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By S. L. May

Tantalum and columbium can be extracted from several of their ores or concentrates by chlorination procedures. Direct chlorination of high-grade minerals in the presence of carbon at temperatures between 500° and 800° C will extract up to 99 percent of the tantalum and columbium. Metallurgical beneficiation of low-grade source materials by carbothermic reduction produces a ferroalloy that is amenable to chlorination at a temperature of 500° C. Over 90 percent of the tantalum and columbium can be recovered.

Jan 1, 1965

By M. S. Seehra, V. S. Babu

"INTRODUCTION The accurate determination of the free silica index in coal mine dusts is an important requirement because severe health hazards are believed to be associated with the inhalation of respirable-sized silica particles.1-6 Free silica refers to the three polymorphs of silica (Si02)viz., quartz, cristobalite, and tridymite-although quartz is usually the dominant form in most mine dusts.6 The free silica index is the concentration in micrograms of free silica in air per m3 of air sampled corrected to standard conditions of 25°C and 760 mm/Hg, the present MSHA (Mine Safety and Health Administration) limit on time-averaged basis being 100 µ.g/m 3 for coal mines. A recent review7 has concluded that quartz, cristobalite, and tridymite particles impart nearly equal long-term hemolytic damage when compared on a per unit surface area basis.At present, two experimental methods-viz., transmission infrared spectroscopy (TIRS) and x-ray diffraction (XRD)-are commonly used for the determination of silica concentrations in mine dusts. In TIRS, which has been adopted by MSHA and is commonly called the P7 method, the silica absorption band near 800 cm - 1 is used for quantification. However the mineral kaolinite, which is commonly present in mine dusts, also has absorption band, albeit weaker, at 800 cm- 1• To correct for this interference, one uses the stronger 915-cm -1 band of kaolinite to determine the concentration of kaolinite, and the kaolinite contribution to the absorbance at 800 cm-1 is then determined from a calibration curve, leading to the determination of silica by subtraction. In the XRD technique, usually an internal standard such as CaF 2 is used to determine the concentration of silica from line intensity measurements. XRD has the added advantage that concentrations of quartz, cristobalite, and tridymite can be determined.8•9 In an exhaustive study on the precision of the techniques ofTIRS and XRD for monitoring worker exposure,9 the conclusion has been reached that both methods measure silica within 253 of the ""true"" value 953 of the time in a single laboratory."

Nov 1, 1995

By J. B. Gayle

The rate of oxidation of coals with nitric acid has been used by earlier investigators4 5 6/ for determining fusain and for studying petrographic composition. These workers accumulated considerable evidence indicating that, for coals ranging from lignite to low-volatile in rank, the method gives values for fusain that agree satisfactorily with those obtained by optical methods. One group5/even concluded that, when discrepancies are noted between results obtained by chemical and microscopic methods, the results based on the oxidation reaction are probably the more reliable. Unfortunately, after concluding that the method was valid, most of these workers apparently lost interest. As a result, no attempt to exploit or apply the method to problems of utilization has been reported. Recent studies of the influence of inert petrographic constituents on the properties of cokes made from various coals7/ have indicated a need for additional means of characterizing coals and blends used for carbonization.

Jan 1, 1960

By R. V. Lundquist

The Bureau of Mines made a laboratory study of the amenability of anorthosite rock ( from the San Gabriel Mountains , Los Angeles County , Calif . ) to treatment by the lime soda sinter process for the extraction of alumina . The study was done under a cooperative agreement with the California Division of Mines and Geology . This report presents the results of the investigation , and it includes a review of the geology of the deposit ( 7 ) by Dr. Gordon B. Oakeshott . Interest in the recovery of alumina from submarginal aluminum silicate ores is stimulated by the fact that the domestic aluminum industry depends on imports of bauxite for its alumina requirements . Of the 8.0 million long dry tons of high - grade bauxite consumed in 1961 for producing metallurgicalgrade alumina , only 0.9 million long tons , or 11 percent , was mined in this country . During past years many organizations have carried out research programs to determine if alumina could be extracted economically from such domestic ores as clays ( 3 , 4 ) , anorthosite ( 8 ) , and other silicate sources . Successful alumina extraction is the ultimate objective of the Bureau of Mines program.

Jan 1, 1963

By Paul W. Jeran

Subsidence over a series of longwall panels undermining sloping terrain in southwestern Pennsylvania was monitored to verify the Bureau of Mines subsidence prediction model for the northern Appalachian coal region. Comparison of the field data to model output shows close agreement. Vertical movements over each panel ceased with the mining of the adjacent panel. Horizontal movements were significantly affected by topographic slope. The distribution of horizontal strains over each panel were similar, with a zone of compression occurring over the center of each panel. The zones of compression were flanked by zones of tension toward the rib. The magnitude of the tensions were affected by the slope. The strains developed at the completion of each panel were not significantly altered by the mining of subsequent panels.

