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From the time of its establishment in 1910, the Federal Bureau of Nines has studied the carbonization of coal, and a considerable part of this effort has been devoted to investigations in the so-called low-temperature carbonization range, 450° to 700° C., in which there is minimum decomposition of primary products and maximum yield of Liquids - a yield two to threefold the amount produced in high-temperature carbonization at 900° to 1,200° C, The solid residue, char, or coke, produced in low-temperature carbonization is 70 to 80 percent of the coal charged and may be used directly as a smokeless fuel or for blending with coals to produce metallurgical coke, Although some thought was given to the use of tar and to the illuminating value of gas derived from lm-temperature carbonization, the main emphasis in early work of the Bureau of Mines was on the preparation of smokeless fuel, especially for home use, For example, a carbonizer was designed and operated for making char and briquets from North Dakota lignite without recovery of by- products; however, the shortage of high-temperature coal-tar products in the United States during World War I had already indicated the potential usefulness of low-temperature tar.

Jan 1, 1959

By Paul C. Hyndman

No minerals have been produced from the McGraw Creek RARE II area. During the 1982 U.S. Bureau of Mines study, there were no active mines in the area. Limestone occurrences (fig. 1, no. 2), four copper prospects (fig. 1, no. 1, 4, 5, 6), and a prospect with no significant mineral values (fig. 1, no. 3) were examined. A moderate potential for high-calcium limestone resources was estimated between ocurrences within the study area near McGraw and Spring Creeks (fig. 1, no. 2). There is low potential for copper resources at the Argenta Prospect (fig. 1., no. 1) in the study area, and the McDougall Prospect adjacent to the area.

Jan 1, 1983

By Donald J. Barnes

There are no producing or developing mines in the study area. The only mineral production was stone from a basalt deposit near Indian View Point. Cinders and sand and gravel have been produced from deposits within 1/2 mi (0.8 km) of the boundary. Stone, sand and gravel, and cinder deposits inside the area are not considered resources because equal or better quality material is found closer to markets. The study area has no known oil and gas, coal, geothermal, or other energy related deposits. However, in 1982 application was filed on 25,000 acres (10,125 ha) of petroleum and on 15,000 acres; (6,0/5 ha) of geothermal leases.

Jan 1, 1983

By Richard L. Rains

The U.S. Bureau of Mines conducted a field study of mines and prospects of the Black Canyon RARE II area (No. 5061), Inyo County, California, from June to October 1981. Geological) geochemical, and geophysical studies were conducted by the U.S. Geological Survey. The Black Canyon RARE II area is east of Owens Valley and 6 mi east of Bishop, California. The principal mineral commodities are gold, silver, lead, zinc, and tungsten. Properties with resources in and adjacent to the area are listed in table 1; the locations are shown on figure 1.

Jan 1, 1983

By Rudolf E. Greuer

This report contains the practical application of a computer program for the simulation of ventilation systems under the influence of mine fires and other emergencies on five hardrock mines. The introduction describes the need for such a program, its basic features, and the range of its applicability which is mainly a function of the available ventilation data. The second chapter discusses program modifications, whose necessity or desirability was, during the application, discovered. The following five chapters, which comprise the major portion of the report, give the detailed description of the program application on the five mines. For every one of the selected mines, the ventilation system, the source of the used ventilation data and their preparation for computer simulations are outlined. Based on data for the airflow distribution solely, fumes concentrations in the mines are calculated for several assumed fire locations. Based on data for airflow and pressure distributions, ventilation disturbances caused by fires as well as the resulting fumes concentrations and temperatures are determined. The consequences for escape routes and the possible means to keep them free of fumes are discussed. To investigate the capabilities of the program, other contaminant sources and other potentially dangerous ventilation factors, like fan failures and changed surface temperatures, are simulated also. The results of the calculations have been entered into ventilation plans which makes them easier to scrutinize. All significant computer printouts have been attached.

Jan 1, 1981

By Steven R. Munts

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied 39,420 acres of the 60,960-acre Skedaddle Wilderness Study Area in order to evaluate its identified mineral resources. There are no known mines or mining operations in the study area. None of the prospects or claims in or within a 1 mile peripheral zone around the study area have recorded production. At least 276 recorded lode, 6 unrecorded lode, and 29 placer claims have been located in and within about 1 mile of the study area. Approximately 191 of the claims are in the study area. Four of these were current in 1985; all four are wholly or partly inside the study area. None of the study area was being explored by private industry in 1985. Metallic and nonmetallic commodities present in the study area consist of gold, mercury, perlite, basalt, pozzolan, stone, and sand and gravel. Perlite is represented by a single deposit which contains 184,000 tons of subeconomic resources in and adjacent to the study area. No other sites contained identified resources. There are no other identified nonmetallic resources in the study area. Occurrences in and near the study area contain small amounts of gold and mercury in vein-type deposits and show characteristics similar to bulk-tonnage, low-grade gold deposits. No base-metal resources were identified. The gold and mercury mineralization and perlite deposit are spatially related to a volcanic center located in the Skedaddle Mountains. Prospects in the Skedaddle Mountains may contain both precious metals and perlite resources, but additional work is required to adequately delineate these areas.

