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By W. H. Young

The thickness of the coal seam is one of the more important items influencing the productivity and general overall efficiency of operation 1 of a coal mine. The average thickness of coal seams mined in the United States decreased 2 inches between 1950 and 1955 to an average of 62 inches, which also is 3 inches less than the 65 inches in 1945. The decrease in thickness is due partly to the increased production from strip mines with thinner seams and partly to the increased percentage of total production at underground mines in certain States having thinner seams. The thickness of seams at auger mines was measured for the first time in 1955 and was 53 inches. Though bituminous coal and lignite is mined today from seams of exceedingly variable thickness -less than 2 feet to ore than 50 feet -a large majority of the production, 65 percent in 1955, came from seams 3 to 6 feet thick. This is not surprising since the coal seam of moderate thickness presents the least mining difficulties.

Jan 1, 1957

By John W. Buch

At a meeting of the Anthracite Investigations Advisory Committee in July 1944 at Washington, D. C., the initial work and objectives of the Anthracite Mechanical Mining Section of the Federal Bureau of Mines were discussed. It was learned that interest existed in an improved performance of mining thin, steeply pitching beds above the gangway by mechanical methods. One company offered the use of one of its mines for experimental work, and this offer was accepted. Following acceptance, an effort was made by Bureau engineers to devise a mechanical method with a performance better than that of a new hand method proposed by company engineers for an actual mining condition. The method proposed by the Bureau was to drive 30-degree slant chutes across a 10-foot bed pitching 85 degrees. These chutes were to be advanced by using a lightweight, compressed air-powered, shearing machine of German origin that had been tried in a flat Pennsylvania anthracite bed in 1934, and which did not then prove successful because of blasting difficulties. An attempt was made to obtain one of these machines from England, where it was known machines of this type had been used. Shortly thereafter John W. Buch was sent to Europe as a member of the Solid Fuels Mission to the European Theater of Operations organized by the Technical Industrial Intelligence Committee of the Joint Chiefs of Staff. Through his efforts the Bureau of Mines obtained two such machines, known as the Eickhoff model DEK, one from England and one from Germany. This report covers the preliminary testing of these machines in order to obtain mechanical operating data for use in determining the power requirements for cutting anthracite with machines of this design.

Jan 1, 1949

By Robert W. Geehan

The Bureau of Mines has been developing deposits of critical and essential minerals in the United States since 1939. A preliminary examination of the Union lead mine was made in November 1944 and January 1945 by W. T. Benson, a Bureau of Mines engineer, who recommended development by diamond drilling. The Bureau conducted a drilling project at the mine from February 12 to May 16, 1947. The property is in sec.12, T. 17'N., R. 19 E., Mount Diablo Base and Meridian, in. southern Washoe County, Nev., about 15 miles south of Reno. The Union lead mane, also known 4s the Commonwealth mine, has been an intermittent producer of zinc-lead-silver ore since 1860. During World War II, ore was shipped to smelter& near: salt Lake City, Utah. The Bureau drilled 21 diamond-drill holes having a total length of 1,549 feet and 20 long percussion-drill holes with a total length of 359 feet. The program was designed to test for horizontal and vertical extensions of the ore body and to prospect for parallel ore bodies. As a result of this program, extensions of the ore zone were established, but no parallel ore-bearing structures were found. The areas drilled were limited by drill sites available.

Jan 1, 1950

By E. K. Stanek

This report contains results of two major efforts related to electrical transients on mine electrical power systems. The first area concerns the use of digital computers to model mine electrical power systems and predict transients or duplicate field recordings of transients. Two existing general purpose circuit analysis programs were used. The first was the TRW Engineering System Simulator or TESS. The second was Electronic Circuit Analysis Program or ECAP. TESS proved to be superior to ECAP in several important characteristics, including system size limitations and modeling nonlinear elements. The second major topic covered in this report is the evaluation of commercially available surge suppression devices. These devices were found to be quite acceptable and guidelines for the selection and placement of surge suppressors were included. The final important item is a listing of the worst-case transients, from a design point of view, for ac and de utilization systems and ac distribution systems.

