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By J. P. Capp

The Federal Bureau of Mines and the Alabama Power Company conducted an experiment in underground gasification of coal at Gorgas, Ala. involving the use of hydraulic fracturing to increase the air acceptance of a coalbed for the introduction of combustion air and removal of product gases. Air acceptance is defined as the flow rate of air which can be injected into the coalbed at 65 p.s.i.g. This was the second time the hydraulic-fracturing technique was used at Gorgas. Sand suspended in a heavy oil served as the fracturing fluid in the first experiment; in the second the sand was two to six times larger and was suspended in a water-starch gel. In addition to providing further tests of the underground-gasification process, the purpose of the second experiment was to determine the effects of the larger sand and greater volumes of a water-base fluid on (1) the extent of the fractured area, (2) the air acceptance of the coal, and (3) the rate at which a gasification path could be carbonized (linked) through the coal, and to compare these results with those of the first experiment. The coal was fractured by injecting 11,000 lb. of sand and 33,580 gal. of water and water-gel at 200 to 600 g.p.m. and 900 to 1,000 p.s.i. The fluid fractured the coal and the sand served as a propping agent to hold the cracks and crevices open. Pressures during the fracturing operation at test boreholes indicated that the fracturing fluid extended only about 150 ft. from borehole H, the point of application of the fracture. Injection of air revealed that the air acceptance of the coalbed within this e t was materially increased. On the other hand, increased air acceptance also was noted at boreholes up to 280 ft. from borehole H and at the electrolinking area 300 to 400 ft. away, indicating that the fracture effects extended considerably farther than was evident from observation. Similar effects were noted at approximately the same distances after the first hydraulic fracture.

Jan 1, 1961

By Arden D. Fugate

The Federal Bureau of Mines conducted extensive studies on solid-state defluorination (laboratory scale) and tests on molten defluorination (intermediate scale) of siliceous fluorspars. The studies were made to develop a pyrohydrolytic process for liberating fluorine from offgrade fluorspars. Test results showed that more than 90 percent of the fluorine can be evolved by solid-state defluorination at 1,300° C., and more than 97 percent can be liberated by molten-state defluorination at 1,420° C. Solid-state defluorination conditions were established by conducting tests on mixtures of ceramic-grade fluorspars and high-purity silica flour. Pelletized mixtures were defluorinated under varying conditions of time, temperature, and relative concentrations of silica, calcium fluoride, and water. The effects of adding various amounts and combinations of aluminum oxide and iron oxide on defluorination were also studied. Investigations of solid-state defluorination indicates that the following two reactions are involved: 2CaF2 + 3SiO2 = 2CaSiO3 + SiF4, and CaF2 + Sio2 + H20 = CaSiO3 + 2HF, The second reaction is dominant, although significant defluorination can be achieved by the first reaction.

Jan 1, 1961

By E. G. King

Thermodynamic data for the hydrated varieties of alumina are sparse, and those for the common clay minerals are virtually nil. This paper partly fills the vacuum by reporting low-temperature heat-capacity measurements and entropy evaluations of diaspore (A10(OH)) and three clay minerals of the composition A12Si207?2H20 - kaolinite, dickite, and halloysite. The heat-capacity measurements were made in the temperature range 510 to 298.15° K., and the entropies were evaluated at 298.15° K. Diaspore has an unusually low heat capacity and entropy compared with boehmite (another mineral of the same chemical composition). The entropies of the three clay minerals differ too little for entropy to be the important factor relating to differences in the thermal stability of these substances.

Jan 1, 1961

By K. K. Kershner

The purpose of this research by the Federal Bureau of Mines was to investigate the recovery of tin from mine-run ores and low-grade concentrates. Over 95 percent of the total tin in such materials was volatilized to tin chlorides at temperatures ranging from 520° to 565° C. Gaseous mixtures of hydrogen and hydrogen chloride were used for reducing cassiterite to stannous oxide and for converting this compound to tin chlorides. The chlorides were swept from the reaction zone of an oscillating kiln by a rapid flow of reactant gases and collected in a condensing system. Losses of tin that occur in current metallurgical processing were prevented. Approximately the same time of treatment was required for minus 35-mesh mine-run ores and low-grade concentrates. In a continuous process, the circulating gases would require some enrichment.

Jan 1, 1961

By T. A. Henrie

One objective of Project Gnome is to study the feasibility of a phase of the Plowshare program recovering thermal energy from an underground nuclear explosion. The test will be conducted in an underground salt deposit. It is anticipated that some of the energy thus released will be stored as thermal energy in molten salt. This report describes the pre-Gnome experiments conducted at the Federal Bureau of Mines Metallurgy Research Laboratory, Boulder City, Nev. The objectives of this study were to determine the problems involved in the recovery of thermal energy from molten salts to assist in planning the experimental program for the Gnome project.

