Search Documents

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal workers’ pneumoconiosis is the leading cause of death due to occupational illness among U.S. coal miners. This disease is caused by miners’ exposure to excessive levels of respirable coal mine dust. A personal dust monitor (PDM) has recently been developed to provide near real-time feedback to miners regarding the level of respirable coal dust in the air they breathe. The main objective of this report is to document coal miners’ reactions to this device and how they make use of the information it provides. It summarizes a field study by the National Institute for Occupational Safety and Health that documented the opinions of 30 miners at 4 underground coal mines concerning the use of PDMs.

Jan 2, 2008

Develop a simple and practical technique to measure in situ rock mass properties for realistic design and stability evaluation of underground structures. Background The Bureau of Mines has developed basic principles and techniques to determine in situ rock mass properties including Poisson's ratio, deformation modulus, and yield and failure strengths. An instrumentation package consisting of three pressure cells is installed in a single drill hole. Cell pressure response data are acquired and used to calculate and determine the rock mass properties. How It Works A test hole of BX size (approximately 5.7 cm) or larger is drilled to the approximate depth of the measuring point. The last portion of the test hole is drilled with precision bits to EX size (approximately 3.8 cm). The instrumentation package, which consists of one 3.8-cm-diameter cylindrical pressure cell (CPC) and two 5.7-cm-diameter cement-capsulated, flat borehole pressure cells (BPC's), is then installed. A complete history of cell response to changing strata loads is acquired on a continuous basis with a chart-type hydraulic pressure recorder. From these cell pressure data, Poisson's ratios, deformation moduli, and yield and failure strengths are calculated and determined.

Jan 1, 1990

By W. C. Smith

The U.S. Bureau of Mines examined previous research on rib stability in an effort to develop a practical approach to understanding, characterizing, and controlling weak rib conditions in underground coal mines. Because success in stabilizing ribs depends on a basic knowledge of how weak ribs behave, the report reviews the mechanics of rib failure and the relationship of coal mine geology and pillar constraint to rib instability. Strategies for choosing an effective method of rib support are considered, and various rib support methods are discussed. Finally, the report documents techniques for monitoring ribs and use of models to assess rib stability; such monitoring and modeling can also help determine the most effective method for roof support.

Jan 1, 1992

By Jr. Zipf

Highwall mining is an important surface coal mining method, and it may account for approximately 4% of total U.S. coal production. Highwall stability is the major ground control related safety concern. Ground control plans for highwall mining should specify hole width, web pillar width, barrier pillar width and number of holes between barriers. This paper offers simple design charts for these parameters aimed at providing “ball park” checks. Web pillars containing pre-existing auger holes are analyzed and a design chart for estimating their minimum width is also presented. Finally, close proximity multiple seam highwall mining, which may have caused several serious highwall failures, is analyzed. Web and barrier pillar recommendations for this special situation are presented.

By Frederick C. Trutt, Jeffery L. Kohler, Joseph Sottile

Twenty-five years ago, the former U.S. Bureau of Mines funded a research project aimed at developing the enabling technology for incipient failure prediction in electric power system components as a means of reducing the injuries and fatalities that sometimes occur when equipment malfunctions. Over the ensuing years, interest in this has waxed and waned, but recently interest has been growing for both civilian and military applications. This paper addresses the level of turn-to-turn insulation deterioration that can be resolved using an on-line monitoring technique. The detection of turn-to-turn defects is especially important because they are believed to represent the beginning stage of most motor winding failures.

By F. J. Bailey

"In the fall of 1919, the U.S. Bureau of Mines began an inquiry as to the possibility of utilizing airplanes in conjunction with its rescue work, for quickly transporting engineers and oxygen rescue-apparatus to mine disasters.It was realised that this proposed use of airplanes has serious limitations, and if it were feasible, that the Bureau would have to rely on the cooperation of the established aviation fields of the U. S. Air Service for furnishing airplane service. Therefore Van. H. Manning, Director of the Bureau of Mines, under date of October 28, 1919, wrote the Director of Air Service outlining the rescue and first aid organization of the Bureau, the location of headquarters of district engineers, the distribution of safety cars and stations, and other essential details, and asking whether the Air Service could cooperate with the Bureau in the event of serious mine disasters. Major-General Charles T. Menoher, Director of Air Service, responded that the Air Service would be glad to cooperate insofar as possible, and designated those Air Service stations nearest the district engineers' headquarters, which might be best able to assist.The Bureau of Mines has ten mine rescue cars and eight mine safety stations distributed throughout the mining regions of the United States. The cars are each equipped with sets of oxygen mine-rescue breathing-apparatus and first-aid supplies. The car personnel consists of a mining engineer, surgeon, foreman, first-aid miner, clerk and cook. A foreman miner is in charge of each station and at five of the eight stations are mine safety trucks. The work of the cars and stations is two-fold; (1) Assisting in rescue and recovery work at mine disasters, and (2) training miners in mine rescue and first-aid methods, and in investigations looking to prevention of mine accidents. The country is divided into nine safety districts, with nine district engineers in charge."

