACKNOWLEDGMENTS In the preparation of this paper the writer acknowledges the assistance of R. H. Willcomb, general manager, William Thorson, mine superintendent, and B. P. Bellport, mining engineer, of the Hughesville division of the St. Joseph Lead Co.; and of E. D. Gardner; supervising engineer, U. S. Bureau of Mines, Southwest Experiment Station, Tucson, Ariz.

Jan 1, 1931

Publicize the valuable information resources covering research conducted by the U.S. Bureau of Mines (USBM) and other federal laboratories that may be of interest to USBM customers. Access to this information is important for promoting further research and in transferring the technology to the end user. USBM Information Resources The USBM serves as the Nation's premier agency for mining- and minerals-related research. In sharing the benefits of this research with American industry and the American people, the USBM supports information systems outlining this vast array of technical knowledge. The USBM is dedicated to making its technology readily available and will continue to expand its electronic communications capabilities. The following resources provide instant access to USBM information. U.S. Bureau of Mines Bulletin Board. The Bulletin Board is a free service accessed by computer modem. All that you need are a computer, a modem, and communications software. The telephone number for the Bulletin Board is 202-501-0373; for information on using the system call 202-501-0406. Use X-modem protocol set to 1200, 2400, or 9600 baud, 8 data bits, and 1 stop bit (8,N,1). The information on the system can be viewed or downloaded. This service includes the following: announcements on Bulletin Board and other USBM activities; mineral news, features, and press releases from the Bureau's Office of Public Information; a list of recent publications and articles by USBM authors; mineral commodity data and Mineral Industry Survey reports; USBM Technology News, concise factsheets announcing milestones in USBM research and technology; a current list of computer products available from the USBM and the National Technical Information Service (NTIS); and a listing of cooperative research opportunities with the USBM.

Jan 1, 1995

By T. J. McDonald

The methods used and the results obtained in the application of high-expansion foam on a recent fire in an operating mine in western Pennsylvania were reviewed. This is the first instance where foam has been applied extensively to a fire under actual mining conditions although considerable research has been conducted and experimental fires have been controlled. The Bureau of Mines began investigating the foam-plug technique in 1957 in its experimental coal mine, following reports of successful trials in Eng-land, where the basic methods, using the normal ventilating current, were developed. Early in the research it was apparent that the normal ventilating current in mines in the United States would not provide adequate air pressure to drive a foam plug the distance that might be required. Subsequently, the Bureau of Mines developed a portable high-expansion foam generating unit consisting of a fan having relatively high pressure potential, net, sprays, and metering equipment. To date, foam generators have been constructed by the Bureau, by at least one operating coal company, and by one manufacturer of safety equipment. A number of units from the latter supplier have been adopted by coal-mining companies as an integral part in their firefighting installations.

Jan 1, 1961