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By J. W. Adams

Measurements of surface magnetic field noise were made at various locations over the Geneva Coal Mine near Price, Utah, on June 12, 1973. The locations selected were on the surface over emergency locator beacons underground at depths between 3S0 meters (1150 ft.) and 488 meters (1600 ft.). The surface terrain where these measurements were made was mountainous, and access was difficult. There were no power lines within several miles, and the weather was clear; therefore, the magnetic noise levels were about as low as will normally occur. Results of measurements of distant sferics indicate rather sharp cutoff frequencies below which broadband, impulsive noise is attenuated. The mechanism of propagation for this noise above the daytime cutoff frequency of 3500 Hz and the nighttime cutoff frequency of 1700 Hz is deduced to be a waveguide formed by the D or F layers of ionosphere as an upper plane and the earth as a lower plane.

Jan 1, 1974

By Dorsey A. Lyon

"The ceramic industry of the United States has a total yearly manufactured product of nearly half a billion dollars, despite large foreign importation.After careful investigation of the industry by the Bureau of Mines, it is the belief of those in charge that the usefulness of the industry can be greatly enlarged and the importations greatly lessened through the development of processes that will lead to a greater and better development of the ceramic resources of the United States. This will result in a greater industry with more men employed than ever before, and perhaps a world's supremacy in ceramic trade matters.Investigations in behalf of the ceramic industry are being made at the Bureau of Mines experiment ceramic station at Columbus, Ohio, under the supervision of R. T. Stall, superintendent, who reports a number of instances of practical, beneficial cooperation between the industry and the station during the last fiscal year.Graphite to Crucibles:Prior to 1914, practically all graphite crucibles manufactured in the United States were made from Ceylon graphite bonded with German Klingenberg clay. It was the general belief among graphite crucible manufacturers and users that good crucibles could not be made from American bond clays and graphites.Graphite crucibles were essential for melting certain alloys and special steels urgently needed for the manufacture of war materials. The demand for such metals was so great that it created an unprecedented demand for graphite crucibles.After the European war began no Klingenberg clay could be shipped out of Germany. However, it was fortunate for the cyucibly makers that they had large stocks of Klingenberg clay on hand. When the stock of Klingenberg clay became exhausted, it was necessary for the credible makers to turn their attention to American clays. There were no data or other information available to guide the crucible makers in the selection of good bond clays for their crucibles. It was necessary for them to select their clays more or less by ""guess"", which resulted in the period of service or life of graphite crucibles being shortened 15 to as much as 60 per cent."

Feb 1, 1921

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

By C. H. Elder

Coal degasification boreholes drilled from the surface have been success-fully hydraulically stimulated to increase the flow of gas from the coal. This Bureau of Mines report describes the hydraulic stimulation procedure for a coalbed, the equipment required, and design criteria for the treatment. Three examples of stimulation treatment show from fivefold to twentyfold increases in gas production. The tests were conducted in the Pocahontas No. 3 coalbed, Buchanan County, Va., the Pittsburgh coalbed, Washington County, Pa., and the Mary Lee coalbed, Jefferson County, Ala. Two sites where the coal was hydraulically stimulated and exposed by subsequent mining show no adverse effect on mining operations through the treated zones. The induced vertical partings were confined to the coalbed and did not in any way affect either roof or floor rock.

Jan 1, 1975

By B. J. Dalton

The Bureau of Mines Helium Research Center has as a long-range objective the development of an equation of state for helium that will allow all of the thermodynamic properties to be calculated within the accuracy with which they are known. If this objective is to be realized, a method of calculation must be known. This report gives the principles of the method we use in such problems. A computer program was developed for predicting these properties, including those at the critical point, that is perfectly general and applicable to any equation of state. To demonstrate the efficacy of our method, this computer program was used to evaluate thermodynamic properties of a Redlich-Kwong fluid in the two-phase region. Expressions for calculating various thermodynamic functions specific for this particular equation of state are derived. Numerical values are tabulated and graphs are presented for all functions calculated. It is shown that for a Redlich-Kwong fluid there are finite discontinuities in (1) the second temperature derivative of the Gibbs free energy or chemical potential at the critical point, (2) the second derivative of the vapor pressure curve with regard to the temperature on passing through the critical point, and (3) the measured heat capacity at constant volume on passing through the critical temperature when the calorimeter is filled to the critical density. It is also shown that the heat of vaporization is infinite for a Redlich-Kwong fluid at absolute zero.

