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The U.S. Bureau of Mines evaluated water-jet-assisted longwall shearers in full-scale laboratory tests and underground. Both test programs showed that use of high-pressure water did little to reduce the shearer motor energy required to maintain a given cutting rate. However, three other major benefits were achieved with the use of water-jet-assisted cutting. At a pressure of 1,800 psi, respirable dust levels were reduced about 80 pct compared with the dust levels of the conventional water spray system operating at 340 psi. Operating at higher pressures required for water-jet assist also resulted in an increase in the average size of coal cut, which translates into a decrease in product fines. Finally, although no controlled measurements of bit wear as a function of water pressure were made, mine personnel reported that the shearer bits lasted longer when water-jet-assisted cutting was used.

Jan 1, 1989

By T. O. Llewellyn

The Bureau of Mines, as part of its goal to develop technology that can conserve domestic mineral resources investigated beneficiation methods for recovering phosphate minerals from two Southern Florida deposits with high magnesium content. Chemical analyses of sized fractions indicated that no coarse pebble concentrate could be produced from either deposit. Conventional fatty acid-fuel oil batch flotation tests on two phosphate samples, analyzing 6.8 and 8.5 pct P205, yielded concentrates containing 28.97 to 29.80 pct P20S at recoveries ranging from 72.4 to 76.9 pct of the flotation feed. The MgO content ranged from 1.20 to 1.36 pct. Bubbling S02 gas through an aqueous concentrate slurry, further reduced the MgO content of these phosphate concentrates to 0.5 and 0.8 pct, but with a concomitant loss in the phosphate recovery. Settling characteristics of slimes from both phosphate samples showed a slow settling rate, which is a typical characteristic of other slimes in the region.

Jan 1, 1981

By H. V. Makar

A study was conducted by the Bureau of Mines to determine problems associated with the use of ferrous fractions from urban refuse as melting stock for steelmaking and to evaluate the resulting steel products. The study involved 50-pound ingots from laboratory melts and 50-pound ingots from 1-ton electric-arc-furnace melts. The 50 pound ingots from the laboratory melts and the arc-furnace melts were hot rolled to provide material for mechanical and corrosion testing. Results obtained in the study include the following: Most steels rolled successfully and exhibited acceptable surface and edge condition. Tensile strengths of the plain carbon steels were not significantly affected by copper up to concentrations of 0.65 pct and were not affected by tin content up to 0.16 pct. Yield strength increased with increasing copper and tin contents, and impact strength decreased with increasing tin content. Hardness increased slightly with increasing copper content. In general, properties of the steel produced were not measurably affected by charge composition (that is, melting stock), melting practice, or method of scrap preparation.

Jan 1, 1975

By G. A. Brady

Seven samples of Pennsylvania anthracite from the Bottom Ross bed were analyzed and tested to obtain data on cleaning characteristics, proximate and ultimate analyses, specific gravity, grindability, heating value, and ash softening temperature. Ash content of the samples varied irregularly from 9.0 to 34.4 percent, the range being narrowed to an upper limit of 14.8 percent ash by removing impurities dense enough to sink in a medium with a specific gravity of 1.90. Ash content of the sink material with specific gravity greater than 1.90 ranged from 56.4 to 80.4 percent; corresponding specific gravities were 2.095 to 2.534. Volatile matter contents were indicated to be higher for the ash-forming minerals than for the pure coal substance in the various specific gravity fractions of a given sample. Specific gravities of anthracites with compa¬rable ash contents but from different locations in the bed varied as much as 0.06. The grindability index increased significantly with increasing ash con¬tent of specific gravity fractions from all the samples.

Jan 1, 1968

By K. O. Bennington

The thermodynamic properites of petalite (Li2A12Si8O20) were determined by the Bureau of Mines. The enthalpy of formation was determined by hydro-fluoric acid solution calorimetry. The values from the elements and from the oxides are ?Hf°298.15 = 2,335.8 ± 3.0 kcal/mole and ?H°295 (from oxides) = -50.60 ± 1.20 kcal/mole. Low-temperature heat capacities were determined by adiabatic calorimetry from 10.69 to 302.11 K. The derived standard entropy is S°298.15 = 111.0 ± 1 cal/deg-mole. Enthalpy increments above 298 K were measured by copper block calorimetry from 298 K to 1,193.6 K. The various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of the measurements. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature from the elements and constituent oxides. The Gibbs energy of formation is ?G°f298.15 = 2,203.8 kcal/mole.

