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By C. C. Knox

In Kiowa County, Okla., extensive deposits of clay are closely associated with pre-Cambrian anorthosites and gabbros. Investigation by the Bureau of Mines, including 1,723 feet of auger drilling, has shown the presence of very large quantities of clay containing between 20 and 25 percent alumina. All of the material contains large amounts of impurities, and even the best clays, selected for their relatively low content of iron, titanium, and magnesium, are unsuitable for the production of alumina by the sulfuric-acid process The soda-lime process gave somewhat better results, the product being nearer specification for commercial alumina. The clays are not amenable to beneficiation by simple sedimentation processes, and the alumina content could not easily be increased to produce material suitable for any alumina process.

Jan 1, 1948

By C. C. Popoff

The development of glass-making industries in the Pacific Northwest as well as other industries that use pure silica has been retarded by lack of local supplies of low-cost raw material. Several quartz deposits along the Skagit River constitute the only known source of relatively pure silica within the range of cheap transportation to the Seattle industrial area. Although some silica has been mined from these deposits, very little information regarding their size, grade, and other physical characteristics has been available to the general public. As a part of its program of investigation of the mineral resources of the Pacific Northwest, the Bureau of Mines assigned the writer to examine the Skagit River silica deposits in October 1946. This report presents the factual data obtained from an examination of the so-called Stoner, Bacon Creek, and Pressentin deposits. These deposits are the largest and most easily accessible known to exist in the area. The deposits are near Marblemount, which is on State Highway 17A. They are within 1 mile to 1-1/2 miles of the Skagit. River Railway, which provides transportation to Seattle, a distance of 130 miles. None of the deposits has been developed thoroughly. The Stoner deposit, however, has been developed by a quarry about, 5,0 feet square and has been exposed by hydraulic removal of the overburden throughout a distance of 180 feet along the hanging wall of the vein

Jan 1, 1949

By K. K. Kelley, W. W. Weller

This report contains experimentally determined heat capacity data for four crystalline sulfides -- AsS , GeS , NiS , and Ni3 S₂ -- over the temperature range from 50 ° to 298.15 ° K. The heat capacity data were used to evaluate the entropies of the sulfides at 298.15 ° K. Entropies of formation from the metals and rhombic sulfur and from the metals and diatomic sulfur gas are also included .

Jan 1, 1964

By R. L. Grant

Study of the ignition of firedamp by explosives and the phenomena that underlie it is one of the long-term investigations of the Bureau of Mines. This report is the third in e series by the Explosives Branch summarizing the progress made at Bruceton in this study. The first paper described preliminary work on small, carefully controlled cannon shots the second discussed the results of suspended shots.5/ In this paper, experiments are described and interpreted that extend and support the concept of ignition presented previously. ACKNOWLEDGMENT The authors wish to thank Bernard Lewis, former chief, Explosives and Physical Sciences Division, and Guenther von Elbe, former chief, Physical Sciences Branch, Explosives and Physical Sciences Division, for their guidance and constructive interest.

Jan 1, 1954

By John W. Taber

Discovery of these unusual fluorite deposits was brought to the attention of the Bureau of Mines late in 1951, shortly after the first locations were made. A brief investigation of the deposits by the Bureau revealed seven principal outcrops of fluorite in two areas. The smallest outcrop continuously exposes massive fluorite over an area 25 by 55 feet; the largest outcrop is a similar exposure 180 by 240 feet. The deposits appear to be sharp-walled, low-angle-, tabular ore bodies in granite and are at least 10 feet thick. The Bureau investigation of the deposits included bulldozer strip-trenching, drilling and blasting rock cuts, and channel sampling across three of the largest outcrops. This sampling indicated an average grade of 97.2 percent CaF2 and 1.44 percent SiO2. Preliminary metallurgical tests on the ore indicate that it can be concentrated to acid-grade specifications by simple gravity methods. One laboratory test recovered 78.4 percent of the fluorite in a product containing 98.7 percent CaF2, 0.25 percent SiO2, and 0.10 percent Fe2O3.

