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A mineral survey of the Rough Hills WSA (Wilderness Study Area) in northeastern Nevada was done by the U.S. Bureau of Mines in 1985 at the request of the Bureau of Land Management. The WSA is comprised of 6,685 acres of mountainous, desert lands within the Elko District of the Bureau of Land Management. The survey entailed investigations of prospects or mineral occurrences to provide information on possible resources within the WSA. No mineral resources were identified in the WSA. The only historical mining activity was for placer gold at the Prunty prospect at the confluence of Copper Creek and the Bruneau River. Total gravel at the prospect is about 6,500 cubic yards; however, the survey showed significant gold values (greater than $0.10 gold per cubic yard) only in the southwestern portion. There, however, the gravel averaged less than $1.00 gold per cubic yard, and only about 3,000 cubic yards are present, a grade and yardage insufficient to be of commercial interest. The occurrence, however, may have value for recreational mining by hobbyists.

Jan 1, 1986

By Zsuzsanna Zborovszky

A circuit is considered intrinsically safe when any spark or thermal effect produced normally (that is, by operating the equipment in its correct operational manner to fulfill its purpose) or accidentally (caused by short circuit, earth fault, defective components, breaking the wiring, etc.) is incapable under prescribed test conditions of causing ignition of a prescribed gas mixture. The test conditions and gas mixture should be at least as hazardous as the true parameters of the environment where the circuit will be operated. According to present practices, the question of whether or not a circuit is intrinsically safe is decided upon experimentally. The circuit is inspected first for mechanical soundness and a survey is made to determine what faults should be considered as probable. Then the individual branches are connected, in sequence, to a test apparatus called 'breakflash" which acts as an opening, closing contact and thus draws sparks from the circuit. This test is repeated a given number of times in the presence of the prescribed gas mixture under specified conditions (electrode configurations, gas parameters, etc.). The equipment will be regarded as intrinsically safe if during testing no ignition has occurred.

Jan 1, 1972

By Aarne Visnapuu

Dissociation and vaporization of gold chlorides and bromides were investigated by a static pressure method and by Knudsen cell mass spectrometer. Two distinct chlorine and three distinct bromine pressure-temperature relation-ships were observed for the respective salts. The chlorine pressures are attributed to the dissociation of Au2Cl6 and Au2C12, and the bromine pressures to the dissociation of Au2Br6, Au2Br4, and AU2Br2, These pressure-temperature relationships were used to calculate dissociation pressure equations, enthalpies, and entropies of dissociation for each salt. Mass analysis of the vapors over AU2Cls between 83° and 152° C confirmed the existence of gaseous AU2C16. Ionization potential of this molecule is 11.0±0.1 ev and enthalpy of vaporization is 28.l±2.0 kcal/mole. Mass analysis of the vapors over the gold bromides detected only Bra in the temperature range 15°-150° C.

Jan 1, 1971

By H. F. Feldmann

This work was done to provide thermodynamic, electrical, physical, and compositional data on the seeded combustion plasmas of seven coals for the design of MHD generators. The systems were assumed to be at equilibrium, and the design data were generated by solving for the composition of both gas and liquid phases with a digital computer. The coals reported in this study include a western subbituminous, a Pennsylvania anthracite, and five representative bituminous coals. The data include dewpoint temperatures of both slag and seed. A Mollier diagram for each coal is given to allow graphical generator calculations.

Jan 1, 1970

By W. W. Adams

With greater production of coal per man-hour of work than ever before achieved, the coal-mining industry of the United States established a better safety record in 1941 than in any year since 1930, the earliest for which complete reports of nonfatal as well as fatal injuries were collected by the Bureau of Mines, United States Department of the Interior. In only one year (1933) of the 12-year period 1930-41 was the fatal-accident rate better than in 1941, whereas the rate for nonfatal accidents was better in 1941 than in any previous year. Accident and employment reports received from mine operators, together with fatal-accident reports received monthly from State mining departments and inspectors, showed that 546,692 men were employed in and about the coal mines of the United States during the calendar year 1941. This number does not include office employees or coke-oven workers. The increase of 1.3,426 over the number of employees in 1940 was accompanied by a gain in man-hours of work performed at the mines and an increase in average number of hours worked per man during the year.

