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By C. G. Maier

Relatively infrequent use by metallurgists of the term "sponge chromium" as contrasted to more than occasional reference to "sponge iron" may be ascribed to the fact that the former material is not a commercial product, while the latter has been known and used, at least in one form (Swedish sponge iron), for several decades. It is doubtful whether a true sponge chromium ever has been prepared heretofore in the laboratory by more than one or two investigators. Nature presents a much. more difficult problem to the investigator endeavoring to make sponge chromium than pertains to the production of more easily reducible elements such as iron or nickel. Recent widespread interest among metallurgists in the possibilities of powder metallurgy is ample incentive to explore the feasibility of producing pure chromium metal in finely divided form. The shift in terminology of this statement from "sponge" to the "finely divided form" is deliberate in emphasis of distinction between terms that occasionally have been used loosely. It would seem desirable that a uniform usage descriptive of finely divided metals be adopted. While to some it might seem preferable that the terra "powdered" metal be reserved for a finely divided form produced by mechanical means, as, for example, chromium produced by the mechanical comminution of electrolytic sheets or flakes, current usage of the term "powder metallurgy' involves no distinction as to source type of material. It is usually accepted, however, that a sponge metal is one reduced from oxide or other combined form at temperatures below the melting point of metal or oxide so that the particles of metal are pseudomorphic, at least macroscopically, with the source material, and, in consequence of the loss of material without change of external shape of the particles necessarily have an open, porous, or "spongy" structure.

Jan 1, 1942

In response to increased aluminum demand, U.S. producers have begun reactivating primary aluminum capacity which was shutdown during the 1974-1975 recession. Reynolds Metals Company started up almost 80,000 tons per year of idled capacity at Listerhill, Alabama, and Jones Mills and Arkadelphia, Arkansas plants. Howmet Aluminum Corporation and Alumax announced that the operating rate at their jointly owned facility at Frederick, Maryland was being increased from 75 percent to 100 percent, equivalent to a 44,000 ton-per-year increase in output. Kaiser Aluminum and Chemical Corp. expected to restart one of the two idled potlines at its Mead, Washington facility in May raising its production rate by 27,000 tons per year. ANTHRACITE - The anthracite market for the larger sizes continues at a good level, and although the demand for industrial sizes has been weak, the current trend indicates an increased demand for industrial fines by the steel, auto, and other industries.

Jan 1, 1976

By M. M. Ayoub

With a return to coal as a major energy source for many companies, more emphasis is being placed on recovery of coal from areas that were formally considered uneconomical to mine. Increasing emphasis is being placed on production from low coal (seam height 48 inches or less) as high coal seams are depleated. Mining in restrictive spaces requires unusual work postures that can turn easy jobs into demanding ones. The objectives of this research were: (1) to evaluate the job demands associated with low coal mining, (2) to survey the anthropometry, strength, and aerobic capacity of low coal miners to determine if they differ from the U. S. population, and (3) to recommend, on the basis of available information, optimal job and work station design for low coal mining. This research effort was supported by the U. S. Bureau of Mines. The male and female anthropometry with the exception of weight and circumferential dimension, was quite similar to the comparison population. Back strength for male and female miners was significantly lower than the industrial worker population. This can be one of the contributing factors of low back problems in mining. Shoveling, timbering, and helpers tasks were physiologically demanding activities. However, due to the frequent stoppage of work, adequate rest was usually available. If work stoppage is corrected, then better work/rest schedules are essential.

Jan 1, 1981

By Mary L. Pearson

Ibis report summarizes the results of the contract. Included are summaries of existing legislation pertaining to outcrop barriers and a state-of-the-art survey of outcrop barrier designs and related, mine closure techniques. Six sites were inspected in the field and are presented as case histories The data analysis presented includes a computer modeled seepage analysis, an overburden blew-out analysis, and a wedge stability analysis. The results tit these analyses are interpreted to form recommendations for coal outcrop barriers which will minimize seepage and the potential for failure. Supplementary support and reinforcement alternatives are also discussed.

