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By Dale William Avery

Thirty mines and prospects were studied; 22 are within the Dolus Lakes RARE II area. Three properties within the area and one adjacent to it were determined to have indicated or inferred gold, silver, or molybdenum resources (fig. 1 and table 1) associated with quartz veins and shear zones or quartz-pyrite stockworks in granodiorite. Five other properties in the area and three just outside have potential for the discovery of gold and silver resources. Minor amounts of very fine-grained placer gold are in glacial outwash in and near the area. The John G. Carlisle Mine (fig. 1, no. 9) produced 120 oz (3.7 kg) of gold between 1897-1899. The Independence Mine produced 481 oz (15 kg) gold, 197 oz (6.1 kg) silver, and 189 lb (86 kg) of copper between 1926 and 1935. These mines are adjacent to the study area's northern boundary.

Jan 1, 1983

By Edward L. McHugh

In 1986, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 5-acre Zwagg Island Wilderness Study Area (OR-12-14) in order to evaluate its identified mineral resources. The study area is located in Curry County, OR, immediately west of Brookings. There is no evidence of mining activity on or near Zwagg Island, and no mineral resources were identified. The steep-sided, flat-topped island is normally accessible from the mainland by way of a sandy beach. The island consists mainly of marine sandstone, mudstone, and conglomerate of the Jurassic Dothan Formation. Dothan Formation sandstone has been used locally as construction material. Rock along the coast has also been used for construction of jetties to improve harbor access; additional work has been proposed at the port of Brookings. Although suitable for other construction uses, stone from Zwagg Island would probably not meet physical requirements for jetty stone. Development of a stone resource on the island is unlikely.

Jan 1, 1987

By J. L. Hoffman, F. W. Wood, R. A. Beall, W. E. Anable

For melting and purifying reactive and refractory metals , two electronbeam furnaces have been constructed and operated on the principle of highpowered vacuum diodes . It was necessary to design the vacuum and electrical systems , mechanical features , and operating procedures to cope with dynamic conditions . Vacuums of 10-5 torr , tens of kilowatts of power at 5 to 10 kilovolts , and the evolution of impurities at thousands of liters per minute constitute a challenging combination . The furnaces have been used to melt either button specimens weighing several hundred grams or , by feeding material as a consumable electrode , small ingots weighing several kilograms . Hafnium is among the metals that can be purified . For example , hafnium starting material with Rhn 94B was softened to Rhn 70B after 2 hours of melting under a 25 - kw electron beam , and impurity levels were reduced as follows : Oxygen , from 700 to 350 ppm ; nitrogen , from 71 to 20 ppm ; hydrogen , from 6 to 1 ppm ; aluminum from 75 to < 20 ppm ; chromium , from 80 to < 10 ppm ; iron , from 100 to 40 ppm ; and silicon , from 40 to < 20 ppm .

Jan 1, 1963

By Robert M. Koerner

The feasibility of using small-scale models to simulate residential masonry foundation walls subject to fatigue loading was investigated. Five wall segments were modeled in one-quarter scale using dynamic similitude equations. The walls were dynamically loaded using a sinusoidal base motion and wall accelerations were monitored. The stiffness, natural frequency response, and damping characteristics were measured. The number of cycles of testing necessary to cause initial visible cracking was recorded. Analysis of the data indicated the importance of the relationship between the forcing function and the natural frequencies of the structure in influencing cracking damage.

Jan 1, 1980

By George A. Savanick

The objective of this research is to develop a method for measuring the tensile strength at the interface between minerals in rock. These measurements reflect the strength of the attractive forces operating at crystalline interfaces in rock. Since these forces act in opposition to the forces set up in various rock fragmentation processes, measuring their strength may help in designing more efficient methods of rock fragmentation. The method developed for measuring the strength of intergranular adhesion in rock involves separating a bicrystal from the rock and determining the tensile strength at its solid-solid interface. This technique has been successfully applied to the study of quartz-feldspar interfaces separated from massive pegmatites, graphic granite, and the Rockville granite, yielding average tensile strengths of 5.86, 8.62, and 10.65 meganewtons per meter squared (MN/m2) (850, 1,250, and 1,524 psi, respectively). The data this technique provides indicate that the members of these bicrystals are strongly adherent. Examirtation of bicrystals broken at the crystalline interfaces indicates that the bonds responsible for this adhesion operate over only a portion of the interfacial area. This work conclusively demonstrates that tensile strength tests can be conducted on small selected areas; for example, grain boundaries in rock. The small-scale zones of strength or weakness determined in this way can be related to the overall strength of the rock.

