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By J. R. Ruark

This report presents results of the research and development work and operations performed during stage II of the gas combustion retorting research program conducted by the Colorado School of Mines Research Foundation and six major oil companies at the Bureau of Mines Anvil Points Research Facilities. The experimental program, including retort modification and air-gas distributor development, effects of shale quality and particle-size distribution, and other variables on the process, is discussed. Although operating problems are not fully resolved, it appears that the gas combustion retorting process can be successfully applied to achieve oil yields in excess of 85 percent of Fischer assay at mass shale feed rates of 500 pounds per hour per square foot of cross-sectional bed area, approximately twice the rate previously demonstrated to be reasonably practicable.

Jan 1, 1971

By W. P. Diamond

It is estimated that more than 1 trillion cubic feet of methane is contained within the coals of the Mary Lee group in Jefferson, eastern Tuscaloosa, and southern Walker Counties, Ala. Most of this methane will be encountered by mining. Coals of the Mary Lee group are presently being mined at depths exceeding 1,000 feet and will in the near future be mined at even greater depths, where the problem of methane gas affecting the mining operations will be acute. It is calculated that approximately 90 pct of the methane is at depths greater than 1,000 feet, and over half of the gas is contained within only 12 pct of the study area which is under more than 1,500 feet of over-burden. Degasification in advance of mining will increase mine safety, reduce ventilation expenditures, increase productivity, provide an additional energy source, and make it possible to mine parts of deep coalbeds that probably could not otherwise be mined.

Jan 1, 1976

A general analytical solution of the effect of an inclined contact separating two media of differing electrical properties on a normally incident plane electromagnetic field has been given (Geyer, 1972). These solutions for the electromagnetic response at any observation point P(r, [u]) are given in the form of inverse Lebedev-Kontorovich transforms. Two modes of excitation are considered: (1) case where current density flows across strike of the contact separating the media of differing electrical properties (only Er , E [u] , and Hx differ from zero) and (2) case where current density flows along-strike (only Hr , H [u] , and Ex differ from zero). The electromagnetic fields in the frequency range of interest and for the rock conductivities under consideration are quasi-static in nature so that to a first-order approximation the horizontal magnetic field at the surface of the earth is constant and continuous across the discrete discontinuity in resistivity for case (1) above, and so that the tangential derivative of the horizontal electric field at the surface of the earth is constant and continuous across the discrete discontinuity for case (2) above. Of course, it is well known that where large horizontal gradients in conductivity exist, there also exists large anomalous components of the vertical magnetic field (Weaver, 1963). The recognition of such anomalous components and their magnitudes due to the presence of lateral resistivity changes in the overburden becomes very important in any wavetilt type measurement which may be used to locate a miner. When the lateral change in resistivity becomes quite large, the integral solutions (expressed as Lebedev-Kontorovich transforms) simplify considerably and allow ready numerical evaluation. Examples of the amplitude and phase responses of the radial electric, horizontal electric, and vertical magnetic field in the vicinity of the contrast in resistivity are shown in Figures 2, 3, and 4. Of particular significance is the fact that the anomalous vertical magnetic field is three orders of magnitude larger near the contact than far from the contact. This fact implies that where large resistivity contrasts do occur in the rocks overlying mine workings, that significant errors may be present in wavetilt measurements as used above for location criteria! Another observation insofar as the anomalous vertical magnetic field is concerned is the linear variation of phase as one proceeds away from strike in induction number (increased distance or frequency). For a pulse-excited communications system this phenomena would have a bearing on where the zero crossings would occur (i.e., 'pulse breadth') in the transient coupling between any given source-receiver configuration and at any given receiver site.

Jan 1, 1973

By D. Bienstock, J. H. Field, M. J. Lempel

A computer program is presented to perform the detailed and numerous calculations required for determining the interface temperatures and steady - state heat flow through a furnace wall composed of several refractories in layers . A method is developed that will allow the designer to determine the various thicknesses for each refractory layer to minimize either the total wall thickness or the cost of the wall per unit of area . A sample problem is presented and analyzed to illustrate the techniques involved .

