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By Steven J. Schatzel, Robert B. Krog

Frictional ignitions are defined as the ignition of a flammable mixture of methane and air that is initiated by frictional heating. Ignitions created through the addition of energy from open flames and exposed electrical circuits are not included in this analysis. Energy released in a roof fall that creates a spark and ignites a methane mixture would be considered a frictional ignition. Frictional ignitions represent the majority of all ignitions in underground coal mines. Over the study period of 1983 to 2005, a total of 1993 ignitions were reported in underground bituminous coal mines in the United States, of which 1589 were frictional ignitions. Reportable ignitions to the Mine Safety and Health Administration (MSHA) are any unintentional occurrences of flame underground regardless of duration. Frictional ignitions were reported in 155 mines and 13 states. Continuous miners represented the largest source for frictional ignitions with 1090 (68.6% of all frictional ignitions). Longwall mining operations represented the highest concentration of frictional ignitions during this study period with 1365 frictional ignitions (85.9% of all frictional ignitions). The 17 mines with the most frictional ignitions were all longwall mining operations and had 1130 frictional ignitions (307 from the shearer) that represented 71.1% of the total. In 1983, mines with frictional ignitions represented 6.9% of operating underground mines and 36.6% of total underground coal production. The percentage of operating underground mines with frictional ignitions and their total production has increased steadily and in 2005 represented 9.8% of active mines and 46.2% of underground coal production. The three coalbeds with the highest number of frictional ignitions (Blue Creek, Pittsburgh No 8, and Pocahontas No 3) had 1049 ignitions that represented 66.0% of all frictional ignitions. The three states with the highest number of frictional ignitions were Alabama (710), Virginia (247), and Pennsylvania (242) that represented 75.5% of the total. Frictional ignitions peaked in 1991 with a high of 114. In 2005, only 34 frictional ignitions were reported. If only frictional ignitions that occur at the face are considered, there have been no fatalities since 1983. Since this time, there were 33 ignitions that caused 53 workers to lose a total of 2912 working days. When including ground falls, then there have been four frictional ignitions with one incident causing two fatalities and injuring eight workers. From 1983-1991, underground productivity and the number of frictional ignitions increased. However, productivity continued to increase from 1991-2000 while total frictional ignitions fell, thereby disproving this connection between productivity and frequency of frictional ignitions. Ninety percent of all frictional ignitions occurred in underground coal mines that liberated more than 393 L/s (1.2 MMcfd million cubic feet per day) of methane through the main ventilation system. Although methane production is not the determining factor for the occurrence of frictional ignitions, it is a good indicator of the anticipated frequency.

By Phillip Allender, Wolf Karo, Knox Van Dyke, Lixin Wu, Ali Ardekani, Jorge Garcia, Jaime Gutierrez

"We report that two different micropolystyrene round beads linked to either luminol or lucigenin have been developed. The 1-µ.m-diameter beads arc useful reagents that allow one to perform chemiluminescent (light producing) phagoeytic reactions without opsonization. It is known that luminol reacts with peroxidases (e.g., myeloperoxidase) while lucigenin reacts mainly with superoxide anion. Luminol and lucigenin beads produce cellular chemiluminescence (CL) with neutrophils, macrophages, monocytes, and differentiated human promyelocytic leukemic cells (HL60). When myeloperoxidase (MPO) is present luminol beads evoke higher CL from neutrophils, but when little or no MPO is present, lucigenin beads produce higher amounts of light. Lucigenin beads appear to be active inside these cells where unbound lucigenin does not enter freely.INTRODUCTIONA variety of cells, e.g., neutrophils (Ns) and macrophages (Ms), can engulf foreign particles (1). This engulfing or phagocytic activity is used by the body to kill bacteria and to eliminate foreign particles such as respirable dusts, e.g., coal, silica, or cotton. The neutrophil engulfs or phagocytizes bacteria which are coated with plasma antibodies and/or complement proteins (Fig. 1). The coating or opsonization allows the neutrophil to recognize foreign substances. Usually the absence of opsonization prevents the cell's recognition of a foreign particle and the particle is not phagocytized. Macrophages, particularly the alveolar Oung) cells, do not require opsonization for phagocytosis. Ms should not be selective toward individual dusts because they serve a major role in eliminating a variety of these.Particle size can also be a factor. Usually a particle with a diameter of 0.5-5 µ.m is considered in the respirable range. Larger particles are trapped before they reach the alveoli Oung spaces where oxygen exchange with blood occurs), ·and smaller particles do not generally settle, and are not engulfed by macrophages (2). Tabato and Ikada (3) found that maximal phagocytosis of microspheres takes place when their diameter is in the range of 1.0 to 2.0 µ.m. In addition, they found that beads with hydrophobic surfaces were more readily phagocytized than hydrophilic surfaces."

