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By S. M. Moore

Technological advances in underground coal mining have reduced fatalities but may not have reduced worker exposure to cumulative injury risk factors. The objective of this study was to evaluate the prevalence of cumulative injuries before and after the implementation of technological advances in underground coal mining and to make a general cost estimate for these injuries. A previously published algorithm was utilized to identify cumulative injuries within the Mine Safety Health Administration (MSHA) database for two data sets: 1983-1984 and 2003-2004. For both, the following were determined: the number and percentage of cumulative injuries, the average days lost, the average age at the time of injury, the average years of experience and the general cost estimate by body part. The percentage of cumulative injuries remained largely unchanged (37 percent in the 1983-1984 period and 33 percent in the 2003-2004 period). The average number of lost days due to cumulative injuries increased (36±55 days and 62±82 days, respectively), which may have been due to the increased worker age (seven years older in the 2003-2004 period), increased length of employment (seven years longer in the 2003-2004 period) or other factors such as changes in medical practices. Cumulative injuries to the back decreased by 10 percent, while cumulative injuries to the knee increased by 8 percent. The reduction in back injuries may be due to the implementation of assist devices, while the increase in knee injuries may be related to kneeling/crawling in low-seam mines. Cumulative injuries were found to remain a major financial burden on the industry. Recently, National Institute for Occupational Safety and Health (NIOSH) developed tools to assist mining companies with incorporating an ergonomics process into their existing health and safety programs. The participating companies have reported tremendous success. Therefore, it is recommended that ergonomics processes be implemented as a means to systematically identify and address the root causes to cumulative injuries and ultimately reduce costs.

Jan 1, 2008

By Deno Pappas, Chrisropher Mark, John Rusnak, Linda McWilliams

Mine planning for a new reserve is based on information obtained from exploratory coreholes. A critical component of an exploration program is the geotechnical evaluation. Poor assumptions about roof conditions greatly add to the risks of mining. Rock mechanics testing is central to a geotechnical exploration program. Typically, 3 to 5 uniaxial compressive strength (UCS) tests are made to characterize a particular roof unit at a given corehole. The average (mean) of these tests is taken as “The UCS” for that location. Isopach contour maps are then used to show spatial trends in roof strength. Two issues are raised by this traditional approach. The first is due to the large variability in UCS values that is typical even within a single unit from a single hole. The average UCS might be higher at Corehole A than it is at Corehole B, but the difference may not be statistically significant. The second issue is whether widely spaced coreholes can identify valid spatial trends in rock strength. The answer depends upon whether rock strength changes over distances that are longer or shorter than the corehole spacing. This is a classical geostatistical problem. While geostatics have been used to investigate many coal quality parameters, they have seldom been used to evaluate rock strength. This paper describes an extensive investigation of these issues conducted by the National Institute for Occupational Safety and Health (NIOSH) in collaboration with Peabody Energy. The study employed the Peabody Rock Mechanics Data Base which contains more than 10,000 individual test results. Data from four important roof units were subjected to statistical analysis: • Brereton Limestone above the Herrin 6 seam (Illinois) • Turner Mine Shale above the No. 9 Seam (Kentucky) • Sandstone above the Eagle Coal (West Virginia) • Shale above the Eagle Coal (West Virginia) The study did not find significant spatial trends in rock strength in any of the cases. Perhaps there are none, or perhaps the exploration coreholes were just too far apart to see them. These results have valuable implications for the design of geotechical exploration programs.

By Richard A. Winters

There are no producing or developing mines or active mining claims in the Deschutes Canyon RARE II study area. Only two prospects were found; they have no identified potential for mineral resources. Thin diatomite deposits occur in the Pliocene Madras Formation. Development of sand and gravel deposits in the area could not favorably compete with similar deposits in the surrounding area which are closer to points of use. By mid-1982, active oil and gas lease applications covered about 25 percent of the area, a reduction from nearly 100 percent in early 1981. No holes were drilled for oil and gas exploration. INTRODUCTION Personnel of the Bureau of Mines, Western Field Operations Center conducted a mineral investigation of the Deschutes Canyon RARE II area during the summer of 1982. The area, about 10 mi (16 km) southwest of Madras, Oregon, covers 10,890 acres (4,407 ha) in the Crooked River National Grasslands (fig. 1). The Deschutes River has incised a deep canyon into the north sloping elevated lava plain near the transitional boundary of the High Lava Plains and the Deschutes-Umatilla Plateau geomorphic divisions (Baldwin, 1964, p. 20).