Jan 1, 1972

By H. C. Fuller

Rhodonite, a manganese silicate, occurs as an important component of extensive veins in the San Juan district of Colorado. Recent work by the Bureau of Mines has demonstrated that typical ores of the area can be upgraded to about 30-percent manganese content. Because of their siliceous nature, such concentrates require further processing to convert the manganese into more usable forms. The investigation described in this report demonstrates the technical feasibility of producing silicomanganese from a rhodonitic concentrate by electric smelting methods. The rhodonitic concentrate used in the smelting research was prepared by dry high-intensity magnetic separation of ore from the Silver Queen vein. The concentrate contained 29 percent manganese, 2 percent iron, and 41 percent silica. The principal minerals in the concentrate were 35 percent rhodonite, 30 percent rhodochrosite, and 25 percent quartz and chalcedony. Limestone was used as the flux and coal was used as the reductant. These minerals were crushed and screened to minus 1/2-inch plus la-mesh size.

Jan 1, 1962

By H. B. Carroll

The performance of commercially available portable instrumentation for detecting nitrogen dioxide, sulfur dioxide, and hydrogen sulfide was evaluated. Length-of-stain detector tubes from several manufacturers were included in the study. The instruments were evaluated in atmospheres with 50-and 80-percent relative humidities at 75° F and containing test gas concentrations of 0.1, 0.25, 0.50, 1.0, 1.5, and 2.0 times the threshold limit values. The results from the gas analyzers were correlated with the known contaminant concentration by calculating and plotting an estimated line of regression, confidence limits, and correlation coefficient for each detector system. An increase in the relative humidity from 50 to 80 percent at /5° F changed the instrument response to the contaminants. The uncertainties in detection precision reported are for the observer-instrument system. The main difference or inconsistency in toxic gas concentrations determined with length-of-stain tubes resulted from the observer&apos;s interpretation of the results rather than from a predominant difference in the tubes.

Jan 1, 1975

By W. K. Tolley

The Bureau of Mines is testing super critical fluids as solvents to selectively extract valuable components from complex matrices. Materials recovered during supercritical fluid extraction are often highly purified. Using laboratory apparatus designed specifically for supercritical fluid research, Bureau re-searchers have measured the solubility of titanium tetrachloride (TiCI4) in supercritical, liquid, and gaseous carbon dioxide (C02), CO2, a commonly used supercritical fluid, is inert, inexpensive, and nontoxic. Supercritical CO2 formed a single phase with TiCl4 at 45° C and 1,500 psig. When the solution was heated at constant pressure beyond 55° C, TiCl4 precipitated from the fluid. Results showed that TiCl4 solubility in supercritical CO2 is not controlled by the vapor pressure of the solute.

Jan 1, 1989

By Raymond W. Hiteshue, Sam Friedman, Martin D. Schlesinger

The Bureau of Mines in cooperation with the El Paso Natural Gas Co. investigated the effect of high temperature and pressure at short residence times on the hydrogenation of a New Mexico coal to gaseous and liquid hydrocarbons . The study was made in a bench - scale semicontinuous unit at pressures of 500 to 6,000 psig , 480 ° to 1,000 ° C , and residence times of less than 1 minute to 15 minutes . Ammonium heptamolybdate was impregnated on the coal to furnish 1 percent molybdenum based on maf coal . Coal could be rapidly hydrogenated at elevated temperatures and pressures to yield large quantities of gaseous hydrocarbons and small quantities of lowboiling oils , high in single - ring aromatics . At 800 ° C and 6,000 psig and a residence time of 1 minute , the yield of hydrocarbon gas was 43 percent and of liquid hydrocarbons 9 percent , based on maf coal . With a 15 - minute residence time , the yield of gaseous hydrocarbons increased to 68 percent with a decrease in yield of oil to 6 percent . At higher hydrogen velocities , the yields of oil were much greater but contained large quantities of asphaltene . Low concentrations of molybdenum (0.01 and 0.1 percent ) or a high concentration of iron ( 1 percent ) were ineffective at 800 ° C , 6,000 psig , and short residence time .