Apr 1, 1920

By Joseph C. Zelanko, Christopher Mark

During August, two eastern Kentucky coal miners died in a roof fall during retreat mining operations. They had just finished extracting one pillar block and were moving to the next one when the intersection they were standing in collapsed. Regrettably, this was not an isolated incident. Since the end of 2000, there have been 28 ground fall fatalities in U.S. coal mines. Of these, 10 occurred during pillar recovery operations. Although pillar recovery has been associated with about one third of recent ground fall fatalities, it accounts for only about 10% of U.S. underground coal production. Statistically, a coal miner engaged in pillar recovery is several times more likely to be killed in a ground fall than a miner on an advancing section of a longwall. Pillar recovery is dangerous because it creates an inherently unstable situation. Once the pillars are extracted, the roof is expected to cave. Safe pillar recovery does not mean preventing roof collapse, it means ensuring that it only occurs after the miners have completed their work and have left the area. Fortunately, there are a number of proven techniques that can greatty reduce the hazards of pillar recovery. These include better mine planning, improved roof support, and safer work procedures. The goal of this article is to describe the most significant "risk factors" associated with pillar recovery, and prescribe control techniques that, taken together, can reduce the overall risk to miners. The conclusions are based on extensive studies conducted by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) that have included detailed analysis of every fatal retreat mining incident since 1992 (25 incidents resulting in 30 fatalities). Risk reduction strategies for pillar recovery can be divided into three main groups: Global Stability: Prevention of section- wide pillar failure; Local Stability: Prevention of roof falls in the working area; and Work procedures and worker location: Minimizing exposure to hazardous areas.

1. In 2002, a total of 2,820 contracting companies reported employment at coal mines to MSHA.

Jan 1, 2004

1. In 2003, a total of 4,357 stone mining operations reported employment to the Mine Safety and Health Administration (MSHA). The major industrial classifications in stone mining are dimension stone (used for construction purposes), crushed and broken stone (aggregates), cement, and lime. • Stone mines comprised 30.3% of all mining operations. • Mines producing crushed and broken stone (n = 3,412) comprised 78.3% of all stone mining operations.

Feb 1, 2005

By Terry J. Close

The highly-mineralized 43,700-ha Rapid River study area, on the southeast side of Hells Canyon Wilderness and west of the village of Cuprum, in Adams County, western-Idaho, was investigated in 1992 by the USBM (U.S. Bureau of Mines) in conjunction with its Idaho Land Assessment Program. The 1992 study updated data gathered during the USBM's 1974-76 Wilderness investigation. The studies consisted of the evaluation of 61 mineralized sites and the estimations of tonnages, grades, and minability of these sites. Most of the sites studied are in two mineralized locales--Windy Ridge and Jackley Mountain. A few isolated sites, peripheral to the two locales, were also examined. The 61 sites contained more than 340 mine and prospect workings, including about 10,300 meters (34,000 feet) of underground workings, plus 134 drill holes.

Jan 1, 1993

By Howard C. Turnage, Dana T. Updyke

An evaluation was made of one of several improved underground communication systems sponsored by the U.S. Bureau of Mines. The system evaluated was installed in a typical metal/non-metal room and pillar mine and utilized UHF repeaters connected to a unique distributed antenna and passive reflector system which provided mine-wide communications. A microprocessor controlled data collection system was assembled and installed for the evaluation. Data consisting principally of times and durations of messages and identities of the originating transceivers was collected between February and August of 1982 (6 mos.). Analysis of the data shows that the principal benefits are reduction in time required for unscheduled maintenance and repair, enhancement of safety, and better coordination of production activities. A cost benefit analysis shows a net benefit over cost, although it is also concluded that the capacity of the system is greater than can be justified by current activity in the mine.

Jan 2, 1983

By D. R. Babich, E. R. Bauer

US. National Institute for Occupational .Safety and Health (NIOSH) researchers are conducting a Cross-sectional survey of equipment noise and worker noise exposures in the mining industry. Surface and underground limestone is one commodity recently sun eyed. The sound levels of milling and processing equipment were recorded to identify noise sources. Full-shift worker noise exposures were completed to determine the exposure of various occupations. This article presents the results o f the noise research conducted in both underground and surface limestone manes, detailing the equipment likely to cause worker overexposures, and the occupations experiencing overexposures. Implications for worker noise exposure reduction are also reported.

