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By Thomas E. Marshall, Patrick A. Kinek, Gerald L. Finfinger

The purpose of this investigation was to evaluate the integrity of the existing shutoff valves and actuators used under high-temperature conditions in the Bureau of Mines' horizontal borehole methane drainage pipe- line system and to determine the potential for improvement in the system. In the field tests, both fire-safe ball valves and standard brass ball valves were initially subjected to a 30-min pan fire without thermal protection. Neither valve could maintain line pressure beyond 11 min in a fire that reached temperatures between 500° and 700° C. Based on the test results, it was concluded that the brass ball valve used in the Bureau's methane drainage pipeline system can be retrofitted with an inexpensive "fire bag" to substantially increase its integrity under mine fire conditions.

Jan 1, 1986

By William E. Wallace, S. J. Page, B. L. Razzaboni, C. A. Hill, Pamela Mike, P. Bolsaitis, M. J. Keane, Val Vallyathan

"Respirable quartz cytotoxicity, as measured by erythrocyte hemolysis and pulmonary macrophage release of lactate dehydrogenase in vitro, is neutralized by boiling in water in glass test tubes for 10 to 40 minutes. The cytotoxicity is reduced to near zero by boiling l to IO mg quartz per milliliter water. For greater concentrations of quartz in water the hemolytic potential after 40 minutes of boiling approaches that of native quartz. Replacing the medium with fresh water midway through boiling results in full detoxification through 20 mg quartz per milliliter water. Pre-boiling the medium with silica reduces the detoxification effect. Detoxification persists after mild drying at l 10°C for 8 hours, and persists after three days of resuspension in water at room temperature.INTRODCJCTIONResearch underway to determine interactions of quartz and other mineral dust surfaces with pulmonary fluids and alveolar macrophages in culture led to the observation that when dusts were autoclaved in aqueous suspension, their cytotoxic effects on macrophages were suppressed, in some cases fully and even after several days incubation with the cells. This finding was in direct contradiction to earlier results from both short term macrophage lysosmal enzyme release assays, as well as longer term cytotoxicity assays from macrophages in culture; in those studies, dusts were steam autoclaved at 121°C with no liquid water but with steam present. 1.2 However detoxification under boiling conditions has been reported in other research. 3 It was decided to use the hemolysis assay to further investigate these findings, because of its sensitivity simplicity and cost.RESCULTS AND DISCCISSIONRespirable quartz dust used in this study was taken from a stock of crystalline silica, Min-U-Sil; obtained from Pennsylvania Sand Glass Corporation, fractionated in air with a particle classifier. The small size fraction retained for use was 80% less than S micrometer particle diameter, with an area equivalent median diameter of 1.24 micrometers as estimated by automated image analysis. The silica was at least 98.S mass percent silica as determined by X-ray energy spectrometric analysis; and the crystalline form was alpha-quartz as determined by X-ray diffraction. It's specific surface area was 3.97 square meters per gram as determined by nitrogen adsorption isotherm methods. I"

Jan 1, 1990

By Edward Thomas

In 1947 the Bureau of Mines, as an accident-prevention measure, decided to advocate the adoption of roof bolting (suspension roof supports) in coal mines where it appeared to be applicable. Subsequent experience has disclosed that the applicability of this support is more general than was first suspected; moreover, comparison of the accident records of mines before and after adoption of the roof-bolting method shows results that more than justify the effort and funds expended. The industry has responded enthusiastically, because roof bolting proved to be not only an accident-prevention measure but also one to increase productive efficiency. In some instances this increase in the productivity of men and machines has been almost incredible and has led many mining men to conclude that through some hocus-pocus they can now cast aside many or all of the time-proven rule of good mining practice. If this tendency is not counteracted, it could easily result in an increase of roof-fall accidents, which may outweigh the benefits of roof bolting and discredit an innovation in roof control that shows great promise of materially reducing our mining accidents. From an economic standpoint it may represent the margin between profit and loss in many mining operations. The purpose of this manuscript is not to propose an inflexible code or set of rules but to summarize the experience to date as a guide for those who have the responsibility for the installation and inspection of roof bolts. This experience consists of approximately 250 investigations of roof failure in which roof bolting was involved either directly or indirectly. It should be pointed out that many of these failures were controlled, occurring during experimental periods, and comparatively few of the accidental failures actually resulted in personal injury, yet a significant number represented potential hazards.

