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By M. Hertzberg

The Bureau of Mines measured the energy requirements for the spark ig-nition in air of Pittsburgh seam bituminous coal dust, lycopodium spores, and polyethylene powder with a 1.2-L furnace and 8-L and 20-L chambers. Thermal autoignition temperatures of the same dusts were mea-sured in the 1.2-L furnace. Electrical ignition requirements are given in terms of both effective spark gap energies, [ ] and stored circuit energies, 1/2 CE2. The measured order of electrical ignitability for the three dusts is consistent with the data of other researchers; however, the absolute values are systematically higher, probably because of higher flow and turbulence levels in the chambers used and lower electrical efficiency in the circuit used here. The temperature dependence of the lean limit of flammability for lyco-podium was measured wi th the 1.2-L sys tem, and those measurements con--firm the applicability of the modified Burgess-Wheeler law to a dust. Due to experimental complexities, the minimum ignition energies for dusts may not reflect intrinsic flammability behavior. However, some valuable information may be obtained from the relative ignition energies of various dusts at ambient and elevated temperatures. In addition, the concept of minimum electrical ignition energies for homogeneous gas mixtures is reevaluated theoretically.

Jan 1, 1985

By Albert L. Toenges

This report is the second of a series describing methods and systems of mechanical mining; where operations are conducted on more than one shift. The first report, Information Circular 7014,4/ describes mining operations at 14 mines and the present paper describes operations at 11 additional mines. The purpose of this study is to analyze the advantages and disadvantages of the various types of equipment and mining systems now used where more than one shift is worked per day. Physical conditions vary in different and in the same mining districts and determine, together with economical considerations, the systems of mining and the types of mechanical loading equipment to be used. The information presented in this paper may be helpful to operators or others who may contemplate installing a mechanical mining system. The equipment used in the mines described comprises conveyors, scrapers, mobile loaders, mobile conveyors, and combination of these types. The description of the mining systems and practices at the mines investigated is detailed only as they relate to and affect mechanization. In computing the operating data in mines that are not totally mechanized, employees not working directly on production have been charged to output from mechanized sections in proportion to the percentage of mechanization. The operating data for comparing various systems are for an average working dry, as the number of men working on idle days varies greatly in different mines.

Jan 1, 1939

This document is Volume II of a two-volume report on underground and surface metal and nonmetal mine fires occurring between 1950 and 1979. Two surface fires from 1980 are included. Volume I discusses the methods of data acquisition, data analysis procedures, and results and conclusions. This volume contains (1) a master list of all fire incidents obtained from MSHA reports, (2) an annotated bibliography of all MSHA reports, journal articles on selected incidents, and non-reportable fires (appendix), and (3) indexes to be used in accessing incidents in the master list and annotated bibliography. These three types of information provide the reader with a complete summary of metal and nonmetal mine fires during the period from 1950 through 1979 and a convenient means to locate incidents of specific interest. The body of this volume is organized around two tables and a series of indexes. The two tables are master lists of underground and surface fire incidents. They are followed by 15 indexes keyed to the master list and annotated bibliography. The Appendix contains three different parts: ? The annotated bibliography of MSHA fire reports (one section each for underground and surface mine fires). ? The annotated bibliography of journal and other periodical articles about selected fires from the MSHA bibliography. ? A listing of non-reportable fires (one section each for underground and surface mine fires). Descriptions of the contents and use of each of the three major components of this volume (i.e., master list, indexes, and appendix) are presented in Section 2.0.

Jan 1, 1980

By J. H. Jansky, P. W. Jeran, G. L. Hassett, M. C. Irani

This Bureau of Mines report tabulates methane emissions from U.S. bituminous coal mines with daily emission rates of at least 100,000 cfd according to States, counties, and coalbeds. Most of the methane emitted is from mines in the Appalachian States. Total daily emissionin 1975 was 216.3 MMcfd, compared with 227.0 MMcfd in 1971 and 214.5 MMcfd in 1973. Thirty counties in nine States had daily methane emissions of 1 MMcfd or more, These emitted 93 percent of the total methane. The highest emissions were from Monongalia County, W. Va,, which accounted for 18.9 percent of the total. This was followed by Marion County, W. Va., 9.6 percent; Buchanan County, Va., 8.5 percent; Jefferson County, Ala., 6.1 percent; and Washington County, Pa., 5.9 percent. The Pittsburgh coalbed emitted 45.7 percent of the total methane, followed by the Pocahontas No. 3 coalbed with 12.9 percent. The report lists 196 mines, of which 60 had daily methane emissions of 1 MMcfd or more. Included in this compilation are the identification and thickness of the coalbed, methane emission, coal production and ventilation rates, number of drifts, shafts, and slopes used for ventilation purposes, shaft depth, age of mine, and gas-to-coal ratio.

