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By Richard A. Allwes

This U.S. Bureau of Mines report presents the results of structural analyses and full-scale physical tests conducted on a steel-set arch and tri-set. The purpose of the analyses and tests was to evaluate the suitability of these structures for use in roof-fall prone areas. The arch canopy test and design procedures previously developed by the Bureau were utilized in this evaluation. Theoretical resistance functions were established for the steel-set arch and tri-set and were representative of the experimental behavior of the structures. The resistance functions were used to determine the energy absorption capacity of the structures and to predict their dynamic response to impact loading. The dynamic tests demonstrated that the arch canopy design procedure is appropriate for tri-sets and yields conservative designs for both steel-set arches and tri-sets. As a result of this work, it is recommended that these two structures may be considered for use in roof-fall prone areas and for rehabilitation work, provided the arch canopy design procedure is utilized for each application and the principles underlying the design procedure are understood.

Jan 1, 2010

By T. E. Gray

This report describes the preparation characteristics of the more significant coalbeds in Monongalia County, W. Va. It is one of a Bureau of Mines series planned to determine coals suitable for producing metallurgical coke, either as mined or after beneficiation. Over 9.5 million tons of coal was produced in Monongalia County in 1957, of which more than 7 million tons was cleaned mechanically in 8 cleaning plants. On January I, 1954 the Bureau of Mines estimated that 1,576 million tons of recoverable coal remained in the county in beds 28 inches or more thick.

Jan 1, 1960

By R. G. Gürtunca

Over the past century coal miner safety and health has seen tremendous improvements, the fatality and injury rates continue to decrease while productivity continues to increase. Many of the hazards that plagued miners in the past, such as coal bumps, methane and coal dust explosions, ground fall accidents and health issues have been significantly reduced. The contribution of NIOSH research includes products for prevention and survival of mine fires, methane control measures, design procedure for underground coal mines, methods for excavation surface controls, methods and procedures for blasting, laser usage in underground mines and prevention of electrocution from overhead power lines that have reduced accidents and injuries in underground coal mines. Health research has produced products such as the personal dust monitor, noise abating technologies and ergonomic solutions for equipment operators. Research priorities at NIOSH are set by considering surveillance statistics, stakeholder inputs and loss control principles. Future research in coal mining is directed towards respiratory diseases, noise induced hearing loss, repetitive musculoskeletal injuries, traumatic injuries, falls of ground and mine disasters. The recent spate of accidents in coal mines resulted in the Miner Act of 2006 which includes a specific role for NIOSH in future mine safety research and development. The mine safety achievements in the USA reflect the commitment of industry, labour, government and research organizations to improving the safety of the mine worker.

By G. W. Birge

Fifteen coal samples, representing the Winifrede, Chilton, Alma, No. 2 Gas, Powellton, Eagle, Douglas, Sewell, Beckley, Pocahontas No.4, and Pocahontas No.3 beds in Wyoming County, and five samples, representing the Fire Creek, Pocahontas No.6, and Pocahontas No.3 beds in Mercer County, W. Va., were carbonized at 9000 C by the Bureau of Mines-American Gas Association (BM-AGA) method, and yields of products and physical properties of cokes were determined. Expansion characteristics of the majority of samples were determined in the Bureau of Mines sole-heated oven. Chemical analyses and agglutinating values were determined for all coals. The coals were mostly strongly coking and low in ash and sulfur content. Dry, mineral-matter-free fixed-carbon content of the Wyoming County coals ranged from 63.0 to 83.4 percent. The Mercer County samples were all low volatile in rank. Yields of carbonization products were generally in accord with yields from similar rank coals of the Appalachian region. Because of their expanding tendencies, most of the medium-and low-volatile coals would require blending with lower rank coal for normal coke production.

Jan 1, 1965

By Mark Sheppard

This paper is the second of a series recording the results of tests made at various quarries throughout the United States to determine, (1) the relation between the size gradation of feed to, and product from, primary crushers; (2) the particle shape of crushed product; (3) the differences in gradation and particle shape produced by different tries of primary crushers; and ( 4) the differences in gradation and particle shape caused by crushing different kinds of stone. Primary crushing has received comparatively little attention in the technical literature in spite of tine fact that the design of the whole crushing plant should be correlated to the performance of the primary crusher.

