Search Documents

By Gregory J. Chekan

As part of the initial investigation and validation of a new boundary-element formulation for stress modeling in coal mines, the underground stresses and displacements at two multiple-seam coal mines with unique stress problems were modeled and predicted. The new program, LAMODEL, calculates stresses and displacements at the seam level and at requested locations in the overburden or at the surface. Both linear elastic and nonlinear seam materials can be used, and surface effects, multiple seams, and multiple mining steps can be simulated. In order to most efficiently use LAMODEL for accurate stress prediction, the program is first calibrated to the site-specific geomechanics based on previously observed stress conditions at the mine. For this calibration process, a previously mined area is "stress mapped" by quantifying the observed pillar and strata behavior using a numerical rating system. Then, the site-specific mechanical properties in the model are adjusted to provide the best correlation between the predicted stresses and the observed underground stress rating. Once calibrated, the model is then used to predict future stress problems ahead of mining. At the two case study mines, the calibrated models showed good correlation with the observed stresses and also accurately predicted upcoming high stress areas for preventive action by the mines.

Jan 5, 1999

By J. B. Littlefield

The Greenburg-Smith impinger was developed at the Bureau of Mines in cooperation with the United States Public Health Service in 1922 in the course of an investigation of dust-sampling instruments available at that time. Although it is not used extensively outside of the United States, it is now soused in this country to collect samples for the determination of any dustiness, and most of the information correlating degree of dustiness with physiological effect has been obtained by the impinger method. The chief disadvantages in the use of the regular impinger, especially in mines and other places accessible with difficulty, are its bulk weight, and power requirements. It requires a source either of electricity or of compressed air, which necessitates connections and extension of existing supply lines to each sampling point; the only alternative is the use of a relatively large pump hand-operated with considerable effort.

Jan 1, 1937

By W. M. Dressel

A simple field test for detecting the presence of germanium in rocks, coals, and flue dust has been developed by the Bureau of Mines. The method consists of dissolving germanium from the samples by either acid or fusion treatment methods, adding a few drops of hematein or phenylfluorone dye, and extracting the resulting colored complex with carbon tetrachloride. INTRODUCTION Germanium is obtained commercially as a byproduct of zinc production, as a coproduct of base-metal refining from germanium-bearing mineral, and as a recovered product from the ash of some coals. The growing use of germanium in the electronics industry has increased demand for this semiconducting metal to the extent that an intensive search for new sources of supply is necessary.

Jan 1, 1962

By J. H. East, D. Harrington

Fires in metal mines have resulted in some of the worst disasters in American mining history insofar as loss of life is concerned. One fire caused the death of 163 miners and individual less spectacular fires have cost the lives of scores of workers. Metal mines are often very deep, and the men working on numerous levels far removed from direct communication with the surface. In many instances they cannot be warned quickly of an emergency or a mine fire by telephone or other usual method of communication, or by messenger, flashing lights, gongs, sirens, or whistles. Telephones are not paricularly effective as a means of warning unless placed at all strategic points and with attendants always on duty; though telephones well placed have a definite value in any well-pla.mied emergency procedure in mines of all kinds. Messengers are slow and men working in remote parts of a mine would not receive a warning quickly enough. Most metal mines are not electrically lighted, except at or adjacent to shaft stations and in principal haulageways, and this limits the effectiveness of flashing lights. Electric gongs and sirens or whistles have been tried as warning signals, but the sound is quickly deadened and does not travel upward into the stopes, especially those of an extensive volume. Shutting off the compressed air is by no means satisfactory as a warning, as not infrequently it is stopped accidently, so that it loses its value as an alarm. The introduction of water into compressed air lines is undesirable as a fire warning and necessitates considerable care, especially in deep mines; pressure-reducing valves must be provided to reduce pressure that otherwise would break connections or split the pipe. A quick, effective method of warning miners underground of the existence of an emergency requiring them to leave the mine immediately, such as a fire on the surface or underground, is provided by the introduction of stenches in the compressed-air lines. This method of warning is by no means experimental, inasmuch as it has been used successfully for many years in

Jul 1, 1943

Develop personal computer (PC) based software for analyzing and/or filtering time- and frequency-domain attributes of seismic and electromagnetic signals from geophysical surveys for the enhanced interpretation of rock masses and subsurface geologic structure. The Problem Both mining and petroleum geophysicists utilize seismic signals to characterize rock masses for delineating subsurface stratigraphy and structural conditions. However, a vast amount of information available in seismic project evaluation data often is unavailable for interpretation unless these data are enhanced. New processing technology increases the quality of these signals for analysis and interpretation. Comprehensive signal processing software is mostly written for petroleum exploration companies. Commercially available signal processing programs are often limited to a single application or are restricted for use with specific hardware, e.g., a digital oscilloscope or a mainframe computer. The programs may use computer codes that are proprietary, restrict user modification to expand capabilities, or may be hard to interface. They may have insufficient documentation for easy use and be support dependent.

