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By H. E. Perlee

Autoignition temperatures and limits of flammability of nine halogenated hydrocarbons in atmospheres of air, oxygen, and nitrogen tetroxide were measured in a modified standard autoignition apparatus and limit-of-flammability apparatus previously developed at the Bureau of Nines. Of the nine halogenated hydrocarbons investigates--bromochloromethane, bromotrifluoromethane, bromochlorodifluoromethane, 1,1,2-trichlorotrifluoroethane, 1-bromo-l-chloro-2,2,2-trifluoroethane, dibromodifluoromethane, l,2-dibromo-1,1,2,2-tetrafluoro-ethane, 1,1,1,3,3-pentachlorotrifluoropropane, and l-bromo-2,4-dichloro-1,1,2, 3,3,4-hexafluorobutane--two formed flammable mixtures with nitrogen tetroxide and six with oxygen; none formed flammable mixtures with air. Three of the halogenated hydrocarbons formed no flammable zones with any of the three oxidizing atmospheres. For those halogenated hydrocarbons that supported combustion in oxygen atmospheres, explosion pressures developed during constant-volume burning of mixtures near the middle of the flammable zone were observed to range from about 6 psig for dibromodifluoromethane to 158 psig for 1-bromo-1-chloro-2,2,2-trifluoroethane. In all cases, the calculated burning velocities of these mixtures were less than 8 in/sec.

Jan 1, 1966

By G. Richards Gwinn

Vermiculites are secondary minerals formed by the: alteration of biotite and philogopite mica and are associated with basic rocks such as dunites, serpentines, and pyroxenites. Vermiculite was first described by T. H. Webb in 1824. It remained a mineralogical curiosity until 1913, when the first commercial deposit was discovered in the Turrett mining district of Colorado. Expanded or exfoliated vermiculite was first marketed in 1915 from a deposit in this district 5 miles southeast of Hecla, Colo. This activity was brief, but successful and continuous commercial development began in 1921 in Montana. 'Deposits in other States have been found and developed, but Montana is by far the largest producer. Vermiculite has also been found in South Africa, Western

Jan 1, 1944

In 2004, data obtained from the Mine Safety and Health Administration (MSHA) indicated a total of 891 underground (6.2%) and 13,587 surface (93.8%) mining operations.

Sep 1, 2007

By CDC CDC

In 2004, a total of 251 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Metal mines were the smallest mining commodity sector, comprising 1.7% of all mining operations. • Gold mines

Sep 1, 2007

By M. A. Reyes

This experiment investigated the effects of different machine mounted area lighting technologies on visual performance. The primary objective was to conduct a comparative evaluation of the lighting technologies based on the visual performance of thirty-six human subjects in a simulated underground mine environment. Incandescent (Incand), fluorescent (Fluor), and light-emitting diode (LED) technologies were used to create four lighting combinations. Visual performance was quantified for the detection of movement in the peripheral field of view and the identification of ground hazards. Measurements were made of the speed [response time measured in milliseconds (ms)], the accuracy (the number of targets and objects missed), and the subjective discomfort rating of the glare experienced for each lighting combination. A secondary objective explored the effects of aging on visual performance. The results indicate that lighting combinations which consisted of LED area lights significantly improved visual performance for the detection of hazards found in the peripheral field of view, as well as those found on the ground. They furthermore, indicate that age plays a significant role in visual performance.

Jan 1, 2009

By J. W. Town

As part of the Federal Bureau of Mines titanium resources examination program, samples from seven deposits in the Pacific Northwest were tested for amenability to various beneficiation techniques. The samples obtained by the Bureau's Office of Mineral Resources at Spokane, Washington represent a large potential source of titanium. This report summarizes the results of tests at the Bureau's Metallurgy Research Center, Albany, Oregon. Recoveries from tabling placer samples were about 50 percent at grades of 30 percent titanium dioxide. Flotation was the most effective method for concentrating the fine ilmenite in clay samples; recoveries of approximately 50 30 percent titanium dioxide. Flotation was the most effective method for concentrating the fine ilmenite in clay samples; recoveries of approximately 50