Jan 1, 1951

The Bureau of Mines evaluated short-delay coal mine detonators manu-factured by three domestic companies for electrostatic sensitivity, strength, and no-fire current level. Electrostatic sensitivity was studied in pin-to-pin and pin-to-case modes employing lO-kV potential. Strength of detonation was measured in the Bureau's underwater test fa-cility. No-fire current was measured using a constant-current power supply unit. Test procedures and experimental data are included.

Jan 1, 1985

By A. J. Barry

To determine the torque-load relationship for SIB-inch (nominal)-diameter roof bolts, the Bureau of Mines tested 5 makes of expansion shells and 2 types of bolts (regular and high-strength) in 2 sandstone and 2 shale mine roofs. Unused flat-steel bearing plates in as-received condition were used in these tests. The relationship between torque and load was found to be approximately 50 pounds of load per foot-pound of torque for both the regular and high-strength bolts. This relationship is valid up to 130 foot-pounds for the regular bolts and up to 175 foot-pounds for the high-strength bolts. A torque of 130 foot-pounds on a regular bolt will produce a load of 6,150 ± 1,910 pounds 90 percent of the time, and a torque of 175 foot-pounds on a high-strength bolt will produce 8,050 ± 2,750 pounds 90 percent of the time. Above these values, the torque-load relationship tends to be erratic due to binding between the bolt and plug threads. Binding causes excessive torque to be expended in producing torsion in the bolt rather than tension. This torsion adversely affects the yield load of the bolt. Therefore, the installed torques should not exceed the 130-and l75-foot-pound values. A statistical analysis of the data showed that the torque-load relationship was not significantly affected by the type of bolt or expansion shell unit but might have been affected by the type of rock.

Jan 1, 1956

By M. J. Brevoort

Research work in the Bureau of Mines cryogenic laboratory requires the use of high-sensitivity galvanometers of the d'Arsonval type in a building that is subject to unusually severe vibrations. A modified form of the galvanometer suspension described by Julius3 has damped the vibrations so successfully that a short note concerning it is thought to be desirable, The laboratory is on the site of the Amarillo helium plant near a building that houses gas engines of from 180 to 250 hp., driving compressors and electric generators. The distances from the galvanometers to the individual engines range from about 80 to 180 feet. The subsoil, consisting of black clay loam, transmits the impulses without much damping. The usual methods of protecting galvanometers from vibration were tried and proved fruitless. A Julius suspension purchased on the market was carefully installed in the hope that it would overcome the difficulty, but the conditions were too severe even for this elaborate arrangement. Several mudifications of the original Julius suspension, which were then introduced, resulted in almost complete elimination of all vibrational effects.

Jan 1, 1931

By James W. Townsend, William H. King

"INTRODUCTION As a byproduct of its mineral investigation program, the Bureau of Mines has developed a number of operating devices and techniques worthy of note. This paper, prepared under the direct supervision of Paul T. Alisman, chief, Salt Lake City Division, Mining Branch, and under the general supervision of Lowell B. Moon, chief, Mining Branch, reports upon ore such technique.The Wright borehole-surveying instrument developed at the Homestake mine, Lead, S. Dak., has been described in several publications. 3/ For the benefit of those to whom the publications are not available, the instrument is described here. However, this article will be concerned mainly with the technique developed by the Federal Bureau of Mines for using the instrument.In the use of the Wright borehole-surveying instrument, it was found advantageous to develop a standard practice of operation covering type of film, preparation and care of film, loading film in instrument, placing instrument in container, exposure time, unloading film from instrument, development of film, and determination of dip and strike from film impressions."

May 1, 1947

By D. B. Dow

The transportation of any commodity which is actually or potentially a source of fire or explosion, has been made safe, insofar as humanly possible, by rigid requirements as to inspection mechanical safety devices, and by printed labels. For the most part these precautions have been sufficient. This is evident when it is considered that in the thousands of instances in which commodities with a great fire risk have been transported, few disasters have occurred. This paper deals with the recent gasoline explosion which occurred at Memphis, Tennessee. At 7:50 a.m. January 24, 1921, vapors from a tan: car of gasoline became ignited and resulted in a blast that killed eleven people and badly injured nineteen others. Probably forty or fifty men, women, and children received slight injuries from falling debris or from burns. The explosion wrecked an oil plant, leveled a block of frame buildings, and broke window panes within a radius of five blocks.

