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Reduce the time, complexity and expense of dissolving metal and mineral samples in solution in preparation for chemical analysis. Approach In earlier research, the Bureau of Mines developed a rapid and inexpensive method for the dissolution of mineral and metal samples in plastic pressure bottles heated in a boiling water bath. Using this technique, samples could be prepared for chemical analysis in less than one hour compared with several hours by traditional dissolution methods (see Technology News No. 85, December 1980 for further details). By heating in a microwave oven, sample dissolution time can be reduced to approximately 5 minutes.

Jan 1, 1983

By EINAR M. ARENTZEN

This information circular. deais primarily with an engineering descrip- tion of a type of longwall cutting and loading machine developed by Eick- hoff Maschinenfabrik, Bochum, Germany..: This machine is supposed to have been developed and tested during the latter part of 1941 and early 1942. The only source of information is con- tained in certain literature and engineering data, with drawings which were acquired by the Allied Military Authorities when Germany was occupied; and the information will have to be limited because the writer has not seen the machine in the factory or in operation. However, the information may be of interest to the coal-mining industry in this country, and for this reason our Government has decided to publish the data procured so far. The Eickhoff cutting and loading machine is particularly suitable for the longwall mining system. It can only be used under that type of mining system and is not suitable for the more common type known in this country as room-and-pillar work. The material for the description of the machine and its operation was compiled and translated from German drawings and operating instructions. These detailed drawings and instructions are on file with the Bureau of Mines and are available for inspection by any responsible person interested in the details of the construction of the machine.

Dec 1, 1946

By A. W. Khair, L. D. Gehl

"This paper describes the study of bit wear characteristics on three types of rock namely Tennessee sandstone, Berea sandstone and Indiana limestone. High content of quartz with quartz cement in Tennessee sandstone causes removal of material from the bit body and dam2ge to the tip of the bit resulting into excessive weight and height loss as compared to other two types of rock. The drum speed and water spray pressure do not contribute significant effect on bit wear. The polycrystalline compact diamond (PCD) tipped bits are more wear resistant than the ordinary tungsten carbide (WC) tipped bits, but, due to wider body of PCD bits, the wear rate increases particularly at greater depth of cut. INTRODUCTIONThe impact of bit-rock interaction during the cutting process in underground coal mines has always attracted the-interests of mining operators, researchers and the manufacturers. Coal cutting bears directly on airborne coal dust generation which causes ""black lung"" in coal workers. On the other hand, rock cutting generates frictional sparks causing face ignitions. The bit wear not only produces airborne rcspirable coal dust , but also affects the productivity, safety and economy. Hun and Evans (J) concluded that the point attack bits have greater ignition potential than the conventional wedge shaped bits. The results of a study (2) suggested that after 7% of weight loss, the bit should be replaced. In a survey study (3), it was found that the bit consumption of bit had an effect on the productivity and utilization of the continuous miners. The mining industry is yet to receive a solution which could provide them with optimum operating parameters for coal cutting machines in underground C9al mines.The study was, therefore, taken up to determine wear characteristics as influenced by the rock propenies and varying operating parameters. For the purpose of this study, three types of rock, Tennessee sandstone, Berea sandstone and Indiana limestone were used. The machine operating parameters included (i) drum speed, (ii) water spray pressure and (iii) bit type. Besides studying the wear characteristics, the effects of these parameters on the required cutting force, specific energy consumption, acoustic emission generation and bit temperature rise were also studied. Also, the preliminary experiments were performed to compare the bit wear between PCD and WC tipped bits."

