Search Documents

By R. A. Guidotti

The Federal Bureau of Mines studied the thermal decomposition of the nitrides of the Group V A metals (CbN, Ta3N5, and VN) with the goal of preparing high-purity metals. Solid-state purification and arc and electron-beam melting were examined. Electron-beam melting proved to be the most efficient means of nitrogen and oxygen removal. Columbium and tantalum of 99.9-pct purity were prepared by this technique; in the case of vanadium, however, nitrogen could not be reduced below the solid-solution level.

Jan 1, 1976

By B. G. White

NIOSH researchers have identified a pattern of fracture zone development that suggests an explanation for fracture formation around rectangular openings in underground mines. This pattern is characterized by shearing and dilation that result in either faults or in the repeated formation and propagation of en echelon fractures from sites of tension. Two computer modeling codes, Fast Lagrangian Analysis of Continua (FLAC) and Particle Flow Code (PFC), were used to model different aspects of this pattern. Use of very small elements with FLAC enabled the identification of sites of initial tension near the skin of square-cornered rectangular openings, while PFC allowed the initiation and progressive development of fractures from these sites to be followed as the fractures evolved. Such studies can lead to a greater understanding of how roof support can be better selected and installed for specific conditions in underground mines prone to roof falls and rock bursts. These studies may also lead to modifications of corner and opening shapes that could be incorporated into mine designs to produce more stable mine openings and reduce the risks of rock falls and rock bursts.

By R. O. Dannenberg

A metallic displacement process, utilizing easily available steel wool or steel window screen, was devised and successfully used for the recovery of silver from waste photographic fixing solutions. Laboratory and prolonged commercial-scale testing established that the iron filament type unit will efficiently precipitate silver, as a high-grade sludge, from acidic waste photographic fixing solutions ranging in grade from less than 1 to over 10 grams of silver per liter. Data and design information are presented to facilitate the construction and operation of a practical unit of any desired size. A smelting process for recovering pure silver from precipitated sludge containing 27 to 80 percent silver was devised.

Jan 1, 1968

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

APPENDIX E REFUGE CHAMBER LEAKAGE ANALYSIS Variables p 0 = pressure outside of chamber (psi) p = pressure inside of chamber (psi) i q = leakage flow rate (cfm) Q= total leakage (cu ft. ) V = chamber volume (cu. ft. ) t= time (minutes) p= nominal atmospheric reference pressure (14.7 psi) A= chamber leakage coefficient (cfm/psi)

Jan 1, 1976

By Alan G. Mayton

A prototype end-cab shuttle car (SC) design has been developed to improve protection and address ergonomic concerns of the SC operator in low coal mines. The new design features an end cab transversely mounted to the SC and equipped with a closed-circuit video system. The end cab was retrofitted to a low-coal SC and evaluated in surface trials at the U.S. Bureau of Mines. During surface trials, test operators evaluated the end-cab SC relative to visibility; cab features-space, seating, controls, and operator position; tramming-inby, outby, and turning corners; and dumping. Trials were conducted using 12 test subjects; 6 were experienced SC operators. Results of the trials were promising. Of the experienced operators, the only operator with low-coal experience gave the new design the highest rating. Four experienced operators rated the end-cab design "better" to "much better" than a standard center-driven, side-cab SC for visibility when tramming, protection from roof and rib hazards, and no change in seat position with direction of travel. This report discusses research to modify a used 21SC JOY SC, retrofit the SC with the Bureau-developed end-cab, and evaluate the retrofitted end-cab SC in surface trials.

