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By James S. Browning

Heavy liquids have been used to separate minerals of different specific gravities for many years.4 5 6 7 8 9/ The method permits substantially quantitative evaluation of a variety of minerals and requires much less time than the usual methods of chemical analysis. This Bureau of Mines investigation was conducted to determine the applicability of heavy liquid mineral separation to the evaluation of certain spodumene and kyanite ores, prepared mixtures, and plant products. After careful standardization of the particular mineral and associated gangue, estimates of chemical analyses could be obtained from results of heavy liquid separations.

Jan 1, 1960

By Martin Hertzberg

The early and reliable detection of the self-heating of combustible substances in mines is of considerable importance to the mining community. This Bureau of Mines report describes the results of a variety of studies of incipient combustion and its detection. Heated samples of coal, wood, and various polymers were used to evaluate the relative sensitivities of several types of detectors. The laboratory results indicate that submicrometer particulate detection is the most universal and sensitive method. Carbon monoxide detection was as sensitive as submicrometer particulate detection for pyrolyzing coal but was relatively insensitive to pyrolyzing wood or plastics. The conventional type of ionization smoke detector was the least sensitive for coal and of intermediate sensitivity for wood and plastics. Self-heating experiments with Pittsburgh seam coal piles of varying particle sizes gave ignition temperatures of 170° C for 4-to 7-µm dust, which increased monotonically with particle size. The measured heating rates were compared with data from an adiabatic calorimeter to obtain preexponential rate constants. The preexponential rate constants varied linearly with the surface area per unit mass of sample as would be expected for heterogeneous surface oxidation. The propagation behavior of ignition waves and the overall self-heating appears to depend critically on the magnitude of the convective flows induced, which counteract the depletion of oxygen in the void spaces of the pile. Classical theories of thermal ignition require substantial modification to be applied reliably to such cases.

Jan 1, 1977

By R. D. Leitch, W. P. Yant

"In the course of another investigation4 during 1926 and 1927, samples of water collected from a few abandoned coal mines indicated that their drainage was usually lower in acidity than water from active mines in the same locality. In order to determine whether this condition might have a bearing on the advisability of sealing abandoned mines, a number of such mines were visited, samples of drainage were collected, and as much information- as possible was obtained from officials of the mining companies and older residents of the district. The results of this work are the basis of the present report.The authors are indebted to E. W. Robertson, F. F. Spowart, J. H. Nagle, and W. D. Adams of the Northwest Mining & Exchange Co.; E. M. Fasset, Fred Lane, Wm. Humphreys, and Dr. T. A. Hutchison of Brockway, Pa.; C. W. .Faulk of the Shawmut Mining Co.; James Hau of Kersey, Pa., and to others for information received; and to Dr. R. R. Sayers of the Bureau of Mines, under whose direction the work was conducted.The Lower Kittanning is the most important bed in the locality studied. A great many of the abandoned mines examined are in this bed, and nearly all of the present active ones are. The Upper Freeport bed is also mined to some extent, and a number of the abandoned mines formerly worked this bed. As only three active mines are now (1927) working the Upper Freeport, the comparison of acidities is necessarily limited. Of these three, one had been idle since 1922 until shortly before it was sampled.The location of most of the mines was already known from previous work, but some of them had to be located by following up streams known to contain acid waters. A sample of the- outflow was collected in self-sealing bottles known as ""citrate bottles"" for the determination of dissolved oxygen by the Winkler method.5 Another sample was taken for the determination of acidity according to standard methods of water analysis.6 Ferrous iron was determined at the mine or very soon after taking the sample by titrating with a standard solution of potassium permanganate in acid solution. The hydrogen-ion value was determined by a standard double-wedge comparator.7From the total acidity values in each sample, which are the most important values, the total iron was calculated on the assumption that acidity as sulphuric acid was due to dissolved ferrous sulphate. This assumption is commonly made for mine waters, but is inaccurate to the extent that free acid is already present, and some of the iron is present as ferric, rather than ferrous, sulphate. The amount of ferrous sulphate may be a rough measure of the extent to which oxygen is lacking within the mine. The permanganate titrations just mentioned showed what part of this total iron was in combination as ferrous sulphate, and the difference .was assumed to be that in combination as ferric sulphate, after correcting for the amount of free acid already formed as shown by the titration values."