Most laboratory sealant studies were carried out in 2.0 inch I.D. Plexiglas tubes of 9.0 inches height containing 4.0 to 4.5 inches reconstructed soil from an 0-8 or 8-16 inch soil horizon at the Lanse site. (When soil was used from the Kato site, the top soil horizon was approximately 0-4 inches. The 4-8 inch horizon was somewhat comparable to the Lanse 8-16 inch horizon.) A 20 mesh Saran or steel screen was placed over the rubber stopper with a bottom drain to a 100 ml measuring cylinder. In some earlier experiments a 1/2 inch bed of 1/4 inch pea-gravel was then added, but in later experiments this was eliminated as it showed no particular utility. Field soil samples collected by a shovel were stored in sealed containers and sieved through a 4 mesh screen just before use. (Moisture content was typically about 25% for A horizon soil and about 20% for B horizon soil.) The sieved soil minus roots was then added in increments of about 1 1/4 inches. Compaction was effected by dropping a weighted ramrod (1-7/8 inches O.D,) five times from a height of two inches. If about twenty tamps were used or if the soil columns were rapped vigorously while water-logged, compaction was high with no detectable percolation. Freezing such samples would then usually cause very slow percolation, e.g. 1-2 ml/day. Using this as a standard procedure, percolation flows were usually stablized after two to three days to rates of about 100 to 200 ml/hour. Percolate was recycled carefully to minimize disturbance of the soil surface. When percolation flows were about 100 to 200 ml/hour, various additives (sealants) were introduced to the moist column in two to three increments to maintain a slight head. Additive concentrations were usually 2-1/2% with some at 5% in earlier experiments. Typical use of 40 ml of 2-1/2% additive corresponds to 4400 lbs/acre. When no more additive was present as supernatent liquid, water washes of about 15 ml were then used several times followed by special additives as needed. More water washes were then used to maintain a head of about 1/2 inch. Percolate was collected in 100 ml cylinders to measure percolation rates in ml/hr. Turbid percolate was evaporated to determine amount of eluted latex. Percolate was sometimes checked for pH by Pan-pH Indicator Paper9,10 reading in 0.5 units. Surface tension measurements were sometimes made by a DuNouy tensiometer10 in experiments using a surfactant for pretreatment.

Jan 1, 1972

By R. V. Ramani

This report, Volume I of the seven-volume Final Report on the U. S. Bureau of Mines research contract no. G0254030 titled Application of a Total System Surface Mine Simulator to Coal Stripping with the Pennsylvania State University provides an executive summary of the purpose and scope, objectives and results of the research. The remaining volumes of the Final Report, listed below, describe in detail model development, input and output documentation and the three case studies. Under the project, an existing surface mine simulator, Open-pit Materials Handling Simulator (OPMHS) was modified and extended for application to surf ace coal mining. In addition, two equipment selection models, and a cost model were also developed. Volume II: OPMHS User's Manual Volume III: Equipment Selection Models Volume IV: Surface Mining Cost Model Volume V: Application of OPMHS to an Illinois Mine Volume VI: Application of OPMHS to a South Eastern Ohio Mine. Volume VIII: Application of OPMHS to a South Western Mine.

Jan 1, 1978

By R. Blickensderfer

Test equipment that simulated frictional impacts between coal-cutter bits and mineral inclusions at a coal face during operation of a continuous coal mining machine was used by the Bureau of Mines in the laboratory to study the incendivity of impacts between various rocks, metals, and hard-metal alloys in an explosive mixture of air-7 pct natural gas. Quartzitic sandstone was found to be the most incendive of several rocks tested. Limestone concretions from a coal seam, known locally as "sulfur balls," sparked furiously but were not incendive. Among the metals tested, the type of steel used in commercial coal-cutter tools was the most incendive material tested. A l7-4PH stainless steel was less incendive and appears to be the most promising high-strength steel alloy, reasonably economical, for use in coal-cutter bits. Some hard-metal alloys, primarily titanium and zirconium diboride composites, were also evaluated as possible replacements for the conventional cobalt-bonded tungsten carbide used in the tip of coal-cutter bits. The metal-bonded diborides were generally less inc endive but more brittle than the conventional tungsten carbide. Carbonitride coatings on tool bits were also tested but found to have no advantage. The source of ignition during frictional impact between metal and rock was studied. Immediately after impact, a yellow flash was observed and a smear of metal near its melting point occurred on the rock. This hotspot on the rock, rather than the yellow flash or sparks or metal fragments, was observed to be the cause of the ignition.