Jan 1, 1961

By R. L. Crosby

The Bureau of Mines investigated alloys of copper with 2, 3, and 4 vol pct alumina and with 2 vol pct yttria. Alloys were prepared by a coprecipitation process and were fabricated by pressing and sintering of powders, extrusion, and swaging. Tensile properties at room and elevated temperatures, stress-rupture strength, electrical conductivity, and density were measured. The superiority in elevated temperature strength of dispersion-strengthened copper to OFHC copper was confirmed. Increasing the oxide content from 2 to 4 vol pct produced only a small improvement in strength properties and decreased the electrical conductivity. The 3 vol pet alumina alloy had the best overall combination of properties.

Jan 1, 1969

By Raja V. Ramani

Productive and beneficial use of reclaimed surface-mined land is a concern of industry, government, and the general public. An investigation was conducted of current mined-land planning practices to aid in the development of a procedure for evaluating postmining land use potentials. This investigation considered both the industry and public planning approach to mined-land planning. It included a detailed review of the impact of regulation, factors that determine land use, and current site planning methods employed by the mining industry. The methods of this investigation included three in-depth case studies of surface mines in the eastern, central, and western United States. A site planning pro-cess has been developed and applied to the surface mine case studies to evaluate the economic, environmental and social impacts of postmining land use alternatives. In add it ion, guidelines are proposed to enhance the cooperation between local land use planners and surface mine planners, as well as to improve comprehensive planning with regard to mineral resources at the local and regional level.

Jan 1, 1983

By P. S. Haury

"INTRODUCTION Many ore deposits were discovered in the Wallapai Mining District, which covers the Cerbat Range in Mohave County, Ariz., during the early period of mining there from about 1865 to the 1890's. A considerable amount of production was obtained from shallow lead carbonate ores that carried considerable gold and silver.Mining was revived in 1906 and again during the First World War, and soma of the mines were deepened into the underlying sulfide zone. Substantial quantities of metal were recovered from two mines, the Golconda and the Tennessee-Schuylkill, that were, developed to depths of 1,600 and 1,400 feet, respectively. The Golconda is credited with $6,500,000 gross productions. 2/ This mine was not operated after 1917. The Tennessee-Schuylkill is still operating after a yield of about 300,000 tons of ore that averaged 4.33 percent lead and 7.74 percent zinc and contained an appreciable amount of gold and silver.Many of the old mines were reopened in 1942 or 1943 under the stimulus of premium prices for lead and zinc. A large proportion of this work was finished with loans from the Reconstruction Finance Corporation. It was believed that a good deal of lead and zinc could be recovered from the mines if a custom mill for concentration of the ores was available locally."

Aug 1, 1947

By Brian T. Brady

The year 1991 recorded unprecedented change throughout the world; war in the Middle East, economic recession in key industrial nations, upheaval in Eastern Europe, and the disintegration of the former U.S.S.R. These issues and growing environmental concerns will affect the entire world mining industry. Environmental issues continue to have an ever greater effect on industrial minerals. In the United States, major issues involving the Clean Air Act, Clean Water Act, and the recent Stormwater Rule by the U.S. Environmental Protection Agency (EPA) affect many types of mineral operations. Significant developments include an important decision in 1991 by a Federal Appellate Court to overturn EPA's asbestos ban on certain products, partly on environmental grounds, and proposed legislation that would overhaul or abandon the 1872 Mining Act. On a global scale, prominent issues include environmental concerns over mining in the Antarctic and Arctic regions and a cutback in plans to clean up the Kola Peninsula in the Commonwealth of Independent States (C.I.S.).