Jan 1, 2010

By E. L. Garton

An active list of permissible explosives was published in July, 1931, as part of United States Bureau of Mines Report of Investigations 3134, under the title of "Active List of Permissible Explosives and Blasting Devices Approved Prior to June 30, 1931." Changes in that list were authorized in August, September, October, November, and December, 1931, and January and March, 1932, as published in Reports of Investigations 3140, 3147, 3150, 3155, 3158, 3161, and 3163, respectively. By these changes the following explosives were added to the active Permissible list: Austin Red Diamond No. 1, L. F. Gel-Coalite W, L. F;" Austin Red Diamond No: 5. Gen-Gel No. 2. Black Diamond Nu-Gel No. 1 Genite C-1 Burton 1, L. F. Liberty No 4 Burton 2, L. F. Liberty No. 5 Burton 10, L. F. Peerless D Burton 12, L. F. Permigel 1, L. F. Burton F, L. F.

Jan 1, 1932

By BUREAU OF MINES

A complete list of permissible mining equipment, rescue apparatus and gas masks tested prior to July 1, 1928, was published in Bureau of Mines Information Circular 60772. The present list includes practically all equipment tested and, approved by the Bureau, up to and including Jan. 1, 1929. It covers electric air compressors, coal drills, mining machines, loading machines, conveyors, mine pumps, room hoists, mine telephones, rock-dusting machines, switches, electric cap lamps, flame safety lamps, electric hand and trip lamps, flash lamps, methane indicators and detectors, blasting units, storage barrery locomotives, tandem locomotives, power trucks, concrete mixers, self-contained oxygen breathing apparatus and gas masks. The system under which those devices were tested permits the manufacturer, after his equipment has passed certain tests prescribed by the Bureau of Mines, to mark his equipment with a seal shoring that it has been "approved" by the Bureau. These tests are designed to insure that the equipment has the minimum requirements for safety in use. The only object of the Bureau in making such tests and pub- lishing lists of permissible equirment is to safeguard the lives of workers and to help lesson the hazards of mining.

Jan 1, 1929

By N. E. Hanna

An important goal in the development of coal mining explosives has been to improve their safety characteristics through suitable formulation. In the United States no systematic effort to establish factors influencing the incendivity to firedamp and to coal dust of explosives through research was made until the last decade. In consequence, American permissible explosives underwent only very slight modifications and many remained substantially the same as in the early years. As part of a long range program for increasing the safety of permissible explosives, the Bureau of Mines undertook to determine how the amounts and particle sizes of the principal constituents of these explosives affect their incendivity. It was found that an increase in the relative amount of sodium chloride and a decrease in its particle size significantly decreased the incendivity of our permissible explosives to firedamp (7-9).6 This is in agreement with findings reported by Dolan (4) for compositions of nitroglycerin and salt. One important result of the work at the Bruceton station has been the recent introduction of salt-formulated permissibles by several explosives manufacturers. This paper describes a statistically designed experiment for studying the effects of the particle size of ammonium nitrate and the type of carbonaceous materials used on the incendivity of permissible explosives. Interest in these particular effects goes back as far as the first formulations of coal mine explosives, around 1910 in the United States and even earlier in Great Britain and other countries. Although it is well established that fine

Jan 1, 1961

By Bruce D. Sartwell

A program was written which utilizes a remote teletype input to a time- sharing computer to plot charged particle or X-ray energy spectra which are stored in the memory of multichannel analyzers. The program, written in FORTRAN V, accepts the data printed out by the pulse height analyzer on paper tape and then, after reading these data tapes into the computer, plots on the teletype the desired energy spectra on a scale automatically adjusted for the maximum number occurring in the data. The program is flexible enough so that the researcher can subsequently expand or contract the vertical (intensity) or horizontal (energy) scales. With a slight modification, the program will accept data printouts from scalers or analog to digital converters. The program also includes a feature for integrating the energy peaks obtained by pulse height analysis.

