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By Stephen D. Smith

The following tables summarize data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in these tables is what is termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines. Because of inadequacies in the statistics available, some series deviate from the foregoing definition. For copper, gold, lead, silver, tin, and zinc, the quantities are recorded on a mine basis (as the recoverable content of ore sold or treated). However, the values assigned to these quantities are based on the average selling price of refined metal, not the mine value. Mercury is measured as recovered metal and valued at the average New York price for the metal. The values shown are in current dollars, with no adjustments made to compensate for changes in the purchasing power of the dollar.

Jan 1, 1995

By Omotayo Kalejaiye

The Siwek 20-L chamber is widely used throughout the world to evaluate the explosibility of dusts. This research evaluated the quality of dust dispersion in the Siwek 20-L chamber using Pittsburgh coal, Gilsonite, and purple K dusts. A Pittsburgh Research Laboratory (PRL) optical dust probe was used to measure optical transmittance through the dust cloud at various locations within the chamber. A total of 540 tests were performed, with triplicate tests at five nominal dust concentrations and six locations. The two standard dispersion nozzles (rebound and perforated annular nozzle) were compared. The transmissions corresponding to the normal ignition delay period were used to: (a) determine variations in spatial uniformity of dispersion obtained with both nozzles; (b) make comparisons between the experimental transmission data and those calculated from theory for the three dusts; and (c) make comparisons with transmission data measured in the PRL 20-L and Fike 1-m3 dust explosion chambers. The uniformity of dispersion for the three dusts was similar with both nozzles, despite the differences in nozzle geometry and mode of operation. Transmission data of the three dusts were all significantly lower than those calculated from theory. This was discovered to be, in part, due to significant reduction in particle size that occurred during dispersion. By measuring particle sizes before and after dispersion, values of 60%, 50%, and 20% reduction in particle size (based on the surface-weighted mean diameter) were obtained for Pittsburgh coal, Gilsonite, and purple K, respectively. Transmission data from the PRL 20-L, Fike 1-m3 and the Siwek 20-L chambers indicated comparable results in terms of uniformity of dispersion. However, transmission data from the Siwek 20-L chamber were significantly lower than those of the PRL and Fike chambers. Again, this was attributed, in part, to the significant reduction in particle size that occurred during dispersion in the Siwek chamber. The design of the outlet (dispersion) valve of the Siwek 20-L apparatus charge vessel was largely responsible for the particle break-up. The contribution to particle break-up by the dispersion nozzles and the high level of turbulence in the chamber were found to be minimal. This is a significant finding in that the dust particle size tested for explosibility in the Siwek chamber is considerably smaller than the original dust sample.

Jan 1, 2010

By K. E. Soroka

More than 500 fires are now burning in abandoned coal waste banks and coal deposits in the United States. Once established, such fires can burn for decades, and extinguishing them by conventional methods such as surface sealing to exclude air, excavation to remove fuel, or flushing to cool the fire zone is usually difficult and always expensive. Burnout Control, a technique developed by the Bureau of Mines for the control of abandoned coal fires, involves the accelerated combustion of coal in place with total management of the heat and fumes produced. A burning waste bank or mine is placed under negative pressure relative to the atmosphere, and heat and combustion products are drawn from the combustion zone through an exhaust ventilation system. Heat produced appears as sensible heat in the exhaust, at temperatures as high as 1,0000 C (1,832° F), and could be recovered for the production of steam, hot water, process heat, or electricity. The Bureau's first held field demonstration of Burnout Control was at Calamity Hollow in Allegheny County, PA (near Pittsburgh). Calamity Hollow was the site of an underground mine in the 1900's and was surface mined in the 1940's. In the winter of 1961-62, a fire of undetermined origin was discovered in the exposed coal. In 1963, the Bureau constructed a trench barrier around the fire and a surface seal over the affected area. The fire was isolated but not completely extinguished. In 1979, when the Bureau began work on the Calamity Hollow Mine Fire Project to demonstrate controlled burnout, the fire was still smoldering on the hot side of the trench barrier. The project, which was begun in December 1979 and ended in July 1982, consisted of the design, construction, operation, and subsequent dismantling of a Burnout Control ventilation system. This report is the fifth in a five-part series that describes the Calamity Hollow Mine Fire Project. The first report, part 1, describes the design and construction of the field installation. Part 2 will present the results of a continuous 4-month burnout operation. (Because part 2 involves the analysis of a substantial body of data, it will not be published until after publication of parts 1, 3, 4, and 5.) Part 3 describes the instrumentation used to control and monitor the progress of the burnout operation. Parts 4 and 5 deal with the closeout phase of the field demonstration. Part 4 describes the procedure used to quench the fire, and this part (part 5) describes the final excavation and backfilling of the heated zones. The reports in this series document the Calamity Hollow controlled burnout demonstration which showed that (1) controlled in situ combustion is a feasible method for controlling underground fires in abandoned mines, (2) the resultant thermal exhaust output is sufficient for energy utilization, and (3) water injection-fume exhaustion is a potentially effective method for cooling large underground fire zones. Further investigations of both Burnout Control and the water-injection-fume exhaustion quenching procedure are planned.