Jan 1, 1988

By Thomas Fraser, J. D. Davis

"INTRODUCTION Preliminary tests of the Oyon coal constituted part of a wartime exploratory and development program in which many agencies participated. The general objective was to find new and adequate source of fuel and other raw materials for greatly expanded industry.The Oyon coal field, known for at least a hundred years to the mining people of Peru, offers a possible source of high-grade process fuel for the growing metallurgical industries of South America and the Pacific coast. Santolalla 4/ reports that low-volatile coal from this region was used in local smelting operations as early as 1850. It has been mined in very small quanti¬ties for many years and used in neighboring mining camps and villages. Small quantities are regularly used at Oroya for the manufacture of carbide, and in recent years small-scale coking operations in specially designed ovens in the region have demonstrated that these coals will make dense coke.During this long period of desultory operations many small openings have been made scattered over a wide area in this general region, indicating very extensive occurrence of the coal measures, although systematic exploration work has not been undertaken. However, current development work of the Banco Minero del Peru has opened up several substantially parallel highly inclined or vertical beds of workable thickness and has followed these deposits to sufficient lateral extent to prove fairly well the existence of substantial reserves on this property."

Mar 1, 1948

By Mary F. Koehler

Interoxidic compounds, such as vanadates, have not been studied extensively in the field of thermodynamics. This is a report of three vanadates of sodium--metavanadate, pyrovanadate, and orthovanadate. Vanadates of other metals will be considered in future reports. The heats of formation at 298.15° K. of the three sodium vanadates (both from the oxides and from the elements) were derived from the results of sodium hydroxide solution calorimetry. Free energies of formation were obtained by combining heat and entropy values. The results support the conclusion that the three sodium vanadates were stable with respect to all possible decompositions in which vanadium retains its pentavalency.

Jan 1, 1960

By Frank G. Horino

This report describes an instrument designed by the Bureau of Mines for quantitatively identifying texture of rock surfaces produced by grinding or extremely rough surfaces beyond the range of commercial surface measuring instruments. The transducer for the instrument is a linear variable differential transformer that converts mechanical motion caused by surface roughness, waviness, and lay to an electrical output. The electrical output is recorded graphically as an X-Y plot of the line traversed on the rock surface. Details of the synthesized device and its calibration are given. The sensitivity of the unit is 2 percent of the scale setting of the amplifier. The horizontal scale is adaptable from ¼ inch to 15 inches of specimen length with a sensitivity of 0.01 inch if a 10 to 1 magnification is used and 0.1 inch if a 1 to 1 magnification is used.

Jan 1, 1968

By R. E. Head

"The microscopic work described below was engaged in primarily into ascertain the approximate proportions in which the copper sulphides existed in the ore examined, and by a comparison of the results obtained from a study of both head are tailing samples to supply data which might be of value in treating the ore by flotation. Incidentally, the physical characteristics and association of the sulphides were noted in order to determine the possible relation or bearing of these features on the present conditions of treatment. Since the copper in the ore occurred as three distinct sulphide minerals - chalcopyrite, chalcocite, and bornite each containing copper in different proportions, there appeared to be little or no possibility of obtaining the desired information by chemical methods of determination.Type of material examinedThe material examined was in the crushed condition and was said to be representative of the flotation feed or heads and the resulting tailing. No hand samples of the ore were examined nor any account taken of the physical condition and association of the minerals in place, because the possible value of the analytical results depended on conditions as they existed in the crushed ore. As the problems under consideration dealt only with the sulphide minerals, especially those of copper, the products from screen sizing were concentrated by hand panning and the gangue discarded. The concentrate obtained consisted almost entirely of the sulphide minerals, since the panning had been very carefully done. The object of this procedure was to obtain a sufficient quantity of high-grade sulphide material, from the sample of each screen size selected for examination, to permit its being so prepared for examination as to be representative of the physical characteristics exhibited by a large number of sulphide grains from each respective size, In the tests and investigations carried on by the company' treating the ore the following sizes had been used in tabulating data and basing conclusions:+48, +65, +100, +150, +200, and -200. These same sizes were used in the microscopic investigation, since the results obtained thereby could be most readily utilized for comparison with the results obtained in previous experimental work, together with deductions based on actual concentration of the ore on a commercial scale."

