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By Leonard Obert

The various underground rooms in the Bureau of Mines Oil-Shale mine, Rifle, Colo., have been open for periods ranging from 3 to 5 years. During this time 3 roof falls have occurred; 1 was induced, and the other 2 were unintentional. The three roof falls are described in this report. Two causative factors are discussed -a time-dependent deterioration of the roof rock and an unfavorable system of jointing that occurred in the strata overlying the present roof horizon. Irrespective of cause, the operating life of any stoping area would have been short com-pared with the life of the roof (1 to 4 in the most unfavorable instance), if a high-production system of mining had been employed. The report is concluded with several recommendations that should be considered in planning future mining operations.

Jan 1, 1958

By Frederick C. Trutt

This report is intended as a reference for personnel interested in the computer anlaysis of coal-mine-electrical-power systems under either normal operating conditions or fault situations. The procedures developed for this purpose are described and implementation considerations are discussed with respect to the mine-power system. Considerations for choosing a solution technique and a number of examples are included. Procedures described include the Newton-Raphson iterative technique for the analysis of normal operation as well as a non-iterative Z-bus technique for analysis of unbalanced or balanced faults. During program development, strict attention has been given to the inclusion of core and/or time saving techniques such that these algorithms may be implemented on small as well as large computers. Program languages include FORTRAN IV for batch processing applications and APL or BASIC for interactive applications.

Jan 1, 1981

By Forrest T. Moyer

All general measures of the safety record of the coal mining industry worsened appreciably in 1970. Injury experience for the year was 260 fatal and 11,552 nonfatal injuries at respective frequency rates of 1.00 and 44.40 per million man-hours of worktime. The fatality total was 57 higher and the rate of occurrence was 18 percent higher than the corresponding figures of 203 fatal injuries with a frequency rate of 0.85 in 1969. The worsened fatality record in 1970 resulted primarily from a major disaster (a single accident which results in the death of five men or more) on December 30, 1970, that killed 38 men. There were no major disasters in 1969. The total of 11,552 nonfatal injuries in 1970 was the highest annual total since 1960. It was 1,635 higher and the frequency rate was 6 percent higher than the corresponding totals for 1969 of 9,917 nonfatal injuries occurring at a rate of 41.76. The injury severity rate of 8,308 days lost or charged per million man-hours was 13 percent worse than that of 7,359 in 1969. Similarly, the average severity of 183 days lost or charged per injury in 1970 was 10 days or 6 percent higher than in 1969. Aggregate worktime of 260.2 million man-hours and production of 609.8 million tons in 1970 were, respectively, 10 and 7 percent higher than in 1969. An average of 144,480 men were at work on an average of 227 active days in 6,316 mines and 544 mechanical cleaning plants during 1970.

Jan 1, 1973

By J. E. Zeilinger

The technical feasibility of using energy from explosive ignitions of coal dust to pump water was .demonstrated in an exploratory investigation. Ignition of small amounts of pulverized coal that were dispersed in air over columns of water pumped up to 5.3 gallons of water per cycle when operated against a head of 30.75 feet. Water displacement was accomplished by either manual or automatic operation through a single cycle, and by automatic operation through a continuous series of cycles of I-minute duration. Operating through single cycles, slurries containing up to 3 pounds of coal and 4.6 gallons of water were also pumped. Possible uses of an efficient coal-fired pump would include pumping water for irrigation purposes, removing water from mines, transporting coal from mines in the form of a slurry, and pumping water to elevated reservoirs at electric powerplants so that it could be used to generate electricity during peak periods of demand.

Jan 1, 1966

By P. S. Lewis

Shortage of natural gas is reviving interest in low-Btu fuel gas made by gasifying coal in fixed-bed producers. The Bureau of Mines gasified strongly caking Pittsburgh bed coal over test periods lasting four days in an experimental gas producer located at Morgantown, W. Va, Mechanical stirring throughout the fuel bed was effective for keeping the fuel moving and this stirring made the operation successful; hence, the gas producer was named the stirred-bed producer. Nuclear density gages were applied as control instruments to indicate coal flow and fuel level, and to record the frequency and location of void spaces in the bed, The gas, of nominal 140 to 165 Btu/scf calorific value, could be burned in a boiler for generating steam.

Jan 1, 1972

By E. D. Gardner

The mine of the Eureka Standard Consolidated dining Co. is at Dividend, Utah, in the Tintic mining district. It is operated under the same management and controlled by the Antic Standard Mining Co.; the two properties adjoin each other. The Eureka Standard is worked through a vertical shaft; the ore is mined by a stringer-set-and-fill method. One hundred and thirty men were employed in April 1933. The normal daily tonnage is 100 tons; the ore is shipped to the smelter at Garfield, Utah.