Jan 1, 1987

By Matthew N. Rubin

This report summarizes the work performed under USBM Contract No. H0155155. The purpose of this work was to obtain operational data on retrofit noise control treatments suitable for use in coal preparation plants. This data was obtained by evaluating the performance of four categories of noise control treatments which were installed in a commercial coal preparation plant. The four categories of treatments were resilient screen decks, resilient impact pads, chute liners, and curtains. The selection, installation and initial evaluation of the treatments was documented in the Volume I report issued in 1977. This Volume II report summarizes the results of the long-term evaluation of the original treatments, as well as some additional tests which were conducted on elastomer-clad (resilient) screen decks. This project demonstrated the feasibility of a number of retrofit noise control treatments, some of which also proved to be quite durable over the long term.

Jan 1, 1982

By Thomas V. Falkie

The purpose of this work was to investigate the rate at which coal is delivered from the underground working face by gathering arm type loaders as employed on continuous mining machines, to identify the factors -- geometrical, geological, mechanical, or procedural which affect the delivery rate, and to develop quantitative rate descriptive equations for the loading function. The mathematical techniques employed were factor analysis and multiple linear regression. It was determined that the coal-cutting function of the continuous mining machine is the factor that primarily influences the loading function. The geometrical factors -- the dimensions of the work area in relation to the dimensions of the mining machine - were the factors of secondary influence. Fifty-five percent of the experimental variation in the loading function was explained in terms of the six most prominent independent variables. It is expected that this work will be useful in operations-research studies as applied to underground coal mining, and with refinement will enable mine planners to select equipment based on the operating characteristics of the equipment and the mining conditions.

Jan 1, 1972

By J. Koster

In the western United States occurs deposits of low-grade chromite which, when concentrated, may be reduced to ferrochromiun in electric furnaces that derive energy from dams and hydro plants now in course of construction. Montana ore was chosen for the experiments. A 1-ton sample contained 26 percent Cr203, 17 percent Fed, and 17 percent SiO2, plus other constituents, and the concentrates therefrom assayed 44 -percent Cr203, 23 percent FeO, and 0.79 per cent SiO2, Gravity concentration was found to be the best method. Ferrochromiums are of two grades - high-carbon with 66 to 70 percent chromium and 4-112 to 6 percent carbon and low-carbor with 67 to 72 percent chromium and 0.6 to 2 percent carbon. Both are made in electric furnaces that use anthracite as a reducer and suit-able fluxes. The concentrates mentioned mere smelted under different conditions, and it was concluded that domestic ore could be reduced with anthracite to produce a ferrochromium of S to 10 percent carbon content at yields of 90 percent without retreating the slag. This carbon may be lowered to required proportion with calcium and silicon, but the former requires a great excess and the latter leaves an alloy high in silicon. INTRODUCTION Chromite occurs in several regions of the United States, but the known deposits of this mineral have not been large enough or high grade enough to permit them to compete under normal conditions with imported ores. There are numerous deposits of chrome ore along the West coast. These are generally conceded to be relatively small, although some -were worked during the World War. There are some indications of a revival of interest in California chromites. Montana contains large chromite deposits in Stillwater and Sweetgrass Counties. The utilization of chromite for ferrochromium and. the manufacture of stainless steels is distinctly an electrometallurgical problem; consequently, a study of methods for treatment of chromite might pave the way for the establishment of new electrometallurgical industries in the Western States. This thought is supported by the cheap power that is soon to become available from the western dams. Farther, submarginal domestic chrome deposits might thus be turned into profitable producers.

Jan 1, 1936

By Paul C. Hyndman

Three properties in the Tuolumne River RARE II area, the Eagle Bluff Mine (lode) and the Indian Creek Bar and Bossy Bar Prospects (placer), have identified subeconomic gold resources (table 1). Nineteen other properties have potential for gold resources. Adjacent to the study area, five properties have identified mineral resources, and nine others have potential for resources. Properties having high-grade zones (shoots), but licking enough tonnage to be classified as resources, are listed in table 2. Gold, in lode and placer deposits, is the principal mineral commodity in the Toluene River study area. Ten properties within the RARE II boundary have gold-rich zones or shoots; they range in size from 12 to 2,500 tons and in average grade from 0.09 to 0.97 oz gold per ton.