Jan 1, 1983

To provide operators of large-opening mines with a ventilation planning tool that will help them develop a healthier, safer, and more efficient ventilation system in the underground workplace.

Jan 3, 2006

By Steven J. Page, John A. Organiscak

Laboratory crushing experiments were conducted on a range of low- to high-volatile bituminous coals to investigate the various factors influencing airborne respirable dust (ARD) generation. This research was conducted to identify the principles of ARD liberation from the coal product. Five U.S. bituminous coals were uniformly prepared and processed through a double roll crusher located in a low-velocity wind tunnel. Experimental factors studied included inherent coal seam constituents, coal grind ability, specific energy of crushing, product size characteristics, dust cloud electrostatic field, and specific ARD generated. The results of this investigation indicate that a combination of several factors are associated with ARD generation. One factor is the effect of coal rank, described by the inherent moist fuel ratio, on the product size characteristics, defined by Schuhmann size function parameters. Another key factor is the effect of air dry loss(ADL) moisture in the coal seam on the breakage-induced electrostatic field of airborne dust. The effect of these factors is that different percentages of <10-m coal particles are dispersed as ARD. A discussion of electrostatic field principles, coal ADL, and its effect on ARD generation is presented.

Jan 10, 1998

By Stephen P. Signer, John L. Lewis

This paper presents the results of a case study conducted in a two-entry gateroad in a coal mine where excessive roof deformation and bolt loading resulted in failure of many roof supports. The instruments consisted of 16 fully grouted, strain-gaged resin bolts, load cells on both full and partially grouted cable bolts, and vertical deflection multipoint extensometers. These instruments were installed on-cycle to measure loading on bolts in an existing support pattern and to determine if cable bolts could be used to improve roof stability. Results showed significant amounts of movement within the bolted zone. In some cases, these movements were enough to load the supports past their ultimate strength. Geology appeared to be a significant factor in localized roof degradation; that is, a very weak rock layer in the immediate roof overlain by a very strong rock layer contributed to the development of shear planes. Only one instrumented bolt had a maximum strain of less than 2,000 microstrain, which was the yield point of the steel. The average maximum strain on all bolts was 20,000 microstrain. However, electrical continuity to many gages was lost and a pattern was noted that would indicate possible bolt failure. Wire mesh and concrete cans installed as secondary support performed very effectively.

By E. D. Gardner

"Trolley lines used in connection with electric haulage in mines are a source of danger and many lives have been lost by men accidentally coming in contact with the wires. Usually the wires in metal mines are sufficiently guarded to prevent men from touching them with their person or by pieces of steel which they may be carrying or their shoulders, while walking along the level. However, it is difficult to guard effectively the wires at loading chutes along the haulage ways and in spite of safe guards, chute tappers have been electrocuted through loading bars accidentally touching the trolley line.To overcome this danger the Calumet & Arizona Mining Co., at Lowell, Arizona formely used a hinged V-shaped trough made of 1-inch by 6-inch lumber, that was dropped over the wire in front of the chute, when the cars were being loaded. This arrangement interfered with the easy operation of the chute, and a cut-out device for the trolley line was devised by W. R. Gibson, chief electrician for the company. This cut-out is efficient easily constructed and roes not interfere with the operations at the chutes or with the motors operating on the same level.When the cut-out is open the electric current is carried past the gap by an insulated wire on the opposite side of the drift. A hinged board drops down over the ends of the trolley guard when the slide is open and Prevents anything touching the live wires. About ninety of these cut-outs are now in use in the mine,The levels under the scopes are timbered with drift sets placed 5 feet apart, and the loading chutes take up the space between two sets. All trolley wires in. the company's mines are carried 6 feet above the rails and guarded by two 1/2 by 6-inch boards placed on either side of the wire."