Jan 1, 1961

By W. W. Fowkes

The Federal Bureau of Mines examined a low-temperature tar obtained from a small-scale commercial unit for carbonizing North Dakota lignite for products that might be important to the economic processing of the tar. Tie tar may be divided into three distinct parts: (1) Tar acids, 45 volume-percent; (2) tar bases, 1 volume percent; and (3) neutral compounds, 54 volume-percent. It has a boiling range of approximately 150° to 380° C. (the decomposition temperature) and yields 18 weight-percent as hard pitch. The tar distillate up to 365° C. may be separated as: (1) Tar acids, 48 volume-percent; (2) tar bases, 1 volume-percent; and (3) hydrocarbons, 51 volume-percent. The tar-acid distillate, boiling to approximately 265° C., was characterized in some detail; the neutral fractions and the tar bases were less thoroughly examined. In general, as might be expected of a primary low-temperature tar, the lower boiling fractions are less in quantity compared with the usual high-temperature tar. The homologous series of each major class appears to be rather complete, although some components are present in very small amounts. The tar is quite unstable thermally, and might be more conveniently processed by extraction methods rather than by distillation procedures. The neutral fraction of the tar is highly aromatic, and might be considered as base stock for the production of liquid fuels.

Jan 1, 1961

By R. W. Lewis

The Federal Bureau of Mines Boulder City Metallurgy Research Laboratory conducted experiments in order to develop a spectrochemical method for determining the concentrations of impurities In high-purity tungsten. This report presents a procedure, developed by these experiments, for determining 19 impurities in high-purity tungsten. Metal samples were thermally converted to the oxide, mixed with graphite, which was prepared and mixed with an internal-standard element, and excited in a d.c. arc. Sixteen of the impurity elements were determined with one set of conditions, using germanium as an internal standard. Lanthanum was used as an internal standard in the tests for boron and chromium. Molybdenum required the substitution of sodium chloride for the graphite and the use of copper electrodes. Data on the precision of the method are included in this report. The coefficients of variation vary considerably but average about 15 percent. Higher concentrations of impurities than those investigated may be determined with some modifications of the testing procedure, provided attention is given to the possibility of interelement interferences.

Jan 1, 1961

By John Nagy

The effect of low percentages of methane (0 to 5 pet.) in an air atmosphere on spark initiated explosions of coal dust was investigated. With low dust concentrations (0.1 to 0.4 oz./cu, ft.), small amounts of methane increase the explosion pressure; with larger dust concentrations (0.5 to 2.0 oz./cu. ft.), small amounts of methane decrease the explosion pressure. The rate of pressure rise of a coal dust explosion increases with increase in methane concentration; about 3 to 4 pct. further addition of methane yields a decrease in the rate of pressure rise. Convection currents created by the air or gas blast used to disperse dust produce an increase in explosion pressure and rate of pressure rise. The minimum explosive concentration of the coal dust decreases about linearly as the concentration of methane increases from 0 to 5 pct. The explosion pressure increases linearly as the initial pressure within the chamber increases. Similarities between coal dust and methane explosions are indicated, INTRODUCTION During coal mining, methane occluded in coal or adjoining strata is liberated into the mine atmosphere,4 Normally, the methane is diluted and swept away by the ventilating air. Under some conditions, through accidental disruption of the ventilation system, sudden outburst, or because insufficient fresh air is supplied to a working place, low percentages of methane may be present during mining operations. If it is permitted to accumulate, methane itself presents an explosion hazard; its limits of explosibility arc approximately 5 and 15 pct. The effect of low percentages of methane on the explosibility of coal dust was studied to provide a broader understanding of the hazards of ignition and explosion and thus to facilitate development of control

Jan 1, 1961

By Dorothy M. Richardson

The Bureau of Mines has participated in the American Petroleum Institute Research Project 48A (API-RP48A) program on the Separation and Identification of Sulfur Compounds in Crude Petroleum. The lack of reference compounds or infrared spectral data has made difficult the identification of individual sulfur compounds boiling above 140° C. The recent acquisition of 24 alkylthiophnnes has made possible a limited study of this important class of sulfur compounds. The infrared spectra of 2-monoalkylthiophenes and 2,5-dialkylthiophenes for the 2 to 15p range are reported. Correlations for determining the 2-alkyl and 2,5-dialkyl substituted thiophenes are derived from this information. The 2-alkylthiophenes show a unique pattern in the 5.50 to 6.54 region, while the 2,5-dialkylthiophenes show a distinctive pattern in the 5.6µ to 6.7µ region. A skeletal vibration occurs in the 9.5 to 10.0µ region for all of the thiophenes investigated. These data will aid the infrared spectroscopist in the identification of compounds of the type reported.