Jan 1, 1944

Late in 1974 at a meeting with the Cedar Coal Company in Chelyan, West Virginia, a very definite requirement for an automatic heat sensing fire suppression system for the type coal augers used in their mine was revealed. Several fires had been experienced, and while equipment loss was a consideration, operator safety was also a concern. As of that date no one had developed an automatic system specifically for fire suppression on coal augers. II. EQUIPMENT DEVELOPMENT As a result of the above meeting, an unsolicited proposal was made to the Bureau on March 1, 1975, and a contract was issued to provide the following services: A. Determine and define fire hazard problem on Compton Coal Auger. B. Modify or otherwise mike a Lease "AFEX" system suitable for protecting the fire hazard area developed in paragraph "A". C. Make installation of "AFEX" system. D. Monitor installation for reliability for a period of 90 days after installation. C. ConJurt a simulated fire test to determine effectiveness on system.

Jan 1, 1975

By Robert L. Lagace

This final report documents the work done by Arthur D. Little, Inc. (ADL) on behalf of the U.S. Bureau of Mines, Pittsburgh Mining and Safety Research Center (PMSRC), on Contract R0122026 (which began in August of 1971). Under this contract ADI provided technical assistance to the Bureau on a task basis on virtually all aspects of the Bureau's programs related to present and planned emergency and operational communications and miner location systems for underground coal mines. The work consisted of independent investigations, analyses, experiments, breadboard and prototype hardware development, workshops and technology transfer seminars on mine communications, and on-going evaluations and guidance related to the Bureau's contracted programs on electromagnetic noise, mine communications systems, and trapped miner location. This final report documents the work in two volumes, Volume I, "Emergency and Operational Mine Communications," and Volume II, "Seismic Detection and Location of Isolated Miners." The Tables of Contents of both Volumes are included in each Volume. Phase I of the contract was devoted to performing an in-depth assessment of electromagnetic noise measurements taken by several contractors and other investigators, and then defining a new noise measurement program and instrumentation system tailored to obtain the necessary but missing noise data. These data are required for use in the design of new emergency and operational communication systems. This work, and the follow-on coordination and guidance activities of ADL on this noise measurement program in subsequent phases of the contract, are treated in Part One of Volume I.

Jan 1, 1974

By Virgil Miller, R. G. Knickerbacken

"INTRODUCTION The Bureau of Mines work reported by the Metallurgical Division 4/ in 1934 shows the possibility of producing artificial manganese ore by pre- ferential oxidation of manganese from spiegeleisen produced from manganiferous iron ores of the Cuyuna range, Minnesota. A three-step process is described as being capable of producing a ferrograde ore from this type of low-grade, domestic, strategic material. However, the melting temperature in the last step of the process that forms the manganese product is high, and the phosphorus content is not easily controlled. Also, the tenor of the manganese in the product is not comparable with other methods that use less process energy.Lofquist 5/ patented an improvement of the above three-step smelting method, in which sulfide was added to lower the melting point of the product.More recently, reputedly successful attempts have been made to reduce iron preferentially from manganiferous iron ores, simultaneously removing the phosphorus with the iron, by means of an unusually high temperature blast and excess coke.Anson G. Betts 6/ patented a process for the matte-smelting of manganese ores, in which the ore was mixed with pyrite and enough carbon or coke to serve as thermal energy and reducing, agent in a manner similar to the standard blast-furnace process. This process was intended to give pig iron, a manganese-iron matte, and a waste slag. Wood, Barrett, and Porath 7/ presented data on the treatment of low-grade, domestic, manganiferous iron ores and low-grade, domestic manganese ores by this Betts mattes pelting process."