Jan 1, 1990

By Vibration Research Group, Natasha K. Lee Shee, Tammy R. Eger, James P. Dickey, Paul-Émile Boileau, Lana M. Trick, Michele L. Oliver

Introduction Industrial exposure to whole-body vibration is associated with injury and discomfort. Certain industries, notably mining, construction, and forestry, involve complex 6 degrees of freedom vibration. Laboratory-based studies of vibration are essential for controlled and systematic evaluation of the human responses to vibration2. The purpose of this pilot study was to evaluate whether the duration of the vibration exposure, and rest between vibrations, significantly influence the subjective ratings of comfort during laboratory-based studies of vibration. Methods Subjects: The cumulative vibration dose was calculated, and was below the health guidance caution zone recommended by International standards3. The experimental procedures were approved by the University of Guelph Research Ethics Board. Ten adult subjects participated in this pilot experiment. All subjects completed the entire experimental paradigm; no subjects complained of pain during or after the experiment. Experimental Design: The experiment consisted of four blocks of vibration exposures; either 15 or 20 seconds of vibration (1 df:Z axis, 3 df:XY plane, 3df:YZ plane, or 6 df) alternating with either 5 or 10 seconds rest. The order of presentation of the four blocks was randomized. Each of the blocks was composed of 37 individual sinusoidal vibration exposures in randomized sequence. This abstract focused on ten identical trials, (6.3 Hz vertical vibration, 0.55 m/s2 RMS) interspersed within each block, in order to assess whether the subjects’ comfort ratings systematically varied between the 15 or 20 vibration exposures, the 5 or 10 second rest between vibrations, or within each block. The experiment involved 43 minutes of vibration within the 62 minute experiment. Vibration Apparatus: A commercial parallel robotic platform was used to apply the specific vibration exposures (R2000, Parallel Robotics Systems Corporation, Hampton, New Hampshire). The subjects sat on a passenger seat from a 1992 Honda Accord that was rigidly mounted to the robotic platform (Figure 1). This robotic system performed the specific vibration exposures operating under closed-loop displacement control. A custom-written Matlab program automated the testing sequence.

Jan 6, 2006

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigations beginning with No. 4251, of which this is the fifteenth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by halt townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 halt-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The Descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each halt township is given with the discussion covering that area.

Jan 1, 1948

By Michael S. Contratto, Dave Marshall, Tom Brodersen

The European Union (EU) completed a new directive 2002/44/EC1 called the Physical Agents Directive (PAD) that establishes action and limit values for hand-arm and whole body vibrations. The directive specifies that: “…workers shall not be exposed above the exposure ‘limit value’.” 1 and “…once the exposure action values … are exceeded, the employer shall establish and implement a programme of technical and/or organisational measures intended to reduce to a minimum exposure to mechanical vibration and the attendant risks…” 1 The PAD limit value is effective for new machines starting July 6, 2007 and for used machines by at least July 6, 2010. These requirements apply to the users of machines, but machine manufacturers will be challenged to provide machines and information to help the users comply with the directive. Caterpillar manufactures machines with the goal of enabling our customers to comply with all regulations dealing with health and safety. Caterpillar designs all of our machines to provide a safe, comfortable and productive work environment. This study was to determine if seat suspensions could provide a reduction in the vibration environment experienced by operators of Caterpillar mid sized (<50,000KG) Track Type Tractors Methods Seat manufacturers were asked to provide seat suspensions that provide improved isolation over and above current seat suspension. Each supplier was provided with ride profiles and was asked to demonstrate the vibration reduction on a shaker table. Two suppliers provided suspensions that were compared with the current seat suspension in a field study. Three full factorial experiments were conducted. The first experiment was to evaluate overall suspension performance for four operations. The second experiment was to determine the benefit of the adjustable vertical damper at three different levels and the third experiment was to determine the effect of the fore/aft and side/side isolators. Six operators were used for the study. Acceleration was measured at the seat base and at the operator seat pad. Both the transfer function and the ISO 2631 RMS ride values were used to determine the seat suspension’s effectiveness of isolating the operator from vibration. A structured questionnaire was used to determine the operators’ subjective assessment of the seat suspensions. Results There was significant operator-to-operator variability in the vertical direction (>35%), however there was little variability in the fore/aft and side/side direction based on seat base

