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By Charles W. Huggins

Electron diffraction and electron microscopy were used to determine the unit cell parameters of garnierite [(Ni,Mg)3 Si2O5 (OH)4] and to examine its crystal habit. Bundles of ribbons, many less than 200 A. in cross section, make up the bulk specimen of the garnierite Electron diffraction revealed the unit cell to be monoclinic. Unit cell parameters were: a, 5.33 A,; b, 9.23 A.; c, 14.96 A.; and ß, 94°441.

Jan 1, 1961

By Richard D. Graves

Pitch from low-temperature carbonization of bituminous coal was hydrogenated at cracking conditions in a continuous bench-scale unit to produce low-molecular-weight oils and tar acids. The pitch contained 15.6 pct benzene-insoluble material, 4.0 pct hexane-soluble oil, and 80.4 pct asphaltene by weight. At 475° C, 7,500 psig, and 1.5 hours residence time, hydrogenation products, based on the weight of pitch, were about 36 pct oil boiling below 325° C, 24 pct hexane-soluble heavy oil, 17 pct asphaltene, 1 pct benzene insolubles, and 12 pct hydrocarbon gases. The yield of tar acids boiling below 250° C was 4.3 pct, and the yields of C6 to C8 paraffins, naphthenes, and aromatics were each less than 1.0 pct. The yield of tar acids was within the range of yields obtained by hydrogenation or high-temperature carbonization of bituminous coal (2 to 5 wt pct). Yields of oil boiling below 325° C increased with increased residence time or temperature. There was little or no effect of residence time on yields of alkali- soluble material which contained tar acids. Yields of hydro-carbon gases increased markedly with an increase in temperature from 475° to 500° C. Lowering the hydrogen pressure to 4,500 psig resulted in yields similar to those obtained at 7,500 psig.

Jan 1, 1962

By D. B. McGilvra

This paper, describing the mining practices and methods at the Black Rock mine, is one of a series of similar papers on mining methods in the various mines of the United States being prepared by the Bureau of Mines. The Black Rock mine is located in the northeast corner of the Butte district, about 3 miles from the center of the town of Butte, and is owned and operated by the Butte & Superior Mining Co.

Jan 1, 1930

By W. L. Parker, W. A. Selvig

"Introduction.Powdered or pulverized coal is extensively used as a fuel, the total annual consumption*** in the United States being about 12.000,000 tons, and growing steadily. As the coal is usually pulverized so that 70 per cent or more parses through a 200-mesh sieve, it presents difficulties in sieving, because such finely divided material tends to clog the meshes. A fineness test is desirable in order to judge the efficiency of the pulverizing apparatus, and as an indication of the particle size of the coal being burned.Committee D-5 on Coal and Coke, American Society for Testing Materials, has recognized the desirability' of a standard method for determination of fineness of powdered coal. The Bureau of Mines, in co-operation with this Committee, conducted sieving tests on two standard samples of powdered coal, which are described in this paper. As a result of this work a method for making fineness tests, by band sieving, is recommended as a standard method, while a rapid method, by machine sieving, is given for routine tests.Outline of Investigation.Preliminary trial tests were made by the bureau and tentative methods were formulated for making the sieving tests both by band and by machine.Each of two samples of powdered coal was carefully mixed, and portions were sent to the twelve laboratories mentioned later. These were requested to make duplicate sieving tests on the two standard samples, by the hand-sieving and machine-sieving methods, and to follow the tentative procedure exactly as outlined. All of the laboratories made sieving tests by hand shaking and eight of them made tests by machine shaking."

Nov 1, 1923

By Jun Yi

In this paper, single-component gas sorption and transient diffusion processes are described within coal matrix exhibiting bimodal pore structure. The coal matrix is treated as a poroelastic medium manifesting swelling and shrinkage effects due to the sorption of gas under effective overburden stress. Gas transport is considered Fickian with molecular (bulk) and surface diffusion processes simultaneously taking place in the macro-and micropores of coal, respectively. The numerical formulation is intended to be explicit in nature to investigate the influences of sorption phenomena on the macropore volumes and on the overall gas transport for the cases of gas uptake by and release from coal. Results of the study show the presence of hysteresis during a sorption?desorption cycle of the gas. It is also found that the overall gas transport takes place at a rate significantly less than that in the macropores only. Thus the existence of a retardation effect in the overall gas transport is concluded. This retardation effect is primarily due to the micropore resistances, in particular gas adsorption, and is independent of the changes in the macropore volumes. It is shown that macroporosity of the coal matrix may change during gas transport due to combined effects of pressure and sorption-induced swelling or shrinkage of the coal. It is estimated that the macroporosity variation is non-uniform in space and time, as it is expected in reality, and typically taking values less than ±10 percent of the initial porosity.