Jan 1, 1961

By Nick Derick

The continued growth of steel production in the Western States is contingent upon the development of new iron ore sources. Recent development of economical techniques for concentrating and agglomerating taconites has focused attention on the low-grade magnetite deposits near Atlantic City, Wyo., as potentially important sources of iron ore for blast furnace smelting. Therefore, the Federal Bureau of Mines has made comparative evaluations of blast furnace burdens that incorporate pellets produced from Atlantic City concentrates. The Bureau also has evaluated the relative effect of Utah coke on blast furnace performance, using a high-quality Eastern coke as a basis for comparison. This work was done in the Bureau's experimental blast furnace at Bruceton, Pa. Tests determined the maximum wind rate that could be used while a continuous stock movement was maintained in the furnace. The furnace was operated at wind rates ranging from 800 to 1,400 std. c.f.m., them maximum limit of the blowers for the 1.75 in.-diameter tuyeres used. Using a normal Utah ore burden and Utah coke, the furnace went into a tight hanging condition with a wind rate above 950 std, c.f.m. Using the experimental pellet burden again with Utah coke, the wind rate could be increased to 1,000 std, c.f.m. and probably to 1,050 std. c.f.m, before tight hanging occurs. This represents an increase of 5 to 10 pct. in the wind rate. The experimental results indicate an accompanying increase of iron production, as much as 8 pct.

Jan 1, 1961

By T. E. Gray

This report describes the preparation characteristics of the significant coalbeds in Harrison County, W. Va. It is one in a series of Federal Bureau of Mines reports planned to determine coals suitable for the production of metallurgical coke, either as mined or after beneficiation. Over 6.5 million tons of coal was produced in Harrison County, W. Va., in 1958, of which over 3.7 million tons was cleaned mechanically in seven preparation plants. All of the coal cleaned was from the Pittsburgh bed. It has been estimated that more than 1,816 million tons of coal remains in the county in beds 12 inches or more thick. The Pittsburgh and Redstone beds were selected by the Bureau for a study based on current production rates and estimated minable reserves. Sample locations were selected following a study of the literature, conferences with mining engineers and mining company officials in the field, and examination of the available sites. Six samples were collected from the Pittsburgh bed, and three samples came from the Redstone bed, Float-and-sink tests of the samples collected from the Pittsburgh and Redstone beds showed that neither coal could be upgraded to a metallurgical fuel under the standards set up for this study, even after intensive preparation. Finer crushing of the samples moderately increased the yields and slightly reduced both the ash and the sulfur contents in the 1.30-specific-gravity float fractions. Finer crushing slightly decreased the yields in the 1.58-specific-gravity float fractions, whereas it reduced the sulfur content 0.11 percent for the Redstone sample and 0.46 for the Pittsburgh sample.

Jan 1, 1961

By A. Gene Collins

Rapid, sensitive, and precise methods of determing major, minor and trace constituents of oilfield brines are needed. Several methods have been developed or adapted by the Federal Bureau of Mines at the Petroleum Research Center, Bartlesville, Okla. The following methods are described in this report: Spectrophotometric and volumetric for iodides and bromides; potentiometric for pH, alkalinity, acidity, borate boron, total boron, and organic boron; gravimetric for potassium; disodium ethylenediaminetetraacetate (EDTA) volumetric for total hardness, calcium, and magnesium; spectrophotometric for fluorides; and color comparison .for arsenic. Adequate sensitivity, precision, and accuracy were obtained for each method. The Bureau of Mines pioneered in research on the analysis of oilfield waters (2, 46, 47).6 However, several of these early procedures were quite time consuming. Also, they did not include methods for determining trace and minor constituents of brines.