Jan 1, 1938

By R. D. Leitch

"The pollution of streams has received much attention during the last few years, and although there are many other and more serious forms of pollution, the problem of acid mine drainage is important in certain sections of the country, particularly in Pennsylvania. At the request of the United States Public Health Service the Bureau of Mines undertook to determine some of the factors contributing to formation of acid mine waters, the yearly variations in quantity and quality of drainage, effect of mining methods, and various other questions arising in connection with the problem; some attention was also given to its economic phases.In acknowledgment, the writer wishes to thank Dr. R. R. Sayers, Chief surgeon; A. C. Fieldner, chief chemist; and W. P. Yant, supervising chemist, health laboratory section of the Pittsburgh Experiment Station, all of the Bureau of Mines, under whose direction the work was conducted.Because no data of a like nature had previously been determined, and with the thought that such data would throw additional light on the general subject, a stream having a number of mines draining into it was selected for observation in both high-sulphur and low-sulphur bituminous-coal districts, as designated in commercial rating. These mines and streams were visited in both wet and dry seasons to note the quantity and variations in acidity of mine drainage and the subsequent effect on streams. Maps of these streams with the sampling points are shown in Figures 1 and 2. In a report of this nature a great deal of tabular data is best emitted, but reference to the maps will serve to indicate the factors that determined sampling points, such as tributary streams and gobs."

Sep 1, 1928

By H. C. Carpenter

Data are presented comparing results obtained with 17 different catalysts in hydrogenating crude shale oil to gasoline in single-pass operation. A method is described for predicting the maximum yield of gasoline obtainable at constant pressure for each catalyst from results of a limited number of experiments at different temperatures. Operating variables have considerable influence on yields and properties of products. With most of the catalysts, at operating temperatures below 890° F. liquid yield exceeded 100 volume-percent. Above this temperature the volume of liquid product decreased rapidly. Maximum gasoline production in most instances was achieved at a temperature higher than that at which the maximum volume of liquid product was produced.

Jan 1, 1959

By Irving Hartmann, Edward Thomas

"INTRODUCTION Adoption of rubber-tire shuttle cars underground in conjunction with mobile coal-loading machines has introduced new problems in the control of dust on mine roadways. Where this type of loading and transportation is used, development and extraction are generally rapid, with the result that much coal is spilled from the shuttle cars during normal operation, Coal in the roadways from this source and from sloughing of the ribs is ground to fine dust by the wheels of the 'shuttle cars and by the treads of the loading and mining machines. The coal dust usually is somewhat contaminated by pulverized rock, and the mixture could not be loaded with the run-of-mine coal without undue contamination of the product even if it were cleaned up promptly.The presence of large quantities of fine, loose dust, which is constantly stirred up and kept in suspension in air by the traffic, constitutes a grave explosion hazard, reduces visibility along the roadways, and is physiologically harmful to the workmen who breathe the air. From the operating standpoint the loose material is undesirable along the roadways because it provides poor traction for the trucks and thereby increases wear and power consumption. The dust-explosion hazard could be eliminated or reduced by frequent application of sufficient rock dust on the roadbed; but this would not remedy the other difficulties, and in fact it might intensify them. Where practicable, the most direct and effective safety measure is to clean up and remove promptly all dust that forms and settles on the roadways. Unfortunately, in many cases this procedure is not feasible. A third Suggested remedy is to prevent dispersal of the dust into the air and to promote its consolidation on the floor by wetting the dust particles.During the past few years several mines have used calcium chloride on shuttle-car roadways to allay the dust thereon. When exposed to the' humid atmosphere of the mine this salt absorbs Moisture from the air and deliquesces, and in this way wets the dust on the floor of the roadway. In a survey conducted in coal mines in southern West Virginia and in eastern Kentucky where calcium chloride has been in use, somewhat conflicting re- ports were received regarding the merits of the application, and several operators have abandoned the practice either because of actual or assumed disadvantages. The purpose of the study described in this report was to collect and correlate evidence and, on the basis of experimental data obtained in the field and in laboratory tests, to present a clearer picture of the factors involved in the allaying of dust by use of salts."

Sep 1, 1945

By Thomas V. Falkie

The new international fact of life that has emerged in the 70's is that foreign energy sources can no longer be considered either reliable or low in price. As a result, the United States is turning its full attention to its domestic energy resources. The figures about proved domestic reserves are often used to reassure us about the Nation's energy future: assuming a 50 percent recovery factor, there are at least 219 billion tons of recoverable bituminous coal and lignite, of which 31 percent is available by surface methods; proved reserves of crude petroleum and natural gas liquids total 34.3 billion barrels and 6.4 billion barrels, respectively. There is also about 4 billion tons of recoverable anthracite coal, a premium low-sulfur fuel of high heating value, which is all but priced out of the market because of the high costs of producing it. Total fossil fuel resources are even larger, although there are no guarantees concerning how much might become usable, and when, and at what cost. The figures, however, are impressive. They include the equivalent of about 200 billion barrels of oil potentially recoverable from high grade oil shale; 100 billion barrels in "heavy oil" deposits; and the equivalent of 25 to 35 billion barrels of oil in domestic deposits of "tar sands," and substantial quantities of conventional oil and gas resources. There is also the prospect of a significant increase in electric power generation

