Search Documents

By Kim B. Shedd

An initial evaluation of the flow of cobalt-containing materials in the United States was prepared. The following aspects of materials flow were included: cobalt released as a result of mining and processing other metals and minerals; scrap generation and subsequent recycling or cobalt recovery; and cobalt losses resulting from the generation of wastes, dissipative uses, and disposal of used products. Where possible, estimates were made to quantify the amount of cobalt lost from the materials flow. More than 2,000 metric tons (mt) of cobalt are released annually from mining and mineral processing in the United States, including 480 mt of cobalt in coal produced in the United States. Metallurgical industries examined in this study have well-established recycling or cobalt recovery practices. The petroleum industry recycles spent catalysts, and some chemical catalysts are also recycled. Losses generated during cobalt chemical and powder processing were estimated at 50 to 80 mt of cobalt annually. Losses from alloy processing and the manufacture of parts and products were estimated to be 360 mt. These industrial losses are greatly outweighed by an estimated 2,780 mt of cobalt' consumed in the United States each year to make products that will ultimately be disposed of.

Jan 1, 1992

By A. F. Colombo

The western Mesabi range nonmagnetic taconites containing about 34 percent Fe were evaluated by the Bureau of Mines in a 900-pound-per-hour pilot plant employing a selective flocculation-desliming-cationic flotation technique. The flotation step was a reverse flotation process and involved the flotation of the gangue minerals. The objective of the research was to increase the availability of domestic raw materials for the iron and steel industry. The beneficiated ores yielded concentrates containing 62 to 64 percent Fe and less than 5.5 percent Si02 with accompanying iron recoveries that averaged about 75 percent. Comparable flotation results were obtained with either fresh or 80 to 90 percent reclaimed water. Recycled waters having turbidities as high as 5,000 ppm Si02 did not affect the flotation process. Reclaimed waters containing residual calcium contents of less than 10 ppm gave better flotation concentrates than those containing 15 ppm.

Jan 1, 1976

By H. Polat, Q. Hu, S. Chander

"The collection efficiency of dust particles was determined in a laboratory dust chamber equipped with a water spray. Measurements were made in the presence of selected nonionic, cationic and anionic surfactants. For the nonionic and the anionic reagents, efficiency was maximum in a narrow range of concentration. The surfactant concentration corresponding to high collection efficiency was usually much below the commonly used concentration of l "", however. In comparison, much higher collection efficiency was observed for a cationic surfactant at extremely low concentrations. For delineating the mechanism of capture of dust particles, surface tension and contact angle results were used to obtain a correlation between the work of adhesion and the efficiency of collection. Such a correlation was reasonable for the nonionic surfactants but not for charged surfactants. In the latter case, electrostatic interactions between charged droplets and particles were more important, especially for the cationic reagent. INTRODUCTIONSeveral methods are used to control dust in mines. These include: ventilation, foam, scrubbers and sprays. This article is concerned with improving the effectiveness of water sprays, which are widely used to remove dust particles during continuous mining, by adding small quantities of surfactants. Water sprays produce small droplets which act as collectors of dust particles suspended in air. Sprays directed at the actual source of dust have the additional property of wetting the coal before the ·particles become airborne (Hamilton, 1974). Wetting agents, also called surfactants, arc known to play an important role in many applications where dust is a problem. However, conflicting reports exist in the literature with regard to the effectiveness of surfactants in water sprays (for a review, see Chander et al., 1988). In spite of the conflicting reports, the use of surfactants for dust control has increased over the years. In a recent study by the Bureau of Mines, a 27'6 reduction in respirable dust levels was observed in a mine test when surfactants were added to sprays (Foley, 1991)."

Mar 1, 1992

By C. H. Manney

This report deals with the feasibility of the use of vocoders as an integral part of a mine electromagnetic voice communication system. Limitations imposed by the nature of the transmission path, background noise and equipment are examined. Some properties of vocoders and apparent advantages of the use of vocoders in a mine communication are discussed. The conclusion is reached that the man-made noise level will ultimately determine the workability of such a system.