Jan 1, 1964

By Franklin H. Persse

The Bureau of Mines estimated reclamation costs for 13 surface coal mines in nine States west of the Missisisppi River. With the exception of the Pacific Coast coal province, at least one mine in each of the western coal provinces was studied. Cost estimates were, made using standard estimating procedures from data obtained from company records, interviews with industry personnel, and onsite observations. Estimated costs are presented in four categories which represent the four phases of mined-land reclamation: (1) Design, engineering, and overhead; (2) bond and permit fees; (3) backfilling and grading; and (4) revegetation. Estimated costs as of the first quarter of 1976 are expressed as averages and ranges in terms of per acre, per ton of coal produced, and per million Btu. Total reclamation costs ranged from $860 to $7,200 per acre, from 6 to 84 cents per ton, and from 4 to 35.3 mills per million Btu. A mine in the Northern Great Plains coal province (Region D) showed the highest per acre cost whereas mines in part of the western region of the Interior coal province (Region A) experienced the greatest per ton and per million Btu cost. The high cost of reclamation in the Western United States is reflected in the backfill in and grading category, particularly in the cost of topsoil removal and subsequent replacement as required by individual State reclamation regulations.

Jan 1, 1977

During the summer of 1973 we were asked to perform a theoretical investigation of the propagation of low frequency (LF) radio waves down deep (10,000 feet) hoistshafts* for the case where the hoist cable ("rope") is the only metal conductor present. Propagation is by means of the TEM coaxial mode of transmission in which the hoist cable serves as the inner conductor and the surrounding rock acts as the outer conductor. Since the rock is a relatively poor electrical conductor the current in the outer conductor of the coaxial line is not confined to a very thin surface layer as in a metal coaxial cable, but spreads radially to a distance that is generally many times the shaft diameter. This feature of the wave propagation requires a more sophisticated theoretical treatment than the approximate skin-depth theory that is adequate for metal coaxial lines. In this Part we treat the hoist shaft wave propagation loss, characteristic impedance, and the field current distributions in the surrounding rock medium. We also show that the large penetration of the wave into the rock outer conductor does not present a difficult problem with regard to coupling the transmitter or receiver to the transmission line with a minimum of insertion loss, but that the large impedance mismatch caused by the capacitance termination between the cage and shaft wall may well be the most significant contribution to overall system loss. Inductive coupling and impedance matching to the hoist rope/shaft transmission line are also treated briefly. Preliminary results indicate that a broad minimum in overall system loss should occur between 100 kHz and 1 MHz, possibly centered around 300 kHz. Further work is needed to better quantify this signal loss behavior, compare it with hoist shaft electromagnetic noise spectral data recently acquired by NBS, and identify the most favorable operating frequencies.

Jan 1, 1974

By Richard A. Dick

Eight blasts were fired in a 2-1/2-ft bench in the Stewartville member of the Galena Limestone formation in an aggregate quarry near Stewartville, Minn. The shots were dimensionally proportional to production-size bench blasts and were about 5 to 10 percent of full scale. The effects of site, timing of initiation, and burden-to-spacing ratio were studied in a 2 x 2 x 2 factorial experiment, using three boreholes, caw;, containing a 1/2-in charge diameter of high-density ammonia dynamite, in each blast. Detonation velocity measurements indicated that the dynamite detonated satisfactorily in the 1/2-in charge diameter. The effects of the three experimental variables were analyzed by weight for the percentage of oversized material produced and for size distributions determined by screening the entire muckpiles. The bench faces were painted before each shot in an effort to determine the origin of the oversized material. The square pattern (burden and spacing = 15 in) produced finer overall fragmentation and less oversized material than the rectangular pattern (burden = 15 in; spacing = 22-1/2 in). Sites 1 and 2 were about ft apart. Although site 2 produced slightly better overall fragmentation than site 1, the amounts of oversized material produced showed no significant difference. The timing of initiation (instantaneous or delayed) did not significantly influence the overall fragmentation or the amount of oversized material produced.

Jan 1, 1973

By R. H. Sprute

Extensive Bureau of Mines laboratory testing has shown that electrokinetic densification can be an effective method for dewatering and consolidating unclassified metal mine mill tailings. The report describes results of a limited field test of this technique. Eighteen-cubic-yard concrete model stopes, 18 feet long by 6 feet deep by 56 inches wide, were filled with unclassified tailings slurry from a metal mine in the Coeur d'Alene, Idaho, district. Five different tests were performed. They showed that a strong, dense, dewatered fill can be obtained in a reasonably short time using electrokinetics, with typical power consumption of 25 to 30 kW-hr/yd3 of densified fill. At present power costs in the Coeur d 'Alene district, this would amount to 10 to 12 cents/yd3.