Jan 1, 1952

By Jon I. Voltz

The U.S. Bureau of Mines has conducted fundamental coal fragmentation studies to evaluate the effects of impact energy and direction of bedding planes on dust generation, size distribution, and impact-output energy relationships. Product size distributions were obtained for the fragmented samples by screening to minus 150 mesh. The minus lS0-mesh fines were analyzed with a light scattering photometer with a measurement range of 176 to 1.9 /.tm. Increased input energy produced a significant increase in the weight of plus 3/8-in material for impact perpendicular to the bedding planes. No significant trend was observed for parallel impact. Impact direction had little influence on dust size distribution, and input versus output energy relationships. As expected, total airborne dust measured at time of impact and percent particulates below 11 /.tm in size generally increased with increased input energy for both directions of impact. Energy used for sample fragmentation increased with increased energy input.

Jan 1, 1989

By Elger. G. W.

The Bureau of Mines investigated preheating of continuously fed, fragmented ferrous scrap charges by furnace offgases and utilizing substitutes for imported fluorspar to condition electric steelmaking slags. Three types of continuous scrap charging procedures were investigated to determine electrical energy consumption in a I-st (short ton) electric arc furnace. Cold and preheated scrap charges were continuously fed at rates averaging 37.5 and 43.7lb/min, respectively. The feed rate varied appreciably from test to test owing to hangup of the scrap in the charge bin. Approximately 7 pct less electrical energy was consumed in melting scrap preheated to 8400 to 1,1100 F by furnace off-gases than in melting cold scrap. Overall energy consumptions were 888 kW'h/st for cold scrap, 829 kW'h/st for preheated scrap" and 637 kW'h/st for conventional backcharged scrap. Stack gases from scrap preheating averaged 1200 F and a flow rate of 1,615 scfm compared with 2200 F and 1,302 sefm for cold-charged scrap. Slag conditioners tested included synthetic fluorspar, boric acid, hydroboracite, used aluminum potlining wastes and aluminum anode tailing wastes, and Sorelflux B. The boron-containing conditioners fluidized the slags the best, followed in order by the conditioners containing fluorine and titanium.

Jan 1, 1987

By R. S. Norman

The objective of this program was to select approximately 100 acoustic materials for flammability evaluation. Noise control programs have been initiated on several types of mining equipment and vehicles which can be used in underground coal mines. Often, the materials which are used in these noise reduction programs have not been tested for flammability properties according to the same reference standard. During this program a variety of materials were selected for measurement according to ASTM E-162 procedures. A radiant heat energy source was used to measure flammability properties of 15.2 x 45.7 cm. samples. In the absorptive materials category, 45 percent of the materials tested had a flame spread index of less than 25. For barrier, damping, and isolation materials the corresponding values were 40, 43, and 9 percent.

Jan 1, 1979

By David P. Conover

The U.S. Bureau of Mines (USBM) has developed a computer-assisted Ground Control Management System (GCMS) for near realtime evaluation of underground coal mine ground conditions. The GCMS combines existing mine-monitoring system and sensor technology with automated computer analysis techniques to enhance the acquisition, analysis, and display of geostructural data. The GCMS, which combines mine structure data with other information, such as geologic conditions and mine layout, has provided information on mining-induced stress transfer and pressure buildup associated with several ground control events. The GCMS collects and analyzes shield-leg pressure, ground pressure, and strata movement data to evaluate the structural behavior of an active Western U.S. Iongwall coal mine. Field data are transmitted over a dedicated phone line to the USBM Denver Research Center (DRC) mine monitoring laboratory, 240 km (150 miles) from the mine site. Real-time collection, processing, and analysis of mine structure and shield pressure information has proved to be an effective method for near-face ground conditions while mining progresses. The GCMS provides the mine operator with information to rapidly identify and manage potentially hazardous ground conditions while mining is in progress.

Jan 1, 1994

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Jan 1, 2011

By Suresh K. Bhatt

A mathematically simulated modeling technique is used in this U.S. Bureau of Mines report to represent a hypothetical mining operation with existing mining technology and prevalent mining costs. Mining scenarios were prepared and evaluated for potential benefits and costs available through computer-assisted mining. Base criteria, parameters, and methodology are described.