Jan 1, 1972

1.0 SCOPE AND REGULATIONS 1.1 This specification covers the minimum requirements for material handling and associated equipment including design and materials. 1.2 This specification requires compliance with all federal, state, local laws and regulations which may be applicable including the Occupational Safety and Health Act, Construction Safety Act as well as rules, regulations and standards of the Secretary of Labor.

Jan 1, 1979

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 A. C. Fieldner

[The Sectional Committee on Classification of Coals, functioning under the sponsorship of the American Society for Testing Materials and the rules of the American Standards Association, in its 1934 report recommended to the American Society for Testing-Materials that Specifications for Classification of Coals by Rank be adopted as tentative. These specifications, slightly modified as recommended by the Sectional Committee, in its 1935 report,6 wore approved as tentative standards by the society in 1935. The specifications rover the classification of coals according; to their degree of metamorphism, or progressive alteration, in the natural eerie s from lignite to anthracite. The basic scheme of classification is according to fired carbon and calorific value (expressed in B.t.u.) calculated to the mineral-matter-free basis. The higher-rank coals are classified according to fixed carbon on the dry basis, and the lower-rank coals according to B.t.u. on the moist basis, that is, containing its natural bed moisture but free of visible surface moisture. Agglutinating and weathering indices arc used to differentiate between certain adjacent groups.]

Jan 1, 1935

By K. E. Tame

Pollution from radioactive nuclides, principally Ra226, in liquid waste from uranium mills can be minimized by reusing the waste solution within the mill. Such reuse of waste solution in the Vitro Chemical Co.-type process was investigated in the laboratory. Vitro employs an acid leaching process for dissolution of the uranium, countercurrent decantation for liquid-solid separation and washing, and amine solvent extraction for recovery of the uranium from solution. The simulated reuse of barren raffinate in the mill circuit was carried through two separate laboratory campaigns of 29 and 31 cycles. Conventional chloride stripping of the amine was employed in the first campaign, whereas nitrate stripping was used in the second campaign. Dissolution of uranium from the are in the acid leaching circuit averaged 96 percent. Washing efficiencies of 98 to 99 percent were attained by using 4 volume tons of combined raffinate and makeup water per ton of ore. Uranium recovery from the pregnant solution using a 5-percent solution of amine LA-1 in kerosine ranged from 99.3 to 99.9 percent.

Jan 1, 1962

By J. W. Town

Recrystallization studies on chrome-bearing spinel materials were made by the Bureau of Mines to determine the effects of certain fluxing agents and cooling rates on the chromium-to-iron ratio of recrystallized spinel. Statistically designed and evaluated tests showed that the ratio of chromium to iron in naturally occurring chrome spinel could be increased from 1.5 to 1 to over 7 to 1 and that the ratio of chromium to iron in the chrome-spinel in a stain-less steel slag could be raised to over 18 to 1. Silica, magnesia, and lime had significant positive effects, while alumina had a significant negative effect. Cooling rates of 200 C per hour in a programmed spiral globar electric furnace were satisfactory for growing crystals of recoverable size.

Jan 1, 1967

By J. J. Dowd

1. The Pittsburgh bed is the most important bed in Brooke County and virtually the entire production of coal in the county comes from this bed. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 tons per acre-foot of coal in place, are estimated at 191 million short tons as of January 1, 1954. Of this total, 190 million short tons are in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1955

By Carl F. Wingquist

In support of Bureau of Mines studies of thermal fragmentation of rock, the elastic moduli of four types of rock were measured at temperatures ranging from room temperature up to 1,500° F (1,089° K). The sonic method was employed to determine the resonant frequencies of the rock specimens and from these frequencies, the elastic moduli were calculated. Data for Young's modulus, shear modulus, and Poisson's ratio are given as a function of temperature for Dresser basalt, Reserve taconite, Jasper quartzite, and Charcoal granite. Young's modulus and the shear modulus decreased with increasing temperature up to about 1,200° F and then became relatively insensitive to temperatures from 1,200° to 1,500° F.