Jan 1, 1975

By Thomas H. Dubaniewicz

Fiber optic systems are being deployed in locations where explosive gas atmospheres are normally present or are present under fault conditions. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory (NIOSH, PRL) conducted a study of laser safety in potentially flammable environments. Researchers conducted experiments to estimate the mean and standard deviation of laser powers needed to ignite 6% methane-air atmospheres using single mode optical fiber tips covered by two types of iron oxide (Fe304 and (FeMn)203) mixed with a ceramic adhesive. The iron oxides, heated by a 1064 nm continuous wave laser, ignited the methane-air mixtures ,at similar powers. The minimum igniting power and maximum non-igniting power (10 tests) were 407 and 350 mW, respectively, using a 62.5 pm fiber. Laser beams guided by 125 and 80 pm diameter cladding single mode fibers produced similar methane-air igniting powers. Ignition was not observed using coal particles at powers that produced ignition with the iron oxides. Threshold ignition delays using the single mode fiber were approxinlately proportional to the inverse square of the igniting power. Ignition delays were significantly longer than the reported activation time for a comnlercial fiber optic power limiter. Comparisons are made with the results of other researchers. Published by Elsevier Ltd.

By R. Karl Zipf, Z. T. Bieniawski

"Researchers at The Pennsylvania State University are engaged in a project to understand the mechanics of respirable size fragment formation in coal. The project is based on the premise that a thorough understanding of the fundamental mechanics of fine fragment formation may lead to techniques for reduction and better control of coal dust problems in mines. Presently, it is believed that the mode of fracture propagation which can range from pure tensile to pure shear or any mixed mode in between and the loading or displacement rate can influence the amount of respirable size fragments that are generated on new fracture surfaces during the fracture propagation process The essence of any coal cutting process is one of mixed mode fracture propagation. To study the crack propagation process, a unique mixed mode testing rig was designed and fabricated. This rig is capable of applying loads to a prenotched test specimen that range from pure Mode I (tensile mode) to nearly pure Mode II (shear mode) or many mixed mode loading combinations. It is also possible to apply different loading or displacement rates to the test specimen. With this rig, it is possible to create new fracture surfaces via the different fracture modes and under various loading conditions.These new fracture surfaces are examined with a scanning electron microscope (SEM) to characterize the amount of structural damage and respirable size fragment formation that occurs during the fracture process. Initial observations suggest that the amount of fine fragment formation and the new fracture surface appearance is related to the fracture initiation conditions, particularly the fracture mode and the loading rate. Mode II loading and higher loading rates seem to generate more structural damage and respirable size fragment formation that Mode 1 loading at slower rates.With the mixed mode test rig, the mechanics of fracture initiation for a single crack can be controlled to better understand its influence on respirable size fragment formation. Such understanding may lead to methods which characterize the tendency of specific coal seams to produce undesirable fine fragments during the fracture process, or it may lead to rational recommendations and design guidelines or coal mining machines which inherently produce less dust.IntroductionAs part of a larger effort to reduce the incidence of coal workers pneumoconiosis (black lung) in coal miners, researchers at The Pennsylvania State University are engaged in a project to understand the fundamental mechanics of fine fragment formation in coal. This project is part of a com¬prehensive research effort within the Generic Mineral Technology Center for Respirable Dust which is jointly administered by The Pennsylvania State University and West Virginia University.The principal source of the coal dust in underground mining is the cutting operation. The U.S. Bureau of Mines (USBM) and various European research organizations have conducted investigations into the mechanics of coal cutting for many years. These studies of airborne respirable dust (ARD) formation have concentrated on empirical studies of the various cutting parameters and their effect on ARD for¬mation. The parameters study include depth of cut, cutting speed and bit spacing.(1,2) Other studies investigated the effect of symmetric and asymmetric bit wear and various bit geometries and designs (3-5) Roepke(6) summarized the principals of proper coal cutting to minimize dust formation by recommending to ""cut at maximum depth (maximum advance rate) at all times, at minimum RPM, with the fewest possible bits, having the lowest possible included tip angle."" Most coal in the U.S. is mined with the continuous mining machine which inherently cannot meet these design recommendations.(3)It is recognized that respirable size dust particles are formed and/or liberated by a fracture process. One extremely interesting and useful study performed very early in the USBM dust re"

Mar 1, 1989

By Paul Biggs

This Bureau of Mines report provides information on 138 waterflood projects in Wyoming. Injection was in 25 producing zones and 65 fields. Specific data presented include field location, discovery and development, water supply and injection, oil and water production, estimates of oil in place, and oil recoveries by primary and secondary methods. The 138 projects studied will, if successful, recover about 800 million barrels of secondary oil. Almost all of the injection water is from deep water wells.