Jan 1, 1990

By R. L. Hopkins

The work described was performed to determine whether sulfur compounds of the thienothiophene class occur in crude oil. The presence or absence of various classes of sulfur compounds in crude oils is of interest and value to petroleum science. The Bureau of Mines, for the first time, identified hydro-carbon products of desulfurization that point directly to the identity of two individual thienothiophenes, namely 3-methylthieno[2,3-b]thiophene and 2-meth-ylthieno[3,2-b]thiophene, in Wasson, Texas, crude oil. These identifications, described in detail, were accomplished using microdesulfurization, mass spectrometry, and gas-liquid chromatography.

Jan 1, 1966

By T. Whitrnoyer, J. Sneckenberger

"The acOustic impedances of seven rat lungs were measured at frequencies between 100 and 6400 Hz. Rats were divided into two groups: a silica exposed group (N=3) and a control group (N=4). The silica exposed group was injected intratracheally with silica solution. Three of the control group were intratracheallyinjected with saline. Between four and six weeks after theinjections, all lungs were excised and degassed. Lungs were,suspended in a pressure Chamber, with the trachea canula attached to the end Of a tapered impedance tube. The lungs were subjected to transpulmonary pressures between -30 cm H2O and 6 cm H2O to simulate deflation and inflation. With transpulmonary pressure being held constant, the impedance tube was excited with random noise. A dual channel analyzer calculated H12(f), the transfer function between the two microphones. This function was used to calculate the lung's impedance at that pressure. The impedance magnitude spectra of both groups typically had peaks at 2000,3500, and 5500 Hz. Statistically significant differences. (90%confidence level or greater) between the two groups occur at the 3500 Hz peak at transpulmonary pressures of 20, 8, 6, 4, and 2 cm of H2O. This fact seems to confirm that this method can detect. lung disease. Further research will indicate whether this method will be able to detect the onset Of coal worker's pneumoconiosis.INTRODUCTIONOne of the first studies of impedance Of the human lung were conducted by DuBois et al.[2] using the forced OscillatiOn technique. This technique, however, was limited to frequencies below 30 Hz. Further studies by Van Den Berg [6] revealed thatthe lung reflected higher frequency sounds (100-10,000 Hz), instead Of behaving as an anechoic termination. This discovery has lead to several studies of the acoustical properties of both human and animal lungs at high frequencies [3,4,5]."

Jan 1, 1988

By A. Bartkowiak

The lower flammability limit of methane at 0 p.s.i.g. and ambient temperatures is 5.6 volume percent in chlorine, 5.2 in oxygen, and 5.0 in air. The corresponding upper limit values are 70, 60.5, and 15 volume percent, respectively, so that the range of flammable mixtures is greater in chlorine than in oxygen or air. The lower flammability limit of ethane at 0 p.s.i.g. and ambient temperatures is 6.1 volume percent in chlorine, 3.0 in oxygen, and 2.9 in air. The corresponding upper limits are 58, 66, and 12.5 volume percent, respectively. In this instance the range of flammable mixtures is greater in oxygen than in chlorine or air. Generally, the limits of flammability for both methane-chlorine mixtures and ethane-chlorine mixtures widen with increases in temperature and pressure.

Jan 1, 1960

To provide a simple means for rapidly checking methane concentrations at working faces in coal mines while remaining under permanently supported roof. The Approach: A light telescopic probe, through which a gas sample can be pumped Into a methanometer, has been developed. See Figure 1 [ ] How It Works: The telescopic probe consists of sections of small stainless steel tubing encased in sections of lightweight fiberglass tubing. When fully extended the probe is almost 19 ft. long; fully closed it is approximately 5-1/2 feet long. It can be used In either of these positions as well as at intermediate extensions. An approved methanometer is clamped to the probe by a support bracket.

Jan 1, 1975

By J. W. Town

The Bureau of Mines studied the effects of reducing gas composition, tem-perature, and superficial gas velocity on the regeneration rate of alkalized alumina. Regeneration was assumed to follow the simple first order reaction for removal of sorbed S02: dµ/dt = -Kµ. An Arrhenius relationship can be plotted, which shows an activation energy of about 75 kcal/mole for simulated reformed propane. The general effects of the individual gases can be described as follows: (1) CO and H2 produced rates proportional to their con-centrations, up to about 5 percent for each; (2) addition of CO2 had no effects on the regeneration rate by CO; (3) the regeneration rate by H2 was lowered by the addition of H2O while the regeneration rate by CO was increased by 0 addition; (4) H2S showed a positive effect up to concentration levels of about 2 percent and then produced a rapid negative effect; (5) carbonyl sulfate (COS) increased the sulfur content; and (6) propane was as effective in regenerating the loaded pellets as was simulated reformed propane.

