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By W. W. Adams

The first full year of the second World War for the United States presented a picture of the metal-and nonmetal-mining 4 industry which, without proper analysis and explanation, would convey a distorted view of achievements during 1942, especially because employment at gold and silver (lode and placer) mines-the largest group-declined to such an extent that the over-all totals for the country were reduced even though increases were made at mines producing copper, lead-zinc, iron, miscellaneous metals, and non-metals. A complete panorama of the metal-and nonmetal-mining industry, exclusive of coal mining, reveals a decrease in the number of men employed, the man-hours of employment, and the accident-frequency rates. Were the gold and silver (lode and placer) mines to be considered as a separate category; it would be seen that the number of men employed at all the other groups of mines increased appreciably over 1941. These other increases must be considered important, since these mines produced the vital war minerals that made valuable contributions to the military successes of the United States and its Allies during the year. A separate analysis of each of the various groups of mines may be found elsewhere in this bulletin. For the purpose of maintaining continuity in this series of bulletins, however, the discussion in this introduction will be confined to the entire metal-and nonmetal-mining industry (excluding coal mining, for which a separate bulletin, No. 462, has been published).

Jan 1, 1945

By H. A. Doerner

"During the year which has passed since the last progress report on reduction of zinc by natural gas,3 the laboratory experiments on this investigation have been completed. In this concluding report, the whole subject will be reviewed and additional data presented.Chemical ReactionsIn a thermodynamic study of zinc smelting, Maier 4 discussed the use of methane for reducing zinc oxide, and predicted equilibria at various temperatures for the sore important reactions. The study has been extended to include the following list.Maier predicted that 870°C. would be the critical temperature above which reaction (1) would take precedence over reaction (2) and that reaction (1) at equilibria would be substantially complete at or above 927°C. A subsequent papers described experimental verification of these predictions and gave data on reaction rates under various conditions.It methane is passed through a heated bed of zinc oxide at a low enough rate reactions (1), (3), and (4) reach an equilibrium which can be expressed by reaction (10). The equilibrium concentrations for the products of this reaction in the temperature range 900° to 1100°C. were calculated by applying the thermodynamic constants to the stoichiometric relations. 6 The results of these calculations are listed in table 1 and shown graphically in figures 1, A and B. These data have major importance, and experimental work has shown that they are subtantially correct."

Dec 1, 1934

By E. G. Davis

Large-scale ultrafine grinding tests of a coarse kaolin were made using the Bureau of Mines developed attrition grinding process in continuous open-and closed-circuit systems. A 20-inch diameter attrition grinder, designed and constructed at the Tuscaloosa Laboratory, was used. Studies included single- and multiple-stage open-circuit grinding, and also continuous grinding tests in closed-circuit with a 6-inch-diameter solid bowl centrifuge. Clay feed, containing 9.0 percent minus-2-micrometer esd, was used at fates up to 840 pounds per hour. Multistage grinding tests gave better results than single-stage treatment when equivalent clay feed rates were used. Closed-circuit grinding tests yielded ground products containing slightly more minus-2-micrometer-esd clay than the open-circuit grinding when using the same clay feed. Energy consumption was lower in closed-circuit grinding than in batch or open-circuit grinding. A modified two-stage closed-circuit grinding system gave the best grade of product and amount of minus -2-micrometer-esd clay produced per pound of clay feed. The ground product from this test contained 88.5 percent minus-2-micrometer-esd material and electrical energy consumption was 327 kilowatt-hours per ton of minus-2-micrometer-esd material produced.

Jan 1, 1973

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 H. Reginald Hardy

This report describes the results of a research project carried out to investigate the feasibility of using transducer arrays, located on surface or in shallow boreholes, above an active coal mine to detect and locate the source of underground microseismic activity which normally occurs during mining. The initial stage of the project involves the design and development of a self-contained mobile microseismic monitoring facility capable of use in remote field locations. Following this a variety of transducers, and transducer field installation techniques were investigated to obtain optimum sensitivity and high signal-to-noise characteristics. Preliminary efforts were also undertaken to develop semi-automated techniques for analysis of microseismic field data. Using the facilities and techniques developed field studies were carried out at a number of surface locations over a central Pennsylvania coal mine operating at depths of the order of 500 feet. In particular studies were con-ducted over a previously mined development area, troubled by extensive problems of roof instability, and over two longwall panels during mining. Although many of the field studies were carried out during the development stage of the project, results in general have been most encouraging. Limited results were obtained over the development area, however excellent microseismic signals, correlating with underground strata instability, were detected over both long-wall areas, proving the general feasibility of surface monitoring techniques. More recent studies, carried out as part of a subsequent project, and utilizing modified geophone installation techniques at a third longwall site, have verified explicitly the feasibility of measuring underground microseismic activity from surface locations. Sections of typical field data are included in this report along with a brief review of the studies carried out at each of the field sites. Detailed analysis of data obtained at the second and third longwall test sites will be presented in a later report.