Jan 1, 1980

By J. H. Maysilles

The Bureau of Mines, U.S. Department of the Interior, is investigating several types of low-grade uranium deposits. Projections indicate that an increased percentage of future production will be derived from such sources. One material studied was from the Coso Mountains of California; this material contained 0.04 to 0.12 percent U3O8. The deposit contains at least two distinct types of mineralization. The material representing the bulk of this deposit was amenable to acid leaching; 80 to 85 percent U308 extraction resulted from leaching with 20 to 40 pounds per ton of sulfuric acid. No oxidizing agent was required. This ore fraction could be treated by either agitation or percolation leaching. Uranium recovery and purification from the acid leach solution was accomplished using anion exchange followed by precipitation with hydrogen peroxide and ammonia. The second type of mineral was very refractory to acid leaching; a maximum extraction of only 44 percent was obtained with sulfuric acid. Nitric and hydrochloric acids were ineffective also.

Jan 1, 1978

By B. J. Scheiner

The Bureau of Mines investigated an electrolytic technique for oxidizing ore slurried with brine to determine its effectiveness in extracting mercury from ores. Optimization experiments conducted on a 2.5-pound-mercury-per-ton ore resulted in 95 percent mercury extraction with operating conditions of 30° C, a current density of 0.5 ampere per square inch, and a treatment time of 3.5 hours. Corresponding power consumption amounted to 38 kilowatt-hours per ton of ore treated. Amenability experiments conducted on 62 different mercury ores resulted in 90 to 99 percent mercury dissolution from ores containing 0.6 to 20 pounds of mercury per ton of ore, Treatment time ranged from 1 to 7 hours in 4-to 20-percent sodium chloride solutions, and power consumption was in the range of 10 to 50 kilowatt-hours per ton of ore. Pilot mill experiments in a 100-to 200-pound-per-hour extraction plant have been in progress to quantify power and reagent requirements. These data will be reported in a subsequent publication.

Jan 1, 1973

By William P. Diamond

A 3-inch pilot hole was directionally drilled to intercept the Freeport coalbed horizon horizontally at Mather, Pa., as part of a Bureau of Mines degasification project. The original concept was to continue the horizontal drilling into the coalbed, after the initial intercept, with a total of three horizontal holes eventually being completed. However, the erratic thickness (0.0 to 4.3 feet) of the Freeport coalbed at Mather was not sufficient to support the horizontal drilling degasification technique, and the site was abandoned after six attempts to locate adequate continuous coal thicknesses. The drilling of coreholes in the immediate vicinity of proposed well paths to evaluate coal thickness is essential prior to future slant hole operations. Although mechanical failures of the new directional drilling equipment, mud pump and rig breakdowns, directional control problems, and exploratory horizontal drilling in the Freeport horizon more than doubled the anticipated cost of the pilot hole, continuing improvements in directional drilling equipment and techniques should significantly reduce the time and costs of future drilling operations.

Jan 1, 1977

By David C. Oyler, Herbert H. Fields, William P. Diamond

A 3-inch pilot hole was directionally drilled to intercept the Freeport coalbed horizon horizontally at Mather, Pa., as part of a Bureau of Mines degasification project. The original concept was to continue the horizontal drilling into the coalbed, after the initial intercept, with a total of three horizontal holes eventually being completed. However, the erratic thickness (0.0 to 4.3 feet) of the Freeport coalbed at Mather was not sufficient to sup- port the horizontal drilling degasification technique, and the site was abandoned after six attempts to locate adequate continuous coal thicknesses. The drilling of coreholes in the immediate vicinity of proposed well paths to evaluate coal thickness is essential prior to future slant hole operations. Although mechanical failures of the new directional drilling equipment, mud pump and rig breakdowns, directional control problems, and exploratory horizontal drilling in the Freeport horizon more than doubled the anticipated cost of the pilot hole, continuing improvements in directional drilling equipment and techniques should significantly reduce the time and costs of future drilling operations.