Jan 1, 1935

By E. V. Cilento, K. A. DiGregorio, R. C. Lantz

"An electro-optical method was used to quantify superoxide (SO) release from single rat pulmonary alveolar macrophages (PAM) exposed in vitro to respirable quartz and kaolin dusts and in vivo to quartz. Release was determined by measuring the reduction of nitroblue tdrazolium (NBT) to a diformazan precipitate at 550 nm from video-recorded images of individual cells. In vitro exposure to 0.025 or 0.05 mg/ml kaolin for 40 minutes resulted in no significant differences in either the total diformazan produced (max) or the maximum rate of diformazan production (R)./n vitro exposure to 0.025 mg/ml c1uartz decreased max 38 percent while no significant change was found using 0.05 mg/ml. However, R was decreased 31 percent and 24 percent for the low and high dose, respectively. In contrast, PAM obtained from animals exposed in vivo to quartz dust for two or four weeks in inhalation chambers exhibited increased production of diformazan. However, only PAM analyzed three days post-exposure showed significant increases, while PAM from animals sacrificed ten or 31 days post-exposure were not significantly different from control. The combined in vitro and in vivo quartz results might suggest that there is an initital acute response to exposure that decreases the ability of PAM to produce SO, followed by recruitment of production of PAM with increased SO producing capability. It appears that removal of animals from the source of exposure permits PAM to return to control levels of SO production by31 days. Whether this would be true for chronic exposure remains to be elucidated.IntroductionPulmonary alveolar macrophages (PAM) protect the lungs by phagocytizing foreign debris and bacteria.(1) This process involves ingestion as well as destruction of foreign matter. Phagocytosis usually is accompanied by a respiratory burst which increases cellular oxygen consumption leading to the release of highly reactive oxygen metabolites.(2) These agents have been implicated in the killing of bacteria by phagocytes, but they have also been shown to be toxic and,have been linked to cancer, emphysema, arthritis, diabetes, and other diseases.(3) Toxic effects may be a result of 1) an abnormally low production of metabolites, resulting in damage to lung tissue by the respired bacteria and/or dusts; or 2) an abnormally high production resulting in direct damage to lung tissue by metabolites themselves."

Mar 1, 1989

By C. C. Shale

Current-voltage relationships for air at high temperature in negative corona are compared with relationships predicted by theory. Deviations are discussed. Eased on the latest theoretical concept of electron detachment from negative ions and recent findings in basic research on free electron gases, results of applied research show the existence of free electrons in air at high temperature and high field strength-to-pressure ratios.

Jan 1, 1967

By Larry R. Wilson

The development effort described herein was directed toward the design and development of a flexible communication system to provide two-way section communications between any telephone on an MCM-101 telephone FDM exchange and a miner provided with a uhf walkie-talkie transceiver. The system also provides normal communication between miners within a working section through the uhf coupler interface repeater.

Jan 1, 1976

By Ronald D. Rothchild

This report describes the results of a study of longwall ignition hazards and specific suppression systems to minimize each of the major hazards. The major ignition hazards were identified by conducting a literature search and conversing with knowledgeable individuals in the United States mining industry. Three classes of potential ignition suppression systems are discussed: triggered suppression systems for face ignition, passive suppression systems, and control of ignition hazard in the gob. The triggered suppression systems included protection for the shearer, head and tail gates, welding equipment, and the shearer power cable. Passive systems include improved ventilation and water sprays, and charges in the shearer head. Gob protection can be improved by isolating the gob from working areas and by introducting inerting agents into the gob.

Jan 1, 1976

By F. W. Hoertel

Near-optimum parameters were determined by the Bureau of Mines for vapor deposition of rhenium on heated copper substrates by hydrogen reduction of rhenium hexafluoride (ReF6). High-purity deposits of nearly 90-percent theo¬retical density were obtained with the reaction chamber at 250° C, with an H2 to ReF6 volume ratio of 25 to 1, and with an ReF6 flow rate of 5 grams per hour. Some rhenium deposited as a loose, black powder. When the established near-optimum parameters were carefully followed, this could be minimized but never completely avoided. Varying the reaction chamber pressure, both above and below atmospheric, yielded excessive quantities of rhenium powder. Deposition efficiencies, based on only the coherent metal, ranged between 70 and 75 percent. Massive deposits contained only spectrographic traces of impurities. The average microhardness (Knoop, 100-gram load) of vapor-deposited rhenium was 907. Limited research on the deposition of rhenium-tungsten alloys by reduction of the mixed hexafluorides produced deposits in which linear composition gradients were pronounced; this nonhomogeneity was attributed to the wide variation in optimum hydrogen-reduction temperatures of the two hexafluorides (250° C for ReF6 and 550° C for WF6). Using deposition temperatures between 250° and 550° C did not eliminate the composition variations.

