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General economic conditions continued to improve in the second quarter of 1984 as real gross national product advanced at an annual rate of 7.5 percent (table 1). This followed an even larger first quarter annual rate increase of 10.1 percent. The slower second quarter growth was greeted as a sign that the economy is not over-heating. The signs of slowed growth in some sectors suggest that the recovery may continue well into 1985 without the inflation symptomatic of a rapid recovery. Most of the slowdown in growth was absorbed by business inventories, personal consumption of durable goods, and residential fixed investment. Business inventories grew by only 68 percent as much as in the first quarter, personal consumption for durable goods grew by 58 percent of the first quarter rate, and residential fixed investment slowed to only 44 percent of the first quarter growth. Sectors with accelerated growth in the second quarter included personal consumption of nondurable goods and of services, which increased at annual rates of 9.6 percent and 3.8 percent, respectively, and Federal purchases of goods and services, which increased at an annual rate of 47.9 percent.

Jan 1, 1984

By George W. Healy

The direct retorting of zinc sulfide concentrates in the presence of lime and carbon was examined on a laboratory scale with ten-gram charges of loose mix or fifteen-gram ones of pellets. A slow stream of nitrogen swept through the furnace tube over the boat of reactants, carrying with it the zinc vapor, which condensed on a rolled-up steel sheet near the exit, permitting weight of zinc produced to be obtained after completion of a run. Variables explored were percent of theoretical reagents, temperature, and time. During the runs gas samples were analysed periodically, and the content of CO2, CO and nitrogen were obtained. The quantities of the carbon gases could be calculated because the nitogen flow rate was measured. The gases were also examined for sulfur species, but neither COS nor SO2 could be detected at maximum sensitivity. Zinc recovery increased with excess carbon and lime and with temperature. It ranged from 77% at a ten percent deficiency to 90% at a ten percent excess at 1100°C. Going to 1200°C and theoretical reagents gave 93% recovery. Increasing time from 200 minutes to 300 minutes increased zinc yield by up to 10%. Results from sphalerite and a commercial concentrate from AMAX gave generally similar results. The reaction rate of zinc sulfide as sphalerite and of calcined sphalerite indicated that the latter reacted almost twice as fast, and recovery of zinc was five percent higher. Though the retorting step using sulfide, lime, and carbon proved to be non-polluting, it was feared that on storage the calcium sulfide in the residues would decompose, giving off noxious gases. Consequently the stabilization of the residues by oxidation was essayed. Because of the presence of unreacted zinc sulfide, the first product of oxidation was S02. Reaction of CaS to CaSO4 was incomplete, going from 20% at 800°C to 90% at 1200°C. Thus the non-polluting nature of the process as a whole is in doubt, and its economics are likely to be unfavorable compared to the traditional way of calcining the concentrates, followed by retorting of the oxide with carbon.

Jan 1, 1982

By Walter D. Holland

This is one of a series of instruction guides developed to help instructors present health and safety training courses to workers in the metal and nonmetal mining industry. This course is intended for training those, usually the safety officers, who perform surveys for inhalation contaminants in above ground work areas. The handbook entitled ?Handbook for Surveys of Inhalation Contaminants in Above Ground Metal and Nonmetal Mining and Processing Work Areas? is used as a manual for the course and as a prime reference when performing the actual surveys or interpreting the sampling results. There are six experiments for the students to perform during the course to familiarize them with the sampling devices routinely used during the surveys.

Jan 1, 2011

By John W. Buch

This is the first progress report to be released on the anthracite, mechanical mining research and engineering development program of the Bureau of Mines. This phase of Bureau work, which was initiated as an aid to stimulating wartime production of anthracite, has been continued after the war to assist primarily in improving the general economic position of the anthracite industry. Field work was started in. the 1945 fiscal year with the cooperation of an advisory committee representing management, labor, and the Commonwealth of Pennsylvania. For a beginning, several matters were suggested by members of this advisory committee as being worthy of investigation, and sections of underground mines yore offered for test purposes. Among the suggestions accepted for investigation was the problem of increasing the rate of advance for driving gangways in thin, steeply pitching anthracite beds 4 to 6 feet thick and pitching 60 degrees or more. The problem was undertaken as a field study, and this report relates to accomplishments on this project to June 30, 1947.