Jan 1, 1993

By C. A. Frenzel

Extensive spectroscopic data are needed in making reliable vibrational assignments for use in calculating thermodynamic functions of polyatomic molecules. The fundamental vibrations of organic molecules may be observed at any wavelength from 2.5 to 200 microns (micron = µ = 10-4 centimeters), but most often in the region from 3µ to 50µ. Raman spectra generally cover the range in which fundamental vibrations occur, but equally important infrared spectra usually are not measured at wavelengths longer than 25µ. This limitation results because most infrared spectra are determined for analytical purposes, which seldom require information outside the region 2µ to 25µ. Measurements of infrared spectra in the range 15µ to 35µ recently were begun by the Bureau of Mines to obtain data needed in making vibrational assignments. This report presents the spectra of the following thirteen compounds: Tetrahydrofuran, 1-methylpyrrole, piperidine, 2-methylpyridine, 3-miuthylpyridine, 2-propanethiol, cyclopentanethiol, 2-methyl-2-butanethiol, 3,3-dimethyl-2-thiabutane, cyclohexanethiol, cyclopentyl-l-thiaethane, 2,4-dimethyl-3-thiapentane, and hexamethyldisiloxane.

Jan 1, 1960

By Robert W. Ageton

Optimal planning for mining the deep, lead-zinc-silver deposits of the Coeur d'Alene mining district, Shoshone County, Idaho, could be facilitated by a knowledge of the magnitude and direction of the pressure acting in the virgin rock. The distribution of primary stresses should be considered in order to prevent possibly destructive mining-induced stress concentrations. This particular investigation was concerned with determining stress in a zone 4,000 feet below the surface and known to be ender stress concentrations due to mining operations. Disking of the stress-relief cores obtained in a vertical down hole permitted qualitative evaluation from visual observations; the results indicate that a high lateral stress existed at the time the measurements were made. Stress-ellipsoid determinations gave a compressive principal stress of -13,000 psi oriented about N 45° W and nearly horizontal, a compressive principal stress of -11,000 psi oriented about S 45° W and abut 60° off the vertical pointing away from the vein, and a compressive principal stress -5 -7,000 psi oriented N 45° E and about 60° off the vertical, pointing toward the vein. Subsequent to the overcoring stress-relief drilling, a rock burst occurred about 100 feet northwest of the test site.

Jan 1, 1967

By Arthur L. Murray

"During recent months much criticism as to the efficiency of mine labor has been heard from various, sections of the country. No doubt much of this criticism has been well founded. The present lack of efficiency and of stability is due primarily to a spirit of restlessness and partial irresponsibility engendered during the transition from war conditions to peace time conditions. This spirit or unrest not only among the laboring classes but in every branch of the human family following a period of intense nervous tension in a nation appears to be a natural sequence of war and beyond the control of man. This condition will gradually disappear, and the majority of our people will again assume their natural order of living, but labor will for a considerable period be sensitive to these influences, whether they be exerted for good or for evil. Employers of labor should take cognizance of this fact and bend every effort towards the development of measures that promote efficiency and permanence of the working force.Labor efficiency depends upon many and varied factors. Some of these factors as applied to mine labor are briefly enumerated in the following paragraph:Selection and Placement of Manpower:In the selection of men the two main considerations are physical ability and adaptability. The laws of mechanics should be applied in the selection of men as in the selection of machinery. If a machine is required for a certain class of work, the type of machine known to be mechanically fit for such work is selected. Likewise, men should be selected with regard to their physical and temperamental fitness for the kind of work expected of them."

Apr 1, 1920

By John J. Sammarco

Illumination plays a critical role in an underground miner?s safety because miners depend most heavily on visual cues to recognize hazards. Mobile mining machinery, located in the miner?s peripheral field-of-view (±10° to about ±60° off-axis), may pose potential pinning and striking hazards. The main objective of this research was to determine if there were peripheral visual performance improvements for the detection of moving objects when using cool-white light-emitting diode (LED) cap lamps as compared to incandescent (INC) light bulbs commonly used in miner cap lamps. The cap lamp variable of interest is the spectral power distribution (SPD); the illuminances were normalized by a diffusion filter. The second objective was to determine if age is a factor for peripheral visual performance. This is important because the workforce is aging ? the average miner age is about 43 years old. Thirty subjects participated in the study; ten subjects each in the age groups of younger (18 to 25 years), middle (40 to 50 years), and older (50+ years). Visual performance was quantified by the subjects? speed and accuracy of response to detect the rotation of high-contrast (white) circular targets located 3.83 meters (m) away at -20°, 40°, and 50° off-axis. The speed of detection and the number of missed target rotations (accuracy) were measured. The prototype LED cap lamp results were best with a 11% to 15% improvement compared to the INC and LED cap lamps respectively. Age does appear to be a significant factor. For the middle and older age groups?, target movement detection time increased 75% and 60% and the number of missed targets increased 500% and 450% respectively in comparison to the youngest age group. The results also suggest that target location is a significant factor. The subjects? target movement detection time for the 40° and 50° target movements increased 16% and 69% respectively as compared to the -20° target.