May 1, 1921

By M. Kawahata

Methane sensors using principle of catalytic oxidation of methane are employed for determination of methane content in ambient air of coal mines. Certain foreign gases or vapors in the air poison the catalyst of the sensor effecting the sensor&apos;s response. After literature search of poison compounds of Pt and Pd oxidation catalyst, experimental studies of catalyst poison kinetics were made for three siloxane compounds, tributyl-phosphate, monobromotrifluoromethane, and hydrogen sulfide, selected as poison vapors. Concentration range of the poison vapors was varied in a range from 3000 to 0.1 ppb (v/v). Three siloxane vapors produced strong catalyst poison effect, followed by tributylphosphate, hydrogen sulfide and monobromotrifluoromethane for the high concentration level of the poison vapors. The poison effects are influenced significantly by concentration of the vapors. Threshold poison vapor concentrations where effect of the poison vapors on the sensor is minimal were determined experimentally. Experimental studies were made further for prevention method of catalyst poison by adsorption techniques. Use of activated carbon cloth inserted on the sensor&apos;s head prevented catalyst poisoning efficiently.

Jan 1, 1981

By J. B. Zadra, S. M. Shelton, R. B. Fisher, M. M. Fine

"INTRODUCTION An extensive test program is in progress by the Bureau of Mines to determine ways and means of recovering ferromanganese ore 5/ from the widespread domestic manganese and manganiferous iron deposits.Samples were received from the Stance property in southwestern Virginia, 12 miles northwest of Stoney Gap, in Bland County.The Stange mine is situated on the crest of Flat Top Mountain and is developed by open-cuts extending over several acres. The manganese deposit occurs in the Oriskany sandstone largely as a replacement of the sandstone, to some extent as breccia filling in the crusted parts of the sandstone, and as veins along joints, and bedding planes.The mine was first worked in 1917 and was operated during the war years. A long period of idleness was followed by intermittent operations in recent years. A small log-washing plant, consisting of a 20-foot log washer, was operated 1-1/4 miles northwest of the mine. The log-washer concentrates were crushed to minus- 1/2 inch and then washed in a second log washer to remove as much of the siliceous sandstone as possible. According to a communication from the operator, the double-washed concentrates were jigged and the jig concentrates marketed without further beneficiation."

Apr 1, 1942

By Merle L. Bowser

An alinement (steering) sensor for continuous mining machines has been developed under a Bureau of Mines contract. A laser source in the entry projects a beam parallel to the centerline of the entry. The beam is optically shaped to a narrow, vertical fan and illuminates an array of optical sensors bunted on the mini machine. These sensors interpret the location of the beam into meter readings of heading (angle) error and lateral displacement errors. The system, which was tested for 5 months in an operating mine, appears to be fundamentally sound, and with some modification, should be applicable to remote or automatic guidance of continuous miners and other machines.

Jan 1, 1976

By C. S. Compton, D. R. Dolinar, D. C. Oyler

More than 80% of U.S. roof bolts are fully-grouted, but about 1500 roof falls are reported each year. Anchorage failure of a fully grouted bolt can occur when the roof is active near the top of the hole. This paper reports on an extensive series of short-encapsulation pull tests (in which the bolts are installed with only 1 ft of resin) that were conducted in the National Institute for Occupational Safety and Health (NIOSH) Mine Safety Research Laboratory and operating mines in WV and PA. The tests confirmed that poor anchorage can been countered under some weak rock conditions. Suggestions for improving anchorage are included.

By C. C. Popoff

This report reviews the phosphate deposits, mines, and industry, and prospects in 10 districts covering most of the Montana phosphate field. These districts are discussed individually, and an evaluation of the resources and potential of each is presented. Phosphate rock produced from underground mines in the Garrison district is shipped to Canada for processing to fertilizers, utilized locally for production of animal feed supplement, and pulverized and sold for direct application to the soil. Production from the Melrose district is shipped to Silver Bow and processed to elemental phosphorus. The Maxville-Philipsburg district is destined to become a major producer with the development of the Douglas Creek mine and beneficiation plant by Montana Phosphate Products Co. Montana ranks fourth after Florida, Tennessee, and Idaho in total annual production in the United States. Production him increased from about 60,000 long tons of acid-grade phosphate rock in 1940 to more than 660,000 tons of acid-, beneficiation-, and furnace-grade ore in 1961. Montana has the second largest potential resources in the Western field; in the area south of Butte there are approximately 1.2 billion tons of phosphate rock (+18 to +31 pct P2O5) available above and within 100 feet below entry level; and in the northern part of the field there are about 67.6 million tons available above entry level. In contrast to Idaho, most of the phosphate deposits in Montana are best suited to underground mining.