Jan 1, 1975

By C. B. Manula, R. L. Sanford, R. A. Rivell

Part I. DATA INPUT ALTERNATIVE 1

Jan 1, 1974

By R. R. Wells

As a part of the strategic minerals program of the Bureau of Mines, nine chromite-ore samples were obtained during the period 1949-56 from mines in the vicinity of Red Mountain, near Seldovia, Kenai Peninsula, Alaska. This report summarizes the results of beneficiation studies of the samples at the Bureau's Juneau, Alaska, and Albany, Oreg., laboratories. In general, the ores were found amenable to concentration by gravity methods for producing concentrates that assayed over 48 percent chromic oxide. Intimate association of chromite and gangue minerals, however, necessitated fine grinding and limited the amount of chromite recoverable. Recovery of chromium in concentrate that assayed 48 percent chromic oxide or higher ranged from approximately 20 percent for low-grade ores (10 to 12 percent Cr203) to more than 95 percent for 1 high-grade sample (42 percent Cr203). The iron content of the chrome-bearing mineral -hence, the chrome/iron ratio of finished concentrate -appears to vary with the grade of the ore. Concentrates made from high-grade ores had chrome/iron ratios as high as 3.1:1; the concentrates from low-grade ores, however, had chrome/iron ratios as low as 1.8:1.

Jan 1, 1957

By Dupuy. Leon W.

"INTRODUCTION For many generations the Indian tribes of the southwestern deserts knew of the thermal springs of the Coso District in southwestern Inyo County, Calif. Belief in the reputedly healing qualities of the waters and muds of the area was widespread. F. J. Sanders discovered mercury in the siliceous sinter around the hot springs while he was exploiting the district as a health resort. In searching for new domestic sources of supply of strategic minerals, authorized under the Strategic Materials Act, 3/,the Geological Survey 4/ first examined the deposits, which were drilled and sampled by the Bureau of Mines in the spring of 1941.The deposits investigated comprised three units known, respectively, as The Devils Kitchen, Nicol, and Wheeler. Most of the work was done at the first two.Of particular interest in the Bureau's work on the project was the adaptation and use of the bucket drill as a tool for sampling shallow, soft ore deposit."

Mar 1, 1948

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 Constantine C. Popoff

The Hermada antimony deposit is in the Sewtooth Range in southwestern Idaho, about 77 miles by road northeast of Boise. Stibnite mineralization occurs over an area one mile wide from west to east and two miles long. It is locally referred to as the Swanholm district. In 1947 high- grade stibnite ore was discovered on the East Fork of Swanholm Creek. Since then, ore in commercial quantity has been produced by the Hermada Mining Co. The total output for 1947-50 was about 5,000 tons of ore, containing 640 short tons of antimony metal.

Jan 1, 1953

By J. E. Doo1ey

To process and use the heavy ends of petroleum effectively, the development of suitable separation and characterization procedures not currently available was required. A systematic procedure was developed by the Bureau of Mines using such techniques as isothermal and molecular distillation, chemical treatment, silica-alumina gel chromatography, gel permeation chromatography, and spectrometry. Using these techniques, the Bureau achieved a detailed separation and characterization of a 370° to 535° C distillate from Gach Saran, Iran, crude oil. Such a systematic procedure and the semiquantitative data resulting therefrom should be of value in selecting feedstocks and in optimizing petroleum processing operations.

Jan 1, 1973

By Lloyd Williams

A vertical air shaft in the Birmingham, Ala., iron district was sunk with a circular cross section and lined with concrete at a relatively low cost to provide needed ventilation for an iron-ore mine. The method of sinking the shaft is described, and the costs are stated in mar-hours with a descriptive list of equipment and a statement on the size and use of temporary buildings. Preparation began May 2, 1955, and the shaft was completed at a depth of [680] feet by September 22, 1956. By October 1956, all temporary building and [aft]-sinking equipment had been removed. The total direct-labor cost for the operation, including preparation and dismantling, was 50,700 man-hours, or 30.2 man-hours per foot. Total rock and dirt removed amounted to 17,523 cubic yards (in place), and the shaft lining required 4,635 cubic yards of concrete to form a circular air shaft with an inside diameter of 16 feet.