Jun 1, 1921

By H. A. Johansen

Recent advances in the metallurgy of chromium have enabled this metal to begin to take its place among the refractory metals. Considerable work is being done on the development of high-temperature alloys containing high percentages of chromium.1/2/ In spite of the relatively large amount of work done on these alloys, little is known of the properties of the pure metal. Information in the literature concerning the tensile properties of pure chromium metal is quite scant. This deficiency maybe explained by the great difficulty of preparing test specimens from such a brittle material, resulting in many losses in each phase of the specimen preparation and testing procedure.

Jan 1, 1954

By A. W. Deurbrouck

The Bureau of Mines reviewed available data on the effect of crushing high-sulfur coals for the liberation of impurities in the light of increasingly stringent air pollution regulations. The survey, which provided information on Appalachian region coals only, indicated that such important coal- beds as the Upper and Lower Freeport and the Upper Kittanning show significant sulfur reductions when crushed to 14-mesh top size. For many other coalbeds amenability to sulfur liberation by crushing was indicated, although too few samples were available to draw firm conclusions,

Jan 1, 1966

By A. W. Deurbrouck

The Bureau of Mines reviewed available data on the effect of crushing high-sulfur coals for the liberation of impurities in the light of increasingly stringent air pollution regulations. The survey, which provided information on Appalachian region coals only, indicated that such important coal-beds as the Upper and Lower Freeport and the Upper Kittanning show significant sulfur reductions when crushed to 14-mesh top size. For many other coalbeds amenability to sulfur liberation by crushing was indicated, although too few samples were available to draw firm conclusions,

Jan 1, 1966

By Wesley A. Grosh

The Valzinco mine, Spotsylvania County, Va., is a lead-zinc deposit with minor quantities of copper. The property was reopened n 1942 by Panaminas, Inc. The Bureau of. Mines, in an effort to increase the reserves of the deposit to justify greater production, diamond-drilled nine holes totaling 4,213 feet during 1943. Drilling by the Bureau delimited the original ore body and discovered another ore body on the hanging-wall side, which was being developed by the company at the close of the project.

Jan 1, 1949

By B. J. Scheiner

Extraction of molybdenum from molybdenite ore by an electrolytic oxidation procedure was investigated by the Bureau o f Mines. Various parameters affecting molybdenum extraction, such as salt concentration, temperature, treatment rate, current density, and particle size, were studied. Molybdenum extraction of 95.2 percent was achieved on a laboratory scale from an ore containing 0.35 percent molybdenite. Corresponding power consumption was 24 kwhr per pound of molybdenum extracted with a base consumption of 4.5 pounds of sodium carbonate. Laboratory and pilot plant experiments are in progress on low-grade molybdenum concentrates containing rhenium and copper. Preliminary results indicate that molybdenum extractions in the 90- to 99-percent range and rhenium extractions of 93 to 99 percent can he obtained without appreciable oxidation of associated copper minerals.

Jan 1, 1972

By O. C. Blade

The southeastern region of the United States is becoming more important as a petroleum-producing area, and it is receiving increasing attention from oil operators. In 1948 total production of crude oil from six southeastern States - Alabama, Florida, Kentucky, Mississippi, Tennessee, and Virginia - was 55,244,000 barrels, which represents 2.7 percent of the Nation's output during that year. Kentucky and Tennessee have produced crude oil since the early days of the industry, but the remaining four States have had production only few years. Data on annual production of crude petroleum in the six States are given in table 1.

Jan 1, 1950

By Gwendolyn D. Hood

The U.S. Bureau of Mines developed a dewatering technique for treating wastewater that was tested on waste slurry from a commercial tile company in Alabama. Raw wastewater samples were pretreated with 10 Ib calcium chloride and 10 lb Wyoming bentonite per 1,000 gal of slurry. After pretreatment, polyethylene oxide (PEO) at dosages varying from 0.05 to 0.20 lb per 1,000 gal was mixed with the waste slurry, forming strong, tough floes that were separated from the clarified water using a trammel. The flocculated slurry was dewatered to a consistency that could be handled for subsequent disposal in a landfill. The clarified water quality was equivalent to that of the company's present treatment system.

