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The U.S. Bureau of Mines evaluated water-jet-assisted longwall shearers in full-scale laboratory tests and underground. Both test programs showed that use of high-pressure water did little to reduce the shearer motor energy required to maintain a given cutting rate. However, three other major benefits were achieved with the use of water-jet-assisted cutting. At a pressure of 1,800 psi, respirable dust levels were reduced about 80 pct compared with the dust levels of the conventional water spray system operating at 340 psi. Operating at higher pressures required for water-jet assist also resulted in an increase in the average size of coal cut, which translates into a decrease in product fines. Finally, although no controlled measurements of bit wear as a function of water pressure were made, mine personnel reported that the shearer bits lasted longer when water-jet-assisted cutting was used.

Jan 1, 1989

By E. R. Bauer

Noise-induced hearing loss (NIHL) continues to be a concern of the mining industry. A new noise standard (30 CFR, Part 62) is aimed at reducing NIHL in mining through engineering and administrative noise controls. However, the difficulty and expense of implementing engineering controls can make administrative controls an attractive alternative for reducing worker noise exposure. Over the last three years, the National Institute for Occupational Safety and Health (NIOSH) has conducted worker noise exposure surveys in underground and surface coal mines and in coal preparation plants. The surveys revealed numerous possible administrative controls and an approach to implementation and analysis. The surveys have shown that worker dosimetry, time-motion studies and equipment noise profiling are important aspects of effectively utilizing administrative controls. A description of the approach for selecting, implementing and evaluating administrative controls and a list of possible administrative controls are reported.

Jan 1, 2007

By J. Robert Wells

The Bureau of Mines has developed a spectrochemical procedure for determining 19 impurity elements in high-purity titanium metal, titanium oxides, and titanium halides in which all samples are converted to titanium dioxide. Determination of these impurities was studied in the general concentration range of 0 to 1,000 p.p.m., but different determination limits were found for the various elements. The procedure is quantitative for 18 elements but semi-quantitative3 for beryllium and has an overall relative standard deviation of 15.8 percent. Two mixtures were used, one composed of graphite and lithium carbonate plus gallium oxide and the other of graphite and lithium carbonate plus germanium dioxide. Each mixture was blended mechanically with an equal weight of titanium dioxide. Lithium carbonate served as buffer-diluent. Gallium was the internal standard for 1 impurity element, germanium for 7, and titanium for the remaining 11.

Jan 1, 1962

By Je M. Oh

The Bureau of Mines is conducting research to determine the high temperature oxidation resistance of substitute stainless steels (SS) containing two less strategic elements, Al and Si, instead of Cr. Chromium is considered to be a critical and strategic metal. Although the Cr content was reduced to 8 wt pct, the alloys showed better oxidation resistance than did 304 SS containing 18 wt pct Cr. Specifically, the alloys that contained Fe-8Cr-16Ni with combinations of Al and Si showed excellent oxidation resistance even at temperatures up to 1,000° C. In this study, the effects of the alloying elements on oxidation kinetics and morphology of oxides were investigated using a Cahn Rg electrobalance, scanning electron microscopy, an energy-dispersive X-ray analyzer, X-ray diffraction, and an electron microprobe. Aluminum and silicon additions in combinatin were more effective in providing oxidation resistance than either element was alone.

Jan 1, 1986

By Michael Rieber

Among the principal gathering/distribution systems for coal is over-the-road trucking. Where alternative trunk line modes such as barge or rail links are weak or nonexistent, trucks may, particularly for relatively short line hauls, act as substitutes. Their major application, however, appears to be in connection with smaller mines or coal users particularly where terrain problems are significant. Truck use has increased as rail lines have been abandoned or suffered neglect. For example, in 1956 about 38 percent of the coal transported in eastern Kentucky and about 8 percent of the coal moved in western Kentucky went by truck. By 1975, the percentages were almost 77 percent and 26 percent, respectively [4,U-11]. While rail route .limitations and deterioration played a part in the change, increased emphasis on road building, particularly during the 1950's and 1960's, and improved truck load capacity and efficiency were also important.

Jan 1, 1977

By N. H. Coates

The Bureau of Mines determined average film coefficients of heat transfer for helium flowing through smooth, water-cooled tubes at Reynolds numbers of 5,000 to 25,000, helium inlet temperatures of 1,600° to 2,600° F, average temperature difference across the helium film of 800° to 1,300° F, and heat flux to 215,000 Btu/(hr)(sq ft). Since helium was the only gas used, the ranges of values for physical properties of the fluid are limited--thermal conductivity from 0.15 to 0.20 Btu/(hr)(sq ft)(O F/ft), viscosity from 0.082 to 0.104 lb/(ft)(hr), and Prandtl number from 0.63 to 0.68. Four equations, three of them dimensionless, correlate these coefficients with other properties of the helium--bulk temperature, film temperature, dimensionless parameters based on temperature, and the ratio of wall temperature to bulk temperature.