Jan 1, 1964

By Glen C. Ware

The Bureau of Mines determined the factors involved in the corrosion of starting sheets used in the production of electrolytic zinc with the ultimate purpose of adapting zinc starting sheets to commercial practice . Under present practice , zinc is electrodeposited on aluminum cathodes and subsequently stripped for melting . The use of zinc instead of aluminum would eliminate the need to strip the deposit , thereby reducing the cost of handling and melting it , but zinc has not been suitable because it was too vulnerable to the corrosive attack of the electrolyte . Serious attack was found to be limited to the areas of the cathodes situated immediately above the surface of the electrolyte and to re - entrant corners . It was possible to avoid solution - level corrosion by immersing the starting sheets completely , exposing only a relatively heavy suspension member to solution - level attack . Zinc starting sheets could be made as reliable as aluminum and could be continued in residence for periods up to 39 days . Periods as long as a week were feasible under conditions similar to those found in commercial practice . A test of zirconium as a starting - sheet material showed that it promoted corrosion of the deposit to a lesser extent than aluminum and that the deposit adhered less tenaciously . These two properties lend themselves to the development of ways to strip deposits mechanically from zirconium starting sheets . Titanium was unsuitable for use as a starting - sheet material .

Jan 1, 1963

By Jonathan Ludlow

This document is the final report of a study aimed at defining the relative contributions of various sources of respirable airborne dust on longwall faces. In order to define the contribution of various primary sources, continuous dust level data were recorded on five longwalls for an average of five shifts at each. By analysis of these data with records of face activity, it was possible to determine the overall contribution of each of the major elements of the longwall system to overall respirable dust exposure at various face locations. Average levels were determined for roof support generated dust, conveyor and intake dust and for dust levels during various shearer activities. When average levels are compared between mines, a significant degree of consistency is noted. The next phase of the study was aimed at differentiating the various dust sources associated with the shearer. To this end &apos;fly cuts&apos; varying from 6 in. to 30 in. were closely monitored as were dust levels at operators&apos; positions over the various segments of longwall cycle. These data indicated that the clearance ring of the shearer drum as a disproportionately heavy contributor to shearer dust make. A statistical analysis of the effect of shearer haulage speed on dust make revealed that high haulage speeds are associated with low specific dust make.

Jan 1, 1983

By Eric E. Cather

A mineral survey of a portion of the Lake Eleanor RARE II area (No. 5807), Trinity County, California, was done by the U.S. Bureau of Mines and U.S. Geological Survey (USGS). Approximately 8,650 acres (3,500 ha) of the Lake Eleanor RARE II area not examined for this report had been previously investigated by U.S. Bureau of Mines and U.S. Geological Survey personnel and published as part of USGS Bulletin 1371-B, (Hotz, 1972) Mineral Resources of the Salmon-Trinity Alps Primitive Area, California. The report showed that the section included in the rake Eleanor RARE II area contained no metallic mineral resources. Geochemical sampling indicated that the Lake Eleanor RARE II area contains no potentially important mineral resources. About 4,650 acres (1,880 ha) of the eastern part of Lake Eleanor RARE II area were examined for this report. The Bureau of Mines was responsible for detailed examination and sampling of mines, prospects, and mineralized zones; the Geological Survey conducted geological, geochemical, and geophysical studies of the area. This area is underlain mainly by granitic rock and serpentinite.

Jan 1, 1981

This document is Volume II of a two-volume report on underground and surface coal mine fires occurring between 1950 and 1977. Volume I discusses the methods of data acquisition, data analysis procedures, results and conclusions. This volume contains (1) a master list of all fire incidents obtained from MSHA reports, (2) an annotated bibliography of all MSHA reports, journal articles on selected incidents, and non-reportable fires (appendix), and (3) indexes to be used in accessing incidents in the master list and annotated bibliography. These three types of information provide the reader with a complete summary of coal mine fires during the period from 1950 through 1977 and a convenient means to locate incidents of specific interest. The body of this volume is organized around two tables and a series of indexes. The two tables are master lists of underground and surface fire incidents. They are followed by 14 indexes keyed to the master list and annotated bibliography. The appendix contains three different parts: o The annotated bibliography of MSHA fire reports (one section each for underground and surface mine fires) o The annotated bibliography of journal articles about selected fires from the MSHA bibliography o A listing of non-reportable fires (one section each for underground and surface mine fires) Descriptions of the contents and use of each of the three major components of this volume (i.e., master list, indexes, and appendix) are presented in Section 2.0.

