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By G. S. Scott, G. W. Jones

"INTRODUCTION In the course of the investigation the Bureau of Mines is carrying on to determine the causes, behavior, a. control of mine fires, the detection of incipient heating underground in the mines and above ground in refuse banks has received consideration.Many of the anthracite fires have been active for years and have progressed considerable distances free their original source.Some of the fires are in inaccessible territory, and it is often impossible to determine with any degree of accuracy their exact location or even the veins of coal that are afire, especially when the fire is in the upper strata and when it is impossible to go underground because of flooded conditions or the presence of an irrespirable atmosphere.In such cases, the only means by which the trend of a fire may be ascertained (as a result of any fire-fighting methods that may have been employed) are the sampling, exanination, and interpretation of the gaseous products coming from the fire area. The most important information desired is to know whether the temperature in the heated area is increasing or decreasing and to determine whether a fire that has been sealed is cooling down to normal mine temperatures or is maintaining its heat or is increasing in intensity due to infiltration of outside air.Interpretation of the analyses of gaseous products from refuse banks on the surface also should be of value in combating such fires. Refuse bank fires, with the additional danger of starting an underground fire through ignition of the outcrop, are by no means unknown in the anthracite coal region, and the causes of such fires are not always apparent. In a few cases the causes have been strongly suggestive of spontaneous origin."

Jun 1, 1938

By Nicholas P. Kripakov

The U.S. Bureau of Mines examined the applicability of existing material models to solve practical geotechnical mining-related problems by solving a yielding pillar stability problem considering confining effects on strength. Numerical difficulties normally encountered with modeling strain softening behavior were eased with a simplified computational procedure using a quasi-elastic approach to account for residual strength after initial failure. Although in agreement with a confined-core pillar design method using actual mine conditions that include mine layout geometry, overburden geology, and rock properties of the deposit and surrounding structure, the results cannot be verified because measured field data are not available at this writing.

Jan 1, 1981

By R. L. Wise

Heat content studies were conducted on burned shale, spent shale, and three grades of raw oil shale from the Green River Formation. Corrections were made for product enthalpies. The results were compared with previous work, indicating good agreement below retorting temperatures, but some differences at retorting temperatures. A general equation was developed relating heat content to oil-shale grade and temperature.

Jan 1, 1971

Reduce the hazards to which mine personnel are exposed by providing safer procedures for removing dragline wire rope terminations. Background The termination points of wire ropes used on draglines consist of a wedge and socket that lock the rope in place through friction. These components must be separated when the wire rope is changed. At present, the cannon method is the most common procedure used to accomplish this. However this method, using a small cannon and primer (detonator) cord to propel a steel projectile that will knock the wedge out of the socket, has the potential of causing injuries to mine personnel and damage to equipment. The Bureau of Mines, has devised safer, and equally efficient methods of removing wire rope terminations. The Bureau began by studying the cannon method, its merits and draw-backs. Safety guidelines were then developed for the cannon method, and two alternative methods-the pendulum ram and hydraulic pusher-were devised and tested. The Cannon Method The steel projectile used to separate the wedge and socket in the cannon method was found to be very effective. However, the method poses the inherent hazards of any explosive de-vice-hazards that could be increased by lax work procedures. There is no strict uniformity in the manufacture of the cannon or in the work procedures used in the mines employing it. Hazards could be reduced, or even eliminated, with adaption of certain manufacturing and work-procedure guidelines, such as 1) making the cannon and projectile de-signs, as well the work procedures used, uniform, 2) ensuring separate loading of the charge and detonator with insertion of the detonator through a separate port, 3) connecting electrical firing circuits only after the charge and projectile are loaded and the cannon is placed in its final firing position, 4) using approved detonating devices, 5) anchoring the cannon before firing and, 6) placing armor netting over the cannon before detonation.

Jan 1, 1986

By L. A. Readdy

No text. A set of geophysical well logs for U.S. B.M. Pilot Hole "X", Piceance Creek Basin, Colorado.