Oct 1, 1928

By William J. Campbell

The purpose of this investigation was to develop a rapid, accurate method of analysis for small amounts of calcium in wolframite concentrates. This analysis is necessary to determine if the wolframite concentrates meet United States National Stockpile Specification P-57R2, which limits the calcium content to 0.2 percent. Because of the small depth of the sample analyzed in fluorescent X-ray spectrography, the calcium Kaline intensity was a function of the chemical composition of the calcium-bearing particle as well as the total matrix composition. This particle-composition effect was particularly important in this analysis, as the calcium may be present as a carbonate, tungstate, phosphate, etc. Three methods of preparing the sample eliminated the variation of calcium Ka intensity with mineralogical occurrence: (1) Reduction in particle size by extensive grinding, (2) chemical fusion with sodium carbonate, and (3) solution of the calcium by an acid attack.

Jan 1, 1958

By K. E. Stanfield

The Bureau of Mines oil-shale program, initiated in April 1944, is concerned with the future utilization of oil shale in the United States as a source of liquid fuel. One phase of this program is the accumulation of information on the location, extent, and richness of oil-shale deposits that may be suitable for processing to oil and related products. A previous publication5/ presented, by means of logs, the oil yields of sections of the largest known oil-shale deposit in this country -the shales of the Green River formation occurring in adjoining portions of the states of Colorado, Utah, and Wyoming. This present supplementary report presents the oil yields of cores from 48 holes drilled during 1952 to 1954 in the Green River formation of Colorado, which is distributed over an area of more than 1,000 square miles. The oil yields of the 48 oil-shale sections, involving the assay of 9,651 samples, representing 22,451 feet of core, are presented by means of logs. In addition, the oil yields of samples comprising the maximum sections of 15 gallon-per-ton shale are tabulated for these cores and for the 28 cores from Colorado which were logged in the previous report.

Jan 1, 1957

By A. Visnapuu

The Bureau of Mines has upgraded high-iron domestic chromite concentrates by a carbonyl process. The upgraded chromite concentrates show as much as 10 wt pct higher Cr203 content and up to a threefold in-crease in the Cr:Fe ratio, compared with the starting concentrates. The high-iron chromites were first reduced to convert the iron oxides to the metal, and then treated with CO at elevated pressures and low temperatures to convert part of the metallic iron fraction to iron pentacarbonyl. Carbonylation was accelerated by the addition of H2S in small quantities. The iron pentacarbonyl was extricated from the con-centrate in the pressure reactor during carbonylation by a CO sweep through a pressure-reducing valve and passed through a decomposer at atmospheric pressure to convert it back to iron metal and CO. CO pres-sure, temperature, promoter trends, and other factors enhancing iron pentacarbonyl formation are presented.

Jan 1, 1985

By P. J. McDonough

The Bureau of Mines designed and tested a hardware-software system for measuring on-line corrosion rates of materials in a rod mill in operation. Currents ranging from 10-6 to 10-3 A and potentials in I-mV increments were converted to a digital signal. The digitized data were frequency-modulated and transmitted from a rotating ball mill to an FM receiver, where they were decoded by computer and then processed in real time using assembly language software. This design approach would allow accurate measurement and control of systems where signals of small amplitude and large ranges are present.

Jan 1, 1988

By Seth C. Schaefer

The Bureau of mines investigated thermodynamic properties of MnSO4 and 2CdO CdSO4 to obtain basic thermodynamic data applicable to the treatment of mineral concentrates during roasting and sintering processes. Standard Gibbs energies of formation were determined with high-temperature galvanic cells using stabilized Zr02 as the electrolyte. Potential measurements were obtained from the cells?