Feb 1, 1921

By R. A. Beall

Consumable-electrode arc melting is now accepted throughout the industry as the best method for producing ingots of zirconium, titanium, molybdenum, and their alloys. In addition, the technique is widely used in laboratories for fusing samples of such metals as hafnium, chromium, tantalum, columbium, and thorium. The production of consumable electrodes from these metals presents some rather difficult problems, the accepted industrial solution being the use of heavy powder-metallurgy-type presses. This paper summarizes information on fabrication of consumable electrodes by this and alternative means, such as sintering, nippling, and welding lightly pressed compacts of scrap metal. A possible saving of considerable capital investment is shown in the case of sintered compacts. The electrical circuit components of a pilot sintering unit are analyzed. INTRODUCTION The consumable-electrode arc-melting process has been accepted by most of the industry as the best method at present for producing high-quality pure or alloy in-got from sponge titanium or zirconium. This technique is not particularly new, having been patented by Von Bolton (l)3/ in 1909 for melting tantalum. However, it has been applied to industrial-scale operation only in the last few years. Among the important contributions to this technique are the work of Kroll (2) and Parke and Ham (3) and the work reported by the Office of Naval Research (4). The Bureau of Mines-has added considerably to the knowledge of this process (5-9).

Jan 1, 1956

By S. P. Howell

The Bureau of lines as repeatedly called attention to dangerous practices in the transportation and opening of kogs of black blasting powder. In 1914 Diwin Higgins (Prevention of Accidents from Explosives in Metal inos, Miners' Circular 19, Bureau of Mines, p. 15) stated "canisters should always be opened by removing the bung. To use a pick or other sharp tool for cutting a hole in the canister is dangerous. After the necessary amount of powder has boon taken out, the canister should be kept closed. The powdor should always be handled at a safe distance from an open light." In 1919, Geo. S. Rice (onthly Statement of Coal line Fatalities for June, 1919, Bureau of Mines, pp. 16 to 18) calls attention to the dangers that arise in underground transportation and handling of explosives, and calls special attmtion to the danger of hauling explosives in motor trips; the unnecessary risk involved in hauling men on the trip at the same time, and the necessity of keeping open lights away from black blasting powder. In 1919 the writer (Sensitiveness of Explosives to Frictional Impact, Tech. Paper 234, Bureau of Mines, pp. 13, 15) called attention to the fact that black blasting powder is not as sensitive to frictional impact as the nitro-glycerin dynamites and the gelatin dynamites. Black powder may be ignited by direct impact and the writer believes that this may occur without presupposing a preliminary spark. It is well known, however, that black blasting powder is very sensitive to ignition by spark flame, or heated materials, and these may be produced by an electric current, by an open light, by incandescent particles from a pipe, cigar, or cigarette, by the tearing of metal sheets or scraping of metal against metal, and possibly, by other means. -- The above discussion will serve to introduce a newly recognized hazard the ignition of black blasting powder by the forcible opening of kegs with wodden tools. The details of three accidents in which kegs of black blasting powder ex- ploded instantly when a wooden tool was driven forcibly through the top of the kegs are as follows: 1. In 1915, a powder man employed by a coal mining company stated that he was opening a 25-pound log of black blasting powder by driving a hole in the top with a wooden sprag when the powder in the leg ho was opening ignitod. This caused the ignition of fifty-two additional 25-pound logs of the powder, and the fatal burning of this and another powder man. The ono making this statement lived five hours after the explosion.

Sep 1, 1920

By H. H. Lowry

Abstracts of papers on low-temperature tar published since 1942 are included in this selected bibliography. Abstract journals -including Chemical Abstracts, Fuel Abstracts, and B.C.U.R.A. Monthly -have been consulted through 1957. Abstracts of papers on low-temperature carbonization are not included unless information is given on composition, economics, processing, or utilization of the tar; thus, papers reporting only yields of tar from assay tests, pilot plants, and commercial operations are excluded. Listing in the bibliography is alphabetical by authors; arrangement under each individual is chronological. Secondary authors are cross-indexed to the main entry. The subject index uses the main entries: Composition, economics, processing, and utilization with appropriate subheadings. A code letter following the abstract number indicates the country where the paper originated.

Jan 1, 1959

By Sidney Katell

This report is an economic evaluation of the production of hydrogen in a continuous system by the steam oxidation of partially reduced iron oxide in a fluidized bed at 7 atmospheres using producer gas to reduce the iron oxide. The oxidation-reduction step is based on experimental data obtained by the Bureau of Mines at the Pittsburgh Coal Research Center. The estimated capital requirement for a plant producing 30 million std. c.f.d.3 of 99.8 percent purity hydrogen at a discharge pressure of 450 p.s.i.g. is $13,100,000, using January 1961 equipment cost data. Based on a 330-day operating year, the operating cost before profit and taxes with coal price as a variable is estimated to be:

Jan 1, 1962

By A. Visnapuu

The Bureau of Mines investigated carbonyl processing techniques for the recovery of the critical metals Ni, Co, Mn, and Cr from domestic primary and secondary sources. In most cases, the source materials require reductive precarbonylation treatment to metallize the contained Fe, Ni, and Co compounds to render them reactive with CO. The critical metals were recovered either by direct conversion to the respective carbonyls or as upgraded products by carbonyl removal of an undesirable metal. Best metal-to-metal carbonyl conversion was under CO pressure, from 80 atm upward, and at 1400 C. Carbonylation was accelerated by the addition of HzS in small quantities. CO pressure, temperature, promoter and pretreatment trends, and other factors enhancing metal carbonyl formation are presented.