Jan 1, 1949

By Russell E. Griffen

With the development of larger mine-haulage trucks in recent years, the visual field of the driver has diminished correspondingly. Specifically, the operator's lack of direct vision in the right front area and directly to the rear constitutes a serious hazard to personnel in nearby small utility vehicles. Recently developed electronic technology has made it possible to supplement the use of mirrors and fresnel lenses to warn the operator of specific collision dangers in the truck's blind areas. This Bureau of Mines report describes the results of a coordinated contract and in-house research program to develop and test in-mine prototype electronic systems to detect the presence of smaller vehicles within the blind areas of large mine-haulage trucks. Each system utilized transmitters installed on the smaller vehicles and receivers installed on the haulage trucks. Transmitting techniques tested included both low-and high-frequency radio waves. On-vehicle testing established the engineering feasibility of each approach. Further private sector product development to improve reliability and reduce system costs is recommended. Mining companies should consider the advantages of each type of system.

Jan 1, 1988

Endless lines at service station gasoline pumps, limited travel at reduced speeds, thermostats set at an uncozy sixty-eight degrees in the dead of winter-these are but a few of the inconveniences and discomforts that awakened Americans to a realization that our domestic minerals resources, traditionally taken for granted, are not boundless. We begin to accept and practice principles of conservation, yet we are aware that this alone cannot appreciably forestall the inevitable depletion of our minerals, metals, and fossil fuels-resources critical to our Nation's economy. The key to warding off shortages is the development of technology that will insure a continuing, adequate supply of minerals and energy from reliable sources at the lowest possible costs to society and the environment. The mission of the Bureau of Mines is to develop this improved technology. Established in 1910, the Bureau of Mines of the Department of the Interior is the Federal Government's primary research arm in the minerals and fossil fuels fields. In addition to its research role, the Bureau keeps the Government informed of the Nation's mineral posture. The Bureau also seeks to stimulate private industry, through the awarding of grants and contracts, to produce minerals and fuels at a rate compatible with the country's increasing demands.

Jan 1, 1974

By T. C. Davis

Nine organic derivatives of fluorine, silicon, boron, and aluminum were purified for thermodynamic studies using distillation, zone melting, and gas liquid chromatography, The unusual properties of these compounds required the development of special techniques for handling and purification. To determine purities of purified samples, new techniques for analyzing spectral data were developed.

Jan 1, 1965

By L. F. Heising

Ten composite samples of Mesabi Range nonmagnetic taconite from the Hibbing, Minn., area were evaluated by flotation and by reduction roasting-magnetic separation to determine their potential as a future source of iron are. Only one of the composites yielded concentrates that could be considered marketable, using as a criterion a 10-to-1 iron-to-silica ratio. Cursory petrographic examinations of all 10 composited samples and a detailed mineralogical study on 1 sample suggest that unfavorable mineralogical associations between iron and gangue minerals are responsible for their poor beneficiation characteristics.