Jan 1, 1977

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

APPENDIX G TABLE IX MINE A 1 General Total Employees 3000 Maximum No, of Men Underground/Shift 800 Shifts/Day 3 Type of Ore Copper Daily Production (TPD) 25,000 Mining Method Room and Pillar Vein Dip/Thickness l0°/l5 ft Number of Levels/Max Depth 1/0 to 1800 ft 2 Haulage, Conveyances and Travelway Main Haulage Rubber Tire/10 miles belts Man-Ways - Typical Route of Travel to most Remote Sites Rubber Tired Vehicles Hoists - Capacity/Speed/Depth Depth under construction 3 Ventilation 2,500,000 cfm - 5 surface fans 4 Compressed Air N/A cfm 10" and 12" lines 5 Incendiary Storage 2 day powder 1000 gal fuel oil 6 Communications 1 complete system - all shops, dinner areas, and feeder/breaker stations 2 partial systems 7 Escapeway- Systems Man Check System Section boss log and punch cards Alarm System Mine phones with paging system Posting of Escape Route Maps No Escape Signs Every intersection, fluorescent paint Evacuation Drills 2/yr/shift Refuge Chambers - 1 cinder block - No longer required

Jan 1, 1976

By R. D. Leitch

"REASONS FOR AND PURPOSE OF WORKIn 1924 the United States Public Health Service was requested to undertake a special study of stream pollution. At that time the proposal that the United States Bureau of Mines take up the study was made by the Public Health Service because in point of training and experience the personnel of the latter was considered not to be as well, suited to this type of investigation as was that of the Bureau of Mines. H. Foster Bain, then Director of this bureau, promised to undertake the work, and, accordingly, field investigations were begun in the spring of 1925. The problems of mine-drainage wastes and of gas-house and coke-oven waste were investigated in the laboratory, and a method of treatment by sodium hydrate and benzol was found to be promising. The idea was obtained by A. C. Fieldner, chief engineer of the Bureau of Mines experiment stations, while in Germany in 1924, where he was shown a practical application of the process, but no information was obtained as to definite chemical or mechanical processes. Because of the then pending American patent application by the German firm, we made no attempt to develop our findings further. Shortly after, a similar method of treatment was developed in the United States, and since that time we have devoted our attention entirely to mine drainage. This paper is a presentation of some general facts and information gathered during the past five years on coal-mine drainage.SCOPE OF WORKAt the time our work was begun there was such a diversity of opinion on the whole subject and apparently so little was accurately known, that it was decided to undertake a basic study from which (1) certain definite information might be evident, and (2) what might be considered side issues of the original investigation would be suggested for subsequent study.A stream in a district thought to be representative of those in low to average sulphur bituminous coal fields and another in a high sulpbur district were selected for study, A fair (weber of factors entered into the tentative selection of these streams, the chief ones being their accessibility and freedom from other industrial or domestic pollution, besides, of course, the presence of mine drainage in these streams."

Apr 1, 1931

By J. E. Chilton, C. R. Carpenter

The U.S. Bureau of Mines has developed an intrinsically safe carbon monoxide (CO) monitoring system for mines by coupling a fiber-optic data telemetry (FODT) system with a prototype electro- chemical CO monitor. The CO monitoring system can be used in a coal mine as one component of an early fire warning system. This system may be used in belt haulage entries when the entries are used for supplying ventilation air to working places. The FODT accepts a 0.1- to 1.1-V analog signal from the monitor and converts it to pulses (0 to 5 V) at frequencies from 1.1 to 11 kHz that drive a light- emitting diode (LED). An electrically nonconducting fiber-optic cable carries the LED signal to a remote receiver. The receiver analyzes the incoming light signal and displays the measured CO concentration in parts per million. This report discusses the performance of the FODT system and characteristics of the CO monitor such as response times, linearity, and temperature and pressure effects.