Jan 1, 1983

By T. A. Henrie, J. D. Marchant, E. S. Shedd

Cerium metal was electrowon in a fluoride bath from cerous oxide and tapped from the cell during prolonged operation . Electrolyte constituents were CeF , BaF₂ , and LiF. Twenty- seven pounds of metal of 99.8 percent purity were produced at a rate of 3 pounds per hour and tapped from the cell . Principal impurities were molybdenum , aluminum , oxygen , and carbon . The operating parameters , such as electrode geometry , bath compositions , and oxide feed rate , were investigated . Anode reactions were found to be important factors in cell operation . Stable cerous oxide reacted more uniformly at the anode surface than ceric oxide . Electrowinning was conducted in crucible hearths consisting of both frozen electrolyte and molybdenum metal . Both materials proved satisfactory and did not react with the molten cerium . Stable cerous oxide was prepared by carbothermic reduction and used as a feed material . Cell design proved to be an important factor in continuous cell operation . Complementary to the investigations of electrowinning of cerium , the metal was purified by electrorefining in a chloride electrolyte .

Jan 1, 1964

By G. H. Keith

A vanadium-base alloy consisting of the following elements in weight-percent--molybdenum, 20; titanium, 10; carbon, 0.1; silicon, 0.5; and yttrium, 0.5--had exceptionally high strength at temperatures up to 1,200° C. This alloy was capable of fabrication to sheet of ~ 1 mm thickness by a combination of hot swaging and hot and warm rolling. In the warm-rolled condition at ambient temperature, its ultimate tensile strength was 1,205 MN/m2. The strength at 1,200° C was 150 MN/m2. Within the temperature range of 25° to 1,200° C, the ductility of the alloy as measured by elongation increased from 4 to >90 percent. Strengthening was achieved by both solid-solution and dispersed-phase mechanisms. Alloys of 20 percent molybdenum and 10 percent titanium were stronger than the other molybdenum-titanium alloy compositions tested. Strength was increased 15 percent in the temperature range of 25° to 800° C, with no accompanying loss in ductility, by the addition of 0.5 percent silicon. Workability was improved by additions of 0.25 and 0.5 percent yttrium.

Jan 1, 1970

By B. C. Parks

This paper is a report on the relationships between petrographic composition, chemical composition, physical properties, and thermal behavior of banded bituminous coal. It describes the relationships between petrographic composition, behavior in various laboratory tests, and carbonizing properties of different petrographic types of coal that occur in relatively thick benches in a single bed of high-volatile A bituminous coal - the Hernshaw bed of Boone County, W. Va. Thin-section microscopic analysis and free-swelling index determinations of the thin-section samples were made of a standard column sample. A standard face sample, a representative channel sample, and representative samples of two prominent petrographic benches of bright and dull coal were subjected to chemical analyses and free-swelling-index, plasticity, dilation, agglutinating, low-temperature carbonization, and BM-AGA retort tests. A float-and-sink separation was also made of part of the standard face sample. The fractions from this gravity separation were subjected to petrographic and chemical analysis and free-swelling-index, plasticity, and dilatation tests.

Jan 1, 1959

By H. R. Babitzke, H. Kato, M. D. Carver

A number of columbium and tantalum alloys were investigated to determine their suitability for use at elevated temperatures . Columbium-vanadium , tantalum-vanadium , and tantalum-hafnium alloys , and also columbium- 10 wt pct titanium alloys modified with additions of 0.1 to 2 mole pct ZrO2 , TiO2 , ZrB₂ , TiB , ZrC, or TiC were prepared and examined . Workability , tensile properties , and oxidation resistance were tested . Of the columbium alloys studied , the columbium- 12 at . pct vanadium exhibited the best properties ; it compared closely with the columbium- 10 at . pct vanadium alloy studied in a previous investigation.