Jan 1, 1981

By M. Carrales

This Bureau of Mines report presents information on the sulfur content of crude oil in the United States and in some foreign countries. Data are presented for oil produced in 1971 from fields in 26 States that accounted for about 76 percent of total U.S. oil production; the foreign data cover fields in 24 foreign countries that accounted for about 64 percent of the total oil produced from these countries in 1971. Most of the data are presented in tabular form.

Jan 1, 1975

By L. C. Brichta

The Tri-State zinc-lead catalog, compilation of which was initiated by the Bureau of Mines in August 1949, is designed to provide a continuing record of avail-able drill-hole logs and maps of mine developments in the zinc-lead district in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma. The maps and data thus preserved constitute a reservoir of factual information readily available to individuals and firms interested in planning mineral explorations, to Government agencies for formulating estimates or ore reserves, and to the mining industry in the district for general uses. The areas to be included in the catalog embrace the explored and mined tracts within 760,000 acres of the more active western part of the district. The consensus among local mine operators, geologists, and mining engineers is that over 100,000 boles, costing more than $30,000,000, have been drilled in the district. Records of some of the early drilling and mine developments are destroyed or lost, but the Bureau of Mines has copies of about 47,500 drill-hole logs and is accumulating and recording on microfilm those that are currently available. As of May 1, 1954, the logs of approximately 28,000 drill holes had been microfilmed and are available for inspection at the Bureau of Mines office, Joplin, Mo.

Jan 1, 1955

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining the potential for reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A bibliography of pertinent literature is included as an appendix. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978

By E. B. Nelson, B. W. Gandrud, B. M. Bird

"The Lewisburg No. 2 mine of the Sloss-Sheffield Steel & Iron Company is located in Jefferson County, Alabama, about 7 miles due north of Birmingham. At this point the coal from the Mary Lee seam when coked in by-product ovens yields an excellent quality of metallurgical coke suitable for use in the iron blast furnace; it is also an excellent steam coal. In mining, all three benches are worked. Coarse impurities are largely gobbed by the miners underground.In addition to giving the data obtained from screen-sizing and float-and-sink tests of a representative sample of the raw coal, this report presents the results of slotted-screen tests to show the proportions of flaky particles in selected sizes, and the results of tests to show how much coal is liberated from impurities by crushing the coarsest sizes. These data have been obtained in connection with an extensive study of coal-washing now being conducted by the U. S. Bureau of Mines and the University of Alabama, with U. cooperation of the different operators of Alabama. As the work progresses other reports will follow containing furtner data on the washability both of the Mary Lee seam and of other seams in Alabama and giving the results obtained in preparing these coals by various methods.Although a great amount of investigative work on the preparation of the Mary Lee scam was previously carried on by the various coal companies of the district, comparatively little of this information has been published. In governmental publications three references have been found. Forbes5 gives a number of sections with proximate and ultimate analyses of face samples taken in the mines. Gandrud and Britton'' show sections of this seam at Flat Creek and New Castle; they also give the specific gravity and ash contents of the partings of coal and impurities. In their paper Yancey and Fraser7 include washability studies and washing data from the Sayreton mine of the Republic Iron & Steel Co."