Jan 1, 1969

By C. C. Clark, R. R. Backer, J. D. Vickery

This report presents the results of tests conducted by the U.S. Bureau of Mines to determine the transport characteristics of highly concentrated paste backfill mixes made from dewatered total mine tailings. The slurry concentrations of the mixes were all above 78 pct by weight with slumps ranging from 6.4 to 16.5 cm (2.5 to 6.5in). Laboratory material property tests and full-scale pumping tests were conducted using pipe diameters of 102,128, and 154 mm (4, 5, and 6 in) and a positive-displacement pump. The results indicated that the tested backfill mixes can be successfully transported as a stiff paste and identified the influence of and the interaction among the various mix and system variables.

Jan 1, 1995

By Ronald D. Hill, Elmore C. Grim

Surface mining drastically alters the ecological characteristics of the area disturbed and in some cases has a decided effect on surrounding areas. Vegetation is removed, topographic features and characteristics are changed, and the original geologic overburden profiles are destroyed. Spoil banks generally are a heterogeneous mixture of rock fragments, rock particles, and soil-sized material derived from the overburden strata. With proper mining techniques, the various strata can be partially or completely segregated. Segregation of over- burden material offers the opportunity to bury the toxic, acid, or salt-pro producing strata under growth supporting material. In some situations, lower strata may have more desirable characteristics than surface material and can be placed near or on the surface. For example, limestone strata appear in some lower overburden profiles that have shale and/or sandstone near the surface. Also, some lower strata have higher nutrient levels that have been leached from the surface. Experience has shown that natural revegetation is a very slow process on strip mined areas. Native vegetation may not be compatible with the environment on the mined areas, for example : 1. Low nutrients in the spoil. 2. Toxic spoils (very acid or highly alkaline ). 3. Surrounding vegetation may be of the climax type and may not have pioneer- or primary-invader-type species present. 4. The seed source may be to far away from the adjacent mined areas. Early attempts to revegetate strip-mined lands with trees also proved to be unsatisfactory as they did not provide the initial ground cover required to stabilize the spoil. Erosion control with trees only may take up to 10 years before the canopies close and an effective cover is established. They are slow to form soil profiles and do not provide effective chemical pollution control until long after planting. A quick growing cover of herbaceous species is necessary to obtain quick stabilization and initial protection against erosion by reducing runoff and rain-drop splash. Vegetative cover will also build up a concentration of organic matter in the soil, which in turn will

Jan 1, 1974

By Charles Vaught

This is the second in a series of four articles that discuss underground firefighting preparedness. As with the first article in the May-June issue, it is based on interviews with 214 miners conducted at 7 underground mines (?A? through ?G?) by researchers of the National Institute for Occupational Safety and Health?s (NIOSH) Pittsburgh Research Center [Vaught et al. 1996].In the first article, the authors presented an overview of the study conducted by NIOSH on mine fire response preparedness and provided a general perspective on underground mine fires. In this article, we will describe miners? preparedness to evacuate a fire and their experience with incipient fires.

Jan 1, 1997

By A. W. Fahrenwald

The art of flotation has developed rapidly. Numerous technical staffs and individual investigators have, by their combined efforts, developed practicable methods of concentrating ores which ten or even five years ago were considered complex and impossible of commercial treatment. Also the work of those who have been engaged in pure research on the fundamentals of flotation has helped greatly to expedite the general development of the process. However, in spite of the highly successful practical operation of the flotation process, results are obtained and things happen that we are unable to explain completely, although much is known about the theory of the process. The rapid stride in flotation concentration, it is noteworthy to point out, is due to the freer exchange of facts and data by the staffs of the larger mining companies and the patent controlling corporations, and by investigators in general. Generally speaking, one may visit any mining plant and by presentation of proper credentials, be shown all that is going on or that is being done.