Jan 1, 1960

By Fred N. Kissell

In This Chapter [Instruments available to measure methane in mines and tunnels Using a portable detector in both accessible and restricted spaces Machine-mounted monitors: placement and response time Calibration of catalytic detectors for different gases and Misinterpreting warning signs This chapter gives guidelines for methane measurement in mines and tunnels. The emphasis is on the measurement procedure and the interpretation of the measurement rather than on the instrument itself.] The failure to properly sample for methane is a major contributing factor to methane explosion risk. Sampling errors are most likely to occur at mines or tunnels where the presence of methane is not suspected or during nonroutine tasks at mines or tunnels known to have gas. More specific information on methane sampling at continuous miner sections is in Chapter 3. Chapters 4 and 5 discuss sampling at longwall sections, and Chapter 14 discusses sampling at tunnels. METHANE DETECTORS FOR MINING Many models of gas detectors are available to measure methane concentrations, as well as most of the other contaminant gases found in mines and tunnels. An example is the iTX Multi-Gas Monitor, a portable gas detector available from Industrial Scientific Corp., Oakdale, PA. This handheld instrument measures several gases simultaneously. The cost (2004) ranges from $1,300 to $2,200, depending on the number of gases measured. Similar instruments are available from other manufacturers. Most methane detectors used in mining use a catalytic heat of combustion sensor to detect methane and other combustible gases. These have been proven through many years of reliable operation. For detection of methane, proper operation of catalytic heat of combustion sensors

Jan 6, 2006

By M. S. Seehra, V. S. Babu

"INTRODUCTION The accurate determination of the free silica index in coal mine dusts is an important requirement because severe health hazards are believed to be associated with the inhalation of respirable-sized silica particles.1-6 Free silica refers to the three polymorphs of silica (Si02)viz., quartz, cristobalite, and tridymite-although quartz is usually the dominant form in most mine dusts.6 The free silica index is the concentration in micrograms of free silica in air per m3 of air sampled corrected to standard conditions of 25°C and 760 mm/Hg, the present MSHA (Mine Safety and Health Administration) limit on time-averaged basis being 100 µ.g/m 3 for coal mines. A recent review7 has concluded that quartz, cristobalite, and tridymite particles impart nearly equal long-term hemolytic damage when compared on a per unit surface area basis.At present, two experimental methods-viz., transmission infrared spectroscopy (TIRS) and x-ray diffraction (XRD)-are commonly used for the determination of silica concentrations in mine dusts. In TIRS, which has been adopted by MSHA and is commonly called the P7 method, the silica absorption band near 800 cm - 1 is used for quantification. However the mineral kaolinite, which is commonly present in mine dusts, also has absorption band, albeit weaker, at 800 cm- 1• To correct for this interference, one uses the stronger 915-cm -1 band of kaolinite to determine the concentration of kaolinite, and the kaolinite contribution to the absorbance at 800 cm-1 is then determined from a calibration curve, leading to the determination of silica by subtraction. In the XRD technique, usually an internal standard such as CaF 2 is used to determine the concentration of silica from line intensity measurements. XRD has the added advantage that concentrations of quartz, cristobalite, and tridymite can be determined.8•9 In an exhaustive study on the precision of the techniques ofTIRS and XRD for monitoring worker exposure,9 the conclusion has been reached that both methods measure silica within 253 of the ""true"" value 953 of the time in a single laboratory."

Nov 1, 1995

By E. R. Palowitch

Coal wasted with mine refuse represents losses in overall recovery of merchantable coal to the mine operator and a concomitant reduction in domestic reserves of available coal. Fraser, Kelley, and Graham3/ in studying the available coal in mine refuse in the Pittsburgh district of western Pennsylvania have estimated that at least 1 ton of mine refuse is produced for each 10 tons of merchantable coal and that 20 percent of this mine refuse might be recovered as salable coal by mechanical cleaning. SUMMARY This investigation dealt with the mechanical recovery of coal from wine refuse by a dense-medium washery employing pulverized mine rock as the dense medium and operating at a rate of 175 tons per hour. Two types of mint refuse were tested: Freshly mined and that .which had been mined 2 years before and piled on a waste dump.

Jan 1, 1955

By Robert W. Smith

In a certain application2/ it was necessary to compute the beta function B(p, q) for a certain set of values p and q. Since t he set of p and q values was much mo re finely spaced than those in any published tables, the authors decided to make their results available in this report. In connection with this application the functionB(p, q) was needed at various points in the p, q plane at intervals of 0.05, 0.05<p = q< 10.00. Fletcher, Miller, and Rosenhead2/ state that the only tables available in the desired range are those of Rearson.4/ However, the interval used by Pearson was not small enough for the present application. For this reason it was decided to calculate B(p, q) for p = q =0.05 (0.05) 10. 00.2/ This table is published because of the fundamental importance in mathematical analysis of the complete beta function.

Jan 1, 1953