Jan 6, 2006

By S. H. Ash

THE ANTHRACITE region of Pennsylvania contains over nine-tenths of the total anthracite deposits of North America and produces all but an insignificant proportion of the total output of anthracite in the Nation. The whole economy of the northeastern section of the United States depends, to a large extent, on the mining of Pennsylvania anthracite, which is shipped to New Jersey, New York, and New England and is a principal source of energy and heat for that entire region. The responsibility of the Federal Government for developing an engineering method that will prevent inundation of the Pennsylvania anthracite mines and keep them in operation has long been recognized. To obtain a reliable picture of the anthracite-mine-water problem and to solve that problem, it is necessary to have factual data on the volume and the quality and character of the mine water handled by the pumping plants in the anthracite region, as well as the kinds of pumps utilized and problems concerning their operation.

Jan 1, 1953

The coal-bearing strata of Oklahoma occur in the eastern part of the state over an area of 14,500 square miles, 20.7 percent of the state&apos;s total area. Commercially valuable deposits of bituminous coal cover about 8,000 square miles in seams ranging from ten inches to five feet thick. Estimated reserves in Oklahoma are 1.6 billion tons, representing 0.3 percent of U.S. coal reserves. The vast majority of coal mined in Oklahoma used in a single power plant within the state. Oklahoma gained primacy when its regulatory program was conditionally approved January 19, 1981. Authority for the state to administer the Abandoned Mine Land program was granted January21,1982. On April 30,1984, the Office of Surface Mining substituted direct federal enforcement of the inspection and enforcement portions of the Oklahoma program. This substituted enforcement was based upon a finding by OSM that Oklahoma had not operated the inspection and enforcement portions of its program effectively. As of January 1, 1986, Oklahoma inspection and enforcement authority was reinstated. Full program authority was granted to Oklahoma on January 14, 1986.

Jan 1, 1992

By Doss H. White

In 1989, Alabama&apos;s nonfuel mineral industry produced a State record of $463 million of nonfuel mineral commodities, an increase of $4 million over that reported by the State&apos;s mineral producers in 1988. The new record marked the fourth consecutive year in which mineral production increased over that of the previous year. Alabama ranked 22d among the States in total mineral value. Cement, stone, and sand and gravel were the three leading mineral commodities produced, accounting for 77% of Alabama&apos;s total mineral value. During the year, there were several acquisitions by Alabama cement and stone companies, and the only tantalum mine in the United States completed its first full year of operation.

Jan 1, 1991

By Wallace W. Roepke

Research on coal cutting at the Bureau of Mines Twin Cities Research Center (TCRC) has evolved from a purely mechanical approach, specifically to reduce dust or frictional methane ignitions, into an understanding of the complexity of the cutting system relationships. Achieving an understanding of these relationships requires a wide variety of testing techniques and equipment. Laboratory facilities and the associated equipment exist for shallow to deep cutting in both coal and coal-inclusive rock with any desired bit type. Research efforts with this equipment are providing insight for significant advances to help solve the problems of pneumoconiosis and frictional ignition. This effort will ultimately affect both respirable dust and methane ignitions at the face through better bit design and will increase the salable percent of run-of-mine (ROM) coal processed. It will also affect the design of rotary-drum cutting continuous mining machines (CMM) and longwall machines. This report describes the main features of the coal cutting research facilities at TCRC.

Jan 1, 1983

By L. Cheng

This report describes a laboratory investigation of the effectiveness of low-pressure steam and a steam-water spray sequence for the collection of airborne respirable (<10 µm) coal dust. Comparison of present results to previous results obtained with water spray alone indicates that the use of steam in a steam-spray sequence increases the collection efficiency by about 14 percent over that obtained by water spray alone. However, the use of steam to collect airborne dust requires cooling the steam-dust mixture in order to achieve condensation of the steam, and steam does not appear to be an attractive approach for collecting airborne dust in underground coal mining operations.