Aug 1, 1942

By J. D. Warne

The ferberite district of Boulder County, Colo., has been an important producer of tungsten since 1900. During World War I, high prices for tungston concontrates resulted in a brief period of intense activity, and the production in 1917 was 2,707 tons of 60 percent W03 concentrates. Production declined thereafter, and in 19.2 the tungsten produced in Boulder County represented about 4 percent of the Nation's output, being exceeded only by the scheelite production in California, Nevada, and Idaho. Boulder County has boon an important source: of tungsten in the Korean emergency; the present report does not describe this recent activity, as it will be covered by a future publication. Tungsten occurs in small ore shoots of narrow and irregular veins. Most of the ore shoots have been found outcropping on the surface. Core drilling; has been used by the larger operators to explore for new veins and to locate extensions of known veins.

Jan 1, 1953

By P. M. Sullivan

The principles and application of amalgam electrolysis to the recovery of zinc and tin from secondary products were studied; this Bureau of Mines project was one phase of investigating the development of more efficient methods for processing iron-bearing zinc and tin to produce both base metals of high purity. Zinc of 99-99-percent purity was recovered from galvanizer's dross with recovery efficiency of 98 percent. Tin of 99.9-to 99.99-percent purity was recovered from hardhead with recovery efficiency of 81 percent. Both materials were treated by the same method in separate systems. Mercury was used to leach zinc from dross and tin from hardhead to form amalgams of each metal, both of which were subsequently refined electrolytically to produce high-purity metal. Impurities that were contained in both secondary products behaved as theoretically predicted; impurities that were insoluble in mercury remained as sludge in the leaching column. Except for lead, the readily amalgamated impurities were prevented from fouling the electrolyte by the blocking action of the amalgam electrode. Lead impurity in the tin-refining system dissolved and immediately precipitated as the sulfate. The primary advantage of the amalgam refining method lies in direct recovery of the extremely pure base metal from highly contaminated secondary material.

Jan 1, 1961

By Charles B. Carpenter

For many years, studies of ground movement and subsidence accompanying subsurface mining operations have been part of the research program of the Bureau of Mines. Periodic observations by engineers of the Mining Division of the Bureau of man-built structures beneath which mining operations are conducted offer indisputable evidence of subsidence in the form of creeks in masonry structures and fractures and depressions in the surface of the earth. As the removal of subsurface rock and earth material by mining, especially by the room-and-pillar method, is equivalent to withdrawing some of the foundation of a building, subsidence of the formations above, the mining levels in certain areas is easily understood as a gravitational adjustment of the overlying earth formations.

Jan 1, 1940

By Charles B. Carpenter

For many years, studies of ground movement and subsidence accompanying subsurface mining operations have been part of the research program of the Bureau of Mines. Periodic observations by engineers of the Mining Division of the Bureau of man-built structures beneath which mining operations are conducted offer indisputable evidence of subsidence in the form of creeks in masonry structures and fractures and depressions in tie surface of the earth. As the removal of subsurface rock and earth material by mining, especially by the room-and-pillar method, is equivalent to withdrawing some of the foundation of a building, subsidence of the formations above, the mining levels in certain air-as is easily understood as a gravitational adjustment of the overlying earth formations.