Jan 1, 1970

By David W. Houseknecht

Probabilities of encountering coalbed discontinuities during vertical or horizontal drilling in a specific coalbed can be estimated based on analysis of mined-out areas of the coalbed where the size, shape, orientation, and distribution of discontinuities are known. The result-ant probability estimates can be applied to cost-risk evaluations of drilling programs proposed for exploratory, developmental, or methane drainage purposes in undeveloped areas of that coalbed. Data compiled from mine maps of the Beckley Coalbed in southern West Virginia were used to estimate the probabilities that discontinuities would be encountered in two illustrative hypothetical drilling programs--one for drilling vertical boreholes and the other for drilling horizontal boreholes. Analysis based on a mined-out area of the Beckley Coal bed indicated that vertical methane drainage boreholes spaced 1,000 feet apart in a square grid pattern would each have a 29 percent probability of encountering a discontinuity in a geologically unexplored area of the coalbed. It was also determined that exploratory vertical drilling could locate most of the discontinuities if a borehole spacing of 2,500 feet were used. For horizontal drainage boreholes in the Beckley Coalbed, the analysis indicated a linear relationship between hole length and the probability of encountering a discontinuity.

Jan 1, 1982

Various aspects of judgment and decision-making are key themes in this book. The model presented here serves as a loose structure for the chapters that follow this one. The notion of a model is introduced because growing research interest in the subjective aspects of group and individual behavior has led to a debate over whether judgment is a skill that can be understood scientifically. A related point of contention is whether such an understanding could lead to the development of methods for estimating people's ability to make good decisions during an emergency. There is some literature that supports the potential usefulness of this approach. However, little agreement seems to have been reached on how to define and operationalize even those basic concepts necessary to assess the soundness of decisions from within their environmental and group contexts [Jensen and Benel 1977; Godden and Baddeley 1979; Baumann and Bourbonnais 1982; Brecke 1982; Stone et al. 1985]. A look at the real-world process is clearly needed. The need to attempt a better understanding of judgment and decision-making properties stems from those occasions in the existence of an organization when there is a lot at stake. The process of decision-making (which is part of the exercise of judgment) has been analyzed in situations such as corporate takeovers [Janis and Mann1977], military combat [Begland1979], clinical emergencies [Baumann and Bourbonnais 1982], and aviation events [Billings and Reynard1984]. The fundamental assumption of these analyses is that, while there are untold successes, there are also notable numbers of failures resulting from decisions that can be ascribed to one or more errors in judgment. From a cognitive perspective, any person engaged in decision-making (either alone or in a group) is actively involved in a process characterized by certain elements. These were mentioned in chapter 1, but are reiterated briefly at this point: (1) detection of a problem, (2) definition or diagnosis, (3) consideration of available options, (4) choice of what is perceived as the best option given recognized needs, and (5) execution of the choice based on what has transpired [Flathers et al. 1982; Baumann and Bourbonnais 1982]. At any moment in this process, there are factors at play that have a large impact on one's ability to solve complex problems in a limited time: (1) an internal state [Hedge and Lawson 1979] is the sum of a person's psychomotor skills, knowledge, attitudes, etc.; (2) uncertainty [Brecke 1982] is caused by faulty or incomplete information received from the external environment; (3) stress [Biggs 1968; Jensen and Benel 1977] is generated both by the problem at hand and any background problem that may exist; and (4) complexity, as it is used here, refers to the number of elements involved that must be attended to. These variables are depicted in figure 5.1, and their relationship to each other and to an outcome is indicated. This schema is designed to suggest interaction, because while the judgment and decision-making process may be conceptualized as discrete stages, experience tells us that this is not the way people function in real-world situations.

Jan 1, 2000

By Robert C. Hickman

"INTRODUCTION The Big Four fault and the Sandy Creek fault, with several cross faults, traverse the Stalion-Curnel fluorspar prospect in a northeasterly direction. The Big Four mine, about three-quarters of a mile northeast of the prospect, is the only active mine in the immediate area.A resistivity survey was made of a portion of the prospect by the Division of Geophysical Exploration, Bureau of Mines, in May and June 1946. As a result of this survey, five holes were drilled by the Bureau of Mines during the period from October 8 to December 16, 1946. Two Longyear No. 12 Junior Straitline diamond drills were used for the work.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The project was under the supervision of Mitchell H. Kline, chief, Raleigh Branch, Mining Division."

Mar 1, 1948

By Oliver Bowles

Enormous quantities of limestone are used for metallurgical purposes. Approximately 23 million tons were so used in the United States in 1925 chiefly for smelting iron ores in the blast furnace. Smaller amounts are used in basic open-hearth steel manufacture, and in smelting lead, copper and antimony ores. Most limestone producers lave little knowledge of the way in which their stone is used in metallurgy. Maximum tolerances of silica, alumina, sulphur and possibly magnesium; and minimum content of calcium carbonate may be arbitrarily fixed for the guidance of the producer, but aside from these requirements little information is available to producers on the manner in which their stone is used, the office it performs in smelting, or the effects of impurities. More complete [wledge] of utilization would enable limestone operators to solve their production problems more intelligently.

