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By Zabetakis M. G.

This Bureau of Mines report presents a brief summary of the explosion trends in United States coal mines for the past 160 years. These trends show that in spite of the overall improvements in mine safety, the number of fatalities from ignitions of methane has actually increased in recent years. Suggestions are made of procedures that can be utilized to reverse this trend.

Jan 1, 1973

By E. P. Youngman

Tantalum is a rare element ; estimates indicate that there is less tantalum than gold in the earth's crust . After remaining a laboratory curiosity for many years , it was used to a limited extent and for relatively few years (1903- 1911) for incandescent electric-light -bulb filaments . Another wave of interest in tantalum appeared when its electrolytic-valve action was taken advantage of in charging storage batteries , especially for radio work . Tantalum chargers were eventually displaced by other types of chargers , but for a time they were manufac tured in sufficiently large numbers to create a demand for the metal and to bring about its production on a commercial scale in the United States . As tantalum became available in larger quantities and at substantially lower prices , and as high prices for platinum encouraged the employment of tantalum as a substitute , the metal was put to many new uses . Ferrotantalum was made and sold before the World War , and patents have been taken out for a number of special alloys for industrial purposes , but probably the largest use for the metal to-day is in vacuum tubes .

Aug 1, 1930

By W. E. Robinson

A laboratory study wan made to determine whether drying and preheating Colorado oil shale with waste retort gases has any appreciable effect on its oil yield. Samples of crushed oil shale were heated at subretorting temperatures in a specially constructed electric furnace by gases similar in composition to waste gases from oil-shale retorts. The results of this study showed that preheating oil shale with nitrogen or a reducing mixture had no effect upon the oil or water yield. However, oxygen in the preheating gas caused a decrease of oil and an increase of water. In general, the oil yield decreased with (1) increase in oxygen content of the heating gases, (2) increase in temperature of the heating gas, (3) increase in heating time, and (4) decrease in the particle size of tho shale. The decrease in oil and the increase in water resulting from preheating were due to oxidation of the benzene-insoluble organic material (kerogen) rather than to oxidation of the benzene-soluble organic material (natural bitumen) in the shale, A small amount of oil was volatilized during preheating, which would constitute an additional loss if prober precautions were not taken to recover it. The results obtained in this laboratory study indicate that oil shale can be preheated without appreciable decrease in oil yield by proper selection of preheating conditions.

Jan 1, 1951

By V. E. Edlund

As part of its efforts to devise new and improved methods for recovering lithium from unconventional resources , the Bureau of Mines investigated a lime -gypsum- roast , water- leach technique for processing lithiumenriched ( 0.01-0.68 pct Li ) clays . This report presents the results of a study of the technical feasibility of extracting lithium from raw material representative of clay beds associated with the McDermitt Caldera complex in Nevada and Oregon . prepared from water used Pellets suitable for bench-scale roasting studies were mixtures of minus 200 -mesh clay , limestone , and gypsum , with as the pelletizing agent . Roasting pelletized charges at 900 ° to 1,000° C temperatures for 1- to 4-h periods produced calcines that leached readily , yielding water - soluble lithium sulfate ( Li₂SO4 ) . A 5-3-3 ( weight ratio ) mix of clay , limestone , and gypsum produced calcines with the best leaching characteristics . More than 91 pct of the contained lithium was extracted from pelletized mix batches roasted in covered refractory boats . Lithium recovery decreased to about 87 pct when the mix was roasted under dynamic conditions in a gas - fired rotary furnace . A reaction mechanism was postulated which indicated that dilution and loss of SO2 and oxygen in the combustion exhaust adversely affected the leachability of the dynamically roasted calcine .

Jan 1, 1983

By J. B. Zink, M. J. Peterson

A semiquantitative spectrochemical method was developed and applied to the analysis of ash of U.S. coals . A low- temperature ashing procedure was used to minimize the loss of volatile elements . The analytical procedure provides for the estimation of 68 elements including major , minor , and trace constituents . Standards for the trace elements were prepared in a synthetic base mixture that approximates the average composition of U.S. coal ashes . Excitation was achieved with a d- c arc , spectra were recorded photographically , and interpretation was made by visual comparison of spectra of unknowns with spectra of graded standards series . Thirty- six trace elements were found in the analysis of 900 samples . Details of the procedure are presented , including sample and standards preparation , excitation and exposure conditions , spectral lines used , and approximate limits of detectability .