Jan 1, 1940

By H. R. Hardy Jr., E. J. Kimble Jr., H. W. Shen

"The primary objective of this research project is to study the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. Secondary objectives include the investigation of the acoustic emission technique as an indirect method for coal dust characterization and remote bit wear monitoring. The results of the project will be useful in developing efficient coal cutting techniques which significantly reduce the harmful coal dust components, and in providing methods for remote monitoring of bit condition and associated coal dust character. This paper will outline recent experiments carried out on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. During the experiments acoustic emission and a variety of other mechanical parameters were monitored. · A commercially available artificial intelligence computer package, namely: JCEPAK (Intelligent Classifier Engineering Package), has been utilized to provide a powerful and objective means for AE waveform analysis. This program is able to evaluate a number of features of each AE event and to make objective comparisons between AE signals associated with different loading or cutting parameters. Finally, the paper will discuss the results obtained from a variety of coal breakage tests.INTRODUCTIONStudies to date clearly indicate that the reduction of the severity, and eventual elimination, of Coal Workers' Pneumoconiosis (CWP) depends on gaining fundamental understanding in a number of major areas. These include dust generation and entrainment, transportation, suppression, medical effects of dust and possible treatment. At present a project is underway by the authors to investigate the character of the bit-coal interaction during coal cutting and its influence on the size and shape distributions of the generated dust. An important aspect of this on-going project is the development of acoustic emission (AE) criteria which will make it possible to carry out remote monitoring of coal cutting operations. Suitable on-line analysis of monitored AE data would allow engineers to evaluate factors such as shearer bit condition and cutting efficiency, and to quantify the particle size and shape distribution of the generated dust. The on-going AE studies are fundamental in form and were undertaken to evaluate the general feasibility of AE monitoring techniques using simplified coal cutting procedures. This paper will outline recent experiments on coal under uniaxial compression, linear single-bit cutting, and cutting using a laboratory-scale, single-bit shearer. Additional information on these studies are presented elsewhere [4]."

Dec 1, 1996

By F. D. Stevenson

A metal diaphragm pressure relay system was constructed to measure vapor pressures of the metal halides, oxyhalides, and other substances at temperatures up to 700° or 800° C. The vapor pressure of arsenic (III) oxide (As2O3) was determined to verify the reliability of the apparatus for such measurements. The data for the liquid AS2 Os (2820 to 4830 C) are represented by the equation, log Pmm = 6.875 - 2,929/T, from which the normal boiling point was calculated to be 461° C. The heat of vaporization calculated from this equation was 13.40 ±0.09 kcal/g mole As4OS and is essentially constant over the interval studied. The melting point of the octahedral arsenic (III) oxide was determined to be 278° C from the inter-section of the solid and liquid vapor pressure curves, A thermal analysis apparatus is also described by which melting and transition temperatures could be checked by a method independent of vapor pressure data. The melting points of the monoclinic and octahedral forms were determined to be 314.4 ±1.4° C and 278 ±5° C, respectively.

Jan 1, 1963

By J. B. Carman

This paper, describing the mining practices and methods at the mine of the Molyb¬denum Corporation of America, is one of a series of similar papers on mining methods in the various mines of the United States being prepared by the Bureau of Mines. The mine of the Molybdenum Corporation of America is in the Red River mining dis¬trict, Taos County, northern New Mexico (fig. 1), The mill and camp are in the valley of Red River, about 7 miles east of the town of Questa; the mine is 1 ¼ miles away, in Sulphur Gulch, a tributary of Red River. The mine is about 600 feet higher than the mill, at an altitude of about 8,700 feet. The climate is cold in winter, but does not interfere serious¬ly with continuous operation. The mine normally produces about 40 tons of sulphide molybde¬num ore per day, which is concentrated at the local mill and chipped to the plant of the Molybdenum Corporation at Washington, Pa.; there it is made into either ferromelybdenum or "molyte" (calcium molybdate), for use in alloys. The ore is mined from narrow, irregular veins by the cut-and-fill method. About 65 men are normally employed underground and on the surface at the mine.