Jan 1, 1992

By J. P. Coughlin

The U.S. Bureau of Mines has developed a monitoring system that acquires and analyzes data for use in determining the conditions that may precede mountain bumps in coal mines. Based on a UNIX workstation linked to an array of geophones in a working longwall operation, the system captures complete waveforms of microseismic events and simultaneously obtains continuous samples of the voltage levels of each geophone. Event rates and locations are calculated and displayed in real time on the UNIX workstation, which is situated in an underground instrumentation room. These results also are transmitted from the workstation to a display computer near the longwall face. The system runs continuously and has the capability to acquire, analyze, display, and archive microseismic (transient) data and single point data, such as closure and pressure changes, simultaneously.

Jan 1, 1993

By John P. McDonnell

This U.S. Bureau of Mines report describes the results from an in-mine investigation of an alternative longwall gate road design. The coal mine operator modified the pillar layout (reversed the location of the big and small pillars) in a portion of a three-entry longwall gate road area. The modified pillar layout was an attempt to reduce stress and, subsequently, stress-related ground control problems (cutter roof and dynamic floor heave events) in the tailgate region during "second-panel" mining. The results from borehole pressure cells installed in the modified gate road area showed that the ground pressures in the panel edge and adjacent small pillar were significantly reduced during second-panel mining compared with ground pressures experienced in the typical pillar layout gate road areas. The reduced stress levels around the tailgate entry adjacent to the second panel, as compared with the tailgate stress levels with the typical pillar arrangement, contributed to improved tailgate ground conditions in the test pillar zone.

Jan 1, 2010

By R. L. Grayson, T. Simonyi, R. A. Andrel

"The purpose or this paper is to disclose analytical, statistical, and observational results relating to mineralogy and trace elements in respirable dust samples collected from two different mines in West Virginia. Samples were taken from longwall panels, and the panels operated in different coal seams, one located in the northern part or the state and the other in the southern region. Mining conditions and equipment arrangements on the panels will be described along with dust control techniques used. Results from sample analyses are summarized with emphasis on relationships between mineralogy, trace elements and mineral particle size to worker locations. Correlations are made between micro x-ray diffraction and energy dispersive x-ray analyses for sample mineralogy.IntroductionThrough the work of many researchers worldwide, the health of coal miners in modern societies is now protected from harmful exposure to respirable coal mine dust. A vast amount of research culminated in the exposure-response model of Jacobsen, et al, (l) which has been used to establish the 2 mg/m3 exposure limit in the United States. According to the model exposure to respirable dust for 35 years at this level or less could prevent the occurrence of a clinically significant case of coal workers' pneumoconiosis (CWP) in a miner. The exposure limit, of course, must be adjusted whenever greather than five percent free silica exists in the respirable dust.The Jacobsen model was built around a mean mass concentration exposure, which generally showed the highest correlation with both incidence and progression of CWP. As Morgan, et al noted, however, the quantity of respirable dust inhaled is not the only significant factor. 2) They noted that although mass of respirable dust correlates highe.st with the incidence of CWP, it is not a causal factor. Admittedly, the insidious processes causing the disease occur at the lund cell-dust particle level."

Mar 1, 1989

By R. H. Fernald

In investigating general problems that relate to the fuel resources of this country, and in testing fuels belonging to or for the use of the Government, the Bureau of Mines has given considerable attention to the efficiency and economic value of producer-gas power plants. Government inquiries during the past eight years not only have shown a very low fuel consumption per horsepower-hour for these plants but have demonstrated conclusively the possibility of utilizing commer- cially low grades of bituminous coal, lignite, and peat in plants prop- erly designed for the use of these fuels. The anthracite plant has been recognized as a commercial possibility for several years, although the cost of the fuel used has in general restricted these plants to com- paratively small units. The commercial development of the producer-gas power plant in the United States has been largely within the past six or eight years. In 1909 the United States Geological Survey published in a bulletin entitled "Recent Development of the Producer-Gas Power Plant in the United States" a list of producer-gas power-plant installations. The data presented in that bulletin showed a strong development in this field and led to much conjecture as to the future of this type of power. Owing to the extensive introduction of the steam turbine, however, many persons predicted the almost immediate doom of the producer-gas plant. In addition to the inroads made by this formida- ble rival, the interest of the gas-engine enthusiasts became centered to such an extent in the oil engine that the gas producer was relegated to second place by many and absolutely abandoned by some. During the past three years the belief of many who were formerly firm be- lievers in the gas producer has been that this type of power has reached its height of development in this country and that from a commercial standpoint it can no longer be regarded as a complete success. This feeling of commercial decadence has become so general