Jan 1, 1964

By Donald I. Kurth

The Bureau of Mines conducted experimental work on comminuting coal. The size distributions of coarse fragments and fine particles were obtained under different modes of energy application--drop, impact crushing, wedge impact, compression, and shear tests. Four levels of energy application were used in the impact crushing and wedge impact tests. Airborne dust and respirable air-borne dust distributions were obtained for the impact crushing and wedge impact tests. Analyses of nonairborne dust and coarse fragment-fine particle distributions were carried out on impact, wedge, compression, and shear tests. The experimental size data on nonairborne dust were fitted to normal, log-normal, power law, Weibull, log-Weibull, and exponential distribution functions. Both the nonairborne dust and the coarse fragment-fine particle size distributions are best described by Weibull distributions. For the impact crushing tests, mean product size was found to be inversely related to specific crushing energy. The particle counts in a given size range of airborne and nonairborne dust were found to increase with increased input energy and specific crushing energy. However, in another sense the particle distributions were independent of energy level; that is, the percent-ages in a given size range were approximately constant regardless of energy level. Respirable airborne dust was related to respirable-size nonairborne dust by a power law.

Jan 1, 1975

By Glen C. Ware

The Bureau of Mines determined the factors involved in the corrosion of starting sheets used in the production of electrolytic zinc with the ultimate purpose of adapting zinc starting sheets to commercial practice . Under present practice , zinc is electrodeposited on aluminum cathodes and subsequently stripped for melting . The use of zinc instead of aluminum would eliminate the need to strip the deposit , thereby reducing the cost of handling and melting it , but zinc has not been suitable because it was too vulnerable to the corrosive attack of the electrolyte . Serious attack was found to be limited to the areas of the cathodes situated immediately above the surface of the electrolyte and to re - entrant corners . It was possible to avoid solution - level corrosion by immersing the starting sheets completely , exposing only a relatively heavy suspension member to solution - level attack . Zinc starting sheets could be made as reliable as aluminum and could be continued in residence for periods up to 39 days . Periods as long as a week were feasible under conditions similar to those found in commercial practice . A test of zirconium as a starting - sheet material showed that it promoted corrosion of the deposit to a lesser extent than aluminum and that the deposit adhered less tenaciously . These two properties lend themselves to the development of ways to strip deposits mechanically from zirconium starting sheets . Titanium was unsuitable for use as a starting - sheet material .

Jan 1, 1963

By R. E. Brewer

Published investigations show that many different chemical reagents have been used in determining the constitution of coals , but only a few studies have been applied directly in evaluating the effects of such reagents on the carbonization products of coal , Most of the treatments have been so drastic that any permissible conclusions that may be drawn are inferential in respect to any favorable effects on the yields and composition of the usual carbonization products .

Sep 1, 1943

By Charles Prasky

This report describes fluidized bed techniques employed by the Bureau of Mines at Minneapolis to differentially sulfatize the manganese in two samples of low-grade manganiferous ferruginous carbonate slates from the Cuyuna Range district, Minn. Suitable mechanics of operation were established. A space rate of 1.25 to 1.5 fps, a retention time of 3 to 3.5 hours, a temperature of 700° C, and a 10 percent sulfur dioxide gas in air were adequate for sulfatizing the slates by fluidization. Under these conditions the overflow product removal rate from the 4-inch-diameter reactor was 4 to 5 pounds per hour. The sulfur dioxide was used more efficiently in the two-stage treatment than in the single-stage treatment. However, approximately 80 percent of the manganese was converted to sulfate by either treatment.

Jan 1, 1963

By Gopala N. Krishnan

The most promising candidate for the recovery of alumina from non-bauxitic sources is the leaching of clay by HCL acid followed by crystallization of aluminum chloride hexahydrate (ACH) by hydrogen chloride sparging. Hydrothermal precipitation of boehmite ( ?-A100H) from aluminum chloride solution will simplify the process, will reduce energy consumption and will eliminate corrosion problems involved in calcination of ACH to obtain alumina. This report summarizes the results of Phase I of a program to study the precipitation of boehmite from AlC13 solutions. The amount of boehmite precipitation from dilute A1C13 solutions (5 wt%) is . negligible below 200°C. Above 200°C the precipitation increases with increasing temperature approaching 40% at 300°C. Addition of HCl acid to the dilute A1C13 solution even in small quantities drastically reduces boehmite precipitation. Solution impurities such as Fe, Ca, Mg, or Na substantially promote the precipitation of boehmite. No precipitation is observed from concentrated A1C13 solution (30wt%) representing the leach liquor.