Jan 1, 1993

By Robert Roby

The Mouat copper-nickel deposit in Stillwater County, south-central Montana, was examined by Paul T. Allsman, an engineer of the Bureau of Mines, in 1939. Because of the strategic importance of nickel, a project was executed by John East, Jr., J. J. Naughton, and E. W. Newman, engineers of the Bureau, to further delimit some of the copper-nickel sulfide-bearing bodies that had been discovered by the Anaconda Copper Mining. Co. in 1937 and to investigate the central part of the deposit, which had not been drilled previously. This report is based largely upon the results of the. Bureau of Mines investigation and the results of exploration by the Anaconda Copper Mining Co. In addition, a brief description is given of some other copper-nickel sulfide-bearing deposits along tho Stillwater Complex.

Jan 1, 1949

Objective To identify techniques to reduce the probability of gob gas explosions. Background In the last 6 years, seven explosions of methane and/or coal dust occurred within worked-out, sealed areas (gobs) of underground U.S. coal mines. These explosions, believed to have been started by lightning, destroyed many mine seals and caused much damage external to the sealed area. Three of these gob gas explosions occurred in one mine in Alabama over a 3-year period. Fortunately, the explosion forces and the toxic gases that vented from the sealed gob area did not cause fatalities or injuries, but they destroyed several large seals. If miners had been inspecting or working near these areas, the potential for serious injury and/or death would have been high. The United Mine Workers of America and the Mine Safety and Health Administration (MSHA) requested that the National Institute for Occupational Safety and Health (NIOSH) help identify the mechanisms for lightning penetration into the gob and recommend ways to reduce the probability of occurrence of future explosions from such lightning penetrations into sealed areas of underground coal mines. Because three of the explosions occurred in a single mine, special attention was focused on these particular explosions. The first occurred in April 1994 in a sealed area, which enclosed about 1.35square miles of abandoned workings (gob). This explosion destroyed 3 of the 38 seals that surrounded the gob. These seals were less than 2,000 ft away from three 4.5-in-diam steel-cased test wells that extended from the surface into the mine entry. At the time of the explosion, the National Lightning Detection Network (NLDN)verified 12 lightning strikes within 10 miles of the mine, including several above the gob. After the 1994 explosion, the damaged seals were rebuilt using an acceptable seal design capable of with standing a 20-psi explosion, as required by 30 CFR 75.335. On January 26,1996, a second gob explosion destroyed five more cementitious pumpable seals less than 2,000 ft away from those destroyed in 1994and even closer to the steel-cased wells. The NLDN verified72 lightning strikes in the area of this second gob explosion. Compressive strength analyses of fragments from the destroyed seals showed that strengths ranged from 11 to 138 psi, with an average of83 psi. This is over 100 psi below the minimum 200-psi compressive strength requirement for cementitious pumpable seals. These seals were again replaced. On July 9, 1997, the third and most violent explosion occurred in the same vicinity of the last two explosions. Three more cementitious pumpable seals were destroyed, including one newer seal that exceeded the minimum 200-psi compressive strength requirement. The NLDN verified 695 lightning strikes above the mine during the time in which the explosion occurred. MSHA's

May 1, 2001

By Frank E. Cash

"INTRODUCTION The iron—ore ranges in the Lake Superior district are the Marquette in Michigan, Menominee and Gogebic in Michigan and Wisconsin, and the Cuyuna, Mesabi, and Vermilion in Minnesota. These ranges produce about 85 percent of the iron ore mined in the United States. Accident experience in connection with this production is better than that of the regions producing the remaining 15 percent. Production and shipments vary slightly from year to year but closely approximate each other over a period of years.This information circular supplements, continues, and combines the data in Information Circular 7321,2/ including figures of 1944 and 1945.During the 6—year period 1940 to 1945, inclusive, 481,485,475 long tons of iron ore was shipped from the Lake Superior district. 4/ Michigan and Wisconsin shipped 93,787,648 tons, or 19,5 percent of the total, and employed annually an average of approximately 14,300 men; Minnesota shipped 387,697,827 tons, or 80,5 percent, and employed annually an average of approximately 9,300 men. The tons produced per man employed is much greater in Minnesota than in Michigan and Wisconsin, owing to the large open-cut production in Minnesota."