Jan 1, 1961

By Robert K. Koch

The reactions of alumina and alumina monohydrate with wet hydrogen fluoride gas were studied by the Federal Bureau of Mines to determine the feasibility of producing commercial-grade aluminum fluoride from offgases generated by pyrohydrolysis of siliceous fluorspars. The test results showed than an aluminum fluoride reactor operating at maximum efficiency could retain 96 percent of the fluorine contained in off-gases generated by pyrohydrolysis of siliceous fluorspar. The requirements are a reactor temperature of 200° C. and a reactor entrance gas containing 5 mole-percent hydrogen fluoride. Partial pressure equilibrium constants were determined for the reaction of alumina monohydrate and wet hydrogen fluoride gas from 200° to 350° C. and for the reaction of alumina and wet hydrogen fluoride gas from 350° to 700° C. Both reactions are reversible, and they proceed in directions that are dependent upon the temperature and the relative HF:H2O concentration. Logarithms of the equilibrium constants were used to plot the reaction isobars; these can be used to calculate the theoretical maximum efficiency of a reactor processing wet hydrogen fluoride gas between 200° and 700° C. The theoretical maximum efficiency decreases with increasing temperature.

Jan 1, 1961

By Perry D. Teitelbaum

In two earlier studies the Federal Bureau of Mines undertook to explore comprehensively the dimensions of the Nation's energy balance. The first of these studies, published in 1950 as Bureau of Mines Information Circular 7582, by Harold J, Barnett, was primarily concerned with projections of future domestic energy requirements and supplies, because these related to projected growth in major fuel-consuming sectors of the economy, changing rates of energy-use efficiency, and interfuel substitution patterns. But, to provide the essential background for these projections, it was first necessary to assemble and examine in some detail the quantitative information on the size and shape of the current United States fuel economy. Among other things, Barnett's path-breaking study indicated the need to consider energy as an entity, particularly for public and private policy makers, industry and commodity analysts, economists, and others concerned with long range questions of domestic and international energy supply and demand. The study also spotlighted a gap in the fabric of current economic intelligence; no comprehensive collation and reconcilation in any single report of available published statistical information covering the origin -a disposition of all energy materials existed. In response to this latter need, the Bureau of Mines prepared the second of the two studies referred t3 above. This was published in 1951 as Report of Investigations 4805, by W, H, Lyon and D, S. Colby, and it consisted of statistical information on the production and use of each of the various fuels and electric energy in the United States for 1929, 1939, and 1947; all were presented in tabular form and on a uniform basis. The three years selected were chosen largely on the basis of data availability.

Jan 1, 1961

By C. F. Ellis

Interest in the composition of automobile exhaust gases has been greatly accelerated by recent studies that have indicated that these gases contribute to smog formation in urban areas. Several analytical methods have been published for the analysis of the hydrocarbons in the exhaust gases, but similar information has not been published on the analysis of the oxygenated compounds. This report presents procedures for chemical analyses of certain oxygenated compounds, procedures for sampling the exhaust gases for these analyses, and the analytical results of some experimental work in which these procedures were used. A stationary 1956 model, 170 horsepower, V-8, dynamometer-mounted engine, operated to simulate vehicular cruise conditions, was used for the study. Exhaust gases produced from a regular-grade Midcontinent gasoline during 15-40- , and 60-mile-per-hour cruise operations were analyzed by chemical methods for formaldehyde, total aldehydes, total carbonyls, total alcohols, carbon associated with the oxygenated compounds, and the oxides of nitrogen. Experimental results indicate: 1. The range of concentrations of the total of the functional groups of oxygenated compounds, expressed as moles per million moles of water-free exhaust gases, is about 90-100; the concentrations increase with engine speed. 2. Aldehydes comprise about 80-90 mole- percent of the total of the oxygenated groups, and formaldehyde accounts for about 50 mole-percent of the total aldehydes. 3. The order of magnitude of the concentration of the carbonyls is the same as that for the aldehydes, indicating that ketones are not a major group. A colorimetric test indicates that methyl ketones Constitute about 2 mole-percent of the oxygenated compounds.

Jan 1, 1961

By Lowell Stroud

Since 1929, the Helium Activity of the Bureau of Mines has operated a helium-extraction plant at Amarillo, Tex. The natural gas that supplies this plant is obtained from the Cliffside geologic structure 12 miles to the northwest and over the years, has become known simply as "Cliffside gas," There is need for published data on the low-temperature phase equilibria of helium-bearing natural gases. To date, little information has been published on the equilibrium phase compositions, solution of helium in condensed natural gas, condensation characteristics, or equilibrium vaporization coefficients for methane, nitrogen, and helium in helium-containing systems. A windowed phase equilibrium apparatus (8)6 was used to obtain 105 equilibrium samples, representing 35 experimental conditions of condensed Cliffside gas at pressures of 100, 200, 300, 400, and 500 p.s.i.a. and temperatures from 0° to -270° F. Data on equilibrium vapor-liquid composition for Cliffside gas are presented in both tabular and graphic form and are discussed in detail to show their relationship to certain criteria that must be met to effect an efficient separation of helium from natural gas by means of low-temperature processes. Facts about condensation characteristics and solution of helium in the liquid phases are included, The important relationship of these two factors in decreasing the percentage of total helium lost by solution in the liquid phase is discussed.