Jan 1, 1967

By H. W. Wainwright

.1. The purification pilot plant and the equipment, solution, and gas cycle used for removing hydrogen sulfide and carbon dioxide are described. 2. As sulfur recovery is necessary in any large Fischer-Tropsch plant, pilot-plant runs were made at 300 p.s.i.g. to study the efficiency of tri-ethanolamine solutions in removing selectively hydrogen sulfide from gases containing varying amounts of carbon dioxide. 3. Aqueous solutions of TEA of 20, 30; 35, and 50 percent were investi¬gated. Data indicate that 30 to 35 percent is the optimum concentration if both selectivity and economy are considered. Slightly better selectivity is obtained with the.20 percent solution, but steam consumption is greater owing to the higher solution rates. Results from our pilot plant runs indicate that a 50 percent solution not only produces an acid gas of lower hydrogen sulfide content but also requires high solution rates to effect hydrogen sulfide purification. 4. Data from 37 runs using TEA are presented in tabular form. In addition, the data are correlated and presented in three sets of curves. By using these curves, it is possible to calculate the compositions of the purified and acid gases for various raw gas mixtures. 5. In cooperation with the Southern Natural Gas Co., investigations were carried out at 300 p.s.i.g. on the simultaneous removal of hydrogen sulfide and carbon dioxide, from gases using various concentrations of diethanolamine. 6. Data from 17 runs employing 20, 30, and 40 percent DEA are reported in both tabular and graphic form. 7. A comparison of the data from one DEA run made at 200 p.s.i.g. with those from the runs operating at 30O p.s.i.g. shows float the absorption capacity of the solution, and, hence, the steam requirements per gallon are about the sage for both pressures. .The only real advantage of the higher pressure is the additional volume of gas that can be treated. 8. The quantity of steam needed to reactivate fouled TEA and DEA solutions increased as the reactivator pressure was increased about 1,0 to 1.1 pounds of steam was required for each gallon of circulating solution when the reactivator was operated at 5 p.s.i.g. 9. A curve is included that shows the effect of the hydrogen sulfide con-centration in a lean 35 percent TEA solution on the hydrogen sulfide content of the purified gas and on steam consumption for reactivation. 10. Both TEA and DEA reduced the organic sulfur content of the raw synthesis gas considerably. Analyses of the lean amine solutions showed a gradual build up of sulfur compounds, indicating that the compounds formed by the amines and organic sulfur do not break down under the ordinary operating conditions of the reactivator. 11. Considerable operating difficulty was encountered in the pilot plant owing to foaming of the amine solutions. Laboratory experiments in which the effectiveness of certain antifoam agents was studied showed Alkaterge C to be most promising for the particular conditions studied.

Jan 1, 1952

By Mark R. Pettitt

Noise surveys conducted in underground coal mines have consistently indicated that auger mining machines subject the operator and helpers to excessive noise exposure. The machine cutting heads have been identified as the primary noise source. This report documents the research program conducted to (1) investigate the nature of the cutting head noise problem, (2) develop noise control concepts, (3) devise in-mine survivable techniques to implement the noise control concepts, and (4) build and demonstrate prototype reduced-noise auger miner cutting heads. The dynamic forces generated during coal cutting by the brittle fracture of coal are predominently low frequency. The low-frequency (less than 1500 Hz) structural response of the cutting head, therefore, determines the noise radiated by the cutting head. The most feasible methods of reducing the cutting head low-frequency response are to increase both the structural stiffness and the low-frequency damping. A technique was devised to achieve these goals. The standard plate helix was replaced by a sand-filled hollow helix of triangular cross section, and the core diameter was increased with an attendant reduction in helix depth. Extended in-mine tests demonstrated the operational capability of the reduced-noise auger cutting heads. The simple noise control concepts are valid for all continuous miner cutting heads. The sand-filled hollow helix technique, which achieved a 10 dB(A) noise reduction for the auger, can be used on any helix-bearing Cutting head.

Jan 1, 1983

By W. H. Tavenner

The Bureau of Mines gathered test data on the use of a continuous borer in mining an anthracite bed, which was 30 feet thick on a pitch of 15° to 45°. Gangways were driven with the continuous borer, ventilation openings between gangways were driven with a large-diameter auger, and the blocks of coal between completed gangways were mined by the long-hole method, Conveyors were used to transport the mined coal. The continuous borer operated on a coal floor that was frequently soft because of heaving. The continuous borer could not bore openings on a grade exceeding 27 percent (15° pitch). Because 150 was also the lower limit of the pitch, of the bed, the continuous borer was used only to drive gangways. The continuous borer virtually filled the workplace, leaving insufficient space to place heavy-duty timber and cushioning material between the timber and coal back to allow for normal expansion of the uncut coal. The light? weight yieldable steel arch against the coal back gave inadequate support to control convergence, which in a disturbed area sometimes occurred with explosive violence. This exposed the machine operator to a hazardous condition, since a satisfactory solution could not be found, the company discontinued the use of the continuous borer.