Jan 1, 1925

By R. Stefanko

The industrial hygiene and safety aspects with internal combustion engine in mining systems is truly interdisciplinary and encompasses many fields such as mine ventilation, exhaust gas and particulate analyses, mine atmospheric environment monitoring, mathematical modeling of generation, dilution and dispersion of pollutants in ventilation systems, and engine testing and approval. Mathematical models of the dilution and dispersion of diesel exhaust contaminants can be useful only if these models can be validated. In this research report, experiments that were specially designed for the above purpose are described. These experiments were conducted in the U.S. Bureau of Mines, Safety Research Coal Mine, in Bruceton, Pa. On the basis of this study, the data collected, and further review of available literature, it is concluded that mathematical models of dilution and dispersion are useful tools for mine ventilation planning. Additional objectives of this study about which conclusions and recommendations are reported here include: (a) evaluation of mine atmosphere contaminant monitoring systems; (b) optimum sampling site locations; (c) model sensitivity and error analyses; (d) computer coding of mathematical models; and (e) development of a diesel bibliography. While an extensive bibliography on diesels is provided in this report, Volume II of this final report has 511 references.

Jan 1, 1977

By Edward L. McHugh, Charles Sabine, Jami Dwyer, David G. Long

Slope failure accidents were responsible for about 12% of U.S. surface mine fatalities between 1995 and 2003. Small surface movements on a mine highwall may be precursors of failure that, if detected, could provide sufficient warning to enable workers and machinery to be withdrawn to safety. Radar interferometry offers the necessary precision to detect these movements. Radar has some advantages over other methods in its ability to cover large surface areas for true two-dimensional monitoring day and night under almost any weather condition. Radar’s active transmit/receive mode of operation provides for more direct sampling than do passive optical methods that depend on solar illumination. Improvements in microprocessor speeds and capacities have led to the development of a number of small, portable, ground-based systems; such systems are now being deployed at several locations around the world. As part of an ongoing study of monitoring technologies, researchers from the National Institute for Occupational Safety and Health and Brigham Young University, Provo, UT, cooperated to assess the feasibility of using interferometric radar to monitor mine slope stability. Field tests of a device incorporating prototype equipment were successful in that small, centimeter-scale displacements on rock slopes were detected.

Jan 4, 2006

By Fred N. Kissell

Methane concentration peaks were measured by the Bureau of Mines at coal mine working faces during entry development. The statistical distribution of peaks was found to be normal or log normal depending on how well the methane was being mixed into the ventilation airstream. A normal distribution indicated good mixing, whereas a log-normal distribution indicated that mixing was poor. In addition, the "highest" peaks over selected intervals were found to fit a type I extreme-value distribution, a result similar to that obtained while mining longwall faces.

Jan 1, 1974

By Noel N. Moebs

The Bureau of Mines investigated severe coal mine roof support problems along a section of main entries in the Pittsburgh coalbed in southwestern Pennsylvania to identify the causative factors. The mine roof was examined in detail, and various sedimentary structures are described that contributed directly to irregular and unstable roof. Small-scale paleochannels, scours, and related slickensides were identified as the leading cause of bad roof, and isopach maps were prepared to illustrate a method whereby the presence of these structures could be inferred in advance of mining. Probably second in importance was the occurrence of relatively incompetent flaggy, poorly cemented sandstone, weakened by coal and micaceous laminea. No effect of in situ stresses on roof stability was detected.