Jan 1, 1961

By J. L. Konchesky

In gasifying pulverized coal with steam and oxygen, the particle size of the coal fed to a gasifier should be as small as economically possible. A potential way to achieve this advantage is to reduce the particle size of the coal by passing the coal-steam mixture at high velocity through a heated tube coil before the mixture enters the gasifier. To evaluate this method the Federal Bureau of Mines flashed coal-water slurries in externally heated metallic tube coils to determine the extent of size reduction. The first of two different laboratory-scale apparatus reduced the average particle diameter of subbituminous C coal from 190 to 110 microns at an outlet velocity of 330 feet per second (f.p.s.). At the same outlet velocity, a second apparatus reduced the average particle diameter from 250 to 140 microns. An increase in velocity produced more finely divided coal, but variation in temperature and pressure had no effect except as they affected velocity. Virtually the same size reduction was noted for five ranks of coal at equal velocities. The rate of increase in particle-size reduction with increase in velocity decreased with a decrease in particle size. The pulverizing mechanism was concluded to be abrasion of the particles with each other and with the tube wall.

Jan 1, 1961

By R. Barany

Thermodynamic calculations pertaining to the minerals gibbsite, kaolinite, halloysite, and dickite have been hampered by the lack of adequate heat and free energy of formation data. Previous data for gibbsite were highly uncertain, and there were no data for the other three substances. By use of hydrofluoric acid solution calorimetry, the Bureau of Mines derived heat of formation values from the elements and from the oxides for the four substances, and the data were combined with known entropy values to obtain the corresponding free energies of formation. The results show that gibbsite and halloysite are thermodynamically unstable with respect to the oxides (a- alumina, a- quartz, and liquid water) at 298.15° K,, while kaolinite and dickite are only moderately stable (to about the same degree), The instability of halloysite, in comparison with kaolinite and dickite, results in a 60°-lower equilibrium decomposition temperature.

Jan 1, 1961

By M. H. Stanczyk

Bench-scale laboratory tests were made by the Bureau of Mines of a segregation-flotation concentrate, assaying 20.43 percent copper, to investigate the influence of various ratios and concentrations of ammonia and carbon dioxide on copper extraction. Leaching the concentrate with a solution containing 900 pounds of ammonia and 360 pounds of carbon dioxide per ton of feed, followed by washing the leach residue with 1.75 tons of a 10-percent solution of ammonium carbonate and about 1 ton of water (as steam) per ton of solids, resulted in a copper recovery of 96.3 percent. Resegregation and flotation tests of the washed residues revealed that 85 percent of the copper in the residue could be recovered. Steam distillation tests of a typical ammoniacal leach liquor, assaying 39 grams copper, 105 grams ammonia, and 77 grams carbon dioxide per liter, recovered over 99 percent of the copper as a mixed oxide-carbonate precipitate. The ammonia losses in leaching, filtering, washing, and distillation were 0.12 pound per pound of copper recovered in the precipitate. Calcination and subsequent hydrogen reduction of the precipitate yielded a metallic copper powder assaying 98 percent Cu, 0.87 percent Si02, 0.10 percent MgO, 0.54 percent CaO, and 0.41 percent R203.

Jan 1, 1961

By P. M. Sullivan

The principles and application of amalgam electrolysis to the recovery of zinc and tin from secondary products were studied; this Bureau of Mines project was one phase of investigating the development of more efficient methods for processing iron-bearing zinc and tin to produce both base metals of high purity. Zinc of 99-99-percent purity was recovered from galvanizer's dross with recovery efficiency of 98 percent. Tin of 99.9-to 99.99-percent purity was recovered from hardhead with recovery efficiency of 81 percent. Both materials were treated by the same method in separate systems. Mercury was used to leach zinc from dross and tin from hardhead to form amalgams of each metal, both of which were subsequently refined electrolytically to produce high-purity metal. Impurities that were contained in both secondary products behaved as theoretically predicted; impurities that were insoluble in mercury remained as sludge in the leaching column. Except for lead, the readily amalgamated impurities were prevented from fouling the electrolyte by the blocking action of the amalgam electrode. Lead impurity in the tin-refining system dissolved and immediately precipitated as the sulfate. The primary advantage of the amalgam refining method lies in direct recovery of the extremely pure base metal from highly contaminated secondary material.

Jan 1, 1961