Jan 1, 1979

By J. W. Town

This report summarizes the results of laboratory investigations made by the Bureau c! Mines on the recovery of mercury from caustic sulfide solutions by aluminum precipitation and by electrodeposition. Statistical methods were used to design the experiments and evaluate the resulting data. Precipitation studies demonstrated tint metallic mercury could be recovered from mercury sulfide-sodium sulfide solutions with aluminum. Other metals and their salts and aluminum, salts precipitated only black mercury sulfide. Over 95 percent of the mercury was precipitated from solutions prepared with reagent-grade chemicals and from cinnabar leach solutions. Two equivalents of aluminum were required to obtain 95 percent precipitation of the mercury. Under optimum conditions 1 gram of aluminum precipitated from 4 to 7 grams of mercury; the excess Aluminum was recovered for reuse. The effects of time and temperature on the precipitation of mercury were minor when compared with the effects of mercury concentration and aluminum equivalents. The particle size of aluminum had no significant effect over the ranges studied. When aluminum was used as a precipitant, the mercury concentration in solution was reduced to below 1.0 grams per liter. Adding arsenic and antimony sulfides to the mercury solution resulted in their coprecipitation with the mercury when the aluminum was added From 95 to 99 percent of both the arsenic and antimony were precipitated as metal, which amalgamated with the mercury.

Jan 1, 1962

By E. A. Holbrook

The data in this bulletin were obtained during an investigation of screening practice by the University of Illinois engineering experiment station and the United States Bureau of Mines under a cooperative agreement between them and the State of Illinois Geological Survey Division. Earlier work on this subject includes a study of the general practice of coal preparation in Illinois, made in 1914 and published in 1916,1 and an investigation of Illinois coal-washing methods, results of which were published in 1912 in a bulletin 2 that contained complete information on the methods then in use for sizing washed coal. OBJECTS OF THE INVESTIGATION The present investigation was limited to a study of screening as applied in preparing mineral products with the expectation of obtaining more comprehensive information on screening machinery.

Jan 1, 1925

By Paul R. Thomas

The Bureau of Mines evaluated the impact of the depletion allowance upon the economic availability of copper from domestic deposits. The potential long-run percentage depletion deduction, cumulated over the life of the properties, was estimated at approximately $2.5 billion for producing properties and up to $11.7 billion for nonproducers. The income transfer, in the form of higher Federal income tax payments if the allowance were repealed, was estimated at $1.5 billion for producing properties and up to $8 billion for nonproducers. The percentage depletion allowance, through its role in determining Federal income tax liability, was found to be very significant in affecting profitability. Repeal of the allowance could result in major domestic copper availability reductions at all price levels, now and in the future, as a result of reduced profit margins for current producers, and postponement of development decisions for nonproducers. It was demonstrated that a 50-percent reduction in the percentage depletion rate applicable to copper would also result in a significant decrease in profitability for nonproducing properties. For producing properties, the percentage depletion rate on copper was shown to be less significant than the income limitation that is placed upon the total amount of the depletion deduction. Repeal of the minimum Federal tax provision was shown to be significant in enhancing profitability for both producing and nonproducing deposits. The report concludes that the percentage depletion allowance operates as an important method of capital recovery and production incentive.

Jan 1, 1982

By Daniel Ng

The U.S. Bureau of Mines-Michigan Technological University mine ventilation mainframe program was successfully adapted for execution in a personal computer (PC). The hardware requirement can be as modest as 256 kilobytes (33) of random access memory (RM) and two floppy disk drives. A version compiled for a PC possessing 512 Kb RAM has arrays dimensioned to accommodate 512 separate mine airways and junctions, and it contains all the features and capabilities of the original version. It has successfully analyzed all the ventilation networks tested, including a very large commercial mine (404 airways, 237 junctions, and 5 fans). In all cases the PC version produced practically identical results as obtained from the mainframe computer. In all respects, the PC version performed the same as the mainframe version with the exception of execution speed When a numerical coprocessor is employed, execution time can be reduced by more than 50%.