Jan 1, 1977

By Jack E. Fraley

Poor lubrication reduces the life of wire hoist ropes when they are used in corrosive environments. Although lubricants are added to ropes during the manufacturing process, these lubricants can deteriorate during use, and it is often necessary to add more lubricant to both the interior and exterior of the rope while it is in service. The U.S. Bureau of Mines evaluated the effectiveness of synthetic lubricants, using electromagnetic nondestructive testing (NDT) to measure deterioration in ropes while they were in service. For nonpressurized lubricant applications, synthetic lubricants appear superior to petroleum-based lubricants in their ability to penetrate to the interior of a rope. Therefore, the synthetics offer better wear and corrosion protection.

Jan 1, 1990

By Kenneth C. Stewart

Eight brands (three samples of each kind) of commercially available audio-dosimeters were performance-tested. Each unit was placed in an anechoic chamber and subjected to various acoustic signals to measure its A-weighting response and overall integration accuracy. All units met the A-weighting tolerance for type II sould level meters, and six brands were within the Bureau I s overall accuracy requirements of ±2 dbA referred to input.

Jan 1, 1974

By Richard L. Sayrs

The Idol zinc prospect, formerly known as the Comstock, was examined by Harold B. Ewoldt, a Bureau of Mines' engineer, accompanied by Deane F. Kent of the United States Geological Survey on July 22, 1943. Previous to that time, the Geological Survey had contoured and studied the area. As a part of the war minerals program, further investigation of the area was recommended. The Dalton property, a mile and a half northeast of the Idol property, was examined during the progress of the work at the Idol, and it was decided to include this property also in the project. From February 7, 1944, to May 16, 1944, six holes totaling 2,739 feet were diamond-drilled on the Idol property and eight holes totaling 1,850 feet were diamond-drilled, and three pits channel sampled on the Dalton property. The drilling showed sphalerite to be sparsely distributed through a 100 foot thickness of the Kingsport member of the Knox dolomite.

Jan 1, 1949

Decrease the dust concentrations at the shearer and reduce downtime associated with spray system maintenance. Approach Increase the quantity and quality of the water supply on longwall faces by decreasing pressure losses, Increasing pump capacity, and installing a "non-clogging" filtration system. How It Works Water sprays and ventilation are two of the primary methods of dust control on longwall operations. Increasing the quantity and quality of the water supply to spray systems is one of the more effective and least costly dust control methods that operators have at their disposal, yet this method is largely ignored. Poorly positioned spray nozzles operating at low pressures (and flows) which plug frequently cannot be effective. Water supply system Improvements should be a fundamental part of all longwall dust control plans. Upgrading a water supply system may require one or more of the following improvements depending upon where a particular system may be deficient: Increasing pump capacity for additional flow and pressure; increasing line sizes to decrease pressure losses: and, decreasing maintenance downtime and Improving water quality by installing a "non-clogging" filtration system.

Jan 1, 1981

By E. D. Gardner

This paper is one of a series on milling methods being published by the United States Bureau of Mines. Atlanta is in Elmore County, Idaho, about 80 miles from the railroad at Mountain Home, Idaho. The concentrator is at an elevation of, 6,000 feet and located in a timbered, well-watered region of relatively heavy snowfall. The snow, however, does not seriously affect local operations. The track road to Mountain Home, which passes over a mountain range, is closed each winter from about November 1 to June 15. During this period concentrates are stored and bullion is shipped by airplane. Power is generated by a Diesel engine and by an auxiliary hydroelectric plant. Gold is the principal metal produced; the or also contains an able quantity of silver.

