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By Michael R. Yenchek

Contacts with energized conductors are a major cause of electrocutions in underground coal mines. Sensitive ground fault interrupters (GFI's) installed on in-mine three-phase ac utilization circuits would probably prevent the majority of these deaths. A sensitive GFI is a protective device that detects and interrupts small deadly ground currents in the milliampere range before those currents can cause ventricular fibrillation in humans. Commercially available three-phase sensitive GFI's have not been specifically designed for application in coal mines. The Bureau of Mines therefore tested three commercial GFI models to determine their worthiness for mine power systems. GFI design and construction, transient immunity, reliability, and time-current characteristics were evaluated in laboratory tests. No commercial device was found suitable for mine use without design modifications. The tests results will serve as a basis for the development of a mineworthy sensitive GFI in ongoing Bureau research.

Jan 1, 1985

By G. R. Palmer

Preliminary studies by the Bureau of Mines were conducted to determine the feasibility of a multiple-compartment, ion-exchange (MCIX) column simulator for examining the effect of multiple-orifice plates in the column. A rectangular, five-orifice, three-compartment, MCIX simulator with a cross-sectional plate area of 0.66 ft2 was used for the investigation. Orifices with open areas of 1, 3, and 5 percent were used with various operating conditions. The study was separated into three separate sections: (1) solution flow effect, (2) fluidization effect, and (3) resin transfer effect. The solution flow and fluidization studies showed that for solution flow rates of about 3 gpm/ft2, a I-percent open area plate functioned best, while at solution flow rates of 9 and 15 gpm/ft2, the best open areas were 3 and 5 percent, respectively.

Jan 1, 1981

By Robert H. Bedford

As a result of the Bureau's general survey of quicksilver deposits in California, the Guadalupe mine area was among those chosen for exploration. Exploration, such as that at the Guadalupe, was aimed primarily at maintaining or increasing production of quicksilver during the critical wartime period. The project as originally planned contemplated sampling the dumps and prospecting some promising surface exposures by bulldozer trenches. Salvage was the objective in the first case and new ore in the second. Later, a program. of diamond drilling was added, designed to add both to ore reserves and to geological information. This report summarizes the history, notes the location and physical features, mentions property and ownership, and presents a brief description of the mine. The geology is outlined, and the work done by the Bureau of Mines is explained and supplemented with accompanying maps. The work involved repairing 1-1/4 miles of roads; bulldozing 13 trenches by removing 2,345 cubic yards of dumps to provide for sampling; digging and sampling 9,284 linear feet of hand trenches, digging and sampling numerous test pits; and drilling 7 diamond-drill holes, totaling 1,000 feet. A total of 419 samples, including 10 percent check samples, were taken. Exploration work in California at the time of this project was under the direction of Spangler Ricker, supervising engineer of the California field office, the late Robert Bedford was in charge of the fieldwork on this project.

Jan 1, 1950

By Stephen A. Swan

Bureau of Mines researchers have collected and evaluated rollover protective structures (ROPS) f or more than 10 yr. ROPS and falling object protective structures (FOPS) are required on specified mining machines under regulations of the Mine Health and Safety Administration (MSHA). Both ROPS and FOPS are required on mining machines used in surface coal mines and surface areas of underground coal mines (30 CFR 77.403 and 7 7.4 13a), and ROPS are required on mining machines used in metal and nonmetal mining operations (30 CFR 55, 56, and 57.9-88). This illustrated manual provides mine safety personnel, MSHA inspectors, and original-equipment manufacturers with guidelines and a check- list for inspecting ROPS being used in the field. The manual discusses specific requirements of the MSHA regulations and minimum inspection and maintenance checks for ensuring compliance with those regulations. An easily reproducible checklist is provided as an aid to the inspection of ROPS.

Jan 1, 1985

By Todd M. Ruff

Current methods of inspecting wire rope for broken wires or excessive wear include visual inspection, physical measurements of rope diameter, and electromagnetic nondestructive testing (NDT). Visual inspection and physical measurement arc the least comprehensive methods. Electromagnetic NDT enables a more thorough assessment of the condition of a wire rope, but the repeatability, accuracy, and objectivity of this method can be improved. One means of achieving this goal is to use a computer to analyze the test data and determine the condition of the wire rope, including the presence of broken wires and corrosion, and the amount of wear. An off-the-shelf data acquisition and analysis system was tested in a U.S. Bureau of Mines laboratory using a continuous loop of wire rope containing fabricated flaws. The test rope was run through a commercially available NDT instrument. The output of the instrument, normally connected to a paper strip chart recorder, was digitized and analyzed with a personal computer. These initial tests were successful in showing that the use of a computer can improve current methods of NDT waveform collection and analysis.