Jan 1, 1987

By W. C. Phalen

"The Phosphate Rock Market:Indications, in the fertilizer market, point to a prosperous condition, caused chiefly by the growing demand for all classes of fertilizer material in spite of a shortage of supplies. Both of these conditions have been caused by the war. The shortage in phosphate rock is being relieved as production increases, but the supply has not caught up with the demand for this spring's trade, at least. Reports from Florida are to the effect that more than half the necessary quota of laborers are at work. This may not appear to be a very good showing, but even this situation is en¬couraging because there is a larger force now at work than has been the case for some time, and it is steadily, though slowly, increasing. Some of the producing companies are conducting advertising campaigns to get laborers back to the phosphate fields and attractions in the way of better housing and living conditions are being offered.Producers are far more confident about the situation than they were two months ago, and though the shortage will not be met before the end of 1920, theme is a surplus accumulating over what is going out on existing contracts.Quotations are now being offered on all Florida rock excepting land pebble and this, it is expected, will be soon quoted.Quotations on Florida rock per ton are as follows:"

Jan 1, 1920

By R. L. Grayson, S. S. Peng

"Research has been conducted during the past year on a study to correlate respirable coal mine dust characteristics with worker positions and coal seams. The first characteristic of respirable coal mine dust which has been addressed in the correlation study is respirable dust mass concentration. In fulfillment of this objective, two mines operating in different coal seams have been selected for respirable dust mass sampling on both longwall panels and continuous mining sections. At present, sampling has been completed on the longwall panel operating in the first mine, and one half of the planned sampling has been accomplished on the continuous mining section.The first mine sampled is operating in the Pittsburgh coal seam. The average mining height is approximately 78"" with an average of 8"" of bottom shale being mined. The mine is primarily a longwall mine, and continuous mining machines are used to support the longwall.Figure 1 shows the layout of the longwall panel which was sampled. Intake air is coursed via the track heading up to the headgate area. The air splits at the headgate. Approximately 20,000-30,000 cubic feet of air per minute (CFM) is used to ventilate the longwall face and about 5,000-10,000 CFM is routed down the belt entry. Substantial leakage across the gob was noted during the sampling period. An average of 1800 CFM per 100 feet of face leaked through the shields into the gob from #1 shield to #112 shield. A substantial amount of leakage also occurred between the #1 shield and the solid rib of the headgate development panel. The path of the air used to ventilate the panel is shown with arrows in Figure 1. Direction of air flow was opposite to the coal moving direction on the armored face conveyor.A double-drum ranging shearer is used on the face to cut a 30-inch web of coal. Normal practice is to cut from the tailgate to headgate with the leading drum raised and the tail drum lowered for cutting bottom. After reaching the headgate, the shearer is reversed and both drums are lowered for a clean-up pass. The last 40 feet of face on the tailgate is cut on the clean-up pass.The shearer is equipped with 2 banks of 4 water sprays each and 2 large sprays on the headgate end and 1 bank of 4 sprays on the tailgate end. Additionally, sprays are located above bits on the cutting drums. Actual cutting speed was approximately 14-18 feet per minute, depending on conditions.The cross sectional area for air flow on the face was approximately 60 square feet before a pass was mined and 80 square feet after a pass was mined but before the shields were advanced. The cross sectional area at the shearer was about 35 square feet.The condition of both the tailgate and headgate of the panel was good with no signs of significant roof problems. The roof conditions along the face during the sampling period were variable. At times, as much as 3 feet of drawslate fell from the roof for a span of as much as 40 shields. Generally, however, relatively local areas of falling roof were encoun-tered, usually limited to a 10-20 shield span when appearing.Ten days were spent gathering respirable dust samples on the longwall panel. Mine Safety Appliance (MSA) sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters, and constant-flow DuPont pumps were used to obtain thesamples. The pumps were calibrated at a 2 liters-per-minute flow rate. The 10-mm cyclone was selected for classifying total dust into the desired respirable fraction in order to obtain ""legally defined"" respirable dust samples for detailed physical characterization."