Jan 1, 1969

By S. P. Kinney, P. H. Royster, T. L. Joseph

"The study described in this paper, on the reactions in an iron blast furnace, is part of the investigation being conducted by the Bureau of Mines on combustion of coke and the reduction of iron oxides in the blast furnace. Previous study of the combustion zone of the iron blast furnace, by means of a series of as samples taken through the tuyeres across the hearths of 13 blast furnaces, showed that the combustion of the coke in the blast-furnace hearth is complete at a distance of 32 to 40 inches from the nose of the tuyere, measured horizontally toward the center of the furnace. The results of this previous work are sum¬marized in the curves shown in figure 1, where it will be noted that practically all of the oxygen disappears at a distance of approximately 30 inches from the nose of the tuyere.In order to determine the height at which oxygen is found in a vertical direction above the tuyeres - it had been suggested that the combustion zone turned upward near the tuyere and to obtain comparisons with the samples taken at the Bureau of Mines experimental6 (5-ton) blast-furnace at Minneapolis, the Bureau extended the gas sampling on a commercial furnace to a number of planes between the tuyere level and the stock line. The sampling was conducted on a 300-ton furnace, making foundry iron, operated by the Central Iron and Coal Co., at Holt, Ala. The furnace was smelting Southern red and brown ores and nodules from pyrite sinter. Figure 3 is a vertical section of the furnace showing the six planes sampled."

Apr 1, 1926

By Michael G. Zabetakis

The spillage of liquid diethyl ether in rooms at floor level and 3 feet above the floor resulted in flammable vapor-air mixtures in the immediate vicinity of the exposed liquido The liquid temperature was found to decrease by as much as 35° C., with a resultant decrease in vaporization rate. A search of the literature yielded numerous references to unstable peroxide (residue) formed by the autoxidation of ether. Such residues appear to constitute an explosion hazard in the condensed state.

Jan 1, 1962

By D. Bienstock

To develop a rugged catalyst capable of withstanding hydraulic attrition resulting from the oil-circulation process for synthesizing liquid fuels, use of an iron catalyst containing an active coating surrounding an inert solid core of metal was investigated. This massive-iron catalyst in the form of steel shot and lathe turnings was activated by partial oxidation with steam at 600° C, impregnated with alkali, and reduced with hydrogen at 450° 6. The massive-iron catalysts were resistant to oxidation and spalling, and a 6-month catalyst life was attained. Higher operating temperatures could be employed than with fused iron oxide catalysts, resulting in greater gasoline yields. Because the lathe turnings pack with void volumes of 70 to 90 percent, it has become possible to employ a fixed bed without the danger of cementation that occurs with fused iron oxides.

Jan 1, 1963

By S. K. Ash

In arriving at economic losses in coal mining due to accidents, a statistician is confronted with many difficulties on account of the lack of information relative to nonfatal accidents. For comparative purposes the ex¬ perience of those countries, States, or companies that keep complete records can be drawn upon and an extimate can be arrived at whereby one State can be compared with another, or one mine compared with another in the same district. Such a comparison for the United States has been compiled by the United States Bureau of Mines. It will be observed in Table 1 that the cost per ton for accidents in the State of Washington for the year 1927 is higher than for any other State, with the exception of Georgia and North Carolina, with a small combined tonnage of 130,089 tons. (The figures for coal production in Table 1 are taken from Bulletin 319, 1930, of the United States Bureau of Mines.) The reasons why the cost of accidents in Washington might be higher than the average are on account of physical conditions such as steep pitches, faults, igneous intrusions, highly explosive coal-dust, extremely friable coals, presence of gravel and water, very gassy coal beds, rugged topographic conditions, inherently bad roof and floor, thick beds, and heavy cover. The nature of the coal beds requires the use of preparation machinery. The mines are often deep, and topographic conditions are such that long and fast haul¬ age becomes necessary. All of these factors not only tend to cause high cost of production, which is manifested largely in a. lower than average daily pro¬ duction, per man, but..they.also affect to some degree a tendency toward a higher than average cost for accidents.