Jan 1, 1986

By J. L. Eakin

The Bureau of Mines determined agents that are effective in foaming heavy brines and oil from gas wells in severe concentrations of sodium chloride, in severe concentrations of calcium chloride, or in moderate oil-brine mixtures. Dynamic foam tests were designed to select the more effective foaming agents. Numerous foaming agents were tested in concentrated simulated brines, in oilfield brines having varied concentrations of ions, in heavy natural brines, and in a commercial brine generally used as a reservoir pressure-balancing fluid. Several agents were detected that could perform efficiently in the field under the most severe saline conditions. Agents that promote foaming in oil-brine mixtures were also determined.

Jan 1, 1965

By John C. Feeley

This paper is the result of a field study of prospect drilling in the Florida phosphate fields. The objective is to describe the drilling methods employed . . Since the general policies of the operating companies in the land - pebble area do not permit the dissemination of prospecting information and costs thereof , the writer has carefully avoided mentioning names and locations except by reference to existing publications ,

May 1, 1949

By David C. Oyler

The U.S. Bureau of Mines studied the interaction of longwall shield supports and adjacent strata at the Meigs No. 31 Mine in southeastern Ohio. Twenty-three legs of twenty shields at midface were instrumented with pressure transducers and monitored for 11 weeks. During the project, leg setting pressures were reduced twice to determine the effect of setting pressure on shield-strata interaction. No correlation was observed between setting pressure and leg loading rates. The shield loading profiles were consistent with a model in which the roof consists of two zones, a thin immediate roof loading the shields well below the typical setting force and a main roof zone essentially supported by the coal and gob and loading shields through its convergence. This model was used to develop an equation for estimating average loading rates at the site. The only variable of the equation is time, and the equation consists of an exponential term to account for the immediate roof loading and a linear term to account for main roof loading. The equation gave good correlation with average loading rates, but the variation in loading from cycle to cycle was too great for the equation to give good predictions of individual cycle loading rates.

Jan 1, 2010

By A. E. Kasten

The contract objective was to develop and test automatic fire control systems for large surface machinery in surface coal mines. The effort described by the report covers the period from 31 January 1977 to 11 November 1977 and accomplished the following tasks: ? Data accumulation, mainly from visits to the major manufacturers and mine sites. ? Hazard analysis of blast-hole drill, mining shovel, and dragline. ? Recommended design concepts for automatic fire control systems for each of these vehicles. ? Detail system designs for each of these vehicles. ? Procurement of prototype systems for the blast-hole drill and mining shovel. ? Installation of the prototype systems on machines at a surface mine and demonstra¬tion of performance by fire tests on the machines.

Jan 1, 1977

[In selecting deposits of exploration projects, tabular deposits or large mineralized masses are favored because they may be explored systematically and because they afford the best opportunity for blocking out reserves in advance of mining, whereas irregular, small pipes and scattered]

Jan 1, 1941

By Sarkis G. Ampian

Extraction of alumina was correlated with the sinter and leach products from the lime soda sinter process for anorthosite. The effect of composition and grain size of reactants, time and temperature of sintering, and techniques of sample preparation were investigated. Greater than 90 percent Al2O3 extractions were obtained from dry-mixed minus 200-mesh anorthosite sinter mixes having mole ratios of CaO/SiO2 = 1.8 and Na2O/Al2O3 = 0.8. These sinter mixes were briquetted at 15,000 psi and fired between 1,200° C and 1,320° C for 20 to 60 minutes. The sinter phases that contribute to low alumina recovery were determined by X-ray diffractometry, optical microscopy, and electron probe X-ray spectrography. The mechanism of the sintering reaction was investigated by high-temperature X-ray diffractometry. The contrast in the lime soda sinter process for clays and for anorthosites are discussed. Explanations and suggested solutions are presented for problems such as gelation and variable alumina recovery encountered by previous investigations.