Jan 1, 1988

Remotely monitor overburden response to longwall mining using time domain reflectometry (TDR) and a combination of hardware and software, as part of the U.S. Bureau of Mines (USBM) program to characterize subsidence. Background TDR was developed in the 1960's as a method to locate, discontinuities in coaxial transmission cables. In this method, voltage pulses sent along a cable are reflected by cable defects. The pulse reflections are used to determine the type and magnitude of the defects. The TDR concept was extended to material property measurement by embedding cables into particular materials and evaluating the cable's dielectric behavior as material properties were modified. This technique was adapted by the USBM in 1978 for use in monitoring rock movement during underground mining. The same concept is utilized today. A coaxial cable is grouted into a rock mass that is expected to deform. Progressive rock movement causes the cable to deform, as shown in figure 1, and changes to occur in the cable's electrical properties, which then produce changes in TDR reflection signatures. The technology has advanced to the point where it is now possible to distinguish shear deformation from tensile deformation and to quantify rock mass displacements by analyzing the TDR signatures.

Jan 1, 1995

By George S. Rice

There have appeared, from time to time, comparisons of various features of coal mining practice in the United States and Great Britain. A recent, article, appearing in a British journal, points out that the American miner produces 3 1/2 times as much coal per shift as the miner, at one-half the cost, and proceeds to explain the natural industrial, and engineering causes which lead to this result. Amon« he reasons advanced. is that the American coal miner enjoys the advantage of more easily worked seams of coal, due to the fact that the coal mining industry in the United States is of more recent date than in Great Britain. The latter qualification is not correct, because where these advantages exist, they will persist. The coal beds of the United States are not buried deeply, except in the remote parts of the country, as in the Uinta Basin of Utah. The article referred to states that many of our miners are still employed on out seams reached by "adits", (which we term entries), or by vertical shafts of moderate depth. It is probable in fact that the great bulk of the coal of the United States is taken out from a depth of less than 400 feet.

Mar 1, 1920

By William K. Tolley

The U.S. Bureau of Mines (USBM) is currently investigating the electrochemistry of mineral flotation. A significant need in this area is greater reliability of sensors. The USBM is testing electrolytic methods to clean and condition redox-sensing electrodes to improve the reliability and extend the service life of these instruments in the harsh physical and chemical environment of mineral processing slurries. A novel method for removing scale from fouled electrodes has been developed that includes anodic polarization to 1.2 V versus the Ag/ AgC1 reference potential, followed by brief potentiodynamic conditioning. Laboratory results show that this technique removes calcarious deposits from gold sensing electrodes and returns the electrodes to useful service within approximately 10 min. Mechanical abrasion to remove the scale is thereby avoided.

Jan 1, 2010

By P. A. Wasson, M. M. Fine

Roasting research involving small , batch experiments was conducted to explore the use of solid reductants for converting nonmagnetic iron ore to a magnetic type . Three typical Minnesota ores were tested with one or more of the following reductants : Lignite , lignite chars , anthracite , bituminous coal , petroleum coke , peat , and pyrite . Reductive roasting was accomplished in a 3- by 4- inch externally heated rotating drum . Ore and reductant were placed in the drum and heated to a desired temperature , which was maintained for a predetermined period . Recoveries of over 90 percent of the iron in magnetic concentrates were achieved at 650 ° C , using lignite , some lignite chars , a high- volatile bituminous coal , peat , and pyrite . Pyrite is a novel reductant , which is superior to carbonaceous materials other than lignite and some chars .

Jan 1, 1963

By R. L. Handy

The goal of this research was to adapt the highly successful rock borehole shear test for use in deep, small-diameter boreholes. Operating somewhat on the principle of a rock bolt, the borehole shear test measures both the expansion pressure and pulling force to give discrete measures of rock shearing strength as a function of the applied normal pressure. A new instrument was designed and built to fit into a 2-3/8 inch diameter hole. Unfortunately the design became so complicated, the operation is nut reliable. This is attributed to constraints of the small hole, and added requirements of an in-hole anchor to push against, and a rotating shear plate cleaner for repeated tests down-hole. A clue to the d: vice complexity is its length, which is over 10 feet. Furthermore it employs concentric cylinders and one hydraulic cylinder bored into the piston of another, or it would be even longer. Meanwhile drilling technology has advanced to greatly reduce costs of drilling 5- or 6-inch diameter holes. The downhole tester therefore should be redesigned and simplified for use in a larger diameter drill hole.

Jan 1, 1982