Jun 1, 1930

By Manuel Gomez

This report presents low-temperature tar data from studies by the Bureau of Mines of tars produced in an externally heated (entrained state) pilot-plant-scale retort. Analytical data covering 20 low-temperature tars, derived from the. carbonization of various ranks of foreign and domestic coals, are tabulated. The character of the tar is discussed in relationship to carbonizing conditions and the rank of coal. It is seen that in carbonization techniques that employ entrainment or fluidization of the coal particle, carbonization conditions are secondary to coal rank with respect to tar-oil yields and composition. The influence of distillation conditions on recoverable yields of tar products is presented. The probable yield of commercially important chemical products, based on a ton of pure (moisture- and ash-free) coal, are predicted. INTRODUCTION Low-temperature tars produced by entrainment or fluidized carbonization techniques that employ internally heated reactors represent the most nearly primary tart produced by industrial processes. In brief, such a process involves the application of a heat gradient to the coal particle "boiling" or suspended in a turbulent state in the reactor chamber. Conditions are observed so that the coal particle remains suspended within the reaction zone by a gas stream for a time interval commensurate with maximum tar-oil yield. The heat necessary for the carbonization reaction may be obtained entirely from the hot (preheated) gas stream, or it may be derived partly from the combustion of the volatile products and char by the transport gases, usually air. The volatile material moves out of the carbonizing zone at a rate that approaches the velocity of the transport gas. Carbonizing conditions are ideal when a minimum particle residence time is obtained within the reactor at a given temperature and a maximum yield of condensable volatile matter is released. In industrial practice this objective is a compromise.

Jan 1, 1957

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 Robert H. Bedford

The New Almaden mine was discovered in 1824, and since that date production of quicksilver has exceeded 1,000,000 flasks. Because of this high production record, the New Almaden area was, upon passage. by Congress of the Strategic Minerals Act of 1939, immediately considered by the Bureau of Mines as a promising location for exploration. In 1941, the Federal Geological Survey undertook a survey of the entire district. R. R. Trengove, an engineer of the Bureau of Mines, made a preliminary study for a project in 1942, and in August 1943 the Bureau, in close cooperation with the U. S. Geological Survey, began the development project described herein. The Bureau of Mines drilled 36 holes, totaling 6,807 feet of diamond drilling, along the contact between the serpentine and Franciscan, sandstones and other sedimentary formations. The ore bodies are found along this contact and occur in the carbonate-silica rock. This report briefly describes the location, history, and ore deposits of the property. The recent operations are outlined, and the work performed by the Bureau is explained in detail.

Jan 1, 1950

By H. D. Jacobs

The Federal Bureau of Mines, as part of a program to insure future raw material needs for the iron and steel industry, undertook research to beneficiate the oxidized taconites from the western Mesabi range in Minnesota. The data presented were obtained by applying the Bureau-developed selective-flocculation/cationic-flotation process to the second of three oxidized taconite samples. These three samples are representative of an estimated 10 billion tons of ore analyzing 30 to 40 pct iron. The experimental work was performed in a 900-lb/hr pilot plant. Treating the ore sample (36.1 pct Fe) with the Bureau's process produced commercially acceptable concentrates averaging 63.5 pct Fe and 4.3 pct SiO2, with an average iron recovery of 84.6 pct.

Jan 1, 1980

By Staff

This U.S. Bureau of Mines publication presents the results of investigations into the fire and explosion hazards of oil shale rocks and dust. Three areas have been examined: the explosibility and ignitability of oil shale dust clouds, the fire hazards of oil shale dust layers on hot surfaces, and the ignitability and extinguishment of oil shale rubble piles.

Jan 1, 1989

By A. J. Kraemer

This paper is the second and concluding report of the results of the twenty-fourth semiannual survey made by the Bureau of Mines of motor gasoline marketed in the United states. The first report on this 1931 survey gave the results of the examination of the gasoline samples in accordance with the new Federal specification for United States Government Motor Gasoline. The present paper reports results of the examination of the gasolines for color, doctor test gravity, end point, per cent recovered copper-dish gum, and steam-oven gum. The retail price and the tax at the time each sample was taken are also reported.

Jan 1, 1932

By C. M. K. Boldt

The Bureau of Mines surveyed waste disposal sites at 18 metal and non-metal mines and conducted laboratory and full-scale field tests to de-termine the effects of tailings deposition techniques on physical properties of tailings pond beaches. Survey data included measurements of beach slopes, descriptions of deposition techniques, and measurements of beach physical properties taken at various distances from the point of discharge. Laboratory tests involved depositing two types of tailings, each with different grain-size distributions, into a settling trough and determining the resultant physical properties of settled materials along the length of the beach. Side confinement and the closeness of the water pool to the point of deposition caused the laboratory results to be inconclusive. Full-scale field deposition tests conducted at the tailings pond of a cooperating mine showed that there were similarities in relationships between exit velocities of tailings slurry and physical properties of the settled tailings on the beach.