Jan 1, 1967

By Chas. G. Maier

The bright annealing of copper is an industrial practice of considerable importance. In connection with this process, equilibrium concentrations of carbon monoxide and dioxide, which may exist in contact with copper and cuprous oxide at elevated temperatures, are of interest. Data obtained at the Pacific Experiment Station of the U. S. Bureau of Mines enable estimates of these equilibrium concentrations to be made in two independent ways. Although the publication of final data on one method can not take place until certain further experimental work is accomplished, repeated requests which the Bureau of Minus has had for data relative to the annealing and deoxidation of copper justify the present preliminary report. This paper deals with the calculation of gas concentrations in the reduction of cuprous oxide, using more scientific data which will be published later, and refers especially to those conditions of temperature and concentration of practical implication, and from which critical limits ensue.

Jan 1, 1929

By Irving Hartmann

At the 9th International Conference of Directors of Safety in Mines Research a paper6/ was presented describing the initial phases of research by the Safety in Mines Research Establishment at Buxton, England, on the remote control of timber fires with high-expansion foam plugs in a rock tunnel. The work received extensive publicity, and great interest was aroused by the implied possibility that the method might be used successfully to control coal-mine fires, which for various reasons cannot be approached and attacked by standard fire fighting measures and frequently require sealing extensive, valuable coal properties and lead to loss of production and coal reserves and occasionally loss of lives. To investigate the practicability of the foam-plug technique under American min¬ing conditions, with room-and-pillar-type extraction and multiple entries, the Bureau of Mines in 1957 began an investigation at its Experimental Coal Mine, Bruceton, Pa, In preparation for this work it was necessary to rehabilitate and reinforce an elliptical tunnel in the mine where studies had been made, many years ago, leading to development of a ventilation system used in the Holland Tunnels between New York and New Jersey, and in many other vehicular tunnels.

Jan 1, 1958

By Stanton L. Tainter

When the disruption of gold mining stopped the usual source of siliceous flux needed by copper smelters , sandstone copper deposits in northern Arizona offered possibilities as a source of the flux during the war emergency . The Federal Geological Survey , while making a comprehensive survey of sandstone copper deposits , investigated the Warm Springs mining district in northcentral Coconino County in August 1943. A month later , J. H. Hedges , chief of the Tucson Division , Mining Branch , Bureau of Mines , examined the operations in connection with an application for an access road . Both investigations concluded that the district , as an emergency source of copper-bearing siliceous flux , had considerable merit , provided high prices for copper continued in effect . Early in 1944 , V. M. Ryan and S. B. Atherley requested assistance from the Bureau in exploring various deposits on their property . The Bureau / drilled 152 holes , aggregating 3,756 feet , on the Petoskey and Mackin groups of claims . This report is based upon churn drilling done under contract from October 7 to November 25 , 1944 .

Feb 1, 1947

By Zsuzsanna Zborovszky

Study of the energy transfer from an inductive circuit to the discharge under the conditions of the minimum discharge voltage being smaller than the source voltage. Analysis of the effect of the electrode separation speed on the duration and maximum power amplitude of the discharge. Recommendation for optimal electrode setting. Experimental data on the variation of maximum discharge power required for ignition as a function of volumetric gas content for methane-air and propane-air mixtures. Experimental determination of the ignition limit for discharges derived from a 24, 15, 10 and 6v inductive-resistive circuit in 8.3% methane-air mixture by using the PTB breakflash with Cd disc and W wires, and also with Cu disc and BeCu wires. Method for calculating ignition limits for other source voltages.

Jan 1, 1978

By F. R. Lee

This publication lists permissible equipment approved by the Bureau of Mines during 1967 and 1968 (calendar years), except breathing apparatus and explosives. The purpose of this publication is to inform the public about approved equipment for use in underground mines.

Jan 1, 1970

By A. L. Engel

Simple treatment methods, employing the least possible equipment, can sometimes be established for marginal ores and economical results achieved. In continuation of a long-established part of the hydrometallurgical and ore-dressing program of the Reno Station of the Bureau of Mines, typical ores from newly discovered or recently explored mining districts have been investigated. The purpose of such investigations is to encourage the search for and development of mineral resources and particularly to assist in the economical exploitation of low-grade and marginal ores, as well as the conservation and recovery of values in products from former operations that were discarded because of past inability to treat them economically. Several of these investigations have been limited to preliminary tests of samples from prospecting operations, whereas some involved samples of old dumps or tailings piles. The test, work in these cases was not extensive enough to warrant publication as individual reports, but is of considerable interest inasmuch as it indicates the possibilities as well as the limitations of treating the respective materials; and because, inasmuch as the samples were representative of the districts from which they were obtained, this in-formation should be helpful in the future development of these districts. The present report is a compilation of results of brief preliminary tests on oxide ores only, which contained gold and silver and in some cases base metals. The methods of treatment used include gravity concentration, amalgamation, flotation, and cyanidation. For the most part, only standard laboratory procedures were employed. No attempts were made to develop new methods for the low-grade refractory ores in this group of samples if simple treatment was not successful, as the stage of development of the properties did not warrant extensive experimentation on the samples submitted.

