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By I. D. Shah

The Bureau of Mines investigated the sequence of principal chemical reactions taking place during the roasting of covellite (CuS). Practically all covellite is converted to digenite (Cul.SS) before oxidation to Cu20 begins. Part of the Cu2O is then converted to CuO, which in turn forms CuS04 through CuO?CuS04 as an intermediary. CuS04 and CuO'CuS04 decompose at 600° to 700° C to yield CuO and S03 (g) as final products. An overall mechanism is proposed for chemical reactions occurring at different interfaces of partially oxidized CuS pellets.

Jan 1, 1970

By Anthony W. Sparks

The Bureau of Mines conducted tests designed to compare its breathing metabolic simulator (BMS) with other methods that are currently used to evaluate the performance of respiratory protective equipment. The BMS is a commercially developed device that uses a piston cylinder to simulate breath movement. Using a propane furnace that consumes oxygen and forms CO2, the BMS also simulates the respiratory metabolism of humans. The breathing and metabolic subsystems of the BMS are described in detail in this report. Results are compared from tests that used the BMS to evaluate respiratory equipment and from tests that used human subjects for the same purpose. The BMS was also tested against a pulsatile breathing machine (PBM) previously designed by the Bureau. Both machines were used to test respiratory equipment, and the test results are compared in this report. To illustrate typical applications of the BMS, the report briefly describes how the BMS was used to test two different types of closed-circuit respiratory apparatus, and the test results are presented. This research showed that BMS test results compared more closely to the results of tests that used human subjects than did results obtained using the PBM.

Jan 1, 1980

By David C. Oyler

Three long horizontal holes were drilled from a directionally drilled surface hole at the Emerald Mine near Waynesburg, Pa. The purpose was to adapt the technique of directional drilling for use in draining methane from coalbeds. A 504-m (1,652-ft) long, 76-mm (3-in) diameter, circular arc pilot hole was drilled, using a downhole mud motor, to enter the Pittsburgh coalbed at a vertical depth of 305 m (1,000 ft). The hole was reamed to 222 mm (8-3/4 in) and was cased to a measured depth of 486 m (1,595 ft). Three 76-mm (3-in) diameter horizontal drainage holes were then drilled, totaling 2,909 m (9,544 ft) of horizontal hole. Improvements in drilling methods increased the average drilling rate from 20.4 ill (67 ft) to 64.9 m (213 ft) per day. The cost of drilling the directional and horizontal holes (using a Government-owned drill rig) was $1,169,530, a figure inflated by inexperience and by delays caused by lost-circulation problems and fishing operations. An estimated total drilling cost of $960,000 (including rental of a drill rig) for an improved system, was determined by a detailed cost analysis. Initial gas and water production from November 1979 through May 1980 was low because of caving of the horizontal holes drilled in shale near the bottom of the casing.

Jan 1, 1982

By E. J. Gleim

In the movement of self-controlled direct-current machinery, particularly shortwall cutting, machines, from one place to another in coal mires, "nipping" or it stinging" has been practiced quite commonly. These terms refer to the method of obtaining current for propelling or tramming the machines along trolley haulageways by sliding the trolley trip (hook or nip), which terminates one conductor of the trailing cable, along the trolley wire. This is usually done by the machine operator or runner while sitting on the machine truck and holding the nip terminal against the trolley wire as the machine travels along the rails. This procedure is objectionable for several reasons. Under the best conditions, the area of contact between the nip and trolley wire is snail end, consequently, sparking and flashing ore most likely to be continuous as the machine proceeds. This is undesirable, not only because of the detrimental effect of electric flashes upon eyesight, but because of the pitting and roughening the trolley wheels which decrease the efficiency of current collection by locomotive trolley wheels and shoes and at the same time shorten their useful life by increased wear.