Jan 1, 1935

Pillars with width-to-height ratios of less than 1.0 are frequently created in underground hard rock mines. The strength of slender pillars can be estimated using empirically developed equations. However, the equations can provide variable results when the width-to-height ratios approach 0.5. This paper investigates some of the issues affecting pillar strength at low width-to-height ratios in hard brittle rock. The investigation includes an evaluation of empirical pillar strength data presented in the literature and observations of pillar performance in underground limestone mines in the eastern United States, supplemented by numerical modeling in which failure processes and sensitivity of slender pillars to variations in rock mass properties are evaluated. The results showed that the strength of slender pillars is more variable than that of wider pillars. The numerical model results demonstrated the increasing role of brittle rock failure in slender pillar strength. The absence of confinement in slender pillars can result in a fully brittle failure process, while wider pillars, fail in a combined brittle and shearing mode. The onset of spalling in slender pillars occurs at or near the ultimate strength, while this is not the case for wider pillars. Slender pillars are shown to be more sensitive to the presence of discontinuities than wider pillars, which can partly explain the increased variability of slender pillar strength. Two examples are presented that illustrate failure initiation by brittle spalling and the sensitivity of slender pillars to the presence of discontinuities.

By F. N. Kissell, R. J. Bielicki

The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. Air samples were collected in glass syringes and analyzed by electron-capture gas chromatography. In these studies, the lower limit of detection was about 1 part per billion by volume (ppb) of SF6 per part of air. Experiments conducted in a Pennsylvania limestone mine showed this technique useful in evaluating the effectiveness of auxiliary fans, measuring low flow velocities, probing the air circulating near a working face region where ventilation appeared to be poor, and estimating volumetric flow rates in airways of large cross-sectional area and having low flow velocities. This technique was also used in a western vein-type metal mine to measure the amount of return air being recirculated into the intake air due to leakage through old stoped areas.

Jan 1, 1974

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

INPUT FORMAT INSTRUCTION FILE FOR PROGRAM MFIRE GENERAL RULES FOR DATA INPUT: $THERE IS NO NEED TO DISTINGUISH INTERGER AND REAL NUMBERS. $ $ SYMBOLS FOR NUMERICAL INPUT INCLUDE THE FOLLOWING $ $ 1234567890 -+BLANK $ $ * FREE FORMAT IS ALLOWED. COMMA AND BLANK SPACE CAN BOTH BE $ $ DELIMITERS. SEQUENTIALLY DISTRIBUTED BLANK SPACES ACT AS ONE $ $ DELIMITER. BLANKS ADJACENT TO A COMMA HAVE NO DELIMITING EFFECT $ $ * A ZERO INPUT CAN BE OMITTED BUT NOT THE DELIMITERS EXCEPT WHEN $ $ THE ZERO INPUTS ARE THE LAST ONES ON A LINE. $ $ * A LINE WHOSE FIRST NON-BLANK SYMBOL IS "$ IS AN INSTRUCTION $ $ LINE WHICH WILL BE IGNORED IN A PROGRAM RUN. $ $ * A LINE WHOSE FIRST NON-BLANK SYMBOL IS NEITHER ONE USED IN THE $ $ ABOVE LIST FOR NUMERICAL INPUT NOR "$, OR WHICH CONTAINS MORE $ $ THAN 3 SYMBOLS OUTSIDE OF THE LIST, IS A COMMENT LINE WHICH WILL $ $ BE SHOWN IN THE OUTPUT FILE. $

Jan 1, 1990

By O. C. Baptist

The gravitational pressure gradient (GPG) in porous sandstone containing free gas was determined to define the proper GPG to use when calculating the rate of downdip flow of oil in the Sub-Scalez No, 1 sand, Elk Hills field, Naval Petroleum Reserve 1. The GPG was determined at several gas saturations using long, artificially consolidated sandstone models that were mounted vertically in some tests and horizontally, with rotation, in others. Also determined by laboratory and field tests were relative permeabilities, capillary pressure relations; critical gas saturation, water sensitivity, and depletion drive performance. The critical gas saturation in the models having an absolute permeability of 1 to 2 darcys was about 2 percent of pore volume. The GPG with the critcal gas saturation was that due to the weight of the gas-saturated oil. The GPG in the upper part of the models was reduced as gas saturation increased to a value considerably larger than the critical. The exact gas saturation at which the GPG became less than that due to the weight of the oil could not be determined but was estimated to be of the order of 10 percent of pore volume. Tests indicate that the rate of oil production is not permanently reduced by exposure of the sand to fresh water but that the rate of injection of fresh water will be considerably less than that to brine, Methods for determining the factors mentioned above are discussed.