Jan 1, 1965

By J. C. Edwards

The National Institute for Occupational Safety and Health (NIOSH) implemented a real-time neural network system which can discriminate mine fires from nuisance diesel emissions as part of an atmospheric mine monitoring system in NIOSH?s Safety Research Coal Mine. The real-time response of a neural network to fire sensor outputs was demonstrated for coal and belt combustion in the presence of diesel emissions. The fire sensors consisted of an optical path smoke sensor, a carbon monoxide (CO) sensor, and two types of metal oxide semiconductor (MOS) sensors. The real time neural network was trained with coal, wood, and belt fire experiments with and without diesel emissions background. The trained neural network successfully predicted mine fires with these combustibles in the smoldering stage prior to the onset of flames.

Jan 1, 2005

By E. A. Ziemba

The modified in-situ process is one of the methods being considered for extracting oil from oil shale. One of the questions to be answered for this approach is the environmental consequence of underground retort abandonment. This report outlines a study which addresses the question in terms of a grouting solution. It covers the development of a spent shale ash based grout which will fulfill the environmental requirements in terms of strength, stability, and impermeability. In addition, it will allow the reinjection of up to 50 percent of material mined and surface retorted as part of this process.

Jan 1, 1982

By Albert W. Deurbrouck

This Bureau of Mines report describes the washability characteristics of 13 coalbed samples collected in Colorado. Such data are needed to evaluate the quality of the coals of the West, where most of our low-sulfur-content coal reserves are found. Of the 13 samples included in this report, 11 had a total sulfur content of 1 percent or less. All of the samples contained low percentages of ash or could be readily washed to a desirable ash level with minimal loss of yield. The coals ranged in rank from high-volatile A bituminous to subbituminous B; nine of the samples were high-volatile C bituminous. The coalbeds ranged in thickness from 6 to 26 feet; the average was about 8 feet.

Jan 1, 1970

By John Rusnak, Christopher Mark

Point load testing is used to determine rock strength indexes in geotechnical practice. The point load test apparatus and procedure enables economical testing of core or lump rock samples in either a field or laboratory setting. In order to estimate uniaxial compressive strength, index-to-strength conversion factors are used. These factors have been proposed by various researchers and are dependent upon rock type. This study involved the extensive load frame and point load testing of coal measure rocks in six states. More than 10,000individual test results, from 908 distinct rock units, were used in the study. Rock lithologies were classified into general categories and conversion factors were determined for each category. This allows for intact rock strength data to be made available through point load testing for numerical geotechnical analysis and empirical rock mass classification systems such as the Coal Mine Roof Rating (CMRR).

By Suresh K. Bhatt, Christopher Mark

Fatalities caused by highwall/spoil bank failure in the surface mines, coal and non-metal, increased to an alarming rate of seven during 1999. To determine the causes of slope failure and successful mining practices, the National Institute for Occupational Health and Safety undertook a study. The study included: 1.A review of accident statistics; 2.A review of Federal and state mining laws pertaining to surface mining; 3.A literature review, and; 4.Mine visits. The study emphasized surface mines in the states of West Virginia, Ohio, and Pennsylvania. The review of a decade’s accident statistics using the mine Safety and Health Administration’s (MSHA) database showed that approximately 40% of all ground control related incidents reported to MSHA occurred in just four eastern states: Kentucky, West Virginia, Pennsylvania, and Ohio. The comprehensive literature search provided a historical perspective of highwall stability issues. Eleven mines we visited to obtain data on their mining practice or design. Commodities included coal, sandstone, and limestone. Based on the visits, five case studies were developed to represent typical mining methods and effective ground control practices used in eastern surface mines. Benching was found to be a common technique to reduce the overall highwall slope angle. Decking in the softer zones, such as shale, proved useful in controlling damage due to blasting.