Jan 1, 1989

By Sheridan J. Rodgers

Toxic fumes generated during shot firing were measured in a phosphate rock mine and a copper mine. Fumes generated during firing of explosives in the Bureau of Mines 1350 ft3 test chamber were measured also. The release of fumes from water gels, ammonium-nitrate oil mixtures and nitroglycerin based explosives was studied. Direct reading instruments were used to monitor the fume concentrations. The amount of CO produced per unit weight of nitroglycerin explosives (0.41 ft3/200 grams) was higher than that produced by ammoniumnitrate-oil mixtures (0.24 ft3/200 grams) and water gels (0.16 ft3/200 grams). The amount of NOx produced by nitroglycerin based explosives was also higher than the amount produced by water gels or ammonium nitrate-oil mixtures.

Jan 1, 1976

In attempting the predict coal cleat orientation in the subsurface for effective methane degasification of the coal beds in the Warrior coal field of Alabama, approximately 150 rock joint orientations and 45 coal cleat orientations were measured in each of 37 7 ½ minute quadrangles in Tuscaloosa, Walker, Jefferson, Fayette, Winston, Blount, and Bibb Counties. Data from these surface locations, and coal cleat data from eight underground mines was corrected for magnetic declination and titled beds rotated to the horizontal where necessary and plotted on rose diagrams for comparative analysis. Data collected on each joint and cleat consisted of attitude, quality, type, spacing, persistence, lithology, bedding thickness, surface texture, and filling. File data and published and unpublished reports from the State Survey and the State Mine Inspector&apos;s Office were re-viewed. Twenty-seven mining companies, most of which supplied information pertinant to the project were also contacted. The information obtained consisted of crop line information structure, and underground mine outlines, all of which were put on 7 ½ -minute topographic quadrangles. LANDSAT-1 imagery and Skylab photography were compared to dominant joint and cleat trends in the study area. Detailed results can be found in an open-file report entitled "Fracture Analyses in a Selected Area of the Warrior Coal Field, Alabama." A master&apos;s thesis entitled "The Relationship Between Surface Joints and Subsurface Structure in a Selected Area of the Warrior Coal Field" is being prepared to illustrate the relation-ship of the fracture system to the structure in the Warrior coal field. A proposal has been submitted for research on a project entitled "Rock Fracture Systems and Their Affects on the Extraction of Fossil Fuels in the Warrior Basin, Alabama"

Jan 1, 1976

By J. D. Davis

THE carbonizing properties of one medium- and and five low-volatile coals from West Virginia and one high-volatile A and two medium-volatile coals from Pennsylvania were determined by 800° and 900° C. BM-AGA carbonization tests and expansion tests in the sole-heated oven. Plastic properties of the coals and the yields and quality of their cokes and other carbonization products were determined. The low-volatile coals comprised a mine and a coke-plant sample of Pocahontas No. 6-bed coal from the. Black Eagle No. 1 mine, Wyoming County, W. Va.; a mine sample of Pocahontas No. 6 bed from the Louisville mine, Mercer County, W. Va. ; Davy Sewell bed was sampled at the Twin Branch mine, McDowell County, W. Va.; and Fire Creek bed was sampled at the Dunedin No. 1 mine, Raleigh County, W. Va. The medium-volatile coals were from the Fire Creek bed, Laurel Creek mine, Greenbrier County, W. Va.; Lower Kittanning bed, Springfield No. 4 mine, Cambria County, Pa.; and Upper Kittanning bed, Springfield No. 6 mine, Clearfield County, Pa. The high-volatile A coal represented the Upper and Lower Freeport beds, Kent Nos. 1 and 2 mines, Indiana County, Pa. In addition to the coals listed, high-volatile A coal from the Pittsburgh bed, Warden mine, Allegheny County, Pa., a standard blending coal, was used in blends in this investigation.

Jan 1, 1950