Jan 1, 1971

Minimize the risk of conveyor belt fires in underground coal mines by improving the accuracy of and means by which flammability data are acquired. Approach Develop a large, laboratory-scale flammability test for mine conveyor belting that realistically assesses its fire resistance. Background A conveyor belt fire in an underground coal mine is a serious threat to life and property. To minimize the risk of belt fires, the U.S. Code of Federal Regulations (CFR) for underground coal mines requires approved fire-resistant belting. Despite this precaution, about 25% of the reportable underground coal mine fires from 1983 through 1988 involved conveyor belting. In several instances, hundreds of feet of belting were destroyed. The current flammability test for fire-resistant belting is specified in 30 CFR, Part 18.65 and is conducted by (be Mine Safety and Health Administration (MSHA). The small-scale test is performed in a 21-in-cubical chamber with 6-in-long by 1/2-in-wide belt samples. To evaluate the flammability of conveyor belting under more realistic conditions, the U.S. Bureau of Mines conducted large-scale fire tests of belting. The large-scale data were then utilized in the development of an improved laboratory-scale flame test for fire-resistant belting.

Jan 1, 1991

By David J. MacDonald

Stability constants, that is, equilibrium constants for complex-formation reactions, have been determined by a titrimetric method for complexes formed by the transition metal ions Ni2+, Cu2+, Zn2+, and Cd2+ with the structurally analogous bidentate ligands N-ethylethylenediamine and 2-(ethylthio)-ethylamine. The sulfur containing ligand was found to be the weaker of the two chelating agents for each of the four metals. Absorption spectra of the individual complexes have been determined in order to calculate their crystal field stabilization energies. The combined results suggest a linear relation between free energy of chelation and ionic radius of the metal ion.

Jan 1, 1972

By James R. Means, George Bowser

A new phone system was developed that provides eight full duplex communications channels over a single twisted shielded phone line, with no central switching station or line amplifiers. This system greatly simplifies installation and maintenance over that required with conventional switching systems. The system is based on microprocessor technology and digital frequency synthesis. Frequency division multiplexing is used over a bandwidth of approximately 300 kHz, and a baseband voice channel (compatible with conventional pager phones) is provided as a backup to assure communication if the multiplex features fail. Multiplex operations are controlled over a 30-kHz digital channel. The system is designed to operate with up to 16 km (10 miles) of cable plant and a maximum phone separation of 8 km (5 miles). The digital techniques permit a limited amount of monitoring and control capability to each phone. This consists of two pair of contact inputs or outputs, to be used as desired. These "flags" may be read or controlled by a dispatcher's phone.

By P. Kovalchik

The Bureau of Labor Statistics (BLS) classifies hearing loss as a separate illness category. Hearing loss accounted for 11% of all illnesses in 2005 (U.S. Department of Labor Bureau of Labor Statistics, 2006a). According to occupational data for coal mining provided by the Mine Safety and Health Administration (MSHA) from 2000 to 2005, operators that exceeded 100% noise dosage were from only seven types of machines: auger miners, bulldozers, continuous mining machines, front end loaders, roof bolters, shuttle cars (electric) and trucks (Title 30 CFR Part 62, 2000-2005). Roof bolting machine operators rank second among all underground machine operators that exceed 100% noise dose. There are approximately 600 underground coal mines with 3,930 roof bolting machine operators (U.S. Department of Labor, Mine Safety and Health Administration, 2005; U.S. Department of Labor Bureau of Labor Statistics,

Jan 1, 2008

By A. W. Ambrose

"Introduction.Oil-field operations have often been carried on under great stress and haste, in which the prime purpose has been to put the wells down rapidly as possible, without regard to a few of the various factors affecting cost. In such fields as Burkurnett, Texas, where the well locations are town lots and other small tracts, the operator was concerned primarily with in drilling. In such cases a few thousand dollars more or less in the cost of a well not considered. We are reaching a time, however, when our reserves a,more definitely outlined and properties are being along more economic lines. Operators are becoming more concerned with the actual cost of this work, and are gradually learning that fuel consumption can be reduced in drilling and producing without delaying the speed of drilling, and in the case of production, it will greatly reduce the unit cost per barrel of production.Types of Field Boilers.In the oil fields there are in general two types of boilers; those which are used for drilling wells and are of a more or less portable character, and those established later in a more permanent form and serve for the purpose,of generating steam for producing the oil. As a rule, the latter type of boilers are larger than those of the drilling type. Usually, little care is given to the installation of drilling boilers; particularly in attempting to set them up in such a way as to avoid waste in of fuel. Because of the temporary nature of these installations there may be some justification for not giving them more,attention in this resend, but it is believed that a few precautions could be taken that would amply repay the cost and trouble taken. In connection with the boiler plants that are afterwards established, when a few producing wells have been,brought in with a life of two to ten years and probably longer, much care to the boiler-plant construction and to the installation of recording instruments which will assist in operating the plant at minimum cost."