Dec 1, 1995

At the present time many coal preparation plants handle coal-clay wastes in one of two methods. In one method, the waste is processed in a thickener, followed by further dewatering through filtration, and subsequent blending with coarse waste refuse from the preparation plant. The resulting mixture is then disposed by stacking it in available storage locations. The coal-clay waste is often reslurried by rain or water from other sources, causing a potentially unsafe situation such as mud flows. The other method often used requires thickening and impoundment of the thickened slurry behind earthen dams which poses safety risks if structural failure of the dams occurs. To overcome these two problems, a flocculation method was developed which produces a stable agglomerated material resistant to reslurrying. How It Works The new method involves treating coal-clay waste with lime to raise the pH and flocculating the slurry with a nontoxic polymer of polyethylene oxide. The resulting floes are dewatered on a static screen and agglomerated. For extremely fine waste, further dewatering of the material is accomplished on a rotary trammel screen. The dewatered material may be ponded or mixed with coarse waste from the preparation plant to produce a stable mixture that can be stacked.

Jan 1, 1985

By W. A. Cole

As the mines get older and the active workings get Farther and farther away from the original mine openings, it becomes increasingly difficult and expensive to ventilate most coal-mines properly. At the same time, the avenues of escape for those employed underground have become so extended' as often to make it impossible for them to make their way out of the mine in the event of a fire, mine explosion, or other emergency. Where such Conditions exist, the only satisfactory solution is to make new ventilation and emergency-escape openings near the active mine workings. At most mines this would necessitate sinking shafts, which is often slow and expensive.

Jan 1, 1945

By Jack Wasserman, Don Wasserman, Gretchen Hinton, Logan Mullinix, Shekar Khanal

Human testing has always been a needed way to provide information on the effects of vehicle vibration, however, the manner of testing has not reflected the real situations of driver’s hands on a steering wheel and a seat with back support and driving tasks. The typical system have used a standard sinusoidal excitation rather than the typical types of road – truck excitations The new truck driver training simulators provide the combination of road roughness, speed effects, cab environment and individual tasks. The system has a full six axis simulation potential. The simulators have the protection of the individual by a combination of two ways for the individual to stop the motion as well as an operator with visual capability who can stop the testing. The closed simulator, shown in Figure 1, has the potential for providing motion during the operation.

Jan 6, 2006

By Edward D. Thimons

A remote-actuated stench gas fire-warning system has been designed and tested by the Bureau of Mines. This system makes use of the hard-wire network for the mine's phone pager system, thus greatly reducing the system cost. By locating stench gas canisters with remote-actuation release capabilities near working sections, the fire-warning time can be greatly reduced. In a test of the system in a Missouri lead mine, the time required to warn miners of a fire at two working faces was reduced from about 20min with the conventional system to less than 4 min with the remote-actuated system.

Jan 1, 1984

By S. B. Flagg, J. F. Barkley

In the past few years an awakened activity in power-plant econ- omies has resulted in a marked improvement in the equipment for generating and utilizing steam. Although the improvement in design and construction of steam-driven prime movers has been greater than that of the steam-generating equipment, the economies obtained with the more efficient engines and turbines have stimulated interest and activity in eliminating unnecessary boiler and furnace losses. Much attention has been given to the boiler room in efforts to obtain proper combustion of the coal, because of the importance of the coal item in costs of power production. As evidence of this increasing interest may be cited the record of the development within the past few years of new apparatus for the analysis of flue gases. Many new forms of apparatus have appeared, including those for the determination of carbon dioxide, oxygen, and carbon monoxide, and others for indicating and for recording the content of carbon dioxide only, as carbon dioxide content is usually a good indicator for the control of furnace operation. Because of the large number of steam-power plants operated by the Federal Government and the number of CO, recorders used therein the Bureau of Mines undertook to collect information regard- ing the practical application of such recorders. Articles published from time to time concerning CO, recorders have been mostly descrip- tive, giving little reliable information as to the results that could be expected from the various types of instruments in ordinary prac- tice, and most of the tests made have been of a laboratory nature. Tests of several different types of recorders were made under service and laboratory conditions in order to obtain needed information. The purpose of the Bureau of Mines in publishing the results is to show the factors which may affect the accuracy of a CO, recorder and the manner in which a recorder should be tested. Readers should note that the remarks on different recorders apply to the instruments tested and not to later instruments of the same makers. In the course of the tests the following details were determined: 1. The lag in recording changes of composition of a flowing gas. 2. The accuracy of each type of recorder.