Jan 1, 2008

By W. P. Diamond

It is estimated that more than 1 trillion cubic feet of methane is contained within the coals of the Mary Lee group in Jefferson, eastern Tuscaloosa, and southern Walker Counties, Ala. Most of this methane will be encountered by mining. Coals of the Mary Lee group are presently being mined at depths exceeding 1,000 feet and will in the near future be mined at even greater depths, where the problem of methane gas affecting the mining operations will be acute. It is calculated that approximately 90 pct of the methane is at depths greater than 1,000 feet, and over half of the gas is contained within only 12 pct of the study area which is under more than 1,500 feet of over-burden. Degasification in advance of mining will increase mine safety, reduce ventilation expenditures, increase productivity, provide an additional energy source, and make it possible to mine parts of deep coalbeds that probably could not otherwise be mined.

Jan 1, 1976

By J. B. Gayle

A 1/2-ton experimental coke oven was installed ac the Bureau of Mines Southern Experiment Station, Tuscaloosa, Ala., in 1948. Designated as the Tuscaloosa oven, this unit features a 17-inch carbonizing chamber, globar heating elements, and silica-brick walls designed to simulate as closely as possible the carbonizing conditions for commercial slot-type ovens. Because of the small force exerted on the oven walls in most tests conducted to date (probably owing to the practice of charging coals and blends at a moisture content approximating that normal to commercial plants operating in this district), little information has been obtained about expansion properties. Two sole-heated ovens have therefore been constructed and used as supplementary equipment for determining the expansion properties of coals tested in the Tuscaloosa oven. The reasons for constructing the Tuscaloosa oven, the details of design, the operating, characteristics of the oven and the reproducibility of results have been discussed in previous publications. 3 4 5/ The present report deals with the effects of substituting various high- and low-volatile coals for components of a selected base blend carbonized under conditions similar to those normally used for producing foundry coke. Results of tests of 11 coals and 14 blends indicate that several blends tested rave cokes having physical properties very similar to those produced from the reference blend.

Jan 1, 1957

By G. H. West, R. L. Sebastian, W. A. Darror

"This bibliography was compiled in the course of research work by the Bureau of Mines on the utilization of magnesites in the West. The results of the research will appear as a bulletin of the Bureau.1. ANALYTICAL METHODS. 11 Knight, X. and Wheeler, W.H. Proc. Iowa Acad. Sci., 13, 1907, 167 (C.A.1, 1370). Describes experience in analysing calcite and dolomite. Reports great excess of oxalate unnecessary and separation of sulphates by alcohol is best.2 Meyerhofer, J. Zeit, Angew. Chem., 21, 1908, 592. Direct determination of Mg as phosphate after removal of SiC2, by keeping R203 in solution with ammonium citrate.3 Merckschen Guano Phosphat Werke. Chem. Ztg., 33, 1909, 545 (C.A. 3, 2281). volumetric analytical methods.4 Popel, M. Zeit. Angew. Chem., 21, 1908. 2082 (C.A, 6, 412). Determination of CaO in presence of CaC03.5 Blasdale, W.C. Jour. Am. Chem. Soc., 31, 1909, 91? (C.A. 3, 2658). Studies of separation of Ca from Mg.6 Hundeshrgen, F. Zeit. Offent. Chem., 15, 1909, 85 (C.A. 3, 1853). Valua¬tion of caustic magnesia by analysis. Volumetric methods.7 Frerichs, H. and Krosberg, W. Apoth. Zeit., 24, 1909. 679 (C.A. 3, 2996). Tecting magnesia alba for Fe.8 Schoorl, N. Zeit. Anal, Chem., 48, 1009, 593 (C.A. 4, 5E9). Microchemical tests for Mg, Li, K. and Na.9 Heyer. Chew. 2Ag., 33, 1009, 1157 (C.A. 4, 1588). Determination of CaO in presence of CaCO3. CaCO3 in soluble in cold neutral solution of NH3 salts. Solubility Is diminished by free NH4OH."