Jan 1, 1966

By K. C. Dean

Horizontal and vertical air classification systems were tested individually and in simulated tandem use for the recovery of ferrous and nonferrous metals and of other noncombustible and combustible products from shredded urban refuse. The horizontal air system with a larger tonnage throughput was used to obtain preliminary separations, and a smaller capacity vertical system was used as a cleaning device. Air elutriation, magnetic separation, and screening of shredded minus 6-inch municipal refuse recovered 92 percent of the metal in a relatively clean iron product contaminated only by adhering coatings or entrapped materials, recovered 97 percent of the combustibles in a 97-percent combustible product, and rejected 88 percent of the nonmetal noncombustibles. Cleaning of the preliminary combustible fraction produced a 98-percent paper product while rejecting other combustibles (plastics, rubber, textiles, etc.) into a 94-percent combustible product. Retreatment of the preliminary noncombustible fraction produced a relatively clean glass product.

Jan 1, 1971

By Mayo D. Hercey, Edward W. Butzler

"Purpose and Origin of Investigation.For many investigations of mineral products such as metallic and ceramic materials, especially refractories, a knowledge of thermal conductivity and specific heat at high temperature is required. Such data have been needed by the Bureau of Mines for checking heat balances in kilns, and computing heat loss through furnace walls.Design of apparatus for thermal conductivity tests was undertaken by the Bureau early in 1922, an industry at that time indicated that no equipment intended for extreme high-temperature observations was elsewhere available or likely to be in the immediate future.The Bureau's investigation was begun by C. R. Greenslade, assisted by F. A. Hartgen, and temporarily discontinued owing to their resignations in the summer of 1922. The work was later turned over to the writers of this report, and has been carried forward at intervals, along with other problems."

Jan 1, 1924

By J. J. Demeter

Experiments were conducted in 2- and 4-inch-diameter standpipes to evaluate the effectiveness of standpipes as pressure seals. During the experiments, these standpipes conveyed Alan-Wood magnetite (60 to 230 U.S. standard sieve mesh) by gravity flow from one vessel to another of relatively higher pressure. The information obtained has been helpful in a Federal Bureau of Mines investigation of how to make either synthesis gas or hydrogen by a modified steam-iron process employing a continuous recycling stream of granular iron-iron oxide at temperatures of 600° to 900° C. In this process the mixture of granular material flows by gravity from a reduction vessel at low pressures to an oxidation vessel at higher pressures. Data from the 2- and 4-inch-diameter standpipes indicate that it would be practical to use a standpipe as a pressure seal between the reductor and oxidizer. Investigators found that, by gravity flow, the standpipe could convey the Alan-Wood magnetite against pressure gradients up to 1.07 pounds per square inch per foot of column height.

Jan 1, 1961

By Sidney Katell

The present report, a continuation of the series of Bibliography of Investment and Operating Costs for Chemical and Petroleum Plants, is concerned with articles published from January 1958 through December 1958. The periods covered in previous reports are as follows: January 1930 - August 1948 I. C. 7516 September 1948 - June 1952 I. C. 7705 July 1952 - June 1954 1. C. 7751 July 1954 - December 1956 I. C. 7847 January 1957 - December 1957 I. C. The following sources were used to obtain the references to and the abstracts of the published articles included in this report: 1. Bureau of Mines Information Circulars. 2. Bureau of Mines Reports of Investigations. 3. Chemical Engineering. 4. Chemical Engineering Progress. 5. Coal Age. 6. Coal Utilization. 7. Cost Engineering. 8. Industrial and Engineering Chemistry. 9. Nucleonics. 10. Oil and Gas Journal. 11. Petroleum Engineering. 12. Petroleum Refiner. 13. World Oil.

Jan 1, 1959

By E. G. King

Cerium and thorium sulfides have found use as crucible materials for melting certain radioactive metals. However, thermodynamic treatment of these sulfides has been hampered by lack of experimentally derived entropy values. This Bureau of Mines report describes heat-capacity measurements between 51° and 298° K, and entropy evaluations at 298.15° K, for cerium monosulfide (CeS), cerium sesquisulfide (Ce2S3), and thorium disulfide (THS2). The entropy values, with Literature results for the heats of formation, are used to obtain free energies of formation at 298.15°K. MATERIALS The samples used in this work were supplied by Prof, Leo Brewer of the Department of Chemistry, University of California. The methods of preparation and some of the physical and chemical properties of these sulfides were given by Eastman and coworkers.3 4/ Chemical analyses, conducted in our laboratory, gave the following results:

Jan 1, 1959

By Graham W. Marks, Clyde A. Bridger

"INTRODUCTION An electrolytic process for the preparation of metallic cobalt has been developed recently in the Bureau of Mines Experimental Station at Boulder City, Nev. Chemical analysis shows this cobalt to contain impurities in small percentages, chief of which is nickel. It is desirable to be able to determine these impurities spectrographically. This report is concerned with a procedure for the spectrochemical determination of nickel in cobalt.Previous spectrographic work on cobalt was done by Breckpot and Mevis,/ who used the method of homologous pairs of lines. However, it was felt that a more detailed investigation was needed, employing the method of internal standards.ACKNOWLEDGMENTWe are indebted to B. G. Knickerbockor and his staff at the Boulder City, Nev., station of the Federal Bureau of Mines for their cooperation, and particularly to Richard W. Lewis and Robert G. Sanderson, who prepared nickel-free electrolytic cobalt for us."