Jan 1, 1975

By Frank J. Wiebelt

As a result of the examination of many copper-zinc properties in the West Belt area of California, nine were chosen for exploration projects by the Bureau of Mines. This was part of the Bureau's wartime mineral-development program aimed at maintaining production of essential metals and increasing ore reserves. The properties explored were the El Dorado, El Dorado County; Copper Hill, Newton, and Gray House, Amador County; Constellation, North Keystone, and Collier, Calaveras County; and American Eagle and Akoz, Mariposa County. In addition to surface sampling and mapping, 41 holes, aggregating 18,134 linear feet, were diamond-drilled. Detailed results of the work done on all properties except the El Dorado and Akoz are given in this report. The El Dorado and Akoz were discussed in Reports of Investigations 3896 and 4144, respectively. Figure 1 is an index map showing the location of the mines covered in this publication.

Jan 1, 1951

By Jerry J. Gray

Transportation charges for mineral commodity movements in western Oregon and western Washington were determined mainly by a stratified random sample canvass of producers. Total 1965 mineral production value for this area was $53.3 million; the cost or charge to move this production from the mine to the consumer or to the point of consumption was determined to be an additional $38.7 million. Thirty seven companies were contacted as a sample out of a total population of 349; the statistically expanded sample production value deviated 3.6 percent from that obtained by the Bureau's annual canvass. The agreement between the sample results and the canvass totals demonstrated the effectiveness of the sampling method for obtaining data with a predesigned level of accuracy. For comparison, the north-central Idaho and western Montana area was studied, A random sample experiment was designed, but because of the dominance of a few major companies, a random sample technique would have required more visits to producers than if only the larger firms were contacted. Eighty-four percent of the 1966 mineral value ($198.6 million) was accounted for by interviewing 27 firms out of a total population of 199. Total transportation costs or charges for the area were $26.7 million. The significant difference observed between the relationship of minerals production value and transport charges between the two areas investigated can be attributed to the difference in the minerals produced. The western Oregon and western Washington region is a nonmetals-producing area as opposed to the predominance of metals production in the Idaho-Montana region.

Jan 1, 1968

By E. P. Carman

This report is the 19th in a series summarizing Bureau of Mines research and technologic work on coal and related investigations. The first 17 reports covered fiscal years; however, the 18th report3/ covered the 18 months from July 1, 1952, to December 31, 1953, to permit the publication of this and subsequent reports on a calendar-year basis. Most of the material in this report relates to publications by Bureau authors issued during the reporting period. Some work is referred to on which the results have not yet been published or may not be published for security or other reasons. In a few instances publications are mentioned that were issued before the reporting period but were not included in previous reports. Further details on the published work described herein may be found in the publications cited in the footnotes. Research and technologic work on coal by the Bureau is directed toward developing and encouraging increased conservation of coal resources through safer and more efficient mining, preparation, and utilization. Significant advances were made during the year in these fields, particularly in coal-mine safety and in preparation and utilization of the various ranks of coals.

Jan 1, 1956

By S. R. Zimmerley

[In the course of a flotation investi£ation, a siliceous gold ore was ground in a'ball mill to ':1inns 300-meeh. It wa. found that the small amotIDt of _Ius 300-mesh material had a gole.. assay approximately twice that of the oriGinal ore, &~d that this overs.ize nroduct also contained much abrac..ed iron. .,Joreove I the gold assay of the abraded iron t which was !1epnrated ma§metically', ~iVFl.£ eight ti;nes that of the are. These facts suggested that some r31aticnship ex?...,ted between the abnorma11y high gold content an the prese:1ce of brA-cit)" iron. It was decided, therefore, to investigate furt~er th~ Fl.Gsociation of the bold ~ith the iron abraded from the balls during sri~Qing ]

Jan 1, 1937

By Catherine C. Kilgore

The Bureau of Mines investigated the availability of lead and zinc from 104 domestic mines and deposits. Fourteen primary lead and fifty-three primary zinc operations with in situ demonstrated resources containing 27.3 million metric tons (t) of lead and 53 million t of zinc were subsequently evaluated. Potentially 17.5 million t of lead and 2.4 million t of byproduct zinc could be recovered from 14 primary lead operations. Economic evaluations performed in constant January 1982 dollars determined a long-run total cost per pound of recoverable commodity. Including a 15-pct discounted-cash-flow rate of return (DCFROR), 59 pct of primary lead was potentially available at or below $0.32 per pound of lead. Potentially 40 million t of zinc and 5.6 million t of byproduct lead could be recovered from 53 primary zinc operations. Ninety percent of the recoverable zinc is potentially available from currently nonproducing mines and deposits, and a weighted average of their long-run total costs was determined at $0.98 per pound of zinc. At a breakeven (0-pct) DCFROR, these non producing operations had a weighted average long-run total cost of $0.58 per pound of zinc. Sensitivity analyses illustrated that operations that recover byproducts were most sensitive to fluctuating metal prices, producing operations were more sensitive to increased smelter treatment charges, and nonproducing operations were impacted most by the DCFROR.