Jan 1, 1974

By Charles L. Kimbell

The year 1986 was not a good year for the world&apos;s mineral industry from several viewpoints. Levels of production, both of crude minerals and processed forms, registered declines in the cases of a greater number of commodities than the number that recorded increases. The overall value of world crude mineral production was estimated to have increased, but only very slightly in terms of constant dollars to nearly $997 billion. Although there were modest increases in the consumption of all major fuels and most major metals, the latter at least apparently resulted more from drawdowns of inventories than from increased production (fuel consumption increases did come from higher output levels), and consumption of most major fertilizer and chemical commodities (nitrogen, phosphate, and sulfur) were at lower levels than those in 1985. Prices for a number of mineral commodities declined, headed by the very substantial drop in world crude petroleum prices, but also including downturns for a number of metals and industrial minerals as well. There was insufficient information to reliably fix the level of the dollar value of world trade in minerals, for while output was up in the case of some large-volume materials such as iron ore, coal, and crude and refined petroleum, suggesting that the volume of trade in physical units may have increased, declining prices may well have offset quantitative gains.

Jan 1, 1988

By Tobias W. Goodman, George N. Aul, Joseph Cervik

The Bureau of Mines conducted research to degasify a virgin block of coal in the Beckley Coalbed using long horizontal holes drilled in an array from the bottom of a ventilation air shaft. Eight horizontal holes and an in situ pressure hole were drilled in a radial pattern to depths ranging from 418 to 910 ft (127 to 277 m) and 205 ft (62 m), respectively. The investigation showed the shaft was in a basin saturated with water, which resulted in low gas flows from holes. The in situ pressure at 200 ft (61 m) into the coalbed was 79 psig (544.6 KN/m2). The aver- age gas and water flows for the eight holes were 94,100 ft3/day (2,665 m3/day) and 13 gal/min (49.3 l/min) . After 514 days of degasification, 18.7 million ft3 (0.53 million m3) of gas had been drained. Methane face emissions, which were measured as a section advanced toward the shaft, were reduced about 77 pct, emphasizing the value of drainage by this technique. All holes were grouted before the area around the shaft was mined.

Jan 1, 1982

By Frank G. Schwartz

VARIABLES OF composition and environment affecting storage stability of gasoline-type fuels were studied, utilizing radioactive tracers and other analytical techniques. Changes in gasoline composition brought about by aging were determined and correlated with gum formation. The amounts of reaction of selected gasoline components, measured by radioactive tracers, were determined in a gasoline-type blend and in a mixture of 17 selected pure gasoline components. The data show that sulfur compounds, nitrogen compounds, polycyclics, and olefins enter into gum-forming reactions. Certain sulfur and nitrogen compounds were found to be most reactive in the gum-forming process. Results of this study indicate that the aromatic constituents of gasolines may contribute substantially and directly to gum formation. A mixture of tetralin and indan-type compounds is reactive, and this mixture appears to be the main aromatic portion entering into gum formation. A secondary but significant amount of naphthalenes also appears to have reacted in the gum-forming process. Analyses of the sulfm compounds in a fresh and an aged fuel indicated that elemental sulfur, hydrogen sulfide, thiols, sulfides, and disulfides were depleted during aging, but thiophenes and residual sulfur compounds were not depleted by fuel deterioration.

Jan 1, 1964

By A. R. Kirchner

This paper describing the practice at the concentrator of the Minas de Matahambre, S. A., is one of a series being; prepared by the Bureau f Mines on milling methods and costs. The Minas de Matahambre, S. A., concentrator treats the production of the Matahambre mine and has a capacity of 1,300 tons of copper ore per day by selective flotation. During the year 1930 the heads averaged 4.55 per cent copper, the concentrates 29.20 per cent copper and the recovery was 95.96 per cent.

Jan 1, 1931

By Henry P. Chandler

TONNAGE of natural abrasives sold or used in the United States in 1959 increased 12 percent. Artificial abrasives produced in the United States and Canada jumped 24 percent. Imports, exports, and reexports of abrasive materials also showed gains. Sales of grinding wheels were up 33 percent and coated abrasives 17 percent. FOREIGN TRADE Imports of abrasive materials totaled $91 million, an increase of nearly 51 percent over 1958. Chief commodities contributing to [ ]