Jan 1, 1966

By Larry Joe Linley

The Department of the Interior, Bureau of Mines is reviewing explosion protection methods for use in gassy coal mines. This performance criteria guideline is an evaluation of three explosion protection methods of machines electrically powered with voltages up to 15 000 volts AC. A sufficient amount of basic research has been accomplished to verify that the explosion-proof and pressurized enclosure methods can provide adequate explosion protection with the present state of the art up to 15 000 volts AC. The routine application of the potted enclosure as a stand alone protection method requires further investigation or development in order to clarify performance criteria and verification-certification requirements. An extensive literature search, a series of high voltage tests, and a design evaluation of the three explosion protection methods performed at White Sands Test Facility indicates that the explosion-proof, pressurized, and potted enclosures can all be used to enclose up to 15 000 volts AC, if the performance criteria and verification-certification requirements recommended in this guideline are implemented.

Jan 1, 1982

By R. E. Kennedy

"INTRODUCTION In a previous publication4 results were given of numerous experiments made on the in-flammability of gas mixtures consisting of methane, hydro a. carbon monoxide, nitrogen, and carbon dioxide. Data were obtained and tables prepared giving the inflammable limits of each of these combustibles when mixed with various proportions of carbon dioxide and nitrogen. By the use of these data and the application of Le Chatelier's law, it was found possible to calculate the limits of inflammability of any gas mixture containing any or all of the above gases.Various mixtures of the five gases given above were prepared and their limits determined experimentally and then calculated. Good agreement was found between the determined and calculated results when complex gases encountered in mine safety work were tested. Of special significance was the accurate calculation of the limits of inflammability of gases from mine fires, gases from mine explosions, detonation products of explosives, blast—furnace gases, automobile exhaust gas, and other gases of a similar character.Using the method given in the above report, Yeaw5 investigated a number of industrial gases including oven, coal, producer, blue, carbureted blue, and dry quencher gases, and found the determined and calculated results to agree remarkably well, thus giving further proof of the value of such a means of determining dangerous conditions when combustible gases are encountered in practice.GASES FROM A POTASH MINEGases were recently encountered in a potash nine in New Mexico, containing the com-bustibles, methane, hydrogen, and ethane. In one special case a mild explosion occurred when these gases were mixed with the right proportions of air and ignited it therefore became necessary to know the inflammability of these mixtures in order that the proper precautions could be taken to prevent explosions."

May 1, 1932

By Don M. Coulter

"INTRODUCTION The Margerum bauxite district, in Colbert County, Ala. was investigated in December 1940 and in February 1943 by R. W. Smith of the Bureau of Mines .3/ A geologist of the Federal Geological Survey investigated and mapped the district in the fall of 1942.These preliminary investigations indicated bauxite showings over an area about a mile long by 2,000 feet wide. It was felt that the chances were good for finding one or more large deposits of low- to medium-grade bauxite. The location - within 35 miles of the alumina plant of the Reynolds Metals Co. atLister Hill, Ala. – made it especially attractive. A field office was established in Iuka, Miss., on May 19, 190,, and mineral agreements were executed with four landowners covering 1,146.6 cores.The drilling on the project was done under contract. The power drilling was supplemented by a labor crew that drilled hand-auger holes, where there was little or no gravel overburden, and sampled the old test pits.The Federal Geological Survey, after thorough study of the district, recommended 54 drill holes 4/ to delimit the known deposits and to search for possible extensions. After the drilling started, many of these locations eliminated, and others were changed upon the basis of information gathered from the holes as they were drilled."