Jan 1, 1983

By G. B. Gait

This report is the fourth in a series concerning the Bureau of Mines program for microfilming maps of abandoned mines in the Pennsylvania anthracite region; a catalog of the microfilmed maps of 70 mines in the Western Middle field is presented. Previous reports were catalogs of microfilmed maps of mines in the Eastern Middle field and in the Wyoming and Lackawanna Basins of the Northern anthracite field. Additional catalogs will be published as the microfilming of significant mining areas is completed.

Jan 1, 1971

Confidence in the strength of the U.S. economic recovery was considerably enhanced by third quarter 1983 profits, which showed a 12.8-percent increase over those in the second quarter (table I). Although the increases were not as great as between the first and second quarter of 1983, profits have grown each quarter since fourth quarter 1982. Both total profits and profits per unit of output increased, which the Bureau of Economic Analysis (BEA) attributes to decreases in labor and nonlabor costs (per unit of output), as well as to moderate price increases. [ ] A number of durable goods sectors, however, continue to show profit declines, especially electrical and non-electrical machinery. Profits in the primary metal industry are still negative, but the economic picture of this industry is improving. Between the second and third quarters of 1983, capacity utilization increased somewhat in primary metal manufacturing and stone and earth mineral mining but did not change at all in metal mining. Capacity utilization in metal materials increased from 47.4 percent in the fourth quarter of 1982 to 64.2 percent in the third quarter of 1983 (table 2).

Jan 1, 1983

By Will H. Coghill

This paper on milling methods and costs at a flat river (Mo.), mill is one of a series of information circulars on milling methods and costs which is being prepared by the United States Bureau of Mines, The mill under consideration treats 5,000 tons of load ore daily by table concentration and flotation. It is 25 years old, and yet it is a new mill. Research has been in continual progress at the plant since its beginning, and accordingly a day never passes without a record of change for advancement. The changes have been so orderly that no evidence of obsolete equipment remains.

Jan 1, 1932

By Paul Zinner

An exhaustive program of geologic studies and mapping has been conducted by the Geological Survey in the Iron River district of Michigan since May 1943. Means of contributing to the success of these studies were sought by the Bureau of Mines, and eventually a program involving geophysical studies and core-drilling was undertaken in the area. All of the work was done either to develop data that would contribute directly to geologic studies or to investigate geophysical methods that might be used as a primary means for the discovery of minable iron ore.

Jan 1, 1949

By Hillary W. St. Clair

The purpose of this investigation was to determine the practicability of refining crude aluminum-silicon alloy or aluminum scrap containing silicon and iron by selective dissolution in zinc of the aluminum from the alloy followed by distillation of the zinc from the aluminum.

Jan 1, 1949

By Joan Weinberg

Real output expanded at a 3.0% rate worldwide in 1987, a slightly lower pace than the 3.2% rate in 1986. The decline was accounted for largely by slower growth in the U.S.S.R. and the East European countries, as well as in the developing countries (table 1). According to the International Monetary Fund, output of industrial countries output grew 3.1% and rose most strongly in Japan, the United Kingdom, and Canada (table 2). U.S. economic growth remained at 2.9%, the same as in 1986. Consumer and government spending declined in industrial countries, while gross fixed investment: rent increased. This increase in fixed investment expenditures could be attributed partly to lagged results of some 1986 developments: the fall in oil prices, declining interest rates, and exchange rate changes. The U.S. budget deficit, as well as the large external deficits and surpluses among major industrial countries, hindered further growth .2 A report from the Organization for Economic Cooperation and Development (OECD) indicates that the impact of the October stock market crash was short-lived because it hit economies that were growing strongly, anyway.3 The growth of output in the developing countries slowed in 1987; however, output declined in the fuel-exporting developing countries. These countries have been adversely affected by weakness in oil prices and the depreciation of the U.S. dollar. The weighted average of inflation rates in industrial countries--as measured by the [ ] GNP deflator, was 2.9% in 1987, down from 3.4% in 1986. Prices rose 3.0% in the United States, up from 2.6% the previous year. Inflation for 1988 is expected to remain slightly higher in the United States than in Japan and the Federal Republic of Germany because of recent exchange rates changes and the elimination of slack productive capacity and labor in the U.S. economy. Prices in developing countries as a whole rose more than 10 percentage points in 1987. Higher import prices, caused by