Jan 1, 1931

By Forrest T. Moyer

The National Safety Competition was inaugurated in 1925 by the Bureau o1 Mines, U.S. Department of the Interior, in cooperation With the Explosives Engineer. In the first nationwide contest, 210 mines and quarries were enrolled. In 1962, the thirty-eighth anniversary of the competition, 910 mines and quarries were enrolled. These participating plants were worked a total of 133,292,989 man-hours. Of the enrolled plants, 415 achieved injury-free operations tar the year, the largest number of perfect safety records in the history of the contest. In 1961 and 1962, the National Safety Competition was conducted and sponsored by the Bureau of Mines. In January 1963, the American Mining Congress became a cosponsor and participated with the Bureau in the award activities related to the 1962 contest. The basic purpose of the competition is to stimulate employees to work safely and too give impetus to the building of better accident-prevention programs. A well-designed and efficient safety program helps a company economically by cutting costs, preventing damage to equipment and materials, and reducing nonproductive delays. An effective safety program benefits the employee more directly because his injuries cause personal suffering, lost time, and lower living standards for his family. Since both have much to gain, management and workers should cooperate closely to eliminate disabling work injuries. The greater contest participation and the larger number of perfect safety records indicate increasing safety consciousness on the part of management and employees.

Jan 1, 1964

By Forrest T. Moyer

The National Safety Competition was inaugurated in 1925 by the Bureau of Mines, U.S. Department of the Interior, in cooperation with the Explosives Engineer. In the first nationwide contest, 210 mines and quarries were enrolled. In 1962, the thirty-eighth anniversary of the competition, 910 mines and quarries were enrolled. These participating plants were worked a total of 133,292,989 man-hours. Of the enrolled plants, 415 achieved injury-free operations for the year, the largest number of perfect safety records in the history of the contest.

Jan 1, 1964

By Philip C. Good

Unweathered low-grade calcareous phosphate rock of about 20 percent P205 grade was beneficiated by a procedure in which contained carbonates were decomposed by calcination at about 1,000° C. On quenching the hot calcined rock in water, major impurities passed into a slime phase which was mechanically separated from a coarser concentrate fraction. Phosphate rock of two major types was beneficiated in batch-scale studies yielding concentrates containing 31.3 to 38.5 percent P205 at recoveries ranging from 54.8 to 86.0 percent. The samples were from two major deposits in India. Processing information gained was utilized in extending the work to a continuous-flow system, processing phosphate rock at rates up to 157 kilograms per hour. Superphosphate exceeding 16 percent water-soluble P205 was prepared from concentrate derived from continuous-flow processing.

Jan 1, 1976

By R. L. Rickel

The Bureau of Mines, as part of its minerals environmental technology research, conducted a study of mine waste tailings disposal. Part of the investigation evaluated the sand bed dewatering technique for disposal of alumina mini plant tailings as a means to increase consolidation rates and contain effluents. The technique employs a bed of sand resting on an impervious bottom. The tailings slurry is impounded over the sand layer and is dewatered through bottom drain piping. The study employed a single 10-ft-high, 6-in-diam, clear polyvinyl-chloride (PVC) column, and thickener wastes from the acid leaching of calcined kaolin clay. Results showed a consolidation rate of 41 in in 186 days for a total volume reduction of 37 pct. Sand bed dewatering was an efficient technique for solid consolidation and effluent containment when compared with data obtained from other dewatering studies.

Jan 1, 1982

As part of the overall development of a borehole mining system -develop backfilling techniques to reduce possible damage to the environment caused by either the cavities or the piles of sand tailings that result from in-borehole hydraulic mining. (Borehole mining is described in technology News No. 56.) Approach Water filled cavities at the bottom of boreholes are rapidly and economically backfilled by jetting a sand-tailings slurry underwater. How It Works The Bureau of Mines borehole mining system creates a cavity having a horizontal diameter of more than 50 feet. (See photograph). This cavity can be backfilled with much of the sand previously mined. The sand tailings or similar backfill material is dumped by a front end loader into a slurry mixing tank at the rate of about one ton every three minutes. Enough water is added to give a thick, but pumpable slurry. The slurry is pumped down the borehole through a string of 4-inch pipe to the cavity. After passing through a right elbow at the end of the pipe, the slurry is ejected through a nozzle. The resulting slurry jet emplaces the backfill at the outer wall of the cavity. To obtain an even distribution of fill in the cavity, the nozzle is slowly rotated. The nozzle and pipe assembly is supported from a turntable on the surface. See diagram.

Jan 1, 1981