Jan 1, 1974

By Albert L. Toenges

The Grundy coal field is in process of development, and this circular was written to describe the mining methods and practices in use in the mines now being worked in this field. In lieu of man-hour labor data for individual mines a consolidated sheet of mine costs, which includes expenses for labor, material, and power, is given for all mines. The costs are for a working day only, based on average daily production. Because the demand for coal is seasonal, the costs for idle days, which vary at each mine, have not been estimated. Approximate reserves of coal seams have been estimated from data and maps taken from Bulletin XVIII of the Virginia Geological Survey4/.

Jan 1, 1936

By D. C. Dahlin

The U.S. Bureau of Mines investigated the magnetic susceptibility of minerals as a function of mag-netic field strength to determine how it might affect the potential for high-field magnetic separation as an alternative to other separation technologies. Single-mineral concentrates were prepared from specimens from the same deposit to compare magnetic susceptibilities of minerals that occur together and from specimens from different deposits to compare magnetic susceptibilities of like minerals. A vibrating-sample magnetometer with a superconducting magnet capable of producing a magnetic field of 7.16 x 106 Aim (90 kOe) was used to measure the magnetic moment of the samples. The data were then converted to specific magnetic susceptibility data and plotted as a function of magnetic field strength. Cursory studies were also completed on the effects of iron content and oxidation roasts on magnetic susceptibility in high fields. The results showed that magnetic susceptibility is essentially constant in magnetic fields above those needed to saturate ferromagnetic constituents. Although magnetic susceptibility is influenced by iron content and by thermal treatment, the changes are not large enough to influence separations in fields above 1.59 x 106 Aim (20 kOe).

Jan 1, 2010

By Harry H. Ku

In December 1975, a report entitled "An Evaluation of the Accuracy of the Coal Mine Dust Sampling Program Administered by the Department of Interior" [1] was prepared by the Analytical Chemistry Division of the National Bureau of Standards (NBS), in response to a request by Senator Harrison A. Williams. Chairman, Committee on Labor and Public Welfare. The report attempted to evaluate the adequacy of (1) the personal sampler unit used to measure the coal dust concentration in the mines, (2) the procedures used by the Department of Interior (DOI) to analyze the dust samples obtained from mine operators, and (3) any recent studies made by the Department or private industry concerning the coal dust sampling equipment. Recommendations in the report of NBS included continued research efforts by the appropriate organization to correct the personal sampler deficiencies and to consider the use of area or stationary samplers as a supplement to the personal samplers. Concurrent with the NBS report cited above, the General Accounting Office (GAO) also issued a report in December, 1975 [2], suggesting that improvements are still needed in coal mine dust sampling programs and procedures relating to penalty assessments and collections. Among recommendations made by GAO, the following paragraph specifically called for actions by the agencies involved:

Jan 1, 1979

This project was started 8 June 1971. As set forth in our Proposal of 28 April 1970, responding to the RFP of 30 March 1970, the plan was twofold: 1) choose fluids and develop techniques for measuring coat porosity, and 2) construct a porosimeter for making such measurements, By the time plans for the porosimeter had been drawn up, the picture had changed; and it was found more advisable to do further researches on porosity rather than build the equipment. This development arose from a meeting with Dr. Fred N. Kissell on 14, 15 October 1971, annotated in our letter of 19 October 1971, and was contracted for 6 December 1971. The technical effort of the project was completed 7 May 1972. From the beginning it was realized that the ratio of 'hole volume to the whole volume' might be too simplistic a definition for coat porosity and that its measurement might be confounded by complications which were not yet known, We were hopeful that an exploration of fluids and techniques would provide early feedback on both these points which could be used in subsequent developments. This turned out to be the case.

Jan 1, 1972

By D. Harrington

The number of fatalities from mine explosions for the fiscal year 1945 dropped below that of the year before; continued improvement over the record of the years from 1940 to 1945 is hopeful, but the number of reported explosions has increased rather than diminished, and the number of victims claimed by explosions is often more definitely a factor of chance than forethought. Mine fires and explosions can be eliminated through the methods now well-known to those well-informed in matters pertaining to safety in mining but ignored by many coal-mine operators and employees who follow procedures of the past or their own short cuts, regardless of disasters that may result: Tried and proved safety measures for preventing mine fires and explosions have been recommended to the mining public repeatedly, yet only a relatively small but far-sighted minority have adopted these measures and made them a part of operating practice. That far more explosion disasters did not occur in 1945 is fortunate. In 1945 a coal-mine fire of electrical origin caused heavy loss of life, while several others from the same cause were controlled with but few fatalities; this hazard is now being curbed temporarily to some degree after the bad record of the two preceding years, but a real solution of the problem has not been reached, although cooperating committees trying to produce at least some answer have made progress.