Jan 1, 1960

By J. S. Walker

The Bureau of Mines monitored surface subsidence and water level fluctuations in 10 shallow observation wells above a series of four adjacent longwall panels in southwestern Pennsylvania, for about 4 yr. This study attempted to correlate the changes in the water levels within the observation wells to the measured vertical and horizontal ground movements associated with subsidence. Results of this study indicate that the fluctuation of the water levels appears to be a function of the well location relative to the mine layout and the proximity of mining. Wells are generally unaffected by mining of a preceding panel unless they are located within the angle of draw for that panel. Wells located at the centerline of a longwall panel exhibit the greatest fluctuation and head loss. This relationship may be related to the strain developed by the advancing longwall face. The water levels in the wells monitored fell at the greatest rate when the ground surrounding the well was in tension. The rate of the decline decreased as the dynamic development of the strains was changing from tension to compression. The water levels were found to be near the premining level before the ground was subject to maximum compressive strain. Nine of the ten wells investigated recovered to their premining water level after mining was completed.

Jan 1, 1988

By Gwendolyn D. Hood

The Bureau of Mines investigated techniques for dewatering slurries from talc-processing operations to improve water reclamation and pro-duce dewatered solids suitable for disposal. Various flocculating reagents were evaluated, and a nonionic polyacrylamide was found to be most effective in a specialized flocculation dewatering technique. The flocculation dewatering method was applied in laboratory batch tests and in continuous tests using a static screen, a belt-roller device, and a clarifier-thickener laboratory unit. In continuous tests using the unit, wastes of 3.5 pct solids were dewatered to 56.9 pct solids using 0.03 Ib of flocculant per ton of dry solids treated.

Jan 1, 1983

By J. F. Barkley

Two major problems in the operation of air preheaters for boilers are corrosion and the accumulation of deposits on the heating surfaces. Corrosion or loss of metal necessitates replacement of parts; the accumulation of deposits decreases the size of the gas and air passages, resulting in increased pressure drop for the same gas flow, and also affects the heat transfer. These items, either singly or together, limit the capacity and efficiency at which the equipment can be operated and affect its availability, even causing undesirable shutdowns under extreme conditions The field and laboratory work on regenerative air preheaters described in this report covers research on the relative corrosion resistance of different materials, such as various metals, special metal coverings, and fired clays, and studies on deposits, their nature, analyses, and corrosive effects. This is the first report on cooperative work of The Air Preheater Corp., of New York City, and the Federal Bureau of Mines.

Jan 1, 1953

This manual provides instructions for installing, operating, and maintaining a protective canopy on the Joy Mfg. Co. loader. These instructions are based upon two actual install .at ions: one made in a mine on loader, model 14BU10-11AH, and one in the factory on model 14BU10- 11AH. The parts list and engineering drawings for the protective canopy are included at the end of the manual. And a discussion of some alternative design concepts is also included. The manual can also be used for retrofitting other loaders with similar protective canopies. Skilled mechanics can determine if the instructions herein would be applicable to the other loaders and can determine any necessary modifications if they are not.

Jan 1, 1973

By E. W. GOODWIN, V. F. Parry, J. B. Goodman, L. D. Schmidt, J. D. Davis, A. C. Fieldner, W. S. Landers, J. L. ELDER

The Heliopore process is essentially an arrangement that uses the waste heat in the exhaust gas of an internal - combustion engine to carbonize coal (noncaking ) or lignite . The gases distilled from the coal furnish fuel for the internal - combustion engine , which drives an electric generator . Thus the main products of the plant are electricity and char . A flow diagram illustrating the principles of operation of the Heliopore process is given in figure 1. The primary equipment consists of a carbonizing retort , gas cooling and scrubbing equipment, a gas storage holder, and an engine to burn the gaseous carbonization products . Coal is charged into the top of the retort while the hot gases from the engine travel upward through special ducts in the retort countercurrent to the coal flow . The hot gases never come into direct contact with the coal . Char is discharged at the bottom of the retort and hot gases at the top . The gaseous products resulting from carbonization of the coal are drawn off by an exhauster through the condensing and scrubbing equipment to take out tar and liquor , then to a gas holder , and finally are burned in a gas engine . The gas engine drives an electric generator and the engine exhaust gases are returned to the retort to carbonize coal . The entire process was intended to be continuous and self - sustaining, and to use coal as the only fuel . The plant may be said to be a large - scale pilot plant in that , although it is of full commercial size , its main purpose is to provide data for the design of others of its type . The installation tested had a daily throughput of about 4 tons of coal . Figures 2 , 3 , and 4 picture some details of the plant and equipment used in the experimental testing . Further details of the equipment and engineering drawings of the castings are shown in figures 8 to 22 in the Appendix .

Dec 1, 1943