Jan 1, 2009

By Wm. W. Odell

For a number of years there has been a very appreciable annual,, increase in the production and recovery of natural gas and natural-gas gasoline2 in the United States the latter product being used largely for blending with gasoline from petroleum in the production of motor fuel. On account of the increased amount of oil cracking in the production of gasoline and the accompanying increased percentage of low-boiling constituents in the resulting product, the specifications for the natural gasoline suitable for blending have been altered, that is, the amounts of propane and butane which it can contain have been limited. The result has been that large quantities of the latter materials are wasted because there has been no ready market for thorn in large quantities. Because of this wasteage and because it is probable that large quantities of there and similar materials will be produced in the near future us a result of the more general use of oil cracking processes, a study was made by the Bureau of Mines, under a cooperative agreement with the assistance of the Phillips Petroleum Company, of the suitability of these materials alone or in mixtures for use as gas enricher in the carburetion of water gas for city distribution. This investigation included: (a) A study of the properties of the low boiling members of the paraffin series including pentane with particular reference to their utilization as gases.

Jan 1, 1927

By Alan R. Buehler

A mineral survey of the 67, 110-acre Raven?s Eye WSA (Wilderness Study Area) in the north-central Snake River Plain of Idaho was conducted by the U.S. Bureau of Mines in 1985, at the request of the Bureau of Land Management. The WSA is in Blaine and Lincoln Counties; the northwest corner is about 1 mile east of Carey, 10. A search of county mining claim records indicated that no claims have been located in the WSA. Basaltic lava is the only rock type exposed within the WSA. A platy variety of lava (slab pahoehoe) occurs that is produced from other lava fields in southern Idaho. The material is marketed as decorative stone, used for wall veneers, and retails for approximately $125/ton. Within the W5A, approximately 18,000 tons of indicated reserves are concentrated in two areas, and a total of 12,000 tons of indicated subeconomic resources were found at six other localities. An additional 10,000 tons of inferred subeconomic resources are unevenly distributed over the remainder of the WSA.

Jan 1, 1986

By E. P. Youngman

Except possibly by individual natives and Liberians (small specters), is now being carried on in Liberia, according to a late report. definite information is obtainable with respect to the mineral resources of e country, except that iron ores are said to be abundant. Tin, copper, zinc, site, corundum, lead, bitumen or li nite, and diamonds have all been re- parte, but no commercial Geposits are known to have, been found. Gold has been duce, but not in significant amounts, as may be inferred from the customs - rt for Liberia recording the exportation of gold to the value of $4.80 Germany from the port of Cape Mount in 1925. It is not uncommon for atives to come into towns with African gold and valuable minerals, but they e reluctant to sive information concerning then. Some years ago the Liberian Government was seeing a loan in return for oil concessions, but apparently no drilling bea boon don

Jun 1, 1932

By John Gross

"Introduction.Southern Illinois and Kentucky are credited with approximately 90% of the fluorspar production of the United States. A small amount of high-grade acid, spar is obtained from the ore by band sorting; the greater part, however, is recovered by jigs and tables as gravel spar containing approximately 85% calcium fluoride. In the jigging and tabling operations, galena is recovered, and enough silica and calcite are removed to raise the calcium fluoride content of the gravel spar to 85%. However, the removal of silica and calcite results in a large loss of spar. With increasing depth in the mines, zinc sulphide, sphalerite, is encountered in increasing quantity and the removal of this has become a serious problem. While the sphalerite can be fairly well removed from the spar by present milling methods, a marketable zinc concentrate can not be made. The experiments described below were made on fluorspar ore from Southern Illinois, by the mining experiment station of the U. S. Bureau of Mines, at Rolla, Mo., in cooperation with the Missouri School of Mines and Metallurgy.The ore tested contained. 7.3% lead, 27.9% zinc, 35.7% calcium fluoride, 9.5% silica and 4.7%. calcite.Tests and Results. In some preliminary tests it was noticed that a portion of the finely crushed ore adhered strongly to the sample pans, and upon investigation it was found that the adhering material was practically clean spar. By utilizing this property of adhesion 46.8% of the spar was recovered as a product containing 98.3% calcium fluoride. This suggested the possibility of using electrostatic separation."