Jan 1, 1946

By Jeffrey Y. Foley

The Bureau of Mines sampled surface exposures of podiform chromite in the Caribou Mountain-Melozitna ultramafic belt in the Kokrines-Hodzana Highlands, central Alaska. Fieldwork began in 1979 as part of an assessment of the mineral potential of lands adjacent to the trans-Alaska pipeline corridor, for the Bureau of Land Management, and continued through 1981 as a Bureau of Mines investigation. The belt comprises six complexes of which the three closest to the pipeline corridor were investigated. Concentrations of chromite disseminated in dunite host rock make up mineralized intervals ranging in thickness from less than an inch to 5 ft and in grade from 3 to 23 pct chromium. The largest occurrence has an exposed strike length of 80 ft. Bulk surface samples were collected from 10 of these exposures, and beneficiation tests on the samples produced concentrates of metallurgical, refractory, and subindustrial grades. Part I--this report--describes the fieldwork; part II--1C 8916--describes the beneficiation work.

Jan 1, 1983

By Cleo G. Rall

The value of brine analyses in the study of petroleum-engineering problems was recognized early in the history of petroleum. The Bureau of Mines before 1928 had indicated in several reports.3/ ways in which analyses might be used. Because of the confusion resulting from attempts to correlate the work of different chemists using greatly varying methods of analysis and systems of computation and expression of results, a paper presenting the methods used by the Bureau of Mines was prepared and published in 1928. This system of determining the characteristic constituents of oil-field waters and of calculating and reporting results has been widely adopted by the petroleum industry. The earliest and most obvious use of water analyses is determination of the source of water infiltrating into petroleum and natural-gas wells. For this purpose it is necessary that an analysis of the connate water of the formation from which the oil is produced be available and that an analysis of the contaminated water be made. By comparing these analyses with those of connate waters from formations higher in the structure, the formation from which the infiltrating water comes may be identified.

Jan 1, 1953

By John C. Cook

This was a study to identify and evaluate known technologies employing electromagnetic resonance phenomena in solid minerals for their identification and assaying, particularly assay logging of exploratory boreholes. A comprehensive literature search and study revealed some little known NMR (nuclear magnetic resonance) techniques developed by Professor G. J. Béné's group at the University of Geneva, Switzerland. These are suitable for use in weak, inhomogeneous magnetic fields. Laboratory NMR tests of numerous U.S. ore minerals showed good identifying signals from phosphates, fluorspar, bauxite, oil shale, and spodumene (lithium) ores, but not from the copper, lead, antimony or manganese ores tested. Use of EPR "signatures" for such ores is suggested. A conceptual design for an NMR assay logging system is proposed.

Jan 1, 1978

By E. G. Meiter, S. H. Katz

"Railroad locomotives produce heat, gas, and smoke, which cause considerable discomfort to engine men and firemen while passing through tunnels. In order to try and improve these conditions, the Bureau of Mines has investigated the composition of atmospheres in cabs of freight locomotives while in tunnels; and some of the higher temperatures in the cabs were noted; physiological effects upon men were determined and gas masks and respirators were devised to eliminate the effects of irritating and poisonous gases and smoke. Those investigations were conducted in tunnels of the Baltimore & Ohio, Pennsylvania, and Union Pacific railroads; while that described in this paper was carried out in tunnels of the Chesapeake & Ohio, Railroad, situated in the Blue Ridge and Allegheny Mountains in Virginia and West Virginia, Freight locomotives used by this railroad are of the Mallet type, which have two separate cylinders: and two separate sets of driving wheels on each side. In locomotive language they are of the 2-6-6-2 type. All of the cylinders act as simple engines when starting or in slow, heavy hauling; but at faster speeds the pair of cylinders on each side operate compound, Mallet locomotives are the largest and most powerful now operated.The tendency in train operation has always been to increase the burden upon locomotives, Present traffic needs frequently load even the Mallet engine to capacity, and yet the weight of trains tends to increase. It has been suggested as a means of securing greater power units that Mallets be constructed to operate only as simple engines. This would increase the amount of steam given off as the amount of coal burned and the resulting volume of flue gas emitted."

Jul 1, 1924

By G. W. Weems

The specific objective of this investigation was to determine the compressibility factors for helium and carbon dioxide mixtures at -10° and -20° C and pressures to 1,000 psia. A Burnett apparatus was used. Data from the experiments were treated by the method of Barieau and Dalton. Tables of compressibility factors and approximations of the virial coefficients are presented for 10 binary mixtures as well as for helium and carbon dioxide. The results follow the same trend as data previously reported.