Jan 1, 1979

By Robert W. Freedman

As part of a continuing effort to reduce the weight and bulk of equipment that mining personnel must carry underground, the Bureau of Mines and the Mining Enforcement and Safety Administration (MESA) investigated accurate and convenient gas samplers for use by mine inspectors in sampling mine atmospheres. The samplers are septum-stoppered glass vials commonly used for routine blood sampling. These lightweight, compact samplers yield results comparable with those obtained with conventional bottle samplers of 250-ml nominal capacity.

Jan 1, 1975

By J. E. Dooley

Reference mass spectra and analytical correlations for 20 alkylcycloalkyl sulfides and two dicycloalkyl sulfides are presented 'to provide information that will facilitate the identification of sulfur compounds occurring in natural or synthetic mixtures. Reference spectra indicate relative intensities in addition to parent and base peak sensitivities. Analytical correlations establish the ionic species that reflect major fragmentation paths for the com-pounds studied. Specifically, the correlations show that base peaks are formed by several different processes: (1) Cleavage of the bond a to the ring, (2) fragmentation of the alkyl chain, and (3) fragmentation of the ring plus fragment contribution from the alkyl chain. Useful correlations for deter-mining alkyl chain length involve the CnH2+3S+ and CnH2n+1 + ions. CnH2n-2+ and CnH2n-1 S+ ions reveal the number of carbon atoms in the cyclic ring. Other important ionic species are also discussed.

Jan 1, 1970

By R. V. Higgins

As part of a study of application of the Buckley-Leverett method to an analysis of oil-reservoir performance covering a wide range of relative permeabilities and oil saturations, a method has been devised for quickly deter-mining average water saturation at breakthrough from relative permeability data. The base for the relative permeability used in the report is either the permeability to air or the effective permeability to oil at the irreducible water saturation. The permeability to air also was used because of the large backlog of air permeabilities available to reservoir engineers. The basic data were calculated by an electronic computer and are presented in a single graph from which the point of breakthrough may be obtained. In this study the water saturation at the beginning of the depletion is the connate or interstitial or irreducible water saturation. These water saturations are considered to be synonymous and to have a practical value.

Jan 1, 1960

By Michael D. Dunn

The Bureau of Mines evaluated a quartz schist formation within the Blue Joint Wilderness Study Area which was identified as having a "high potential" for copper-silver-cobalt-barium resources. Stratiform and remobilized copper occurs near, and bedded barite within, the study area. In addition, the black to gray Proterozoic quartz schist may correlate with the Yellowjacket Formation which contains cobalt-copper-gold-silver deposits at Blackbird, ID, about 30 miles to the south. Eighty soil and 43 rock samples collected across the quartz schist formation were analyzed for gold, silver, copper, cobalt, and barium. During the reconnaissance and sampling, particular attention was given to looking for malachite (copper carbonate) and erythrite (cobalt arsenate, also known as "cobalt bloom"). The sample analyses and geology in this localized area do not provide enough evidence to support the "high potential" designation for copper-silver-cobalt resources. Barium potential still appears high, however.

Jan 1, 1987

By Richard V. Ageton

Compressed- air blowers are frequently used both in large and small metal ines , not only as an aid to ventilation , but in some mines as a substitute for an dequate ventilation system . As a temporary fixture , blowers have their uses , but hey should never be used in lieu of a permanent ventilation system. A number Probably the most common error made in placing dependence on compressed- air lowers as an aid to underground ventilation is the tendency to over- rate their cooling efficiency . It is a very common but natural error to assume that compressed air which issues freely from a blower is of the same temperature as the compressed air which issues freely from the exhaust port of a rock-drilling machine . of readings were taken in different mines of the temperature of the rock- drill exhaust , of the compressed air flowing from the blowers , and of the surrounding air In both cases . In general , the temperature of the rock- drill exhaust was from 10 to 30 degrees below that of the surrounding air , in many instances being slightly below freezing , 32° F . The average temperature for a number of compressed-air lowers and for the mine air surrounding them is shown in Table I.