Jul 1, 1921

By A. S. Prokopovitsh

A spectrophotometric method for the determination of small amounts of copper in tungsten metal powder using the principle of solvent extraction has been developed by the Federal Bureau of Mines. The metallic sample is dissolved in hydrogen peroxide, tartaric acid added, the pH adjusted, and the excess peroxide destroyed by boiling. Copper is reduced to the cuprous state, and the reagent neocuproine (2,9-dimethy1-1,10-phenanthroline) is added to form a colored complex with the copper. This colored complex is then extracted into chloroform and the absorbance of the separated chloroform layer measured on a spectrophotometer. Copper contents as low as 1 p.p.m. (parts per million) can be determined. The method is limited to finely divided tungsten powder. The interest of the Bureau of Mines in developing more sensitive methods for the determination of trace impurities in high-purity tungsten prompted an investigation of the possibility of using solvent extraction-colorimetric methods. The organic reagents now commercially available make possible many extremely sensitive colorimetric methods for the determination of metallic ions. Extraction of the colored complex into a small volume of organic phase can be used to further increase sensitivity (4) .4/ This general approach has the added advantage that no special equipment beyond that normally found in an analytical laboratory is required.

Jan 1, 1961

By L. B. Pankratz

High-temperature heat-content values of gallium and scandium sesquioxides were measured over the temperature range from 298° to 1,800° K. The results fill gaps in the thermodynamic information for these compounds; no previous similar data existed. The heat-content values were combined with heats and entropies of formation to obtain free energies of formation of gallium and scandium sesquioxides to 2,000° K. The thermodynamic stabilities of the sesquioxides of aluminum, gallium, scandim, and yttrium were compared.

Jan 1, 1963

By John M. Gomes

The Bureau of Mines investigated two techniques for removing CaO from scheelite (CaW04) prior to electrolysis. In the first technique, a crude tungstic oxide (WO3) containing 0.15-percent lime (CaO) was prepared by digesting scheelite concentrates in hot hydrochloric acid. This oxide was used as cell feed to produce tungsten of 99.9-percent purity. The second technique used a high-temperature, two-phase separation, resulting in extraction of 99 percent of the WO3 in the halide-tungstate phase, while 90 percent of the CaO was retained in the silicate phase. Tungsten of 99.9-percent purity was deposited from the halide-tungstate melt after B203 and NaPO3 were added to form an electrolyte. The two methods were compared with a previously developed technique of depositing tungsten from scheelite concentrate fed directly to the electrolytic cell.

Jan 1, 1971

By R. S. Dean

The principle of explosive crushing depends upon the fact that an expandable substance contained within the pores of a solid body will disrupt such a body upon expansion. Such expansion may be obtained by the detonation of an explosive or by the sudden release of pressure of a superheated liquid. That this principle of disruption may be applied to minerals rests on the fact that cracks, cleavage planes, and pores exist in all minerals to an extent hardly conceived possible heretofore. Crushing by this method takes advantage of forces applied from within the mineral rather than from forces applied from without. The application of a force from within would appear to be more effective.

Jan 1, 1932

By F. Chase, D. Pappas

Pillar recovery has been associated with nearly one third of roof fall fatalities in underground coal mines during the past decade. Safe pillar recovery requires global stability and local stability. Global stability is addressed primarily through pillar design. The local stability risk factors include cut sequence, the final pillar stump, supplemental supports (timbers vs. Mobile Roof Supports (MRS)), roof bolting, and many others. The National Institute for Occupational Safety and Health (NIOSH) has evaluated each of these factors through field research and analysis of accident statistics. The paper discusses design methods and technologies that have been transferred to the mining community and implemented.