Jan 1, 1970

By John B. Gayle

The probable inadequacy of physical tests of coke for the purposes for which they are made has been a subject for discussion for many years. However, little has been published in this connection, even though most workers in the field believe that the physical properties of coke are of major importance in its utilization in the steel and allied industries. In fact, the reproducibility of the recognized tests is largely unknown or can only be approximated. This situation occasions many difficulties when attempts are made to judge the coke-production qualities of various coals or coal blends. During World War II the Coke Production Committee, composed of representatives from industry and the Solid Fuels Administration, concluded that study of existing testing methods and possible improvements would be of material assistance in answering questions relating to coke quality. Since that time the Bureau of Mines has taken samples of coke produced in industrial slot-type coke ovens in connection with studies aimed at extending coking-coal reserves by adding to the list of sources known to be suitable for this purpose. Testing procedures on these cokes were arranged so that the data obtained would yield information on (1) the degree of precision of tests commonly used in the industry, (2) the causes of the known poor reproducibility in several of the physical tests, and (3) possible improvements or modifications of existing physical testing procedures.

Jan 1, 1953

By Oliver Bowles

The conservation of fuel became a critical problem during the recent war, particularly in the East. Fuel-oil supplies were short, the demands for coal increased, and householders were called upon to reduce the temper- atures in their homes. Home owners were urged to employ every means avail- able to reduce fuel consumption, the most important of which was to insulate their dwellings. The Bureau of Mines, United States Department of the In- terior, took steps to promote the conservation of fuel by issuing a report3/ on home insulation which has been widely circulated. The American populace responded patriotically to the requests of various Government agencies for voluntary conservation of fuels; they accepted cheerfully the restrictions imposed, the crisis was weathered, and with termination of hostilities the unhappy situation was relieved. Fuel conservation, however, is not merely a war emergency problem; it is a continuous, ever present issue. Coal and petroleum resources are ir- replaceable assets, and when fuel is burned it is exhausted - there is no scrap recovery. Fortunately, the United States has been richly endowed with mineral fuels; but population is growing, industrial demands for fuel are increasing, and mines and oil wells are becoming deeper and more costly to operate. For the sake of generations to come all national resources, particularly irreplaceable fuels, should be conserved. A long step in the direction of fuel conservation is the general rec- ognition that insulation is an essential element of dwelling construction. Fortunately, when the home owner takes measures to conserve fuel, he is not called upon to make purely unselfish (altruistic) sacrifices to advance the general welfare; he has the added incentives of saving money and promoting more comfortable living in his own home.

Oct 1, 1946

By Philip G. Burkhalter

Total yield and backscattered electron coefficients were measured in this Bureau of Mines study in an microanalyzer as a function of atomic number and of primary crier: ;y in the 15- to 35-kilovolt range. The electron coefficients were obtained indirectly from measurements of the specimen electron current and the primary beam current collected in a Faraday cage and were measured with a precision better than 0.5 percent. Secondary electron emission was suppressed with opposing potential applied to a screen grid surrounding the specimen. The values of the backscattered electron coefficients agreed with published values within 5 percent.

Jan 1, 1965

By Charles Seitz

The Bureau of Mines has modified its parts-per-billion helium-4 analyzer to improve the analytical capabilities of the instrument. The modifications resulted in the following improvements: (1) The analytical precision of the instrument for 10 consecutive analyses was improved to ±1 ppb at the 5,000-ppb helium-4 level, (2) the helium-4 sensitivity was increased almost tenfold, and (3) the minimum detectable limit for helium-4 was improved to 0.5 ppb. The modifications made to improve the instrument included replacing the ion-source control circuit with a direct-current solid-state design, controlling the temperature of the ion source, stabilizing and reducing the pumping rate of the vacuum system, and optimizing peak integration.

Jan 1, 1986

By H. E. Camargo

In an effort to decrease noise-induced hearing loss (NIHL) in coal preparation plant employees, the National Institute for Occupational Safety and Health (NIOSH) is conduct­ing research to identify and control dominant noise sources in vibrating screen (VS) machines. To this end, acoustic measurements of the noise radiated by a dewatering VS were conducted at the Pittsburgh Research Laboratory (PRL) using microphone phased-array technology. These measurements allowed for the identification of the screen as the dominant source in the 250 Hz 1/3-octave band. The sidewalls are the major contributors in the 315 and 400 Hz bands, whereas the eccentric mechanisms and the electric motor are the dominant sources in the 800 and 1,000 Hz bands, respectively.