Jan 1, 2010

By R. D. Groves

Techniques were developed for preparing metallurgical-grade copper powder from industrially produced cement copper. Flotation was used for rejecting discrete gangue particles, acid leaching to remove residual iron and aluminum, hydrogen reduction to eliminate oxygen, sintering to consolidate the fine-sized copper, and grinding to obtain copper powder. Powders prepared from six different cement copper samples contained, in percent, 98.5 to 99.0 Cu, 0.10 to 0.05 Fe, 0.10 to 0.08 insoluble material and the remaining individual impurities less than 0.15 percent. The apparent density, flow characteristics, and other physical properties were suitable for powder metallurgy applications. An economic evaluation showed that this process was economically feasible. Processing costs appeared modest when considering that copper powder commands a price normally about 17.5 cents per pound over that of electrolytic copper.

Jan 1, 1971

By J. C. Judd

The Bureau of Mines investigated the recovery of vanadium, uranium, and phosphorus from low-grade phosphorite ores and concentrate by leach-ing with H2S04. Samples containing 0.12 to 0.23 pct V20S, 0.009 to 0.012 pct U30S and 18 to 30 pct P20S were treated by batch-agitation leaching, roasting followed by acid leaching, salt-roasting followed by acid leaching, and leaching under pressure. Maximum recoveries using leaching alone ranged from 78 to 98 pct of the V20S and 74 to 88 pct of the U30S-Leaching under pressure resulted in extractions of 88 to 95 pct of the V20S and 84 to 89 pct of the U30S. Leaching following roasting--with or without NaCI--produced extractions of 97 to 99 pct of the V20S and 86 to 91 pct of the U30a. Depending on the technique(s) employed, phosphate extractions ranged from 89 to 99 pct. Solvent extraction laboratory tests were conducted to selectively re-cover vanadium and uranium values from acid leach solutions. An average of 95 pct -of the U30a was recovered using di(2-ethylhexyl) phosphoric acid, plus trioctylphosphinic oxide. Essentially all of the V20S was recovered with octylphenyl acid phosphate plus isodecanol. The phosphate remained in the raffinate.

Jan 1, 1986

By Tobias W. Goodman, George N. Aul, Joseph Cervik

The Bureau of Mines conducted research to degasify a virgin block of coal in the Beckley Coalbed using long horizontal holes drilled in an array from the bottom of a ventilation air shaft. Eight horizontal holes and an in situ pressure hole were drilled in a radial pattern to depths ranging from 418 to 910 ft (127 to 277 m) and 205 ft (62 m), respectively. The investigation showed the shaft was in a basin saturated with water, which resulted in low gas flows from holes. The in situ pressure at 200 ft (61 m) into the coalbed was 79 psig (544.6 KN/m2). The aver- age gas and water flows for the eight holes were 94,100 ft3/day (2,665 m3/day) and 13 gal/min (49.3 l/min) . After 514 days of degasification, 18.7 million ft3 (0.53 million m3) of gas had been drained. Methane face emissions, which were measured as a section advanced toward the shaft, were reduced about 77 pct, emphasizing the value of drainage by this technique. All holes were grouted before the area around the shaft was mined.

Jan 1, 1982

By G. W. Birge, D. E. Wolfson, J. H. Lynch

This report by the Federal Bureau of Mines describes the carbonizing properties of coals from the principal beds in Boone County , W. Va . Results are given for samples of coals from No. 5 Block , Stockton - Lewiston , Coalburg , Winifrede , Chilton , Hernshaw , Cedar Grove , Alma , and No. 2 Gas beds . Boone County coals rank as high -volatile A bituminous . Eighteen of the 21 samples tested contained from 3.3 to 7.9 percent ash and 16 of the samples contained from 0.6 to 0.9 percent sulfur . Two samples from the Alma and No. 2 Gas beds , the lowest stratigraphically of the seams tested in Boone County , contained from 1.4 to 2.7 percent sulfur . Most Boone County coals yield