Jan 1, 1916

By Anthony T. Lannacchione, Donald G. Puglio

The Bureau of Mines developed data on the methane content of the Hartshorne coalbed, Haskell and Le Flore Counties, Okla. The methane content is calculated to be between 1.1 and 1.5 trillion cubic feet, based on an estimate of total coal in place of 2.4 to 3.2 billion short tons. Methane increases with depth, but the rate of increase decreases with greater depths. Degasification in advance of mining is recommended for all mines operating at depths greater than 500 feet to reduce hazards and methane explosions, decrease mine ventilation costs, and conserve the natural gas that would be otherwise wasted.

Jan 1, 1979

In connection with tin strategic minerals investigations of the Bureau of Mines and the Geological Survey under authority of the Strategic Materials Act (Public 117, 76th Cong., 1st sess.) a study is being made of tin deposits in the United States in an effort to improve the situation with respect to domestic supplies. These studies include sampling and exploration of some of the larger deposits with the objective of establishing emergency reserves, if possible to do so. Two exploration projects have been completed, and the over-all results obtained are set forth in this progress report. RESOURCES Tin was first discovered on this continent in 100 in the Temescal Mountains of what is now southern California. In the ensuing century, occurrences of tin have been reported in no less than 17 States and Alaska. Although most of these are of scientific interest only, tin-bearing veins and placers in California, Alabama, North and South Carolina, Virginia, South Dakota, Wyoming, Texas, New Mexico, and Alaska have been extensively explored, and largo sums of money have been expended in recurring attempts to exploit them.

Jan 1, 1941

By M. D. Schlesinger

As part of the development of processes for producing synthetic fuels from coal, the Bureau of Mines prepared a special jet fuel in a pilot plant for evaluation by the Air Force. This jet fuel had all the required physical properties, including the important specifications of high heating value and high density. However, the finished fuel did not pass the stability test specified by the Air Force and conducted by the Southwest Research Institute in a high-temperature research coker. The cause for this instability is being investigated because pure compounds of the type identified in this fuel are known to be stable. The tar acid oil used was a 230° to 300° C. fraction of low-temperature tar obtained by carbonization of a West Virginia bituminous coal in the pilot plant of the Consolidation Coal Co. Both the desulfurization at 400° C. and saturation at 300" C. were done in the vapor phase at 2,500 p.s.i.g. After catalytic treatment and distillation the final jet fuel had a boiling range of 194° to 247° C., a net heating value of 18,420 B.t.u./lb. and a specific gravity of 0.8463 60° F./60° F. It also had u pour point below -62° C., and at 0° C. its viscosity was 4.5 cs. The oil was virtually all bicyclic, 41 pct. noncondensed and 56 pct. condensed.

Jan 1, 1961

By James J. Bryja, Thomas M. Barczak, Dennis R. Dolinar, Joe Bower, Thomas P. Mucha

Maintaining ground stability in the gate roads, particularly the tailgate, has always been critical to the success of longwall mining, both in terms of safety and productivity. Several new support technologies have been developed in recent years to replace conventional wood and concrete cribbing for secondary roof support. Since their performance characteristics are unique, the best practices that have been developed with conventional wood cribbing may not be applicable for these alternative support technologies. Therefore, with so many options to consider and the importance of achieving adequate ground control at minimal cost, the trial and error approach to longwall gate road support is no longer prudent. This paper discusses a design methodology for standing secondary tailgate supports. This design technique requires in-mine measurements of tailgate support loading and convergence to establish a tailgate ground, reaction behavior based on the support and strata interaction. The methodology uses the performance characteristics generated in the National Institute of Occupational Safety and Health (MOSH) Mine Roof Simulator (MRS) to match the stiffness and load characteristics of various supports to the measured ground reaction behavior. It can be used to determine the appropriate -- application of alternative roof support systems or to design in- mine trials such that a fair and equitable comparison of different support systems can be made. A case study if the methodology at a western Pennsylvania mine site is presented in the paper, including a comparison of four alternative support technologies to conventional wood and concrete cribbing historically used at this particular mine.