Jan 1, 1967

By A. Visnapuu

The U.S. Bureau of Mines investigated the oxidation of American Iron and Steel Institute (AISI) Type 304 stainless steel (SS) during annealing in simulated combustion products from several air-CH4 fuel ratios. Atmospheres representing air-CH4 ratios of 14:1 and 18:1 contained free 02, while atmospheres representing 10:1 air-CH, ratio did not. A Cr203 layer formed on SS samples annealed in atmospheres containing free 0, while a Cr-Fe spinel layer formed in atmospheres with no free 02. The Cr203 layer was adherent and presented a protective barrier to metal diffusion, effectively limiting oxidation of the metal substrate. The Cr-Fe spinel was not protective and allowed the diffusion of Fe through the spinel to the gas-oxide interface where it was oxidized to magnetite, which spalled from the surface. This resulted in thick scale layers on samples annealed in atmospheres containing no free 02, as compared to layers formed on samples annealed in atmospheres containing free 02. These results confirmed and explained industrial operators' observations that thick, smoky (fine spalled magnetite) scales form on SS annealed in low free-02 atmospheres, while thin protective oxide layers form on sheets in atmospheres containing free 02.

Jan 1, 2010

By Jr. Joyce

This report describes sulfatization of nickeliferous laterites from Puerto Rico and the Philippines for recovery of water-soluble nickel and cobalt sulfates. Temperatures ranging from 665 C to 710 C and a 10-percent sulfur dioxide-air reaction gas were employed during batch-roasting tests and during continuous countercurrent treatment in a 2-inch-diameter shaft furnace. A maximum of 69 percent of the nickel and 76 percent of the cobalt were recovered from one sample of Puerto Rican laterite, and a maximum of 96 percent of the nickel and 91 percent of the cobalt were recovered from the Philippine laterite.

Jan 1, 1965

By B. H. Eccleston

The effect upon automobile emissions in changing from leaded to lead-free gasolines was studied in experiments by the Bureau of Mines in cooperation with the American Petroleum Institute. Typical U.S. leaded gasolines and prototype lead-free gasolines of comparable octane quality were used in eight vehicles operated to simulate city driving. The experiments were run at 70° and 95° F. Exhaust and evaporative emissions were measured and the photochemical effect of the emissions was experimentally observed in an artificial smog chamber. Results of the study reveal the manner and degree in which the changes in fuel composition alter the amount and characteristics of both exhaust and evaporative emissions. Briefly, it is shown that the compositional differences between leaded and prototype lead-free fuels resulted in higher photo-chemical pollution potential of the emissions from the lead-free fuels. The effect is attributed to the photochemical characteristics of high-octane fuel components that are used in greater quantity in the lead-free fuels.

Jan 1, 1970

By T. T. Campbell

Studies were conducted by the Bureau of Mines to develop a process for preparing thorium-magnesium master alloys or pure thorium metal by magnesium reduction of thorium tetrachloride in a semicontinuous reactor. Thorium tetrachloride was prepared in a fluidized-bed reactor by chlorination of thorium oxide or thorium oxalate. Conditions were established for producing a suitable thorium oxide feed for a fluidized-bed reactor. Thorium tetra-chloride was purified by vacuum sublimation and subsequently reduced by magnesium in a semicontinuous reactor to form thorium-magnesium alloys. Relatively pure thorium was produced by removing magnesium from the alloys by vacuum sublimation. Close to 100 percent of the thorium fed into the reactor was recovered either as metal (~93 percent) or as thorium oxide (~7 percent). The oxide can be recycled directly into the process.

Jan 1, 1971

By D. A. Paice

A power supply to operate fluorescent or mercury vapor lamps from 300 volt dc coal mine trolley wires has been developed for the Bureau of Mines. A high frequency regulated inverter unit incorporates ballasts for a mix of lamp loads up to 650 watts. For 600 volt trolley systems an additional power converter unit was developed to step down the dc voltage to 300 volts for the inverter unit. Both units have operated in a working coal mine for over 12 months without need for servicing. The lamp load in these tests included two 100 watt mercury vapor head lamps and six 75 watt fluorescent lamps.