Jul 1, 1960

By Joseph M. Pugliese

The U.S. Bureau of Mines has produced a generic in situ copper mine design manual, which contains a computerized cost model for in situ copper oxide mining. The model specifies (1) site-specific parameters, which must be quantified for mine design, (2) a method for minesite design based on those parameters, and (3) a procedure for assessing economic viability for the mine design. The menu-driven computer program performs calculations for developing commercial mine design specifications, as well as capital and operating costs. The default values are based on 1986 dollars, and indices for updating costs are included. The program also provides discounted-cash-flow rate of return (DCFROR) and allows for sensitivity analyses for an in situ mining operation at any specific undisturbed copper oxide deposit. This report is to be used with the 1990 version of the computer program, which has been made user friendly. It describes the flies, tutorial, input phase, help function, and monitor display of all calculated values and of the DCFROR table. The monitor-displayed discounted initial value of investment and annual operating costs are defined. The dual rate-of-return situation and sensitivity analyses are also briefly discussed. Information is provided on obtaining the computer program on diskette.

Jan 1, 1991

By Maria I. De Rosa

During 1990-2001, a total of 518 fires occurred in all metal/ nonmetal mining categories; 296 of those fires caused 308 injuries and 4 fatalities. Surface operations had the most fires and the highest injury risk rate values. Forty-five fires destroyed or heavily damaged facilities and equipment (including 19 pieces of mobile equipment) because of failure of firefighting methods, late fire detection, undetected fires, or fire size. In the future, many of these fires and injuries might be prevented or detected and extinguished at their earliest stage by improving current fire safety procedures, adopting existing/ improved fire detection and suppression technologies, and/or developing new technologies. Several strategies for reducing and/or preventing the number of fires and fire injuries follow. I. Increase vigilance, improve safety procedures, and develop new technologies in order to prevent fires and injuries caused by fame cutting and welding operations. 2. Improve equipment hydraulic/fuel/electrical systems inspection programs; adopt fire-resistant hydraulic fluids and electrically powered motors for use in underground mines; develop new technologies (equipment/cab rapid fire detection/ prevention/suppression systems, emergency line drainage systems, and fire barriers); adopt an optimal ground level location for the activation of emergency systems; improve operator's fire preparedness training programs; and develop effective and rapid local firefighting response capabilities. 3. Adopt existing/improved systems for continuous and early detection of combustion gases and smoke along beltlines. 4. Adopt existing/improved technologies for monitoring equipment (beltlines) operational functions. 5. Increase vigilance and adopt improved safety procedures for handling f amenable liquids and refueling fuel in the vicinity of heat sources.

Jan 1, 2004

By H. P. Hermance

The Ore Hill zinc-lead mine in Grafton County, N. H., was investigated by the Bureau of Mines from March to July 1943 and from August to October 1944. Fourteen holes with an aggregate bore of 4,899 feet were diamond-drilled, the old workings were unwatered and sampled to an inclined depth of 250 feet, and the tailings dumps were surveyed and sampled. The deposit at the Ore Hill mine comprises a bedding-plane vein of massive sphalerite and galena with subordinate chalcopyrite and pyrite in a series of interbedded metasedimentary and metavolcanic schists about one-quarter mile east of their contact with the intrusive Baker Pond gneiss. The property was first opened about 1850 and was active at times to 1914. Production records are not available, but the output is believed to have been considerable. In 1944, leasers recovered a marketable mica product from mica schist from the dumps and certain outcrops. This report describes the work performed in the Bureau's investigation and presents the data obtained.

Jan 1, 1948

By RV. Ramanl, KV. K. Prasad, M. Swaminathan

The objective of the research in this project is to develop a knowledge based expert system for aiding the planning of mine ventilation systems. This system focuses on mine ventilation system design from a coal mine dust control standpoint. It is recognized that mine ventilation system design is an engineering problem involving not only rote numerical calculations to solve the pressure quantity problem but also substantial judgement and expertise to analyze a problem situation and Interpret the results of an algorithmic program. The thrust of this project is to i) extract this knowledge from public domain sources and recognized experts in industry, government and academia, 11) represent this knowledge in the form of IF ... TI-IEN rules in an expert system (ES) and 111) interface the developed expert system with a mine ventilation network analysis program vis. PSUMVS (Pensylvania State University Mine Ventilation Simulator). By providing the numerical computing and qualitative reasoning aspects of mine ventilation system design in a single Integrated system, better quality decision support will be made available to apprentice users.