Jan 1, 1951

By R. E. Peterson

Scrap iron is partially oxidized at elevated temperatures in the selective oxidation process to produce iron oxide and a dense residual metal of high purity. Investigation of the process was confined to converting automobile hulks into useful products. In one test series, compressed, sheared automobile scrap was processed at 1,000° C in a 36-foot-long rotary kiln at feed rates ranging from 300 to 1,200 lb/hr. Less fuel was required to maintain the temperature at the higher feed rates because of the heat generated from the burning of the combustibles and the oxidation of the iron. The bulk density of the residual metal exceeded 75 pounds per cubic foot. In an attempt to lower the quantity of contaminants in the residual metal, another test was designed using automobile hulks which had been prepared by ripping, a low-cost method of scrap fragmentation. Before oxidizing the ripped scrap approximately 62 percent of the total copper was removed in a tumbling, screening, magnetic separation and hand-sorting system. Cast iron made from the residual metal obtained by selective oxidation contained 0.15 percent copper; iron oxide scale obtained from the kiln averaged 0.13 percent copper. Pellets made from the scale demonstrated compressive strengths necessary for blast furnace reduction; lead and zinc were removed by volatilization when the induration was performed in a reducing atmosphere.

Jan 1, 1972

By N. A. Eilertsen

The Aroostook manganese-bearing deposits lie within a rectangle 30 miles wide and 70 miles long. Over 40 different deposits have been discovered in this area, but they have not been mined because the ores are difficult to treat. In 1949, the Maple Mountain area was selected for detailed investigation by the Bureau of Mines, because study by the State of Maine and the Federal Geological Survey indicated that it was the most promising in Aroostook County for developing a large tonnage of reserves. Investigation by the Bureau of Mines disclosed that all of the reported deposits of the central district were located on the limbs of a syncline underlying a pear-shaped area of 283 acres between the crests of Maple Mountain and Hovey Mountain. The ore area has been outlined by trenching and drilling along three sides of the perimeter, while the remaining side is defined by a fault. The area has a length of 6,300 feet and a maximum width of 3,100 feet. Diamond-drill holes have intersected the deposit as deep as 1,550 feet below surface, but additional deep drilling would be required to determine the intensity of folding or warping at depth. The Maple Mountain-Hovey Mountain deposit lies in the slates of Ordovician age and is classified into three zones, of which the upper, averaging about 57 feet thick, is designated manganiferous purple and red slate. The central zone, also averaging about 57 feet thick and containing the highest manganese content, is manganiferous, banded hematite. The lower zone is manganiferous, interbedded hematitic and green slate with an average width of about 33 feet. Manganese minerals occur with hematite in all three units. Trenching on the northwestern slope of Hovey Mountain uncovered other disconnected deposits of manganiferous rocks of earlier age than the ore of the syncline. The general strike of these deposits, which range from 15 feet to 75 feet in thickness, is southwest a length of 5,000 feet. They dip steeply southeast. The ore of the syncline is predominantly deep, hematitic red, inclining to red-dish black, fine-grained, dense, and thinly laminated. It is hard and siliceous. Hematite has, in places, been altered to magnetite. Because of the fine-grained texture of the ore, the manganese-mineral constituents are difficult to determine. Of the manganese silicates present, braunite is the most readily identified. Manganese carbonates and oxides are found also.

Jan 1, 1952

By Alan D. Hartman

Instabilities in electric steelmaking furnace arcs cause electrical and acoustical noise, reduce operating efficiency, increase refractory erosion, and increase electrode usage. The U.S. Bureau of Mines is investigating methods to stabilize these arcs. To perform experiments to test new hypotheses, Bureau researchers designed and instrumented an advanced, experimental single-phase furnace. This report describes this furnace, which was equipped with high-speed data acquisition capabilities for electrical, temperature, pressure, and flow-rate measurements; automated atmosphere control; ballistic calorimetry; and view ports for high-speed cinematography. Precise environmental control and accurate data acquisition allow the statistical design of experiments and assignment of rigorous confidence limits when potential furnace or procedural modifications are tested.

Jan 1, 2010