Jan 1, 1939

By S. J. Broderick

[The term "nonmetallic minerals? as commonly used is the mining industry, refers to those minerals of industrial importance that are mined essentially for uses other than for the metals contained. The field comprises several hundred rod minerals of industrial importance, of which 70 have can adequately described in the textbook Industrial Minerals and Rocks. A few o f the more important nonmetallic products are sand and gravel, salt, phosphates, clays, refractories, limestone, and cement materials. Some of the minerals, such as bauxite and pyrolusive, have both metallic and nonmetallic applications, but in this report only the nonmetallic mineral phases are considered. In the organic field of nonmetallics only coal is considered, as, the others - petroleum, natural gas, natural bitumens, and hydrocarbons - are of no importance in water softening.]

Jan 1, 1941

By Hylton R. Brown

This publication, an abstract of a progress report covering an investigation of hazards in thermal coal-drying plants has been prepared according to the suggestions and recommendations of a committee6/ appointed by J. J. Forbes, Director of the Bureau of Mines, when the original report was reviewed at a meeting of representatives of the mining industry, operators of coal-drying plants, coal-mine workers, and the Bureau in Washington on May 6, 1955. The investigation on which the report is based was made in accordance with action taken at a previous conference in Washington on May 19, 1954, called by Director Forbes to consider what should be done to prevent explosions and fires in coal-drying plants. Scope of Investigation The investigation was planned to obtain information considered essential for properly appraising fire and explosion hazards in different types of coal driers. A questionnaire sent to Bureau personnel provided preliminary information on coal-drying facilities at more than 270 preparation plants. Information on methods used in operating different types of driers, with their furnaces, fans, cyclones, and other auxiliary equipment, was obtained by personal visits or conferences with the operators at 13 plants. Factual data on operating temperatures, composition of the drying gases, air flow, dust loading of the air or gas currents, use of water sprays, auxiliary air controls, and other factors were obtained by conducting full-scale tests at six different plants and making laboratory investigations with samples of dust and gas collected during the tests.

Jan 1, 1956

By Ted C. Briggs

Twenty-two compressibility runs were made with helium over the temperature range -5° to 80° C and at pressures to 800 atmospheres. A Burnett apparatus was used. Data from the runs were fitted to a fourth degree polynomial equation of state in the pressure and a weighting factor of Pr-3/4 was used. All data for a particular isotherm were treated simultaneously. A temperature function was found to represent the parameters B and C. Compressibility factors determined by this investigation are believed to be accurate to better than 0.05 percent.

Jan 1, 1970

By Warren E. Morrison

Demand for energy in the United States in 1965 was stimulated by the continuing expansion of the economy. A gain of 5.9 percent in gross national product for the year was accompanied by a 4.4-percent rise in energy consumption. Domestic energy resources met about 93 percent of the nation's requirements. The remaining 7 percent consisted of imported fuels, mainly of crude petroleum and residual fuel oil. The major fossil fuels-natural gas, crude petroleum, and coal, in that order-contributed 96 percent of all commerical energy utilized, with the balance of 4 percent being primary electricity from hydropower and nuclear power plants. Production was up for all of the major mineral energy resources in 1965, with the single exception of anthracite, output of which continued to decline. Bituminous coal output for the year was 512 million tons; marketed production of natural gas, 16,039 billion cubic feet; and crude petroleum output, 2,848 million barrels. Among the secondary products processed from primary energy resources, the most significant gains were in coal carbonized for coke which increased 6.7 percent to 95 million tons, and in the output of liquefied gases from natural gas which rose 4.8 percent to 11,257 million gallons (268 million barrels). Within the latter category, the off? take for petrochemical feedstocks continued to rise at a very rapid pace.