Jan 1, 1977

By S. H. Ash

Unusual mining conditions prevail in the State of Washington because the majority of the coal seams lie on extra steep dips, and the roof and floor of the seams are of such a character as to require an excessive amount of timber- ing. The seams as a rule give off a considerable amount of methane, which makes good ventilation imperative. Due to physical conditions, supervision is costly and travel about the workings is difficult. Because of the facts stated, the accident rate has been above the average, and for some time considerable thought has been given the idea of making promotion of safety in and about the mines a responsibility to be shared equally by the employees and the management. With this idea in mind the legislature of the State of Washington, turing March, 1927, passed laws providing that safety committees be selected to function at the coal mines of the State and at the same time recognizing the fact that first-aid education is an integral part of any safety movement; legislation was passed making it mandatory to have all persons in and about the ines trained in first-aid administration. The provisions of the State mining law3 are as follows: "In every mine a general safety committee shall be selected, composed of the mine superintendent or manager of mines, one man selected by the employees or any association of employees in or around said mine, and a third member selected by these two. "The general safety committee shall elect one of the members to act as chairman and one to act as secretary. The duties of the chairman shall be to preside at all meetings of the general safety committee, enforce its rules and regulations and see that its business is conducted in a prompt and business-like manner. The secretary shall keep an accurate written record of the proceedings of all meetings, conduct its correspondence and post notices of regular and special meetings and other matters pertaining to safety. The duties of the general safety committee shall be to investigate all serious and fatal accidents; make bi-monthly.

Jun 1, 1930

By J. D. Dixon

The Bureau of Mines investigated the principles of support-rock interaction, based on structural matrix methods which permit mathematical formulation of the problem and computer solution. The principles are given under two main sections: the first discusses the idealization of the tunnel support structural system for matrix analysis; the latter discusses the analysis procedures necessary for carrying out the solution. A general frame matrix computer program and a medium-size computer should be sufficient for carrying out the procedures involved. The example problem consists of a circular tunnel support which is subjected to a uniformly distributed vertical load, Three wall thickness-radius ratios are studied in combination with four support-rock modulus ratios. This problem illustrates the main procedures of the support-rock interaction analysis involved, and examination of the results reveals the influence of the relative rigidities of the support and the rock.

Jan 1, 1971

Table 1.-Salient aluminum statistics (Thousand short tons and thousand dollars) [ ]

Jan 1, 1967

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 Kenneth L. Cashddollar, Terry G. Montgomery, Eric S. Weiss, John E. Going

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research on dust explosions by studying post-explosion dust samples. The samples were collected after full-scale explosions at the PRI, Lake Lynn Experimental Mine and after laboratory explosions in the PRL 20-L chamber and the Fike 1-m3 chamber. The dusts studied included both high and low volatile bituminous coals. Low temperature ashing for 24 hr at 515°C was used to measure the incombustible content of the dust before and after the explosions. The data showed that the post-explosion incombustible content was always as high as or higher than the initial incombustible content. The MSHA alcohol coking test -was used to determine the amount of coked dust in the post-explosion samples. The results showed that almost all coal dust that was suspended within the explosion flame produced significant amounts of coke. Measurements of floor dust concentrations after LLEM explosions were compared to the initial dust loadings to determine the transport distance of dust during an explosion. All of these data will be useful in future forensic investigations of accidental dust explosions in coal mines or elsewhere.

By H. O. McDonald

The Bureau of Mines reviewed the chemical vapor deposition (CVD) literature on the nonmetal binary and ternary compounds of the group IVB, VB, and VIB elements, with emphasis directed to the following nonmetals: B, C, N, O, and Si. This review examines each of these binary and selected ternary compounds of the group IVB, VB, and VIB elements as coatings and gives some of their preparative methods, uses, and properties. A total of 259 references were found for these compounds of the nine elements. This review was utilized in the Bureau's research to provide abrasion-, erosion-, and corrosion-resistant coatings in order to conserve critical metals and protect various metallic surfaces in metallurgical, mining, and energy conversion systems.

Jan 1, 1983

By S. P. Sandoval, A. E. Clark, S. W. Yopps, J. S. Gomer

The U.S. Bureau of Mines conducted Cu exchange tests for six common clays under simulated in situ leaching conditions. Regression equations were obtained from the data expressing the Cu exchange capacity as a function of Cu concentration, pH, and temperature. Using these equations, an analysis was made of the impact each clay could have on overall Cu recovery. The results suggest that Ca and Na montmorillonite clays could have a major impact on Cu recovery and that attapulgite and illite clays could have a smaller, but still significant, impact. Kaolinite and ripidolite clays pose little threat to loss of Cu from in situ leaching solutions.

Jan 1, 1992