Jan 1, 2009

By S. M. Molloy

The postwar demand for insulating material such as mineral wool, in-creased in proportion to the rapid construction of new buildings, placing an enormous burden on the existing mineral-wool industry both in known sources of raw materials and in available plant facilities. In view of the increased demand on the industry, the Bureau of Mines in its Mississippi Valley Experiment Station" Rolla, Mo., undertook an investigation to aid the industry by establishing resources of raw materials through actual laboratory wool-blowing tests and by developing certain methods for evaluating the physical proper-ties of a mineral wool. As material was received from the public, laboratory-evaluation technique had to be developed, the results of which would reflect in the mineral-wool-industry standards. The methods of testing used by the mineral-wool industry, not only would have required a pilot-plant installation capable of producing a large tonnage of mineral wool, but each wool-blowing campaign would have been very expensive and necessitated considerable personnel and equipment. The present laboratory wool-blowing equipment can produce as high as eight wool-blowing campaigns a day. The nature, simplicity, and size of the physical testing equipment permit testing as small a sample of wool as 25 grams and give information as reasonably accurate as in a 40-pound bag of wool. The purpose of this report is to describe the laboratory method of production and the evaluation of the physical properties of small quantities of mineral wool. Considerable work has already been done, and the interest of the public and industry is measured in the number of samples being submitted for testing.

Jan 1, 1948

By A. B. Hooker

All state mining laws require that flame safety lamps be used in gassy mines; the laws of some States require that safety lamps be kept for emergencies at every coal mine, whether gassy or nongassy. The use of the flame safety lamp has been widespread because it is the only defice readily available for detecting both the presence of methane and deficiency of oxygen. This paper reports the results of an investigation by the Electrical Section, in cooperation with the Gas Section, of the Pittsburgh Experiment station relative to the behavior of permissible flame Safety lamps in mine atmospheres deficient in oxygen and the effects of methan5/ on the detection of oxygen deficiency.

Jan 1, 1937

By A. B. Hooker

All State mining laws require that flame safety lamps be used in gassy mines; the laws of some States require that safety lamps be kept for emergencies at every coal mine, whether gassy or nongassy. The use of the flame safety lamp has been widespread because it is the only defice readily available for detecting both the presence of methane and deficiency of oxygen. This paper reports the results of an investigation by the Electrical Section, in cooperation with the Gas Section, of the Pittsburgh Experiment Sta¬tion relative to the behavior of permissible flame safety lamps in mine atmospheres deficient in oxygen and the effects of methane5 on the detection of Oxygen deficiency.

Jan 1, 1937

By Liming Yuan

[ ]

Jan 1, 2009

By Andrew J. Fergus

The purpose of this study was to provide basic information to aid further research on beryllium mineral flotation. Contact-angle and microflotation (Hallimond tube) methods were used to study collector action and flotation response of beryllium minerals and associated gangue minerals with representative commercial surfactants. Chrysoberyl received prime attention. Results indicated that selective flotation of beryl and chrysoberyl from fluorite and quartz is possible with sodium isooctyl phosphate below pH 2, and fluorite and topaz are readily collected by both anionic and cationic surfactants. Several modifying reagents were studied at one pH and one level of collector concentration. Aluminum sulfate, starch, and sodium silicate proved to be depressants in chrysoberyl flotation.

Jan 1, 1968

By F. E. Cash

Much has been written concerning accidents in coal mines; the fact that accidents cost the employer and employee money is generally well known, but how much accidents actually cost is vague, even in the minds of many operators. Unquestionably there are hazards in coal mining, but many of them can be eliminated; and from the prevention of accidents there can be realized a material saving in dollars and cents as well as in human suffering. In presenting the frequency, severity, and cost of accidents in some Tennessee coal mines, it is hoped that other mines in Tennessee, as well as mines in other States, will by a comparison of the data with their own ex¬ perience be enabled eventually to reduce the number of' their accidents.

Dec 1, 1932