Jan 1, 1967

By Edward A. Mihok

This paper presents plant design and cost estimates for limestone treatment of acid mine water covering a wide range of quality and quantity conditions. The treatment process consists of limestone neutralization, aeration, solids settling, and concentration. The design criteria for the various operation functions are based on pilot plant performance, laboratory data, and established mine water treatment standards. Unit costs have been assumed and are related to general market prices and conditions. These estimates serve as preliminary indicators of what it would cost to construct and operate a mine water treatment plant.

Jan 1, 1970

Use water-jet-assisted cut-ting technology to reduce the exposure of mi ne workers' to respirable dust. Approach Install water-jet-assist on mining machines and evaluate its impact on respirable dust. How It Works Water-jet-assisted cutting involves a mechanical cutting bit working in combination with a moderate pressure (generally up to 10,000 psi) water jet directed just in front of, or through, the bit tip. One of its advantages is reduced dust generation because the jet wets the face of the material being cut more efficiently than a conventional low-pressure water spray, thus capturing much of the dust before it ever becomes airborne. It also removes loose cuttings ahead of the bit before they are pulverized by the bit into respirable dust. Total water consumption is about the same as for conventional low pressure dust control water spray systems. However, there is some increase in power consumption because of the energy needed to provide the high pressure water.

Jan 1, 1987

By C. H. Elder, Maurice Deul

A 5-hole pattern was drilled from the surface at a site near Oak Grove, Jefferson County, Ala., to degasify the gassy Mary Lee coalbed in advance of mining. Gas and water production was monitored for 1 year, 4 months to allow gas flow to stabilize fully. A thickened water stimulation treatment was designed and applied in one hole of the pattern to evaluate this degasification technique for the Mary Lee coalbed. A gas production rate of 70,000 ft3 /day after stimulation treatment indicates that the use of vertical boreholes coupled with hydraulic fracturing in advance of mining the Mary Lee coalbed would provide for more rapid degasification and could provide a possible source of natural gas.

Jan 1, 1974

Develop a down-hole replaceable diamond core bit that will reduce overall drilling costs and increase total available drilling time per hole. Approach A one-piece diamond core drill bit of unique geometric shape has been designed, fabricated and field tested. The bit can be withdrawn (or replaced) from the bottom of the well-bore without removing the drill rods from the hole, saving a significant amount of non-productive drilling time. How It Works The replaceable bit system consists of two basic subsystems: the removable core bit, and the equipment necessary to replace the wornout bit without pulling the drill rods out of the hole. The geometric configuration of the bit is that of a one-piece diamond studded cutting element created by "slicing off" two parallel sides of a conventional diamond cone bit. This geometric configuration, along with some minor modifications to the outer core barrel, allows the bit to be rotated in two planes and, with the retraction-insertion tools, raised or lowered through the interior of the drill rods using a conventional wire-line system. For example, to retrieve the bit, a retraction tool is lowered through the drill rods using a conventional wire-line system and at the hole bottom, the tool automatically orients itself within the outer core barrel.

Jan 1, 1981

Provide blasting-resistant, quickly reusable stoppings for large mine openings. Approach Stoppings are assembled using roof-to-bottom panels of brattice held together by Velcro seams that peel open when struck by a strong air blast. How It Works The Velcro seam is designed to open when exposed to forces lower than would normally damage the brattice. When the seams partially open, they relieve the blast air overpressure to prevent damage to the brattice panels and their anchoring devices. A stopping is returned to service by reclosing the Velcro seams. To hang a brattice panel, its top is stapled to a board, and wrapped once or twice around it. That assembly is then attached to the roof with bolts. The length of the board should be a foot less than the width of the panel to allow for the sealing seam on each side of the panel. The boards are installed end-to-end in an approximately straight line across the roof of the mine opening.

Jan 1, 1979

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