Jan 1, 1967

By Albert J. Rambosek

The results obtained in a study of the stress conditions existing in a drill bit-point area and in the underlying rock, when the bit was in full but nonpenetrative contact with the rock, are presented. This investigation by the Bureau of Mines was the preliminary exploratory phase of a long-range program of research on rock drilling to establish criteria for the maximum economically feasible rate of rock penetration. The photoelastic technique of experimental stress analysis was the principal method used to obtain the data. Transparent models and transmitted light were employed to investigate patterns in drill-bit models and isotropic materials under the bit when subjected to a concentrated static load. Comparative stress data for anisotropic rock were obtained by the reflective photoelastic technique. Brittle lacquer and an extensometer were used obtain supplementary information wherever substantiating data were desired to check photoelastic results. The zone of maximum shear occurs along an arc near the contact face of the bit. The stress distribution pattern in an isotropic model rock near the area contacted by the bit was nearly a mirror image of that exhibited within a similar areal zone of the bit. The stress pattern in granodiorite specimens was similar, though not symmetric, to the pattern in the isotropic model rock. The asymmetry of the stress pattern in the granodiorite was attributed to the anisotropic characteristics of the constituent minerals of various sizes.

Jan 1, 1963

By R. H. Sprute

This report describes Bureau of Mines laboratory test results in electro-kinetic dewatering and consolidation of metal-mine mill tailings from five mines in the Coeur d'Alene, Idaho, district. Classified (coarse) tailings, slimes, and unclassified material were separately tested. Tailings were placed in 0.3 ft3 plexiglass models, and dc potential was applied until dewatering ceased. Time-oriented measurements of water removal, changes in resistivity, and power consumption were recorded during the dewatering process. Moisture content and density of the dewatered material at test end indicated the method to be generally effective for all materials examined, but best results were achieved with well-mixed unclassified tailings.

Jan 1, 1974

By K. O. Bennington

[Thermodynamic properties of two amphibole asbestos minerals were determined by the Bureau of Mines. The enthalpies of formation were determined by the hydrofluoric acid solution calorimetry method. Heat capacity measurements were made with an adiabatic calorimeter over the range of 5 to 315 K. High-temperature enthalpies above 298 K were determined with a copper-block drop calorimeter to 852 K for amosite and to 902 K for crocidolite. Thermodynamic data determined for amosite of the composition Fe5+2.2766Mg1.5209 Fe+03.12Mn0.0825) Si7.9163Al0.0837022.0363)(OH)1.9637 are: S°298 = 168.8 ± 5 cal/deg-mole; ?Hf°298-15 (elements) = -2419.24 ± 2.95 kcal/mole; ?Hf298.15 (oxides) = -30.92 ± 2.47 kcal/mole; and ?Gf° -2260.1 kcal. Corresponding data found for s3 ,1s = crocidolite of the composition (Na1.9Ca0.1)(Fe2+.024Fe2.5 01Mg0.475) (Si7.9713024Fe+2 2.501Mg0.475) (Si7.971 Al0.029022.095) (OH)1.905 are: S2.98-15 - 161.1 ± 4 cal/deg-mole; ?Rf° 2 298.15 (elements) = -2433.56 ± 2.99 kcal/mole, 10298.1s (oxides) = -87.69 1.70 kcal/mole, and ?Gf°298.15 = -2269.8 kcal.] Calorimetric values from this investigation were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of the measurements. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature both from the elements and the constituent oxides.

Jan 1, 1978

By R. G. Nelson

The mechanical properties of low-hafnium, arc-melted, Kroll-process zirconium are presented. The effect of temperature on the ultimate strength, yield strength, proportional limit, elongation, hardness, Young's modulus, electrical resistivity, and impact strength are shown, The effects of cold work and annealing on the tensile properties, bend radius, and formability, as determined by cupping tests, are also given, Tensile properties are compared, in part, to those obtained on earlier graphite-melted zirconium and on crystal-bar zirconium. INTRODUCTION The commercial production of high-purity, low-hafnium bearing zirconium has been achieved, and this metal is becoming available for industrial use. However, there is little published information regarding the physical and mechanical properties of this product; and, since there have been many improvements in the production and arc-melting techniques of zirconium in the past 3 years, it was considered advisable to present the properties of the vastly improved zirconium representative of current production.