Jan 1, 2010

By G. St. J. Perrott, N. A. Tolch

"PURPOSE OF TESTSThe propulsive strength4 developed by the Cardox blasting device depends on the thickness of disk, weight of heater element, and weight of carbon dioxide charge. It might be supposed that the maximum weight of carbon dioxide that can be charged into the shell should give the greatest strength. However, according to the ballistic pendulum, the maximum weight of carbon dioxide with certain conditions of heater and disk has less propulsive strength than a smaller charge; in one condition of test a loss of 39 per cent in propulsive strength was noted. It is therefore of interest to study the effect of the variables that determine the strength of Cardox.ACKNOWLEDGMENTGrateful acknowledgment is made to A. B. Coates, associate mechanical engineer who developed the testing method for measuring pressures in the Cardox shell.DESCRIPTION OF DEVICEThe Cardox blasting device as fully described by the bureau in Report of Investiga¬tions 2920 (1929), consists essentially of hollow—steel shell, cylindrical in shape, an electrode, valve assembly, shearing disk, and discharge cap. The shell is prepared for use by inserting a heater element, closing the open end with a shearing disk, and screwing in place the discharge cap. The charge of carbon dioxide enters the shell through the electrode.The heater element is fired by an electric igniter of the match—head type. The heat released by the heater element completely gasifies the carbon dioxide and raises the pressure of the gas until it is enough to shear the disk."

Apr 1, 1931

By T. E. Gray, A. W. Deurbrouck

This report describes the preparation characteristics of significant coalbeds in Kanawha County , W. Va . It is one in a series of Federal Bureau of Mines reports planned to determine coals suitable for producing metallurgical coke , either as mined or after beneficiation . Almost 9.4 million tons of coal was produced in Kanawha County , W. Va . , in 1959 , of which about 67 percent was cleaned mechanically in 10 cleaning plants . It has been estimated that more than 5,505 million tons remain in the county . Samples were collected from Pittsburgh , Stockton - Lewiston , Winifrede , Cedar Grove , Peerless , Upper Kittanning , Coalburg , Powellton , Eagle A , No. 2 Gas , and the Lower Kittanning beds . These beds were selected by the Bureau based on current production rates and estimated minable reserves . Float - and - sink tests of the samples collected from Eagle A , Peerless , Cedar Grove , Winifrede , and No. 2 Gas beds show that these coals at one location each are suitable for metallurgical use without washing . Lower Kittanning bed at four locations ; Pittsburgh , Stockton - Lewiston , and No. 2 Gas beds at two locations each ; and Coalburg , Powellton , Winifrede , Peerless , Upper Kittanning , and Cedar Grove beds at one location each can be upgraded to metallurgical quality by mechanical cleaning . Crushing the samples to 3/ 8- inch top size increased yields substantially at 1.30 specific gravity of Pittsburgh ( 17.5 percentage points ) and Upper Kittanning ( 13.0 percentage points ) beds and increased yield for the other beds sampled to a lesser amount . At this specific gravity , finer crushing caused In the 1.58 specific gravity float a general decrease in ash and sulfur . fractions of the other samples tested , most of the yields , and ash and sulfur contents , were lowered slightly by finer crushing .

Jan 1, 1963

By R. W. Holliday

To determine the copper and nickel content of reported ore occurrences in the Chippewa mine near Rockmont, Douglas County, Wis., the Bureau of Mines reopened and sampled the old shaft and workings during the summer and fall of 1953. Occurrences of native copper near Rockmont and others near Gordon, also in Douglas County, Wis., are in lava flows, which extend from the Keweenaw Peninsula of Upper Michigan southwest across Wisconsin and into Minnesota. Sporadic attempts have been made to find additional economic copper deposits in these flows since profitable mines were developed in Upper Michigan nearly 100 years ago. The Rockmont and Gordon areas were explored extensively more than 50 years ago. More recently, from August 1944 to duly 1945, an occurrence near Gordon was investigated by the Bureau.2/

Jan 1, 1955

By M. I. Copeland

The investigation of the zirconium-gadolinium equilibrium diagram was part of a program to investigate rare:earth alloys for use as nuclear reactor control materials. Investigation of the zirconium-gadolinium equilibrium diagram revealed a eutectic system with limited terminal solubilities and one peritectoid reaction. The eutectic composition occurs at about 82 percent gadolinium, and the eutectic isotherm, which occurs at 1,220 ±5° C., extends from about 12 to 99+ percent gadolinium. A peritectoid isotherm occurs at 890 ±5° C. and extends from about 2 to 99+ percent gadolinium. The solubility of gadolinium in beta zirconium decreases from about 12 percent at 1,220 ±5° C. to about 2 percent at 890 ±5° C. The solubility of gadolinium in alpha zirconium decreases from approximately 5 percent at 890 ±5° C. to between 2 and 3 percent at 600° C. Vary little solubility of zirconium in gadolinium was indicated. An allotropic transformation of gadolinium was observed at 1,260 ±5° C. A change of the gadolinium transformation temperature on alloying with zirconium was not observed.

Jan 1, 1961