Jan 1, 1970

By Oliver Bowles

In its geologic sense the term marble is applied to rocks consisting of crystallized grains of calcite or dolomite or a mixture of the two. Although limestone has the same chemical composition as marble it differs in that the component particles of calcium or magnesium car- bonates are granular and noncrystalline. In marble the crystals may be intimately intergrown, whereas limestone is an aggregation of unrelated particles cemented together into a solid mass. In its commercial sense the term marble has a much wider applica- tion. As susceptibility to polish is one of its chief commercial assets, all calcareous rocks capable of polish are classed as marbles. Lime- stones that show little crystalline structure may, if they take a good polish, be classed as marbles. Furthermore, serpentine rocks, even if they contain little calcium or magnesium carbonate, are classed as marbles, as they are commercial substitutes of true marbles.

Jan 1, 1916

By Andrew Allan

[This report describe the first experiment of the Anthracite Research Laboratory, Bureau of Miners, in attempting to reduce underground-mining costs and conserve anthracite as a natural r-source by introducing now minim methods. The work war, dons in cooperation with one of the large anthracite-producing companies. It applies to productive mining, characterized by comparatively low cost, per ton and high production per man, as differentiated from development mining, which is always necessary before the, productive or retreat phase can begin. The system d scribed in this report is believed to be generally applicable to beds pitching 70° to 90° and, under certain conditions, to beds pitching loss than 70°. After development hate been completed, an openings is made, extending the full width of the 9- to 10-foot coal bad and reaching from the haulageway to the vertical limits of the solid coal. Long drill holes (20 to 50 feet) charged with about one stick of permissible explosive riper foot of length are fused to break the coal. Once broken, the coal is loaded onto a shaker conveyor by gravity and thence into mine: cars. The coal is mined retreating in 15- to 20-foot sections that are broken and loaded onto the conveyor through a specially constructed chute. In the Bureau?s experimental work, the height of sections arse ranged from 35 to 60 fact, depending on the geologic extent of the coal bed.]

Jan 1, 1952

These inspection standards have been prepared for use in the Federal inspection of bituminous and lignite mines. They are a revision of "Tentative Coal-Mine Inspection Standards," published as Bureau of Mines Information Circular 7204 in February 1942 and employed a guide for Federal inspections. Numerous changes have been made in the original standards owing in part to recognition of shortages of some types of safety equipment due to the war, in part because of need of additional standards to cover certain mine conditions' arid' practices, and in part to conditions not foreseen when the original standards were prepared. About one-fourth of these standards are marked with an asterisk (*) as being of particular importance in preventing accidents in many coal mines; however; failure to carry out the suggestions made in such of the other standards as are applicable may also' lead' to the loss of lives.

Jan 1, 1943

By Richard N. Spencer

This report describes investigations of the economic merits of multiple zone mining and beneficiation versus selective mining of altered Western phosphate rock. The same deposit was considered in both instances and it was assumed that the grade of selectively mined ore was comparable to the grade of the concentrate from beneficiation. The beneficiating scheme used for the investigation was one proved by small continuous circuit operation. All economic factors were found to favor multiple zone mining plus beneficiation. Capital requirements and production costs were lower, and production life of the deposit was extended 4.5 times. The concentrate from beneficiation would be a uniform high-quality feed for acidulation and would be low in stable metallic oxide (R203) content. Such a feed would permit improved plant operating control, and the low R203 would promote more rapid filtration and minimize sludge formation in the phosphoric acid. With the proposed treatment, the concentrate produced by flotation from this deposit would cost about 1.5 times as much per ton as the concentrate produced by classification sizing. Therefore, inclusion of a flotation step in treatment schemes requires an economic analysis for each ore deposit.

Jan 1, 1971

By Holmes, George H. Jr.

The Cherry Creek tungsten district was explored by the Bureau of Mines from April 16 to August 13, 1942. This district is in north-central White Pine County, Nev., 50 miles north of Ely. Principal work was done on the property of the Cherry Creek Tungsten Mining Co. and at the adjacent Chance mine, although the entire district was examined and mapped. The exploratory work was done in cooperation with the Federal Geological Survey and comprised surveying, trenching, sampling, long-hole and core drilling, rehabilitation of mine workings, road building, drifting, and shaft sinking. The more important tungsten occurrences were explored by trenching and diamond drilling. Sixteen holes, having a total length of 2,515 feet, were drilled. The project resulted in partial development of three new tungsten deposits and small increases in the reserve tonnage of two scheelite-bearing lenses that were being mined by the company. The following pages summarize the history of the district, outline the ownership of the properties explored, and describe the physical features and mineral deposits. Mining and milling practices at the Cherry Creek tungsten mine are outlined, and the plan and results of project work are presented in detail together with surface maps, assay maps, and drill-hole logs.

Jan 1, 1950