Nov 1, 1920

By D. W. Frommer, M. M. Fine

Laboratory investigations have produced flotation concentrates contain- ing 91 to more than 92 percent titania, with fair recoveries, from the Christy property, Hot Spring County, Ark. The titanium-bearing ore on the Christy property occurs in a quartz-clay- iron oxide mineralization, which contains, on the average, about 6.0 percent TiO2, chiefly as the mineral brockite; brookite and rutile are different crys- talline forms of titanium dioxide. Recent work by the Bureau of Mines has shown that titanium chloride can be produced readily from the rutile-type mineral by reduction with coke fol- lowed by low-temperature chlorination. Metallic titanium is in turn derived etallic from the chloride by the Kroll process .

Mar 1, 1952

By O. Q. Leone

Composite diaphragms were used in the investigation of electrowinning Ti from TiC14 in a fused LiCl-KCI-TiC'2 electrolyte. Composite diaphragms tested were of two general classes--those consisting of two or more solid materials, and those which contained, in addition, a loose material. An electrowinning cell using a flat diaphragm is described. The maximum current density for these diaphragms was 300 amp per ft2. Lower currents permitted longer operation times. The composite diaphragms gave electrode efficiencies that averaged approximately 60 percent, and the electrowon titanium was of good quality--some Brinell hardnesses were as low as 68.

Jan 1, 1972

By Fred D. Wright

A compressor and utility station, which is believed to be one of the largest mobile units of this type ever constructed, was placed in operation at the Bureau of Mines experimental oil-shale mine near Rifle, Colo., during. 1949. This mobile unit mounts two 770-cubic-feet-per-minute air compressors, a 2,500-gallon water tank, and a 200-cubic-foot air receiver. The mobile base of the unit is a 30-ton trailer 30-feet long and 12-feet wide. Prior to the construction of this unit, compressed air was supplied to underground workings through pipe lines connecting with a stationary compressor plant on the surface. The power consumed in supplying compressed air to underground drilling crews was 0.531 kw.-hr. per ton of shale broken. Use of the mobile unit has cut this figure to 0.421 kw.-hr. per ton of shale broken and, more important, has eliminated the cost of installing and maintaining underground air and water lines.

Jan 1, 1950

By R. M. Winslow

"The phosphorus content of an iron ore is a determining factor as regards the value of the ore and also its metallurgical treatment. If some method of treatment, such as concentration, leaching, etc., could be used and the phosphorus con- tent of the ore reduced, it would be an important advancement in the iron mining industry towards the utilization of high phosphorus ores. Large bodies of material toe high in phosphorus to be marketable under present conditions would be made available, and a great deal of ore from the Cuyuna Range and other places, which is relatively high in phosphorus but otherwise suitable for making spiegel, could be reduced in phosphorus content sufficiently to permit its use in furnaces producing speigel.The form in which phosphorus occurs in iron ore is a much disputed question and it probably varies with the type and location of the ore. The statement has been made that ore piles on long exposure to the atmosphere often decrease in their phosphorus content. (Emmons, S.F. - Ore deposits, 1913, p. 652; Leith, C.K., Mesabi iron bearing district, U.S.G.S. Monograph 43, 1903, p. 275) There is described below experiments on the leaching of iron ores high in phosphorus, to determine whether it was economically possible to reduce the phosphorus content appreciably by leaching. As the research had a practical as well as a theoretical application, only low concentration of acids and alkalies were used.A number of variables were tried, among these being: (1) The solvent used, (2) strength of the solvent, (3) volume of solution used, (4) time ore was agitated (5) type of ore, and (6) screen size of the ore. The amount of ore taken was kept constant."

Jul 1, 1921

Provide reliable, early-warning fire detection instruments, telemetry, and control systems for noncoal underground mines. Approach Industrial-grade fire detection instruments and signal telemetry equipment were modified for long-term exposure to harsh underground mine conditions, then were installed in four mines to evaluate long-term performance and reliability. How It Works The elapsed time between the onset of a fire and its detection is critical because fires tend to grow in size and intensity with time. Early fire detection and warning permit the initiation of a mine's emergency plan (evacuation, fire fighting, etc.) while the fire is still small, or ideally, while it is still in the incipient stage. Fire detection and warning systems, utilizing sensitive heat, flame, smoke, and gas analyzers, provide the most rapid and reliable indication of a developing fire.

Jan 1, 1987