Oct 1, 1923

By G. S. Scott, L. D. Schmidt, J. A. KELLEY, E. L. FISH

One of the war problems with which the Bureau of Mines is concerned is to increase production of iron and steel , in which coke is one of the major factors . The output of byproduct coke for use in iron blast furnaces is insufficient and is being supplemented by coke from beehive ovens (figs . 1 , 2 , and 3) . Some difficulties that cause a reduction in iron output have been reported in the use of some of the beehive coke.6/ About 20 years have elapsed since beehive coke was made on a large scale , and many of the skilled operators of those days are no longer available . Furthermore , in many instances the quality of the coal supplied to the ovens has not been as good as formerly. The ash and sulfur contents are often abnormally high; and in other instances they vary greatly in amount, so that a nonuniform coke is produced . To assist operators to improve quality and yield of beehive coke , the Bureau of Mines equipped a truck as a field laboratory ( fig . 4 ) and sent the authors with it into the Pennsylvania beehive district . The truck contains necessary equipment for sampling and analyzing coke oven gases , measuring temperatures , screen - sizing coal, and float -and - sink testing coal . Coal specimens may be sent to the Pittsburgh laboratory for analysis . Beehive plants producing good coke were visited first to observe details of operation and to collect data on the operating process . These covered temperatures , analyses of the exit ( or trunnel) gases , and coal quality, and were to be utilized in searching for faults in plants not producing good - quality coke and to assist in improving such plants or their operation .

Dec 1, 1943

By R. C. Buehl

An experimental iron blast furnace of 3-foot-diameter hearth, producing about 12 tons of metal per day, was operated for 2 weeks with various proportions of anthracite replacing a corresponding amount of coke. The furnace operated well with anthracite in amounts up to 40 percent of the total fuel and produced metal of uniformly low sulfur and normal silicon contents. An increase to 50 percent anthracite during two attempts resulted in poor operation and the charge hung in the s haft of the furnace. INTRODUCTION Anthracite production in Pennsylvania decreased from 84,400,000 net tons in 1926 to 40,600,000 net tons in 1952, and there was a further decline in 1953 to 30,900,000 net tons. Employment in the anthracite industry dropped from 165,000 men working an average of 244 days per year in 1926 to 57,900 working an average of 163 days per year in 1953,3/ which has naturally resulted in considerable unemployment in the region. The industry is actively engaged in promoting new uses for anthracite to increase the demand and thus improve economic conditions in the region. One possibility is the use of anthracite to replace part of the coke for smelting iron ore in blast furnaces. The tests in this report were made to determine whether this use of anthracite would be feasible.

Jan 1, 1955

By Byron E. Blair

This report describes procedures for using a high-speed camera to study blasting phenomena. Both quantitative and qualitative information can be obtained, provided that proper interpretations of the projected two-dimensional images are made. Geometrical relationships between object and image displacements are given in terms of horizontal and vertical angles of the camera optic axis with respect to the quarry face. Correction factors are given for obtaining true object displacements from image displacements in the camera film plane. The time of initial rock movement also is considered, and the control-ling factors of camera speed, scale factor, minimum increment of projection measurement, etc., are evaluated in terms of minimum time intervals. The high-speed camera and associated equipment are described, and field measurements and laboratory data analysis techniques are outlined. An analysis of a typical high-speed motion picture is made, and the application of the necessary correction factors is illustrated.

Jan 1, 1960