Feb 1, 1948

By Robert W. Metcalf

Since the spread of the European war virtually cut off imports from Denmark, Belgium, and France, the Bureau of Mines has had numerous inquiries as to domestic sources of grinding pebbles and silex or other types of ball mill liners. USES Flint pebbles and tube-rill liners are used by grinders of certain ceramic materials to prevent contamination of the finished product by iron abraded from steal baler and liners. The feldspar industry is one of the largest users of flint grinding mediums; they are employed also by curtain grinders of talc and soapstone, ground sand and sandstone, quartz, and chalk. Some paint materials, such as lithopone, have been ground in pebble Flint pebbles have been used more or less in the past, especially by cement manufacturers, and, for fine grinding of gold, copper, or other ores in which iron contamination is not especially deleterious.

Jan 1, 1940

The generally disappointing results obtained in the present study, together with the high material costs involved, preclude any general recommendation for a continuation of the work. One recommendation arises, however, from some observations on the application of latex to spoil banks. It was found that dilute latex used on a slope of spoil bank material at an application rate of 400 lbs per acre (dry basis) stabilized the soil and made it much more resistant to washout by rainfall. It is recommended that a study be conducted to use latex for temporary stabilization and/or sealing of spoil banks before and during reclamation procedures, on coal slurry ponds and coal refuse piles.

Jan 1, 1972

By David R. Forshey

This Bureau of Mines report presents a quantitative theoretical analysis of a coupled gasdynamics-heat release system involving the kinetics of water condensation in and behind the rarefaction wave in a shock tube using the method of characteristics. The merger of characteristics to form a shock wave is included.

Jan 1, 1977

By P. J. Dallimore

The Bureau of Mines has calculated general time-dependent solutions for radon diffusion from cylindrical and slab rock samples containing uniform radium distribution. Results have been obtained for several sets of boundary conditions. The method is suitable for determining the effective diffusion coefficient and the effective porosity for radon.

Jan 1, 1983

By V. R. Spironello

The Bureau of Mines is involved in research directed toward the conserva¬tion of important raw materials and the utilization of solid waste. Two of the objectives are to conserve high-quality coking coals used for foundry coke and to utilize waste materials of marginal quality but of high calorific value. These objectives are consistent with Bureau goals. Pilot plant cupola trials were made to evaluate the adequacy of various alternative fuels, and to determine to what extent they could replace the foundry coke in cupola charges. Information was obtained on furnace performance, metal and slag chemistry, environmental questions, and the properties of castings. It was shown that anthracite or bituminous coals can partially replace charge coke up to the 40 pet level. Briquetted materials prepared from fuel fines, and waste prod¬ucts or byproducts of high calorific value, all tend to break down on heating in a cupola so that their use must be restricted to below 20 pet replacement. In cases where pitch-bonded coal fines or petroleum coke were used, carbon pickup by the iron was inadequate for gray iron specifications. Although emphasis during this work was placed on basic slag practice, some acid practice results are included.

Jan 1, 1980

By Neil B. Young

Analytical results for nahcolite, dawsonite, total extractable alumina, and oil yield are presented for samples representing Green River Formation oil shales in the saline section of two cores from Colorado's Piceance Creek basin. Analyses are also reported for samples extending the analyzed section of Colorado corehole No. 3 beyond that reported previously. These data permit evaluation of the deposit for possible production of three coproducts--shale oil, alumina, and sodium carbonates--from the saline section of the formation at these sampled points.

Jan 1, 1970

By John C. Holtz

The Bureau of Mines studied air contamination caused by diesel exhaust in a 10,000-ft ventilated tunnel. Sequential air samples were taken at the ends and middle of the tunnel during an operating cycle. Observed and calculated results for carbon dioxide, carbon monoxide, and nitrogen oxides were essentially in agreement. Nitrogen dioxide was present only in trace amounts. It was found that contamination was related to the volume of ventilating air, the number of haulage trips, train speed, and engine load.

Jan 1, 1968

By Thomas Varley

Data on the consumption of reagents used in flotation during the years 1923 and 1924, in metallurgical plants in the Unites States, are presented in this paper. Two previous reports Lave been issued by the Bureau of Mines on consumption of oils and other reagents used to flotation - namely, "Statement of Flotation Oils," by O. C. Ralston, issued in 1913, and Serial No. 2203, "Consumption of Reagents Used in Flotation," by Thomas Varley, for the year 1919, issued in January, 1921.

Jan 1, 1925