Determine whether the total delay time in blasting may be safely increased beyond the currently permitted 0.5 s, without igniting a methane or methane-coal dust atmosphere and determine the minimum borehole spacing to avoid misfires. Approach At present, regulations limit the delay time used in short-delay blasting to a total of 0.5 s. Many in industry and government would like to see this total delay time increased to 1 5 to permit an increase in the number of different delays available for short delay blasting and an increase in the time between delay periods. The Bureau of Mines conducted research to determine whether the total elapsed delay time for blasting coal in underground mines could be safely expanded, with resulting improvements in productivity. The research was conducted at a surface mine in St. Clairsville, Ohio. Experimental shots were conducted in several pits, each of which had a 5-foot-high coal seam (Pitts-burg No.8) in a 50-foot highwall. The coal seam and a mobile gallery provided a good simulation of an underground coal face. The Bureau also examined the relationship between borehole spacing and misfires, to check on reports over the past few years that permissible explosives frequently misfire. These reports were not well documented, but were numerous enough to warrant investigation. Misfires of permissible explosives in an underground coal mine can be very hazardous; a burning cartridge of explosive may be ejected from a borehole and ignite the gas or dust in the mine, or a misfired cartridge in the muck pile may detonate during drilling and mucking operations, causing serious injuries.

Jan 1, 1986

By Bruce K. Cantrell, Winthrop F. Watts

The U.S. Bureau of Mines and others have conducted a number of occupational exposure surveys since the publication of the International Agency for Research on Cancer report of 1989(1), which labeled diesel exhaust as a probable human carcinogen. These surveys have assessed diesel exhaust exposure using measurement of diesel aerosol and/or specific polycyclic aromatic hydrocarbons as indicators of exposure. This report reviews, available diesel exhaust aerosol and gas measurement techniques. Measurement of human exposure to toxic agents is the first step in determining the exposure-dose-response relationship. It is a fundamental step in risk assessment. Measuring exposure to diesel exhaust pollutants is particularly challenging due to the complexity and variability of exhaust components. This paper reviews current occupational health standards for diesel emissions and available diesel exhaust gas and aerosol measurement techniques. Although surveys in mines have primarily assessed diesel exhaust exposure using diesel particulate matter (DPM) some exhaust gas measurements have been used as indicators of exposure. DPM is emphasized because it is a major component of diesel exhaust, is suspected to make a major contribution to the health hazard, and is measurable. OCCUPATIONAL HEALTH STANDARDS Occupational exposure surveys of diesel exhaust frequently measure regulated pollutants, or pollutants that are suspected carcinogens, even if no permissible exposure limits (PELs) have been established. In the United States, various organizations recommend a range of allowable values for diesel exhaust gaseous constituents, including carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO.), nitrogen dioxide (NO2), nitric oxide (NO), and formaldehyde (HCHO). Table I summarizes these recommended levels, showing 8-hour or 10-hour time-weighted-average values where available; where these are not available, 15-minute short-term [ ]

By H. R. Babitzke

The purpose of this investigation was to evaluate the potential of columbium-hafnium alloys as structural materials for use at elevated temperatures. The work described in this report was conducted to determine the properties of columbium-hafnium alloys and to select the more promising ones for further improvement. Properties determined in this report were machinability, hardness, workability, tensile strength, and oxidation resistance. Ten ingots, ranging from 100 percent columbium to 70 atomic-percent hafnium, were prepared and subjected to tests. The test results showed that the alloys with 33 and 50 atomic-percent hafnium were superior in workability, strength, and oxidation resistance. For the alloy series tested, the strength and hardness values increased with the increasing hafnium content. Maximum values were reached with 50 atomic-percent hafnium. The oxidation resistance was poorest at the 1 atomic-percent hafnium level but improved with increasing hafnium content through 70 atomic-percent. Eight of the ten ingots were fabricable at room temperature. The two remaining ingots, those with 5 and 10 atomic-percent hafnium, required hot-working.