Jan 1, 1922

By M. B. Royer

Sulfur is present in many ores and other raw materials that are used in the production of metals and alloys of industrial importance. Its presence, especially in ferrous-metal products, generally is undesirable because of its detrimental effect during processing and upon various physical properties of the finished metal. Therefore, various methods are resorted to for elimination of the element to some specified maximum final content. Such removal or elimination of sulfur is designated as desulfurization.

Jan 1, 1948

By Steven R. Davis

Dear Interested Party: Subject: Notice of Intent to Solicit Outside Opinions Regarding Amendments to the Rules Concerning the Leasing of State Owned Lands for the Mining of Metallic Minerals The Department of Natural Resources, Division of Minerals, is seeking outside opinions concerning the leasing of state owned lands far the mining of metallic minerals. Enclosed for your information in a copy of the Notice of Intent to Solicit Outside Opinions Regarding Amendments to the Rules Concerning the Leasing of State Owned Lands for the Mining of Metallic Minerals.

Jan 1, 1994

By Henry E. Blake

The Bureau of Mines has been engaged in a continuing research effort to develop processes for increasing the recovery and utilization of fluorine from low-grade resources. This current research has shown that over 98 percent of the fluorine in phosphate rock is extracted when the ore is treated with excess phosphoric acid in the presence of water vapor at 150° to 180° C. More than 80 percent of the fluorine can be recovered as fluosilicic acid, which can then be converted to commercially useful hydrogen fluoride or fluorspar by previously developed Bureau processes. Extraction of P205 from the ore was about 98 percent in batch tests and 90 percent in semicyclic tests.

Jan 1, 1974

By Nicholas Kyriazi, John P. Shubilla

A joint effort by the U.S. Bureau of Mines (USBM) and the US. Mine Safety and Health Administration (MSHA) was undertaken to determine how well self-contained self-rescuers (SCSR's), deployed in accordance with Federal regulations (30 CFR 75.1714), held up in the underground environment with regard to both physical damage and aging. This report presents findings regarding laboratory-tested SCSR's in the fourth phase of testing from 1989 to 1993. The SCSRYs were tested on human subjects and on a breathing and metabolic simulator (BMS). These results indicate that most of the apparatus, if they pass their inspection criteria, perform as expected except units with manufacturing defects. However, when the apparatus are carried in and out of the mine daily and stored at the working section, they may suffer abuse. Physical signs of abuse, unless extremely obvious, are frequently not detected by the miners or mine operators. In addition, some apparatus collected for this study had not been returned to the manufacturer in a recall effort for correction of a manufacturing defect. In both cases, the apparatus would have presented problems in emergency use. Recommendations include improved training in inspection procedures and better enforcement of recall notices.

Jan 1, 1994

By Victor Kalcevic

A gas-flow retort for thermal processing of oil shale to recover shale oil was developed by the Bureau of Mines at its Oil-Shale Demonstration Plant, Rifle, Colo., from 1948 to 1952. The retort is a crossflow gas-to-broken-solids heat exchanger. The heating medium is the gas produced in the shale retorting process. The gas is heated in specially designed stoves outside the retort and recycled to the retort. Oil shale from the Mahogany ledge section of the Green River formation in northwestern Colorado was the material processed. Indicated maximum oil recoveries for 20-to 25-gallon-per-ton shale in a l2-inch-thick shale bed and a 20-inch bed are 96 and 91 weight-percent of Fischer assay, respectively. Heat requirements for maximum recovery are 600 to 750 B.t.u. per pound of shale. Properties of the recovered shale oil are affected slightly by shale-bed thickness and extent of retorting. Oil recovery from oil shales assaying over 30 gallons per ton is lower than that from leaner shales.