Jan 1, 1980

By S. P. Holt, Robert S. Sanford

"INTRODUCTION The wartime demand for iron ore and alloy steel on the west coast revived interest in iron reserves in western United States and Alaska. Magnetite was known to have been the most abundant metallic mineral at some of the old copper mines on Prince of Wales Island. In the summer of 1942, the Bureau of Mines began a program of preliminary investigation followed by core-drilling two magnetite deposits on the island.The Poor Man iron deposit on Kasaan Peninsula, Prince of Wales Island, Southeastern Alaska, was examined in August 1942 by Robert L. Thorne, associate mining engineer of the Bureau of Mines, and John C. Reed and B. N. Goddard, geologists of the Federal Geological Survey in September 1942 the area was mapped geologically and a magnetic survey was made by the Geological Survey. In October and November 1942, a more thorough preliminary examination, which included cleaning out and sampling old adits and trenches, was made by thesenior author, Robert L. Thorne, and Aner W. Erickson, engineers of the Bureau. J. G. Shepherd, a consultant of the Bureau, spent two weeks in March and April 1943 investigating the Poor Man and other deposits on Kasaan Peninsula. Core drilling was completed in June 1943.L. A. Warner, of the Geological Survey, examined all cores and interpreted structural data revealed by the drilling."

Oct 1, 1946

By John W. Cole

As part of a general preliminary investigation of lead-zinc deposits in Stevens County, Wash., the Electric Point and Gladstone mines on Gladstone Mountain, in the Northport Mining District, were examined by R. M. Gammell, an engineer of the Bureau of Mines, in June 1946. A trenching and sampling program was executed later the same year under' the supervision of Miro Mihelich and the author. This report presents the factual data obtained from the trenching and sampling operations.

Jan 1, 1949

By B. B. Letson

The heats of formation of lithium chloride and lithium oxalate were determined with the aid of a Bureau-developed, glass Dewar-type solution calorimeter which uses thermistors as its temperature sensing element. Values obtained at 298.15° K were -98.38 ± 0.54 kcal/mole for lithium chloride and -329.02 ± 0.79 kcal/mole for lithium oxalate, using graphite as the standard state for carbon.

Jan 1, 1965

By Robert L. Montgomery

Heats of solution of samarium (III) oxide and chloride in hydrochloric acid and of samarium (III) oxide, sulfate, and hydrated sulfate in sulfuric acid were measured. The heats of solution of this hygroscopic oxide are larger than those from the literature, probably because of more complete removal of water in the present study. From the literature value for the heat of combustion of samarium, the heats of formation of samarium (III) chloride and sulfate are -244.18 ± 0.41 and -928.5 ± 1.6 kcal./mole, respectively. The heat of hydration of the sulfate is -34.7 ± 1.0 kcal./mole. The heats of formation of other samarium com-pounds have been recalculated, using the new data.

Jan 1, 1959

By D. H. Chambers, Arnold M. Lansche

Electro recovery by amalgam methods was investigated to determine the feasibility of recovering pure cadmium from cadmium sponge produced during purification of zinc electrolyte at electrolytic zinc plants . Actual material used in this work was air- oxidized cadmium sponge . An acid rinse and zinc displacement technique was developed to amalgamate this oxidized cadmium . ( In - plant use of the recovery process would probably not require this step because of the fresh state of the sponge . ) Zinc was completely removed from amalgamated sponge by selective oxidation with air . Zinc - free cadmium amalgam was circulated by an electromagnetic pump through an electrolytic cell where cadmium of 99.9+ percent purity was electrodeposited onto a rotating aluminum cathode . Polarographic methods were developed for determining cadmium and zinc in mercury and in sulfuric acid solution .

Jan 1, 1964

By R. A. Guereca

Preliminary to an experimental study of selected physical properties of helium and related gases) the Bureau of Mines Helium Research Center conducted a data-gathering literature survey. This report combines the results of the 1961-63 literature search into a usable format. The data accumulated on the physical properties are presented in tables and graphs. The data in the tables were chosen for exact representation and comparison of specific values. An attempt was made to select the most reliable and consistent value available for a given property without extensively analyzing each source reference. The methods of evaluation are discussed later. The graphs show trends and anomalies which may be obscure in tabular form. (Reprints of the graphs) with the scale grid enlarged 2 1/2 times) are available upon request through the Research Director) Helium Research Center.) The literature search was conducted using Chemical Abstracts as the primary reference source with additional information drawn from Applied Science and Technology Index) Chemical Reviews) Physics Review) Science Abstracts (Physics») and other abstracting services. Part of the data included in this report have been tabulated previously by others (£-1).5 In a few areas) the sources of information are scarce and obscure (for example) refractive index and dielectric constant). The search was extensive; however) some sources