Mar 1, 1948

By G. R. Smith

Critical and strategic metals are often present in small quantities in low-grade domestic ores. When these ores are leached, the resulting solution usually contains the metals in very dilute quantities. Selective electrowinning from dilute electrolytes was investigated by the Bureau of Mines. A metal deposit containing 84 pct nickel was electrowon from the leach solution of a complex domestic ore bulk flotation concentrate originally containing approximately 2 wt-pct nickel. Key to achieving accelerated deposition rates, in the case of dilute solutions, is the rapid movement of the electrolyte through the electrowinning cell. Pure, synthetic nickel electrolytes were used to establish deposition parameters, and to optimize electrolyte velocity or mass transfer rates. Hydrodynamic and electrodeposition parameters for both the synthetic and leach electrolytes are presented and the experimental research described. Selective electrowinning appears to offer a viable alternative to physical separation methods to obtain separate metal "concentrates" from low-grade ores.

Jan 1, 1983

This Bureau of Mines report concerns two subjects important in the application of electric power in mining systems. Electrical transients and their suppression are discussed, and several considerations are explored with regard to the use of explosionproof or other electrical enclosures.

Jan 1, 1979

By H. E. Thomas

[The Bureau of Mines has conducted a field hydraulic fracturing experiment to determine the preferential orientation of induced fractures in oil shale at a depth of about 400 feet in the Green River Basin of Wyoming. The hydraulic fracturing treatment was performed by injecting extremely viscous water-base gel and 8- to 12-mesh sand into the oil shale through straddle packers set in an impermeable section of smooth-walled, 6-1/4-inch-diameter open hole. An impression packer proved that a horizontal fracture, which has an average width of about 1/2 inch at the borehole, was induced. A corehole drilled 100 feet from the fractured well intersected the fracture and confirmed its horizontal orientation. Because a horizontal fracture was successfully initi¬ated, it is inferred that the creation of multiple, closely spaced horizontal fractures may be feasible in Green River Basin oil shale.]

Jan 1, 1972

By Sterling J. Anderson

Through the use of nondestructive testing techniques, the Bureau of Mines is pursuing a goal of improving the efficiency of the rock excava-tion process. Toward this end, 44 laboratory tests were conducted to identify a practical method of monitoring fracture development in rock, as caused by an excavation tool. An acoustic emission CAE) transducer was used to monitor the test samples as they were loaded. The signal from this instrument was recorded in real time along with the radial and axial loads generated by the fracturing device. Through the review of these signals on a common-time base, it was possible to see the relationship between the developing fracture and the loading conditions. As a part of the posttesting investigations, samples that were pletely fractured were sawn and ground to expose the fractures. examination of these samples allowed approximations to be made incom-Visual of the total surface created. Surface area approximations were also made for the completely fractured samples. Quantitative analyses· of the AE signals were conducted for comparisons with the calculated surface areas.

Jan 1, 1987

By R. P. Maloney

Since mining operations began in 1900, Government geologists and mining men have periodically recorded the presence of the minerals of mercury and antimony in the extensive gold placer deposits near Flat in the Iditarod district of the Yukon River region, Alaska. No serious effort was made to recover the cinnabar contained in the gold placer gravels, and there is no evidence that veins of cinnabar and stibnite exposed in the placer operations (as reported by the Geological Survey) were ever explored or developed. A large monzonitic intrusive, which is the dominant geologic feature of the immediate area, is believed to be the lode source of the valuable minerals in the placer deposits. In contact with the monzonite are argillite and quartzite, metamorphic products from the Cretaceous shales and sandstones.

Jan 1, 1962

By Robert Lee Stahl

Comprehensive field tests were made in the Gas Hills, Wyo., to determine whether surface geophysical techniques could be used to detect and delineate faults in marginal uranium deposits. The tests were made on property owned by Federal American Partners, Gas Hills, Wyo., and included seismic refraction, self-potential, induced polarization, magnetometer, electrical resistivity, airborne infrared thermal scanning, and airborne photography. Of the several geophysical techniques tested in the field, horizontal resistivity profiling with electrode spacings in the range of 25 to 50 feet was most diagnostic of faults. The method is quick, cheap, accurate, and one that can be easily used by personnel employed by mining companies to detect and delineate faults.

Jan 1, 1973