Jan 1, 1983

By Phillip R. Moyle

A cobalt/manganese occurrence in Clark County, Nevada was the subject of a site-specific mineral investigation by the U.S. Bureau of Mines in 1988-90. The study site is in the northern part of the Million Hills (wilderness) study area which is administered by the Bureau of Land Management. Field work during a period of one week consisted of geological mapping and sampling of workings and outcrops, and geochemical and geophysical surveys conducted on four transects totalling 7,600 ft. Although the concentrations of cobalt (0.1 to 0.5 percent) detected in samples from the fissure zones are within the range of grades associated with world-class economic deposits, the volume of material enriched in cobalt at the study site is insufficient to warrant consideration as a potential resource. Concentrations of manganese, nickel, copper, lead, zinc, barium, and thallium, although anomalous, are too low for economic consideration. At the study site, workings consist of three trenches and nine pits. The exploration history is unknown, and no production is reported.

Jan 1, 1990

By M. Kanefsky

Two channel polarity coincidence and polarity difference statistics are analyzed. The signal, common to both channels, consists of sinusoidal bursts where the exact frequency of the signal is nearly known, but other parameters such as amplitude, phase, and pulse starting time are unknown. The noise inputs are dependent, narrow band, Markov processes. It is shown that the performance depends not only on the signal uncertainties, but on the precise shape of the cross-correlation functions between the noise in-puts. By using two polairty difference statistics in addition to the polarity coincidence statistic, it is shown that the decrease in performance, as well as the cost of hard limiting due to correlated inputs, can be made small.

Jan 1, 1981

By Robert L. Lagace

A whole-mine experiment to assess the practical feasibility and utility of the dedicated-wire technique for overcoming poor trolley carrier phone system performance at a large underground coal mine was designed, performed, and evaluated. The technique involves the use of a single, low-loss, properly terminated and branched auxiliary wire placed in the rail haulageway. This auxiliary dedicated wire allows signals to electromagnetically couple to the trolley wire/rail transmission line, and thereby significantly decrease the overall signal attenuation rate on the trolley wire/rail line. The in-mine dedicated-wire demonstration program and its results, conclusions, and recommendations are described. The dedicated-wire technique is shown to be a valid and practical one for significantly improving carrier phone system performance in coal mines.

Jan 1, 1981

By Walter E. Pittman

In its role of providing technical assistance to the mining industry, the Bureau of Mines' Tuscaloosa Research Center has conducted research to develop trapped miner location systems which would aid in locating miners trapped by underground mining disasters. Efforts to produce electromagnetic systems for the location of trapped miners underground and to communicate with them were surveyed, from the 1920's to 1981. Theoretical studies of through-the-earth electromagnetic transmissions are described as well as studies of the electrical characteristics of various rocks, minerals, and soil. Several trapped miner location systems are reviewed including the Westinghouse systems, the DEVELCO system, and an automated three-dimensional location system, and the phase difference of arrival technique. Tangential research, relevant to trapped miner location systems is described. A comprehensive bibliography covering all aspects of trapped miner, through-the-earth electromagnetic location and communications systems is appended.

Jan 1, 1982

By Hon-Yim Ko

1972 constituted the second year of the projected five-year study on constitutive relations of coal. The schedule adhered closely to the five-year outline which is summarized in Table 1. This chapter is intended to serve as introduction and concise synopsis of the year's activities and results, which are presented in greater detail in the following chapters, which have been contributed by the individual researchers in charge of the various aspects of the project under study. Coal Sources, Material Procurement, and Sample Preparation Most of the studies performed during 1972 were done on coal from two sources: the Old Ben Mine #22 in Illinois, and the Bruceton Mine in the Pittsburgh seam of Pennsylvania, which may be considered typical of coal sources of economic importance in the Midwestern and Eastern part of the U.S. These two mines have proven to be reliable suppliers of coal material for our research. We have been able to establish good working relations with their personnel and feel that we can continue to count on their cooperation and help.