Jan 1, 1962

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

APPENDIX D DEVELOPMENT AND EXPERIMENTAL VERIFICATION OF ACOUSTIC SEAL CHECKER THEORY 1. Introduction In Section 7 of the report the acoustic seal checker concept was described in a general manner and the parameters which affect the signal level at the microphone were discussed briefly. In this appendix the theoretical basis will be presented and the experimental program described which permitted the extension of the theory into practice. The basic goal of the acoustic seal checker is to relate the reduction in sound pressure level to the size of the residual hole in the fly ash barrier. The smallest hole size that may be measured is determined by the signal to noise ratio, where the noise in this case includes the ambient noise in the mine, the internal microphone noise and the sound transmitted from the acoustic source via the flanking paths through corridors adjacent to the one being sealed. The latter source of noise can be discriminated against, at the expense of increased complexity of the acoustic system, by employing a pulsed source and pulse gating of the microphone signal set to accept sound via the barrier path and to reject the delayed flanking path signals. In order that the acoustic system be insensitive to precise source and microphone location and to permit assessment of system performance on an acoustic power flow basis, a broad frequency band of pseudo-random noise is emitted by the loudspeaker source. The preferred frequency range must be determined, the advantage of a directive source must be assessed, and the necessity

Jan 1, 1973

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

C 2 Complete Hoisting Systems A Above Ground Installations A total of seven companies were identified who supply complete emergency escape hoist units for above ground installations The units have been designed predominately to meet the needs of coal mine operators to satisfy the requirements of the Coal Mine Health and Safety Act of 1969. The seven companies are as follows 1 Dover Conveyor and Equipment Co. 2. Coeur d' Alenes Co. 3. Connellsville Corp. 4. Scott Midland 5. W W Williams Co. 6. Equipment Corporation of America 7. Timberland Ellicott Table VIII contains detailed specifications and price information on each of these units. The units have a number of similarities

Jan 1, 1976

By J. B. Zadra, S. M. Shelton, M. M. Fine

"Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced; although it is well known that there are large deposits of low-grade ore in the United States, the production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stockpiled ore is depleted through inability to procure adequate supplies from foreign sources. Consequently, a program of laboratory and pilot-plant investigation designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines.This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program. The scope of the program and the organization that woo set up to direct and supervise the work were discussed in the foreword of the first paper of this series, Report of Investigations 3606, Manganese Investigations. 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent, and C. R. Schack. Other reports will be published as the work progresses."

Mar 1, 1942

By Robert A. Jankowski

Through laboratory and underground studies, the Bureau of Mines has evaluated the use of passive barriers (dust shields) to help confine dust generated by longwall shearers to the face area. Laboratory studies focused first on selection of the optimum barrier design, which proved to be a simple, gobside barrier (made of conveyor belting), coupled with a headgate splitter arm, which was found necessary to prevent the dust cloud from entering the walkway at the headgate end of the shearer when cutting tail to head. Further laboratory testing was done to determine whether using passive barriers in combination with different water-spray dust-reduction methods, including the shearer-clearer system developed by the Bureau, would improve dust reduction over that from using the water sprays alone. It was found that the combination of gobs ide passive barriers plus the full shearer-clearer system was most effective, and surmised that this would be especially useful in thicker seams. However, underground testing revealed that the shearer-clearer system alone was 35 pct more effective in reducing dust contamination than when used with the gobside passive barriers, and far more effective than using passive barriers with a conventional water spray system. For such an effective system as the shearer-clearer; the reduction in avail-able space over the top of the machine actually impeded system performance; this was shom1 in both eastern and western mines. But when used with comparatively inefficient water spray systems, the passive barriers, used in combination with a headgate splitter arm, provide consider-able help in reducing dust levels in the walkway.

Jan 1, 1986

By G. J. Conroy

Cable whip occurring during normal movement of a shuttle car can result in a personnel hazard and excessive tensions in the cable. This Bureau of Mines report discusses preferred payout and reel-in torque settings to reduce cable whip. A simplified adjustment procedure is described.

Jan 1, 1974