Jan 1, 1964

By John B. Bennett

In this report estimates are presented of the impact of the passage of five recently proposed "acid rain" bills on electric utility costs for coal-burning utilities servicing the domestic aluminum smelting industry, and on the costs of production for affected aluminum smelters. As aluminum smelting is an energy-intensive industry, domestic increases in electricity prices could affect the industry's competitiveness. Energy costs in U.S. aluminum smelting are compared to aluminum smelting energy costs in the rest-of-the-world. Governmental policies affecting these energy costs are discussed.

Jan 1, 1988

By E. B. Kester

A study of the composition of the corresponding fractions of a primary and a high- temperature tar was undertaken to throw light on the net results of the pyrolysis of the primary products of coal decomposition in high-temperature coking practice, with reference both to total quantities of the chemically similar constituents and to their distribution throughout the boiling range. No exactly parallel investigations are on record. The distribution of substances in high-temperature tars, however, is fairly well understood. Such tars are more or less similar, for they consist of the more stable phenols, aromatic and olefinic compounds resulting from the pyrolytic decomposition of a wide variety of primary tar constituents. For example, from a typical distillation curve for high-temperature tar phenols4 it may be seen that the greatest portion of the phenols distills between 180° and 220° C., a fairly narrow range.

Jan 1, 1932

By John W. Walkiewicz

The U.S. Bureau of Mines has conducted studies to utilize rapid microwave heating to stress fracture ore samples. Iron ores containing hematite, magnetite, and goethite were subjected to microwave energy in batch operations at 3 kW and heated to average maximum temperatures between 840 and 940 °C. Standard Bond grindability tests showed that microwave heating reduced the work index of iron ores by 10 to 24 pct. In a microwave chamber designed to simulate a continuous throughput operation at 3 kW, the grindability of a taconite ore was improved by 13 pct at a bulk temperature of 197 °C. Because stress cracking occurred at a lower temperature, less energy was consumed. To further improve the economics of microwave fracturing, higher powers up to 16 kW were used to rapidly heat samples to relatively low temperatures in a continuous, belt-fed applicator. A significant improvement of grindability was obtained with a larger rod mill feed size in comparison to a minus 6-mesh Bond feed.

Jan 1, 2010

By Harry Freund, Kenneth H. Hammill, Francis C. Bissonnette

"Gallic acid is a sensitive, stable, colorimetric reagent for the determination of tantalum in the range of 2 to 40 µ g.Ta/ml. The method consists of the fusion of tantalum oxide with potassium pyrosulfate and solution of the cooled melt in saturated ammonium oxalate, followed by development of a yellow complex with an ethanolic solution of gallic acid. The tantalum-gallic acid complex absorbs over a broad region in the blue and near ultraviolet. Adverse effects due to interfering ions and solution conditions, such as oxalate concentration and pH, can be minimized by a suitable choice of wave length.by a suitable choice of wave length.A new and sensitive colorimetric method is provided that has been used successfully at the Northwest Electrodevelopment Laboratory of the Federal Bureau of Mines for determining minor amounts of tantalum.INTRODUCTIONThe development of corrosion-resistant alloys at the Northwest Electrodevelopment Laboratory prompted a review of the analytical chemistry of columbium (niobium) and tantahnn. Not only are these elements difficult to determine in small amounts, but tantalum especially lacks both sensitive and characteristic color reactions. Various phenolic compounds have been suggested as colorimetric reagents for tantalum, Quentin and Wagner (10, p. 24B) 1/ recommend the use of tannin. The use of pyrogallol was suggested originally by Krivoshlykov (6, pp. 59-60), whose method recently has been subject to a number of modifications (3, pp. 249-254; 5, pp. 1340-1344; 1, pp. 1803-18oi; 4, pp. 345-350). The yellow coloration produced by pyrocatechol in an oxalate solution containing tantalum may also be used to estimate tantalum ( 11, pp, ll-1-4-148) . The use of hydrogen peroxide has been recommended also (7, pp. 164-165; 9, pp. 926-931).Aside from a lack of specificity and sensitivity, the major failing of phenolic reagents is their susceptibility to air oxidation. The oxidation products are highly colored and absorb in the same spectral region as the tantalum complex. Holding reductants are not completely satisfactory in minimizing this effect. Increasing the acidity, while retarding the oxidation, has an adverse effect on the tantalum sensitivity."