By Thomas C. Atchison

The purpose of this Bureau of Mines investigation was to measure the amplitude and shape of the strain pulse and the size of the crushed zone produced in a granite by different explosives and to determine how these quantities are related to the detonation properties of the explosives. The reflection theory of rock breakage has shown that the amplitude and shape of the strain pulse incident at a free surface determine the fragmentation and volume of rock broken. Determination of the properties of an explosive that control the characteristics of the strain pulse produced in the rock will help in evaluating explosives for use in blasting. The investigation showed the different explosives produced a twofold variation in the amplitude of the strain pulse but little variation in the shape of the pulse. The explosives also produced a twofold variation in the volume of the crushed zone, but differences among the explosives were more accurately determined by strain-amplitude measurements than by crushed-zone measurements. The peak amplitude of the strain pulse and the volume of the crushed zone correlated with the calculated detonation pressure of the explosive.

Jan 1, 1959

By William T. Reid

Low-temperature carbonization of coal in Japan served as an important source of liquid fuels during the war. Six plants operating in Japan Proper produced 203,069 KL (53.7 million gallons) of liquid fuel from 1940 until the end of the war in August 1945, while four additional plants in Karafuto and Korea produced 211,943 KL (56.0 million gallons) for a total of 415,012 KL (109.7 million gallons) of liquid products. Semicoke produced in these plants was used for domestic fuel, for gasi- fication in portable gas producers on automotive vehicles, and to replace imported low-volatile bituminous coal in the manufacture of metallurgical coke. Since 1936 one plant had produced more than 300,000 metric tons of semicoke for blending with bituminous coal to form coke, while the total production of semicoke since the beginning of the industry in 1923 is approxi- mately 2,000,000 metric tons. Despite an apparent annual carbonizing capacity of about 2,000,000 metric tons of coal for the entire country, the maximum amount of scmicoke produced during the peak year, 1943, was 468,446 metric tons. The equipment used is primarily of Gorman design. Just before the end of the war, 6 plants using 20 Lurgi carbonizers were operating with a total rated capacity of more than 1,500,000 metric tons of coal per year, while 2 Koppors units had a combined annual rated capacity of 400,000 metric tons of coal. One plant using the Japanese-designed Mimura system was in service but with so much mechanical trouble that its output was small, while in another plant 4 Wanisht carbonizers of Japanese design but based on an early German development were running satisfactorily, and carbonizing about 100,000 metric tons of coal per year. A single installation of 15 American-designed Knowles ovens was operating near Tokyo but was carbonizing pitch for electrode carbon. ..! No true low-temperature process used in Japan could carbonize strongly. caking coals satisfactorily. The Mimura process designed for this purpose was unsuccessful, as was the Shimomura process before it, while the Lurgi, Koppers, and Wanishi systems operated only with noncaking or very weakly caking coals. The Knowles ovens, really a medium-temperature process, could carbonize-caking coal without difficulty...

Feb 1, 1948

By Alan A. Campoli

OD March 20, 1989, a meeting was held at the U.S. Bureau of Mines Pittsburgh Research Center at the request of Senator Pete V. Domenici of New Mexico. The purpose of the meeting was to engender a technical relationship between the National Laboratories and the minerals industry. During the meeting, the Director of the Bureau of Mines, T S Ary, suggested that since the Bureau is the focal point for mining research in the United States, it would be appropriate for the agency to act as the liaison between the National Laboratories and the minerals industry. As the first step in this process, the author was selected to perform a 6-month investigation to better define the proper role of the Bureau in this area. As part of the investigation, the mining and mineral-related technology available at 21 major U.S. Department of Energy (DOE) Research Laboratories was reviewed. It was assumed that the broad range of scientific and technical areas covered DOE research would provide fertile ground for mining-related technologies. It was hoped that the applicability of DOE research to this liaison effort would be indicative of Federal laboratories in general.

Jan 1, 2011