Jan 1, 1913

By T. J. Ballard

Corundum is a natural alumina (A120 ) and is next to the diamond in hardness . Except for the gem varieties , it is used principally as an abrasive , chiefly in grinding , dressing , and polishing metals and optical glass . Natural corundum is preferred to artificial abrasives for certain specialized jobs . Most of the corundum ( excluding emery ) mined in the United States came from the Corundum Hill mine in North Carolina and the Laurel Creek mine in Georgia . The Corundum Hill mine provided over half of the domestic production of corundum prior to 1900. Since 1900 , the importation of foreign corundum and the manufacture of artificial abrasives caused the decline of corundum mining in the United States .

Mar 1, 1947

By Timothy M. Barton

The U.S. Bureau of Mines is conducting research to assess the effectiveness of different chain pillar designs in maintaining gate entry stability. A particular concern is ground control for deep-cover 1ongwalls located at depths in excess of 1,000 ft. The study described in this report was performed in two experimental sections in one longwall headgate section which contained three different pillar designs. Two of the designs used conventional abutment pillars, while the third was a total-yielding pillar system. Both of the test areas were located under 1,800 ft of cover. The purpose of this study was to evaluate the effectiveness of these three pillar designs for gate road stability. As the longwall mined passed the test areas, Bureau engineers monitored entry convergence, roof sag, and changes in roof quality. The study indicated that the all-yield system performed nearly as well as the better of the two abutment pillar systems; but all of the three designs would have failed to provide acceptable stability for second panel mining without considerable artificial support.

Jan 1, 1989

By L. B. Berger, W. P. Yant, George W. Jones

Improper combustion of natural gas is the cause of low efficiency in heating appliances , also the liberation of carbon monoxide , an insidious and deadly gas . Carbon monoxide is produced during the incomplete combustion of any carbonaceous material , and quantities as low as 0.2 per cent may product death in a very short time . For healthy atmospheric conditions in the home , in which the occupants are continuously exposed , carbon monoxide should not be present in amount greater than 0.01 per cent , which value is taken as the safety limit in this report . The tests herein reported give the conditions which produce carbon monoxide when radiant -fire heaters burning natural gas are used . The conclusions drawn are based on tests made on one type of radiant heater only , but the general conclusions should apply to other types of radiant heaters of similar construction . The gas consumption , gas pressure , orifice pressure , size of orifice , and heater adjustments were changed so as to obtain as many different operating conditions as possible . In a general way the tests were carried out under the same conditions that the heater might be operated in the home .

Feb 1, 1923

By D. Hurrington

For severlrl 1e1.rs the Bureau of Mines has studied dust and ventili in metal mines a.s a.tfeoting the hea.l th, safety, and efficiency of underground workers. From its beginning this work haa been directed by G, s. Rice, chief mining engineer, A. cooperative agreement was ma.de in 1915 with the u. s. Publi Health Service; since that time tield obmervations 1n metal mines in Arizona, California, Idaho, Montana, Michigan and Nevada, and less extensive observation, in several other States have been made by mining engineers of the U, s. Bureau of Mines, and doctors of the u. s. Pu.blic Heal.th Service. Most of the analyt:J:eal work has been done by chemists, petrographers, and other specialists in the Pittsburgb station ot the Bureau of Mines, Numerous articles have been printed by the otticial and the technical press on this important in•estigation; 1n response to the need for a btiet bibliography of this literature. it has been compiled to facilitate accp1,intance with published data ot1. the subject,

Jul 1, 1922