Jan 1, 1972

By J. J. Taber

Gas and water permeabilities of a large number of samples from the Pittsburgh and Pocahontas coals were measured at various overburden and mean flow pressures. A wide variation in the air and water permeabilities was obtained for each type of coal. Overburden pressure has the most significant effect on the single-phase permeability. Considerable hysteretic effect was observed for both air and water permeabilities. Gas permeabilities are affected to a lesser degree by mean flow pressures above atmospheric. However, at subatmospheric mean pressures, appreciable increase in permeability occurs for low permeability samples. Air and water relative permeabilities were also measured for numerous samples of Pittsburgh and Pocahontas coals. Tests were performed under steady-state conditions for both drainage and imbibition cycles. Results indicate that the flow of gas is greatly reduced during the latter process, whereas it is largely undiminished over a wide water-saturation range during drainage. It is also shown that imbibition saturation distributions obtained from liquid-water imbibition as opposed to water-vapor adsorption produce gas permeability curves of radically different character. The effective permeabilities to both gas and water were significantly reduced with the application of overburden pressures in the range of 0 to 1,000 psig, but the general shapes of the relative permeability curves remained the same.

Jan 1, 1974

By L. Bruce McDonald

This Federal Bureau of Mines publication is a statistical analysis of all surface and underground coal mine fires reported in the United States from 1950 to 1977. Accounts of selected nonreportable fires and opinion data gathered via interviews with mine safety directors were separately analyzed. Both reported and nonreportable fires were analyzed by time trends, State, ignition source, burning substance, location in mine, equipment, detection, duration, injuries, fatalities, and successful extinguishing agents. It was found that the majority of all mine fires were electrical in origin. The equipment most frequently involved in underground fires was conveyor belts, and in surface fires, it was crushers and/or breakers. Underground fires occurred most often near the working face. Water and hand-portable extinguishers were the most common methods of extinguishment.

Jan 1, 1980

By Roger E. Burleigh

In June, 1989, the U.S. Bureau of Mines, undertook a 9-day evaluation of the tin resource potential of the Sleitat Mountain tin deposit. Significant tin-tungsten mineralization is associated with quartz-topaz-white mica-tourmaline greisen alteration of a multi-unit, 57 Ma, peraluminous, granite stock which intrudes Cretaceous Kuskokwim Group flysch deposits. The granite comprises marginal biotite-, intermediate biotite-muscovite-, and central zinnwaldite-granite units, interpreted as a zoned alteration system. Major vein mineralization is confined to two east-west-trending zones of steeply oriented tabular lenses of greisen interleaved with mildly altered granite. Cassiterite is the dominant ore mineral while arsenopyrite, loellingite, wolframite, pyrite, sphalerite, chalcopyrite, and bismuth-oxides are present in minor to trace amounts. The north and south greisen zones are estimated to contain an inferred resource of 128 to 212 million lbs Sn in 28.6 million st of mineralized rock. An 1,800-lb representative bulk sample contained 0.37% Sn, 0.04% W and 17 ppm Ag and is considered an average grade estimate for the deposit. Drill testing by Cominco Alaska Exploration indicates that substantial widths of high-grade tin mineralization are included within the lower grade disseminated mineralization. Depth of deposit erosion is substantial and there exists a high probability for placer tin deposits.

Jan 1, 1991

By Michael D. Balen

The Bureau of Mines (Bureau), in cooperation with the Alaska Division of Geological and Geophysical Surveys (ADGGS), conducted field investigations from 1987 through 1989 in the 5.7 million-acre Valdez Creek Mining District (VCMD) in south-central Alaska. The objective of the VCMD investigation was to evaluate the mineral resources and the mineral development potential of the mining district. The investigation was part of the Bureau's continuing statewide mining district evaluation program. Nineteen new mineral occurrences were identified as a result of this investigation. Reconnaissance placer sampling resulted in the identification of 10 previously unreported occurrences that primarily contain gold, however, some contain subsidiary platinum-group metals and/or tin. Reconnaissance lode sampling resulted in the identification of two gold-silver occurrences, three platinum-group metal occurrences that contain elevated quantities of subsidiary chromium, nickel and/or cobalt, three copper occurrences that contain subsidiary molybdenum or zinc, and one zinc occurrence.

Jan 1, 2011

By Charles D. Wood

"Selected Topics,? in reviewing the control of emissions from diesel engine powered equipment used in underground mining, explores these fields of interest: hydrogen as fuel; lubricating oil as a source of particulates; applicability of stationary source scrubbers; worldwide diesel exhaust scrubbers; instrumentation technology for measurement of N02; control of emissions through application of sensors and microprocessors; use of fuel additives; technology transfer of marine diesel practice; technology required to use 4-stroke, aftercooled, turbocharged, direct injection engines; oxidation and reduction catalysts for diesel engine exhausts. "Selected Topics? makes recommendations for research and provides a bibliography and lists of references.

Jan 1, 1979