Jan 1, 1954

By T. L. Marchewka

As part of its program to conserve the Nation's natural resources by developing improved performance materials, the Bureau of Mines, U.S. Department of the Interior, in cooperation with the U.S. Department of Energy, has conducted an investigation of materials of construction able to withstand the high temperature and hostile environments encountered in coal gasification units. Refractory pipe liners are required when extremely hot gases or abrasive solids are transported between processing units in the gasification plants. One promising technique for producing refractory pipe (or refractory pipe liners) is centrifugal casting. For this study, the effect of processing variables such as workability, additives, reinforcement and spinning time, and centrifugal force were evaluated using four commercial refractory concretes. In addition, data on characteristics such as strength, density, abrasion, and spalling resistance of 5-inch-diam refractory pipe were developed. Techniques for forming large-diameter (19-inch) refractory pipe also were evaluated. The test results indicated that all four refractory concretes could be made into strong, homogeneous pipe, but that optimum casting parameters had to be determined for each specific composition. The investigation revealed that the major controlling factor in the production of the centrifugally cast pipe was the workability of the refractory concrete.

Jan 1, 1979

By H. E. Powell

The smelting of brass and bronze generates a dust composed primarily of zinc oxide, with lesser amounts of other metal oxides, such as copper, lead, and tin. The small quantity of this waste generated by individual smelters and the relatively low unit value of the contained metals, suggests the desirability of reclaiming the metals onsite or at some nearby point. The Bureau of Mines has developed a process that fits these requirements. The technique consists of (1) dissolving zinc and copper from the dust with sulfuric acid, (2) recovery of copper by cementation, (3) recovery of zinc as zinc sulfate crystals, and (4) recovery of lead and tin as a salable residue. Alternatively, zinc may be recovered by electrodeposition. Free acid is recycled and no major pollution problems are generated by the process.

Jan 1, 1972

By Frederick C. Trutt

Research performed on arcing faults and their interaction; with electrical insulating materials within coal.-mine power-system enclosures is described. This work was performed at The Pennsylvania State University from 1 December, 1976 through 30. November, 1977. Results presented are interim in nature and future research is planned to integrate the simulations which have been constructed, as well as to apply developed experimental procedures to the evaluation of electrical insulating materials for use in coal-mine enclosures. The thrust of this research has been divided into several primary areas. These include the development of a theoretical procedure for computation of three-phase and line-to-line arcing fault currents as a function of time, formulation of an arc model based upon thermal-arc plasma properties so that arc voltages and energies may be computed, development of a simulation for pressure and temperature rises when an arc interacts with an electrical insulating material within an enclosure, experimental evaluation of electrical insulating materials in terms of their tendency to support an arc as well as their potential contribution to enclosure pressure rises, and integration of the above research areas to form overall procedures for theoretical and experimental evaluation.

Jan 1, 1977

By M. L. Williams

In recent years the use of visual aids has expanded the? field of safety education. This is a modern adaptation of a method employed in ancient times, when simple paintings and drawings were the only means of recording current events. In its present application, visual aid employs sound and silent motion pictures, stripfilms, lantern slides, descriptive posters, and color. According to Roberts,3/ "Visual education is a method of imparting information which is based on the psychological principle that one has a better conception of the thing he sees than of the thing he reads about or hears discussed." Dent4/ further defines visual aid as "all the materials used to facilitate the understanding of' the written or spoken word."