Jan 1, 1979

By M. W. Pullen

It is recognized that the determination of electrical resistivity of the earth within a given area may furnish information concerning the location of certain mineralized strata of economic importance. Present knowledge of the electrical resistivity of the various rock formations is almost nil, and the geophysicist who is detailed to make a survey of an area without any data as to the relative resistivity of the underlying rocks is greatly handicapped. Such surveys are usually made within areas known to contain mineral deposits to aid in locating desirable points for drilling. Usually these areas have been prospected by diamond drilling, and drill cores of the various rocks and ores are usually obtainable. Were it possible to make resistivity tests in a laboratory of the drill cores or from pieces of the rocks and ore within an area before attempting a field survey, this would indicate not only the advisability for such a survey but would aid considerably in the interpretation of the results of such a survey. To be of most value a definite method should be used for all such tests, and as yet such a method has not been established.

Jan 1, 1929

By Jerry W. Ramsey

The Bureau of Mines examined a low-, a medium-, and a high-volatile Pennsylvania anthracite by densimetric methods using four mesh si.s of each anthracite. Using high-pressure mercury the macropore volumes and distributions of these pore volumes determined, densities in mercury were calculated, and specific pore vo1.r. ware obtained from these mercury densities in conjunction with helium densities. The helium densities were also used with the ultimate analyses of these anthracites in calculating structural parameters by statistical densimetric methods. The effect of 106 or 108 rads of gamma irradiation in the presence of air and in vacuum upon the properties studied with two mesh sizes of each anthracite. Results of the statistical densimetric method seem to show some breakdown of condensed ring structural units at the lower irradiation level, with subsequent polymerization at the longer period of gamma irradiation. The structural parameters obtained also indicated that in going from high- to low-volatile anthracite, either the number of condensed rings per structural unit increased, or the degree of polymerization increased.

Jan 1, 1965

By B. Dimitriades

Experimental work has been done to refine and to confirm an analytical procedure by which gas-liquid chromatographic (GLC) spectra are interpreted from retention time data alone. The rationale of this spectra interpretation technique involves whether or not a given peak invariably represents the same component or component mixture; if not, what factors influence changes in peak identifications. To answer these questions, peak-identification procedures, based mainly on the use of subtractive columns, were developed and applied to interpret GLC spectra of several exhaust (and fuel) samples.

Jan 1, 1972

By R. W. Hiteshue, R. W. Fridy, W. Kawa

A study of the production of coronene , a high - melting ( 440 ° C ) , highboiling ( 525 ° C) , polynuclear hydrocarbon , was made by the Bureau of Mines to determine the maximum yield obtainable by the hydrogenation of coal and coalderived materials . Experiments were made with anthracite and bituminous coals and with asphaltenes and centrifuged residue obtained from heavy oil produced in a pilot plant by the hydrogenation of a bituminous coal at 2,000 psi and 480 ° C. With anthracite , yields of coronene of 0.5 to 0.7 wt pct of moistureand ash - free coal were obtained at 6,000 to 8,000 psi , 700 ° to 750 ° C , and a residence time of 30 minutes . With bituminous coal , yields averaging 0.4 wt pct of maf coal were obtained at 6,000 psi , 800 ° C , and 30 minutes ' residence time . With asphaltene and centrifuged residue , yields of less than 0.02 wt pct of maf coal were obtained at 6,000 psi , 700 ° C , and 60 minutes ' residence time .

Jan 1, 1964

By Frank E. Cash

Since ventilation adequate in quantity as well as quality is of paramount importance to the health and safety of men working underground in coal mines, mining officials, employees, and State inspection departments should give it the closest possible attention. MINING LAW OF ALABAMA The law governing, and regulating the operation of coal mines in Alabama was enacted in 1911 and amended or revised in 1923, 1925, 1930, and 1935. The original law and subsequent revisions were progressive steps in safeguarding the health and safety of underground employees.

Jan 1, 1939

By Richard F. Hewlett

This Bureau of Mines report presents the computer programing methods and mathematics required to generate either random numbers or normal random numbers to be used for the construction of statistical probability models for simulating mineral deposits by Monte Carlo techniques . Theoretical frequency functions are evaluated as an illustration of simulation applications . Numerical and analytical methods of simulating and dissecting some complex frequency distributions are described .

Jan 1, 1964