Jan 1, 1959

By Larry G. Stolarczyk

This report deals with the creation of an efficient method to determine if command, control, communication and monitoring (3cm) equipment in coal, metal and non-metal mines is susceptible to Radio Frequency Interference (RFI) from the Medium Frequency (MF) radio communications system. A qualitative and quantitative RFI test plan was developed for in-mine and laboratory evaluation of the equipment. The laboratory testing was accomplished using the TEM Test Chamber. Detailed information on the Test Plan and the TEM Test Chamber is included. During in-mine testing of the MF System some underground equipment malfunctioned when the transmitter's radiating antenna was in close proximity. Electromagnetic Compatibility (EMC) testing was done on three levels; Component (circuit or box), subsystems and system. Nine tables are included which show the results of testing various equipment for RFI.

Jan 1, 1986

By R. B. Stroud

Bureau of Mines studies of copper-bearing Permian red beds, which extend from north-central Texas through western Oklahoma to southwestern Kansas, indicate heretofore undefined commercial possibilities for low-grade, medium-volume, strip-mining operations. Potential ore bodies are indicated containing 0.5 to 1.5 percent copper in zones 6 to 12 inches thick. Cost analysis studies indicate a commercial operation is feasible for a hypothecated 1,000-ton-per-day ore mining and milling complex where a maximum of 60 feet of overburden can be stripped in mining a seam of shale 12 inches thick containing 1.2 percent copper

Jan 1, 1970

By H. Dolezal

A laboratory study of acid-ferrous sulfate treatment of low-grade manganese ores from the Cuyuna range, Minnesota resulted in 93-percent extraction of manganese as manganese sulfate with consumption of 3.8 pounds of H2S04 per pound of extracted manganese. Two types of ore were treated in consecutive stages. The first are contained carbonate minerals of manganese and iron, both soluble in H2S04 solution. The second ore contained manganese oxide minerals, insoluble in straight acid solution but soluble in the ferrous sulfate solution obtained from treating the first ore. Leaching data were obtained by countercurrent percolation of coarse (minus-1/2-inch) ore particles at room temperature and by agitating minus-65-mesh ore particles in heated solution. Extraction of manganese and acid consumption were the same, but the percolation leach required 6 days compared with 1 hour for hot agitation. Variations in the size of ore particles treated, leaching time, acid concentration, solution temperatures, and method of applying ferrous sulfate solution to the oxide ore were studied. The effects of several reagents for removing iron from solution and improving filtration were also studied.

Jan 1, 1959

By C. Ortuglio

The Bureau of Mines developed equations to determine the relationship of yields and products obtained from BM-AGA carbonization in 13-and l8-inch-diameter retorts. The developed equations indicate that results of carbonization in l8-inch-diameter retorts can be predicted from results obtained with l3-inch-diameter retorts.

Jan 1, 1966

By David Schlain

The galvanic corrosion properties of titanium and zirconium were investigated by the Bureau of Mines. The dissimilar metals involved in these experiments included magnesium, magnesium alloy FS1, aluminum alloys, zinc, steel, tin, lead, copper, Monel, nickel, and several stainless steels. Couples were immersed in synthetic ocean water, tap water, 5-percent ammonium sulfate solution, 5-1/2-percent sodium chloride solution, sodium hydroxide solution, 0.1 N hydrochloric acid, and various concentrations of sulfuric acid.

Jan 1, 1956

By Sidney Katell

This study estimates capital investment, operating costs, and selling prices for four underground bituminous mines producing coal with annual production ranging from 1.06 to 4.99 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of December 6, 1974, under the Bituminous Wage Agreement of 1974, and costs for material and equipment are based on 1975 indexes. Initial capital investment ranges from $23,629,500 for the 1; 06- million-ton-per-year (MM tpy) mine to $79,907,500 for the 4.99-MM-tpy mine. Total capital investment ranges from $35,336,500 to $1 18,863,500 for the same mines. Corresponding selling prices for the coal range from $13.57 to $11.36 per ton, assuming a 15-percent discounted cash flow rate of return after Federal income taxes.

Jan 1, 1975