Jan 1, 1974

By John B. Shutack

In an effort to improve the performance of the explosive-anchored rock bolt, the Bureau of Mines studied the effect of the detonation velocity of the explosive and type of charge (linear or nonlinear) on the fracturing tendency of the anchor tube. Also, different types of tubing were compared to determine the one most suitable for use as an anchor tube. The Bruceton up-and-down method was applied in tests in which steel shooting blocks having boreholes ranging from 1-3/8 to 2-1/8 inches in diameter were used. Of the four types of tubing evaluated, a welded A-178 tubing that was drawn over a mandrel and renormalized gave the most promising results. The A-179 seamless tubing that is normally used with the explosive bolt was the most inferior. Both types, however, gave significantly better anchorage than the conventional shell when tested in both laboratory and underground experiments. Within the range of velocities studied (5,000 to 7,000 m/sec), the type of explosive showed no significant effect on anchor-tube performance. In general; linear explosive charges provided better anchorage than nonlinear charges.

Jan 1, 1968

By Ivette E. Torres

For a study such as this, which summarizes and amalgamates much information collected, compiled, and utilized by the numerous U.S. Bureau of Mines country specialists and branch chiefs for inclusion in their country and regional reports that comprise the five other sections of 1992 Minerals Yearbook-International Review, it is clearly impossible to cite all sources of information used in its presentation, but some recognition is due. Generally speaking, this study and its related detailed studies on countries and areas would be much more difficult, if not impossible to complete, without the efforts of the personnel of our counterpart national mining and geological agencies throughout the world. Information that they collect, compile, and then publish, either in their own volumes or those of central statistical agencies in their countries, are the foundations on which this work rests. Thus, our appreciation is expressed to the multitude of persons employed by these agencies for their contributions.

Jan 1, 1994

By K. O. Bennington

The thermodynamic properties of synthetic acmite, NaFe3+Si206, were determined by the Bureau of Mines. The enthalpy of formation was determined by hydrofluoric acid solution calorimetry. The values of the standard enthalpy of formation at 298.15 K, ?Hf°298.15, from the elements and from the oxides, ?H°298.15, are ?Hf°298.15 = -615.87 ±0.71 kcal/mole, ?H°298.15 (from oxides) = -32.08 ±0.53 kcal/mole. Various experimental data were combined with other data from the literature to calculate all the related thermodynamic properties in the range of 298 to 1,263 K. The standard Gibbs energy of formation is ?Gf°298.15 = -575.8 kcal/mole.

Jan 1, 1981

By H. S. Chiang, Zhao. Y. F., G. C. Sun, S. S. Peng

"Chiang; H. S. West Virginia UniversityPeng, S. S. West Virginia UniversitySun, G. C. West Virginia UniversityZhao, Y. F.West Virginia UniversityDust sampling was performed in two longwall faces working in two separate seams. Instantaneous dust samples were measured by RAH's. for various locations In the longwall faces. Preliminary analysis of the data shows that in addition to the shearer's haulage speed, there are four major factors that influence the airborne dust distribution in longwall face areas: locations with respect to the position of the shearer's cutting, hardness of the materials, characteristics of water spray, and roof conditions. This paper presents the effects of those four parameters in detail.INTRODUCTIONA research project was initiated in September 1983 to measure and construct .a dust distribution map for the longwall face. During the first year, airborne dust samplings were performed in two longwall panels located in northern and southern West Virginia and working in the Pittsburgh and Eagle Seams, respectively. The physical parameters and equipment employed for both panels are 1 isled in Table 1. Figure 1 shows the detailed characteristics of the coal seams. Notice in both panels floor cutting was involved either to gain sufficient mining height or to reduce the adverse effects associated with a soft floor.The purpose of the research is to define the dust distribution at any instance in the longwall face area so that proper working positions can be determined and/or effective dust control techniques can be developed.This paper presents the partial results obtained during the first year."

Jan 1, 1988

"An active list of permissible explosives was published in September 1935 as part of United States Bureau of Mines Report of Investigations 32S6, under the title ""Active List of Permissible Explosives and. Blasting Devices Approved. Prior to July 31, 1935."" This list included 154 brand names,Changes in the list that have been authorized subsequently placed 24 addi¬tional brands of permissible explosives on the active permissible list as a re¬sult of tests, changes in brand names, or transfer from the inactive list. Eight permissible explosives were transferred from the active to the inactive list. The present active permissible list contains 170 brand names. The brand names of the permissible explosives placed on the active list are as follows:Black Diamond Nu-Gel No. 4 By test.Black Diamond Special A,do.Burton 11, L. F. By change in name,Burton G, L. F. By test.Columbia B By change in name.Columbia C Do.Columbia D Do.Columbia E Do.Columbia. F Do.Columbia G Do.Columbia 1 Do.Columbia 2 D.Columbia 3 DoColumbia 4 Do.Columbia-Gel 1 Do.Columbia-Gel 2 Do.Genite 5, Do.Genite 7, Do.Genite G Do.Lump Coal C By test.Peerless No, 1 By transfer from inactivePeerless No. 8, L. F. Do.Tri-State Special No. 1 Do.Unilite No. 2 Do."

Dec 1, 1936