Jan 1, 1988

By John E. Rourke, O&apos

This report documents the process of site selection, instrument installation, data acquisition, and preliminary data analysis followed to characterize the physical response of overlying strata to longwall mining. A system of surface, subsurface and mine level instrumentation was installed at the Allen Mine in Weston, Colorado where the overburden varied in thickness from 600 to 900 feet. Survey monuments, automatic-recording strain-meters, multi-point rod extensometers, inclinometer-extensometers, stressmeters and tape extensometer convergence stations were installed to monitor displacements and stress changes. A preliminary analysis of the data acquired up until project termination has shown the system to be operative and strata response to be similar to that reported for other subsidence monitoring case histories. Recommendations for continued monitoring of the instrumentation systems are presented.

Jan 1, 1982

By S. H. Lorain

Shortly after the Strategic Minerals Act of 1939 we passed by Congress, the Bureau of Mines was authorized to begin a program of investigation of domestic sources of strategic minerals. Since World War I, the Philipsburg district had been virtually the only one in the United States that was producing manganese on a commercial scale. Consequently, the district was among the first to he investigated. During the summer of 1939, the Geological Survey mapped the geology and ore deposits of the district. In late July 1939 the writer examined the district for the Bureau of Mines. On the basis of this examination and of the work performed by the Geological Survey, the Bureau of Mines diamond-drilled at several properties in the district during the summer of 1940. This report reviews the mining history and geology of the district, and presents the factual data obtained by diamond drilling.

Jan 1, 1950

By Scott A. Stebbins

This Bureau of Mines publication presents a method for estimating capital and operating costs associated with the exploration, mining, and processing of placer deposits. To ensure representative cost estimates, operational parameters for placering equipment and basic principles of placer mining techniques are detailed.

Jan 1, 1987

By J. W. Miller

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and, from the data developed, to determine: (a) Which coals, either as mined or after beneficiation by conventional preparation, are suitable chemically under present standards for producing metallurgical coke. (b) Which coals require special and more intensive treatment in preparation than is now practiced. (c) Which coals cannot be considered potential sources of metallurgical coke, regardless of preparation. This report is one in a county series and describes the preparation characteristics of the coals of Logan County, W. Va. According to present-day standards for metallurgical coal, many believe that the sulfur content of the coal should not exceed 1.25 percent? Coal with more than this amount has been used for making metallurgical coke, especially when blended with coal containing less sulfur. In this series of reports 1.25 percent sulfur is used as a gage to determine whether or not a coal will be suited for metallurgical coke.

Jan 1, 1957

By W. W. Roepke

The linear cutting system, developed by the U.S. Bureau of Mines, uses geometric principles developed by Cardan to produce a nearly constant cut depth. The new system has been extensively tested in a synthetic material under laboratory conditions to verify mechanical capability and to identify operational characteristics. Comparisons between 15-rpm linear cutting and 50-rpm rotary cutting systems show significant improvement in respirable dust entrainment, product size distribution, and energy usage. Respirable dust is reduced by as much as 90 pct. Recovered product showed a 67-pct reduction in -0.32-cm (-1/8-in) material and a 200-pct increase in +5.08 cm (+2 in) material. Average power was reduced by 66 pct for the linear cutting. Because the bit cutting paths differ between linear and rotary cutting, it was necessary to compare the two at the same cut depths and bit types. These comparisons show that low revolution per minute rotary cutting entrains about the same amount of respirable dust as the linear cutting system, but the average shaft torque may be 55 to 130 pct greater for the rotary system.

Jan 1, 2010