Jan 1, 1967

By H. A. Schrecengost

Information presented herein was gathered by examination of 29 fluidized- bed thermal coal dryers and by conferences with manufacturers and users of such equipment to determine what safety features could be incorporated in design, installation, and operation to minimize fire and explosion hazards. Fire and explosion hazards are inherent in certain types of coal dryers in that high temperatures are employed; the sizes and volatility of material handled are capable of propagating explosions; and drying gases are seldom, if ever, low enough in oxygen content to prevent ignitions of dust clouds, distilled gases, or their combinations. This is especially true for fluidized- bed dryers in which the coal is dried in air suspension and in which atmospheric air is constantly introduced to temper the heated furnace gases. Occurrence of fires on heated bedplates, in dust collectors, and in hot gas inlets was common in nearly all the dryers examined. Forceful explosions which produced external effects had occurred in 11 (39 percent), and internal "puffs" or "bumps" had occurred in at least 24 (79 percent) of the plants examined in the study.

Jan 1, 1965

By H. A. Schrecengost

Information presented herein was gathered by examination of 29 fluidized-bed thermal coal dryers and by conferences with manufacturers and users of such equipment to determine what safety features could b incorporated in design, installation, and op ration to minimize fire and explosion hazards. Fire and explosion hazards are inherent in certain types of coal dryers in that high temperatures are employed; the sizes and volatility of material handled are capable of propagating explosions; and drying gases are seldom, if ever, low enough in oxygen content to prevent ignitions of dust clouds, distilled gases, or their combinations. This is especially true for fluidized-bed dryers in which the coal is dried in air suspension and in which atmospheric air is constantly introduced to temper the heated furnace gases. Occurrence of fires on hated bedplates, in dust collectors, and in hot gas inlets was common in nearly all the dryers examined. Forceful explosions which produced external effects had occurred in 11 (39 percent), and internal "puffs" or ?bumps? had occurred in at least 24 (79 percent) of the plants examined in the study.

Jan 1, 1965

By W. A. Selvig

"The purpose of the investigation described herein was to determine how closely different laboratories can check one another in making determinations of fusibility of coal ash with the De Graaf electric coal-ash fusion furnace: how well duplicate determinations by the same laboratory will check, and how the results with the De Graaf furnace compare with those of the standard gas-furnace method of the American Society for Testing Materials.4Thanks are due the following laboratories who cooperated in this study by making fusibility tests with the Do Graaf electric coal-ash fusion apparatus: J. J. Brennan, testing engineer, Northern States Power Co.; R. E. Gilmore, superintendent, Fuel Research Laboratories, Canadian Department of Mines A. T. Leavitt, president, and W. Mueller, chief chemist, Hamilton By-product Coke Ovens. Ltd.; Edgar Stansfield, chief chemical engineer, Scientific and Industrial Research Council of Alberta. Canada; and H. S. Vassar, laboratory engineer, Public Service Electric and Gas Co.The ash-fusibility determinations by the standard gas-furnace method were made in the Coal Analysis Laboratory of the Bureau of Mines at Pittsburgh under the direction of H. M. Cooper, associate chemist. The investigation was made at the suggestion of A. C. Fieldner, chief engineer, Experiment Stations Division of the Bureau of Mines.Routine determinations of the fusibility of coal ash are made in the laboratories of the United States Bureau of Mines by the gas-furnace method. This method was standardized after considerable experimentation5 on the nature of the fusion of coal ash and the various factors which affect its determination. The method was subsequently adopted by the American Society for Testing Materials as one of its standard tests."

Jun 1, 1930

By J. T. McCartney

The Bureau of Mines has developed an automated reflectance scanning microscope system, primarily for determination of volume proportions, size distribution, and mode of association of the physical (petrographic) components of coals. The process, which is potentially more rapid and objective and less tedious than a visual microscopic procedure, involves magnetic tape recording of several millions of reflectance readings on micro-meter sized areas of polished coal surface and computer analysis and interpretation of some characteristics of the coal components. The system was tested in a study of pyrite distribution in steam coals. The application was essentially successful, but defects in polished pyrite surface characteristics and problems in adequate sampling prevented completely satisfactory results. Pyrite con-tent and coal-pyrite particle association could be determined nearly as well as by visual microscopy, but size distribution data were less acceptable.

Jan 1, 1969