Sep 1, 1956

By W. W. Graff

This paper describing the mining practices at Mine, No. 4 on the Marquette range, Michigan, is one of a series of articles on mining methods and practices in various mining districts in the United States. Mire No. 4 is located in the Swanzy district, in the southern end of the Marquette range, about 3 miles from Gwinn, Mich. The Swanzy district is an isolated ore-bearing formation, and Mine No. 4 is at the extreme southeastern end.

Jan 1, 1930

By Charles Vaught, Warren G. Lacefield, Ronald D. Wasielewski, Philip K. Berger, Henry P. Cole, John V. Haley, Shannon L. Price

A comprehensive review of published research was carried out to identify methods for teaching and assessing critical but nonroutine skills needed for coping with emergency situations. Computerized searches of the relevant data bases were carried out, along with identification of relevant articles and materials by personal contact with experts in many fields. The citations listed in this bibliography resulted from this systematic literature search and review. The computer searches and an analysis of this literature are described in technical report 1. Specific methods for assessing critical skills proficiency in aviation, medicine, organization management, the military, and other industrial/ technical workplaces were described. The potential application of these methods for teaching and assessing (1) critical first aid and (2) self-rescue and escape skills to underground coal miners in annual refresher training was explored. Research and development activities that may improve mine health and safety training were suggested. Most of the entries in this bibliography were assembled in 1984 through 1985. Study of these materials contributed to the completion of the project research that followed. This later work is reported in the project technical report 2 and the final report. This bibliography is most useful when combined with examination of technical reports 1 and 2 and the final project report.

Jan 7, 1988

By Robert H. Ridgway

Chromite has been produced commercially for slightly more than a century. Developed, at one time, chiefly as a chemical pigment raw material, it has subsequently found extensive application in other chemical industries - as a refractory material for furnace linings and as the sole source of the metal chromium. For some years prior to 1914, its use as a refractory predominated; but post-war development in alloy steels, principally stainless steels, enhanced the metallurgical demand in the form of ferrochrome with a consequent increase in the demand for chromite. More recently direct reduction of chromite in alloy-steel manufacture has been applied to a limited extent. Alloy steels containing varying amounts of chromium, with or without other alloying elements, now find extensive use in a ride variety of ways - in structural material, machines, industrial equipment transportation by land, sea, and air, sanitary equipment, food preservation, and a multitude of other uses. In recent years chromium plating has had wide application and has become important. industrially, but the amount of raw material consumed

Jan 1, 1936

By P. G. Guest

"INTRODUCTION Need for More information on Spark IgnitionMany questions have yet to be answered more completely concerning the ignition of flammable gases and vapors by electric sparks. Among these one might mention the following: How do the mixture limits for ignition by sparks and by other means compare? Are the most explosive mixtures of the gases the most easily ignited? How ""hot"" must the spark be or what is the minimum energy required for ignition? Does the electric spark act merely as a source of thermal energy or do aggregations of ions, electrons, and metastable atoms formed during and just before the spark play an important part in promoting chemical reactions that ultimately lead to ignition? It is possible for ignition to occur as a result of a silent or brush discharge? How do the ignition energies with single and rapidly recurring sparks differ? What is the relative effectiveness of long, tenuous sparks in ignition as compared with intense, short-gap sparks of equal energy? What is the influence of the material, size, and shape of the spark electrodes? Does the energy for ignition change noticeably with moderate changes in pressure and temperature of an enclosed gas mixture? What order of lag exists between the occurrence of an incendiary spark and the first evidence of flame propagation? What part of a spark in space and time is most effective in producing ignition? Answers to these questions bear directly on the general problem of flame initiation and propagation and, if sufficiently comprehensive, should contribute much to an understanding of the actual mechanism of combustion."

May 1, 1944