Jul 1, 1947

By R. P. Vinson

The Bureau of Mines examined the effects of high humidity and water droplets on the GCA Corp. real-time aerosol monitor (RAM--l). which uses a lO4mm cyclone preseparator. Tests were conducted both in a laboratory and in a full-scale model mine entry. The laboratory tests were conducted in a test chamber saturated with moisture and water droplets. Under these extreme conditions. the RAM-I responded by indicating dust concentrations of 1-1/2 to 2 mg/m3? although the air was dust free. Within the first 2 h of each test. water accumulated in the cyclone and affected the cyclone particle separation characteristics. resulting in readings of 3 to 4 mg/m3. In addition. condensation formed inside the RAM-I case and affected the liquid crystal display (LCD). However. the full-scale mine entry tests revealed that the RAM-I can function ac-ceptably in an atmosphere of water vapor and water droplets similar to the most severe conditions found in an underground mine.

Jan 1, 1984

By H. B. Salisbury

As a part of a research program designed to help minimize national requirements for new mineral commodities by maximizing recovery of metals from domestic secondary resources, the Bureau of Mines investigated the development of economic methods for recovering copper and associated metals from complex electronic scrap. Three types were selected for research: (1) multiple-pin plugs and connectors, (2) obsolete aircraft radio assemblies, and (3) the magnetic fraction of shredded electronic scrap furnished by the Bureau's Avondale Research Center. The plugs and connectors, after incineration to remove plastic components and melting, yielded a brittle ingot, as did the internal portion of the radio assemblies. The brittle ingots were ground to minus 35-mesh for processing, and the magnetic material was used in the as-received condition. A process using pretreated or raw scrap as a copper precipitant in various concentrations of acidulated copper sulfate solution was developed as a means of effecting an initial separation and upgrading in the form of high-grade cement copper containing all or most of the precious metals.

Jan 1, 1981

By M. Clair Smith

The Sweetwater, Castro, Trinidad, New London, and Hilltop chromite properties are situated within an area 8 miles long and 1 mile wide between San Luis Obispo city and Morro Creek, San Luis Obiso County, Calif. Development work at this group of mines was a part of a long-range project by the Bureau of Mines to develop strategic mineral reserves in the United States in accordance with the Strategic Minerals Act of 1939. The junior author of this report participated in the preliminary examinations made in 1941 of the chromite deposits that later in the same year were the subject of more intensive investigation under the immediate supervision of the senior author. The ore occurs in lenses and kidneys in masses of dunite contained in large poridetite areas. Production has boon in the form of lump ore and concentrates from disseminated ore. Work by the Bureau of Miner included surveying, mapping, trenching, sampling, and assaying. It is summarized separately in the text under the name of each mine investigated. The report gives a brief history of the district, describer the concentrating plant of the Castro Associates, and gives detailed results on sampling and assays at the various proportion.

Jan 1, 1951

By J. W. Miller

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and from the data developed, to determine: (a) Which coals either as mined or after beneficiation by conventional preparation are suitable chemically under present standards for producing metallurgical coke. (b) Which coals require special and more intensive treatment in preparation than is now practiced. (c) Which coals cannot be considered potential sources of metallurgical coke regardless of preparation. This report is one in a county series that describes the preparation characteristics of the coals of Mingo County, W. Va.

Jan 1, 1956

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 Raymond L. Carpenter

The thermal conductivity, electrical resistivity, and Seebeck coefficient for nine compounds, based on the formula for enargite Cu3AsS3, were measured in a search for efficient materials to be used in thermoelectric generators or refrigerators. Results indicate that one of these compounds, Cu3SbSe4, has thermoelectric properties approaching those of bismuth telluride. An investigation of the effect of adding small quantities of tellurium to Cu3SbSe4 and Cu3SbS4 in order to improve their properties also was made. A figure of merit of 2.1 x 10-4 °C-1 was obtained for Cu3SbSe4 + 0.1 percent tellurium.

Jan 1, 1963