Jan 1, 1988

By Foster Fraas

The Bureau of Mines investigated a method for calculating values of adsorption energy; the goal was to devise an equation consistent with experimental data accumulated in the investigation of adsorption as related to ore separation processes. Numerical identification of the constants of a previously formulated equation provided an equation by which values of adsorption energy could be calculated. Values thus calculated checked with those obtained by calorimetric measurement.

Jan 1, 1965

By Richard D. Miller

This Bureau of Mines publication contains analyses and related source data for 224 natural as samples from 18 States. Of the total, 191 sam¬ples were collected during calendar year 1981. The remaining 33 samples were collected during previous years, but releases, granting permission to publish were not received until 1981. All samples were obtained and analyzed as part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by the mass spectrometer and special helium apparatus described previously (1-2).3 The results of the investigation of the occurrences of helium are published annually to make the information available as soon as possible to the gas industry and the general public. Twenty-five publications have presented the results of 12,827 gas analyses made prior to 1981. The first three bulletins (1-3) contain analyses and related data on 5,218 gas samples collected from 1917 through 1960; these bulletins have been supplemented annually by information circulars (4-17, 19-24) containing 7,609 analyses of samples collected since 1960.

Jan 1, 1982

The 1967 Lignite Symposium was held at Grand Forks, N. Dak., on April 27-28, 1967. This was the fifth of these technical meetings and the fourth which was cosponsored by the University of North Dakota and the Bureau of Mines. These symposia have provided a meeting place where current developments concerning technology and utilization of solid fuels (lignite) are presented. There was a registration of 255 persons from 24 States, the District of Columbia, six Canadian Provinces, Germany, and India. Many segments of coal or energy oriented organizations at many levels were represented. During the meeting, 18 presentations were made covering developments in electrical power generation, mining, estimation of reserves, combustion, gasification, and chemical and speciality uses of low-rank coals; these are com-piled in this Information Circular to provide a record of the symposium and to permit wider dissemination of the information. Proceedings of the other meetings have also been published.3

Jan 1, 1968

By W. F. M. GOSS

The locomotives in service on the railroads of this country consume more than one-fifth of the total coal production of the United States. The amount is so large that any small saving that can be made effective in locomotive practice at once becomes an important factor in conserving the fuel supply of the nation. For this reason the United States Geological Survey gave attEmtion to the special problems of combustion in locomotive boilers. It approached this task from several different directions. The facts presented herewith constitute one series of results. In the fall of 1906 the locomotive-testing laboratory of Purdue University, at Lafayette, Ind., entered on a series of tests, one purpose of which was to determine in precise terms the degree of efficiency with which a modern high-class American locomotive utilizes the heat energy of the fuel supplied to it. The general interest in the subject, the elaborate plans which had been formulated for conducting the work, and the substantial character of the support which had been pledged to maintain it justified the Geological Survey in aiding the investigation. a The cooperation of the Survey consisted in detailing experts to assist the regular staff of the laboratory in the chemical and calorific work of the tests. These experts, working under the general supervision of the director of the Purdue laboratory, became responsible for the sampling of smoke-box gases, of the fuel used, of the cinders caught in the front end, of the sparks discharged by the stack, and of the refuse caught in the ash pan. The gas analyses were made by them at the university laboratory. The analyses of all solid samples and the calorific tests of the fuels were made at the government fuel-testing plant at St. Louis. The representatives of the Survey were not concerned with other phases of the work.

Jan 1, 1911

By Walter E. Lewis

The Cuyuna iron range in Crow Wing County, Minn., is the principal producer of manganiferous iron ore in the United States. The ore is mined from a manganiferous iron formation in the bedrock of the Cuyuna district. This iron formation is divided into two general lithologic types-thin-bedded and thick-bedded. The unoxidized, thin-bedded iron formation is composed of iron silicate with associated fine-grained carbonates of iron and manganese. The thick-bedded iron formation carries iron and manganese oxides with intimately associated silica. Oxidation and leaching of the original iron formation have been the most influential factors in producing manganiferous iron-ore concentrations in quantities large enough to exploit on a commercial basis. The unoxidized and the partly oxidized and enriched iron-formation materials are suitable as a source of ferrograde manganese ore. These materials have been classified according to their amenability to mineral dressing and degree of oxidation and leaching.

Jan 1, 1958