By R. W. Stahl

One of the broad purposes of the Bureau of' Mines since its establishment has been conservation of mineral resources. As some of the coal beds approach depletion, especially those coals suitable for making metallurgical coke, more and more attention is being given to means of recovering a larger percentage of coal in place. The customary system of mining in the United States is by room and pillar, or some variation thereof, which leaves pillars of coal to support, the roof. In many operations, where the pillars are not systematically recovered, the loss of coal often amounts to 50 percent or more of the original deposit. In many instances in developing new mines, It is planned to recover chain and barrier pillars on retreat when the mine has reached established boundaries. Too often, however, mines are abandoned for some unforeseen reason before completion of mining without recovering any pillars. Usually, these pillars are lost forever. With this in mind, the Mining Division, Region VIII, of the Bureau; of Mines is encouraging mining by longwall methods. It is a generally known fact that almost all of the European coal is mined by longwall methods, which are conducive to a high percentage recovery of coal. A comparison between mining systems usually is on the basis of tons per man per shift. Unless all operating conditions are similar, such a comparison could be misleading. Generally, the output per man shift in European longwall mines is less than that obtained in room-and-pillar mining in the United States. In European mining, maximum recovery of coal is not only mandatory but it must be accomplished without major damage to surface by subsidence. These restrictions necessitate packing or stowing with consequential increases In manpower and decreases in output per man shift.

Jan 1, 1954

By Albert L. Brautigam, Michael C. Leigh, August J. Kwitowski

The U.S. Bureau of Mines developed and tested a teleoperating system to control a new highwall mining system. A remote operator was provided out-of-sight sensory information and control of coal extraction and haulage equipment. Surface and production testing proved that the teleoperating system supplied the operator with sufficient sensory information to operate the mining system. Details on the teleoperating system provided in this report include (1) sensor selection, (2) a description of the electronic control system, (3) equipment selection and modifications, (4) the positive test results, and (5) recommendations for system improvements.

Jan 1, 1992

By R. V. Ramani, A. S. C. Owili-eger

A mass balance equation can be written for the unit block of Figure 7 for changes within the volume during time At as: [ ] where x and y are the coordinates; q is the flow across any surface; p is the density of the fluid flowing through the medium; qvol is the volumetric flowrate; @ is the medium porosity; and Ax and Ay are the dimensions of the block. The subscripts t and (t+At) denote time levels and At is the change in time. Writing this equation in nota- tional form and on rearranging, the following expression is obtained:

Jan 1, 1974

By Jami M. Girard, Ed Mchugh

Slope stability accidents are one of the leading causes of fatalities at U.S. surface mining operations. The Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) is currently conducting research to reduce the fatalities associated with slope failures. The purpose of this paper to discuss some of this research and to present potential new technologies for slope monitoring and design. The paper also briefly discusses various warning signs of slope instability, introduces the most common slope monitoring methods, describes the limitations of various slope monitoring systems, and presents some field results using some of this new technology.

The Ringelmann Smoke Chart fulfills an important need in smoke abatement work and in certain problems in the combustion of fuels. A knowledge of its history and method of preparation is, therefore, of interest to many. Since instructions on its use are not shown on the recent edition of the chart, those included in this revision of the previous Bureau of Mines publication now are a necessary complement to the chart, More detail regarding the use of the chart is included than was given in the earlier version.

Jan 1, 1967

By N. S. Dalal, X. Shi

"Electron spin resonance (ESR) spin trapping methodology has been used to study the reactions of manganese dusts with glutathione, employing a-{4-pyridyl-1-oxide)·N-tert-butyl-nitrone (PBN) and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin traps. The results show evidence for the glutathionyl radical formation in the reactions of both MnO2 and manganese (Ill) acetate with glutathione. Based on these experimental observations, we hypothesise that the mechanism of neurotoxic effects of manganese might be due to the fact that the generation of glutathionyl radicals depletes the glutathione pool and reduces the glutathione shield against free radical products of dopamine metabolism and manganese induced reactive oxygenated species. IntroductionExposure to manganese compounds often occurs as the result of foundries and mining operations (1. 2). Other significant sources of environmental manganese include coal-fired power plants and burning of residual and crude oil (3, 4). Lately gasoline combustion has also started to contribute since manganese (methyl cyclopentadienyl manganese tricarbonyl. 0. 125 g/gallon) is being used instead of lead as an antiknock ingredient in automobile fuels (5. 6). Although manganese is an essential element in certain biological processes it is toxic in excessive amounts. The manganese toxicity is mainly associated with the nervous system (7-9). Symptoms frequently observed in manganese poisoning or manganism are disorientation, memory loss, anxiety, compulsive laughing and crying, mask-like faces, akincsia rigidity and tremor (10). In spite of numerous investigations to understand the mechanism of manganese induced injury. it has not been possible to localize the initial chemical lesion responsible for altered physiology and ultimate cell death. This may perhaps he the reason for failure in developing a successful therapy for manganese intoxication."

Jan 1, 1990