Jan 1, 1988

By N. N. Moebs

The atmosphere in part of an air-sealed coal mine was monitored continuously through a drill hole for oxygen content to determine the effectiveness of sealing a mine against the entrance of air and the major force that caused the phenomenon of mine breathing through the overburden. The differential pressure across the seal and the barometric pressure on the outside also were recorded. A general correlation, obtained between the oxygen level, differential pressure, and barometric pressure, indicates that changes in air pressure are the cause for periodic replenishment of the oxygen in the mine. Mine effluent quality was determined by conditions in many sections of the mine and could not be related to the oxygen level at the drill hole.

Jan 1, 1972

By Charles K. Rose

This paper presents some research studies of the rotary drilling of oil shale at the Bureau of Mines Oil-Shale Mine, Rifle, Colo. The experimental procedures and the rotary drill test equipment are described. Theories of rock drillability, rotary bit cutting action, and bit design are presented and discussed. The actions of various bit designs are analyzed and compared with the observed results of actual drilling tests. A cost estimate is made for drilling Colorado oil shale.

Jan 1, 1955

By R. C. Buehl

[Improvements in refractories for high-temperature service have made possible the use of higher temperature in many processes. Consequently, it sometimes is desirable to use gases heated above 1,600° F., and for moderate rates of gas flow, there gases can be heaters best with pebble heaters. Pebble heaters of the stationary-bed type in which the chanber was lined with mullite brick and pebbles of pure alumina served as the heat-exchange medium have been used recently to heat the air blown into an experimental blast furnace4/ These pebble heaters worked well and made it possible to use air temperature up to 2,500° F. at the tuyere of the furnace. Since little has been published on this type of gas heater, a review of the construction on employed and operating data should assist in selecting applications and designing units.]

Jan 1, 1953

By John F. Papp

The Bureau of Mines has sampled microstructure of low-pressure flat flames by mass spectrometer for normal methane-oxygen-argon and for methane-oxygen-argon-bromotrifluoromethane flames. The physical and chemical phenomena, and the method of analysis of mole fraction data to evaluate net reaction rates are here considered in detail. Included is a computer program listing with output on one flame. Chemical species considered are CH4 , CO, CO2, H, H20, OH, Ar, H2, O2 , O, H2CO, CH3 , CF3Br, HF, HBr, Br, CH3Br, HCO, F2CO, CH2 CF2 , H02.

Jan 1, 1975

By John B. Gayle

During studies of the various methods for determining and specifying the factors that indicate whether a particular coke is better or worse than other cokes for metallurgical uses, questions arose as to the precision of screen-analysis tests on coke. Although the usual index of precision, the standard deviation of the test result, gives a measure of the precision of these data, the experimental determination of the standard deviation for a particular set of conditions requires tests on a large number of duplicate samples. Because this procedure necessaily involves a great deal of labor, an equation for predicting standard deviations from theoretical considerations has been developed. Results predicted with this equation agree satisfactorily with the experimental values and are applicable to tests on coal, coke, gravel, and other bulk materials.

Jan 1, 1952

By Joseph E. Matta

The Bureau of Mines conducted a field study to investigate thin suppression of respirable dust by water sprays on a continuous-mining machine. Determining the importance of the top and bottom sprays for two types of spray nozzles was emphasized. Results showed, at a 90-pct confidence level, that (1) at least 70 pct of the dust was generated during the sump cut, even though nearly half of the coal was mined during the downshear operation, (2) the water sprays on the top of the boom had little effect in suppressing respirable dust, and (3) B.D. 5 spray nozzles mounted beneath the boom reduced dust at least 33 pet more than B.D. 5 sprays mounted on top of the boom. A single-cut technique was developed that gave good reproducibility for replicate cuts (coefficient of variation of 20 pct).

Jan 1, 1976

By C. F. Davidson

The Bureau of Mines studied the extraction of lithium from lithium-containing clays by chlorination with hydrogen chloride (HC1). In bench-scale laboratory investigations, HC1-H20 mixtures were used to selectively chlorinate lithium, but not calcium or magnesium, in lithium-containing clays. The addition of calcium carbonate to the clay was found to improve the lithium recovery. Reaction conditions found to affect the lithium recovery were ratio of clay to carbonate, reaction temperature, and HC1 concentration. The best conditions for selective chlorination of the lithium were 2:1 clay-carbonate, 750° C, and 20 wt-pct HC1. The experimental results and trends in lithium extraction are explained using thermodynamic relationships.

Jan 1, 1981