Jan 1, 1951

During the 20th century, the increased emphasis on worker health and safety and the advent of new mining equipment and methods led to many changes in mine face ventilation practices. Efforts by government and private industry to improve and modify ventilation practices resulted in better health and safety conditions for workers. This article focuses on U.S. Bureau of Mines (USBM) and National Institute for Occupational Safety and Health (NIOSH) research to examine factors that had a significant influence on mine face ventilation design during the past century. Several "milestone" events are discussed along with the impact they had on worker health and safety. Significant ventilation research efforts by government and private industry are presented. This brief ventilation history highlights innovative face ventilation designs and a consistent commitment to mining health and safety. Ventilation has always been a concern in underground coal mining. For many yeas, there was no appreciation of how ventilation could be used to remove harmful contaminants from the air or how to control airflow quantities. The first known problems with ventilation date back to the 14th century, when it was recognized that lack of air was a major impediment to the expansion of mines. The common method of solving ventilation problems at that time was to abandon the existing mine and start a new one nearby. Ventilation in the early days of coal mining was accomplished by means of a natural draft, created principally by a difference in the weights of columns of air between the intake and return openings. Later, in the 18th and 19th centuries, a furnace was introduced underground to increase the updraft in the return shaft. This allowed for a larger quantity of air in circulation. When mines went deeper and became larger, mechanical ventilation became necessary and was first accomplished by steam-driven fans. These fans became more prevalent as furnaces were prohibited in underground mines, especially after the Avondale disaster in Pennsylvania in 1869 (Roy, 1876). Eventually, these fans were replaced by more powerful, electrically [ ]

By M. C. Irani, Maurice Deul, M. G. Zabetakis, T. G. Bobick

This survey was conducted to determine the magnitude of the methane emission and control problem in U.S. bituminous coal mines. The resultant data indicate that the emission rate for any given coalbed depends primarily on the coal production rate and on mine depth, as well as on the nature of the coalbed and the surrounding strata. An excellent correlation was found between (1) the methane emission rate and (2) the product of coal production rate and mine depth for the mines in the Pittsburgh, Pocahontas Nos. 3 and 4, and the Illinois Nos. 5 and 6 coalbeds. The highest total emission rates found in U.S. bituminous coal mines were as follows, in million cubic feet per day: Monongalia County, W. Va., 39; Marion County, W. Va., 30.4; McDowell County, W. Va., 13.1; Washington County, Pa., 11.9; Greene County, Pa., 11.4; Buchanan County, Va., 21.6; Jefferson County, Ala., 10.3; and Franklin County, Ill., 6.6.

Jan 1, 1972

By Richard G. Sandberg

Sphalerite concentrates prepared during processing of Missouri lead ores contain small percentages of cobalt and nickel which adversely affect zinc electrolysis. The Bureau of Mines has evaluated solvent extraction and precipitation techniques to remove and recover cobalt and nickel from zinc sulfate solution prior to zinc electrolysis. Prepared zinc sulfate solutions containing about 190 gpl of zinc and 50 ppm of both cobalt and nickel were treated using various combinations of complexing reagents, solvent, pH, concentration, time, and temperature. The following complexing reagents gave the best results: a-nitroso-ß-naphthol, ß-nitroso-a-naphthol, 1,2 cyclohexane dione dioxime (nioxime), di-2-pyridyl ketone oxime, and dimethylglyoxime. These reagents in suitable solvents lowered the cobalt and nickel levels to <0.1 ppm. Stripping the complexed reagents from the solvents was not possible except for nioxime. Direct addition of the appropriate reagent to the prepared zinc sulfate solution resulted in the precipitation of cobalt and nickel. Several possible flowsheets are presented for the removal and recovery of cobalt and nickel. Good zinc deposits were successfully electrowon from zinc sulfate solutions purified by solvent extraction and precipitation.

Jan 1, 1978

By J. V. Scalera

Because of U.S. dependency on imported critical metals, the Bureau of Mines has conducted research to evaluate the possible substitution of nitrided low-alloy steels for higher chromium-containing alloys. The corrosion data for nitrided steels are limited primarily to the Soviet literature. The objective of this study was to determine the corrosion properties of six commercially nitrided low-alloy steels in a 5-wt % NaCl solution at pH 4. Weight-loss tests indicated that, in deaerated test solutions, most of the nitrided steels were less corrosion resist-ant than nontreated steels. However, electrochemical tests indicated that under more oxidizing conditions, nitrided materials are converted to a passive state with a significantly reduced corrosion rate. Elec-trochemical tests performed in an aerated environment confirmed the passivity of the samples in an oxidizing environment.

Jan 1, 1984