Jan 1, 1927

By A. C. Fielder

It is with some diffidence that I venture to address the Montreal Section of the Society of Chemical industry on the subject of motor fuel from coal at a time when crude petroleum is produced in greater quantities than at any time in history, and at a time when the known reserves exceed all expectations, even the optimistic estimates of the Committee of Eleven of the American Petroleum Institute. Not only are new fields being discovered in America a -an embarrassing frequency but sources outside of the North American Continent show, unmistakable signs of adding materially to the world's sources of oil. Were it not for the tremendous scientific and technical importance of the work done in the past few years in transforming coal into liquid motor fuels, I should prefer to let this subject rest until a more propitious time, such as prevailed some years ago, when the gasoline consumption curve was rising rapidly and the production curve was slowing in its upward rise. That was the period which stimulated the researches which resulted in tetra ethyl lead and anti-knock gasolines on this side of the Atlantic and in methanol, synthetic gasoline and hydrogenation of coal on the other side. Some of you will recall a symposium on Motor Fuels and Oil Conservation held at the Chemists' Club n New York in September; 1925. Dr. R. L. Brown and I presented a paper at this meeting on "Complete Utilization of Coal and Motor, Fuel, in which we pointed out that coal was the most likely raw material source of gasoline substitutes if and when needed. We grouped the present and future, processes' for obtaining motor fuel from coal in three classes, namely:

Jan 1, 1928

By Thomas M. Barczak

This U.S. Bureau of Mines report examines the causes and consequences of longwall face sloughage. Theoretical relationships were developed to evaluate mechanisms that produce slough age. From these relationships, contributory factors were identified for further analysis in field efforts. A survey identified 12 mine sites with sloughage problems, and these were investigated. From these studies, it was determined that the depth of cover and mining height are the two most significant factors causing sloughage on longwall faces. Coalbed friability and cleat orientation also were found to be significant factors in promoting sloughage. It was concluded that sloughage is primarily a problem in thicker seams or seams with friable coalbeds, and that the problem is more severe as the depth of cover increases. Sloughage also was found to increase as the rate of mining decreased. Observations indicated that face slough age can increase dust generation significantly on longwall faces. Current efforts to control dust generation from longwall sloughage are described.

Jan 1, 2010

By John W. Frey

Although there are certain general uniform provisions in the laws ... of the several Provinces of Canada the differences are so great that it is considered advisable to present digests of separate mining laws rather than a digest of Canadian mining law as an entity . This analysis , accordingly , has been divided as follows : Nova Scotia , New Brunswick , Quebec , Ontario , British Columbia , and a group of Provinces under Dominion Law .

Sep 1, 1930

By James E. Bell

Quartz crystals occur on a farm in the vicinity of Laurel Fork, Carroll County, Va., in abundance over a large area, This has been known for several years, but no work had been clone, up to the Bureau of Mines examination in 1943, to determine the amount of crystalline quartz of usable quality. Field exploration was undertaken throughout the month of June 1943.

Jan 1, 1950

By Edward W. Parsons

The explosive-anchored rockbolt was field tested in six mines where rock conditions varied from incompetent shale or mudstone through fairly soft sand-stone to firm sandy shales. The purpose of the testing was to document, under a wide variety of conditions and in comparison to other rockbolt anchors, the quality of the anchorage produced by the explosive-anchored bolt. In addition, the length, strength, and design of the explosive charge necessary to produce positive anchorage up to the yield strength of the weakest component of the bolt were determined. A l4-inch length beaded explosive charge was found to be suitable, in general, in relatively weak strata, and the length can be reduced in more competent strata. Of the 127 explosive?-anchored bolts tested, 118 bolts produced an evaluated anchorage in excess of 17,000 pounds. Only 4 of 43 expansion-shell bolts and 4 of 14 wedge bolts produced anchorage this good. In preliminary tests, properly coupled explosive-anchored bolts did not ignite an explosive gas mixture. Some minor phases included in the investigation were as follows: (1) effect of explosive-anchored rockbolt on surrounding rock; (2) effect of time on anchored bolts based on torque tests; (3) effect of submersion in water on rockbolt anchorage; (4) pull tests to higher loads; and (5) ignition tests.

Jan 1, 1965