Nov 1, 1931

In Bureau of Mines research on recycling chrome refractory wastes, used refractories from argon-oxygen decarburization and electric steelmaking furnaces were beneficiated, concentrates were reformed into briquets, and modulus of rupture tests were conducted at 1,350° C. The test results indicated that the beneficiated minus 6-mesh material could be used for producing magnesia-chrome refractories.

Jan 1, 1980

By Wilbur L. Webb

An electrically powered methane sampling system for application on mining machines was designed, fabricated and laboratory tested. The system will sequentially draw sample air at a controlled rate from up to three machine positions across the mine face and deliver the air to either an approved methane monitor, methanometer or flame safety lamp. The prime considerations in the design were to provide an intrinsically safe, water and dust resistant control box and an explosion-proof power box capable of being operated from the various mining power sources. The power box contains an internal battery that provides operating power prior to mining machine start-up and alter machine shut-down. The internal battery is recharged automatically when mining machine power is available.

Jan 1, 1977

By M. B. Boyer, C. H. Herty, F. A. Hartgen, G. L. Frear

"DEFINITION OF VISCOSITYViscosity has been defined as the resistance experienced by one portion of a liquid moving over another portion, such as one molecular plane moving over an adjacent plane. A measure of viscosity is the force required to keep one plane in motion at Unit velocity, the other plane being considered stationary. Figure 1 illustrates the general idea that the surface friction between two adjacent areas will be greater the larger the molecules. Therefore it may be assumed that viscosity will be increased by molecular association or agglomeration, and likewise dissociation rill decrease viscosity. According to Maxwell (1)6 the unit of viscosity, the poise, is the tangential force per square centimeter of area of either of two horizontal planes 1 centimeter apart, one of which is fixed while the other moves with unit velocity, the space between being filled with viscous liquid of unit viscosity.The need for a satisfactory apparatus and experimental procedure for the determination of viscosity of high-melting materials at temperatures corresponding to those in pig-iron and steel making has been recognized during the past few decades. The condition of the slag during the smelting and refining periods in the iron- and steel-making processes exerts an important influence on the metal product obtained, this slag condition really meaning the state of viscosity or, vice versa, fluidity, which the slag attains under certain conditions."

Jun 1, 1934

By Marshal Scherba

Coal seams approximately 7 feet, 9 feet and 20 feet thick at depths of 250, 600 and 1,000 feet respectively were detected using high resolution seismic reflection techniques. Investigation of seismic profiles indicates that good data are required to delineate faulting with only 20 feet of throw but that faulting with 50 feet of vertical displacement can be detected with poor data. Data acquired from dynamite charges fired in water saturated media were clearly superior to that acquired using charges dry tamped in 10 and 20 foot holes.

Jan 1, 1977

By Fred Leonard

This report is principally concerned with the engineering and economic feasibility of area surface coal mining systems other than draglines. This analysis evaluates shovel/ trucks, shovel/crusher/conveyors, and shovel/rail excavation and haulage systems for an assortment of geologic environments and production rates in the Powder River Basin (PRB) Shovel/trucks, front-end loaders/ trucks, and shovel/crusher/conveyors were studied in a multi-seam, dipping geologic area of the Four Corners Region. The Texas lignite engineering and economic research involved bucket-wheel excavators (BWE), BWE/backhoes, and scraper/backhoe combinations for overburden and coal excavation. The PRE truck/shovel study utilized the most recent computer simulation available in both the design and cost analyses. Detailed engineering analysis, followed by in-depth operating costs (operating and depreciation) result in a complete evaluation of each mining system. Cost comparisons of the different mining systems under similar geologic and production constraints are presented in the report to illustrate the estimated capital investment and production costs per ton of coal and bank cubic yard of overburden.

Jan 1, 1980