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Prevention of coal-mine explosions depends largely upon thorough knowledge of the causes that initiate explosions. A review of coal-mine explosions in one geographical area when supplemented by nationwide data of similar nature, should serve as a guide for the adoption of measures for explosion prevention. Explosions in bituminous-coal mines of the United States during the 10 years ended December 31, 1932, ranked third in the causes of fatal accidents and constituted 16.1 percent of all fatal accidents in bituminous mines. Kentucky now ranks fourth in coal output in the coal-producing States of this country; a study of the coal-mine explosions in this state will be of definite interest locally among coal-mining people, as well as to those in the coal-mining industry who are concerned in preventing coal-mine explosions. This circular reviews gas and dust explosions in Kentucky coal mines to show their hazards, to point out the influence of certain factors in causing explosions, and to indicate the effectiveness of preventive measures.

Jan 1, 1934

By Oliver Bowles

"Introduction.During recent months the Bureau of Mines has conducted a detailed study of the slate industry with special reference to increased efficiency in its production, preparation and utilization. The results of these investigations will be incorporated in a forthcoming bulletin. The purpose of this preliminary paper is three-fold. One object is to bring to the attention of slate producers certain modifications in manufacture and classification which would encourage a wider use of slate. A second purpose is to direct the thought of roofers toward the importance of proper laying of slate, and the third object is to acquaint the general public with its enduring qualities.Origin and character.Without entering into any detailed discussion of the origin and history of slate, a subject to be covered in the bulletin mentioned, it may be of interest to the general reader to know that slate is originally formed from mud or soft clay, carried down by streams and laid down in successive layers in deep water. The pressure of superimposed materials gradually compresses the clay into a firm rock known as shale. In many places this shale was, during the succeeding ages, subjected to intense pressure and folding due to mountain-building forces within the earth. This intense pressure, together with high temperature, changed the clay into other minerals such as mica, chlorite, and silica, which are very resistant to weathering, and also developed a very definite cleavage or splitting direction which characterizes the rock as slate. It is this property which renders slate of value for roofing, for, by using a broad chisel and a wooden mallet, a slate worker can readily split it into thin sheets which are later trimmed into rectangles of various sizes."

Jul 1, 1921

By Gary E. Sherman

The Bureau of Mines estimated the remaining lode gold endowment of eight mining districts in Alaska using historic production data. A log-arithmic model of cumulative tonnage of ore processed versus cumulative grade was applied to the following districts: Chichagof, Fairbanks, Homer, Hope-Seward, Juneau, Ketchikan, Prince William Sound, and Willow Creek. To assess the remaining endowment, a computerized production data base was compiled from Bureau records. These data were aggregated in 5-yr intervals for each district. Data were sorted in order of declining grade, and log cumulative grade was plotted against log cumulative tonnage. Linear regression was performed on the data for each district. The linear equation for each curve was used to predict remaining endowment at a limiting mining grade. Based on conservative extrapolation of the grade-tonnage curves, a substantial total endowment of 8,415,100 tr oz of gold remains in the eight districts. The districts with the greatest remaining endowment are the Juneau, Chichagof, Fairbanks, and Willow Creek Districts.

Jan 1, 1987

By Robert A. Jankowski

"Following passage of the Coal Mine Health and Safety Act of 1969 (Public Law 911173), the Bureau of Mines initiated a research program aimed at controlling respirable dust exposures of coal mine workers. Respirable dust is the dust that gets into, and interacts with, the lungs of those who inhale it. It has long been recognized as a severe health hazard to mine workers. This program has been implemented by a team effort consisting of the Bureau's in-house capabilities, the Generic Center for Respirable Dust, and contractors, as necessary. Over the years, Bureau research has addressed principally three areas:o Compliance with the Federal 2.0 mg/m3 dust standard (1970-76).o Dust control for longwall mining (1976-1983).o More stringent respirable dust standards due to quartz dust (1983-1987).In addition, fundamental studies have been conducted by the Generic Center for Respirable Dust, with emphasis on penetration of dust into the lung. Accomplishments have been significant, but problems remain, as noted later.The Coal Mine Health and Safety Act of 1969, established a 2.0 mg/m3 dust standard for all coal mining operations, underground as well as surface. At the time of enactment of this legislation, the industry was averaging approximately 4.0 mg/m3. The Bureau of Mines respirable dust research program played a significant role in identifying and developing effective technology to allow better compliance with this new standard, thanks to industry implementation and Federal enforcement."

Nov 1, 1988

By E. G. King

This publication presents original thermal data for a typical variety of perlite and supplies basic information for use in computing energy requirements in processes for expanding perlite. Perlite has been defined by Raiston 4/ as any silicious lava containing dissolved water in sufficient amount to errand into bubbles when the material is quickly heated to a suitable point in the softening range." The uses of expanded perlite in) the construction and ceramic industries have been discussed by Ralston 4/ and King. 5/ The work described here had a dual purpose: (1) It was desired to ascertain quantitatively, using a typical variety of perlite, just how firmly the contained water is held, and (2) it was desired to obtain basic thermal data sufficient for energy-requirement calculations in processes for expanding perlite.

Jan 1, 1948

By Oliver Bowles

Slate possesses many admirable qualities, not only as a roofing material, but for blackboards, electrical switch boards, and for various structural uses such as stair trends, floor tile, baseboards, and sanitary enclosures. The American slate industry was established manor years ago, and has made remarkable progress, particularly during the past five years. One of the chief drawbacks to more rapid expansion is the high percentage of waste which reaches 75 to 94 per cent of gross production. Much of this waste is duo to rock imperfections over which man has no control, but a careful study of tae industry by the Bureau of Mines over a period of years indicates that an undesirably large percentage of the marketable slate is wasted in the processes of quarrying and manufacture. The initial step in quarrying slate is to separate from the solid ledge masses of a size that ray be conveniently removed from the quarry. This first step entails a greater waste of material than any subsequent process, and, therefore, invites the most earnest effort toward waste reduction. Attention has consequently been directed toward possible improvements in methods of making primary cuts in the quarry floor. A study of European practice with the wire saw, together with theoretical consideration of its advantages, convinced the writer that it possessed sufficient merit to justify its use as a primary slate cutter in American quarries. No practical conclusion in this matter could be reached except by experiment. Therefore, the desirability of obtaining equipment and trying it out under actual conditions of operation was urged upon operators. While no doubt the equipment could be readily manufactured in America, it had already been developed to the point of practical use in Europe; therefore the writer urged the desirability of purchasing one completely equipped wire saw in Europe, and determining through tests whether it gave sufficient promise of success to warrant its manufacture in America.

Jan 1, 1927

By Jack O. Jones

The Furnish mine, Caharrus County, W. C., was operated intermittently until 1905 as a gold mine. Scheelite was discovered by A. L. Mash in the mine dumps of the Furniss and Phoenix mines, and he later informed the Bureau of Mines of his discovery. The Bureau of Mines, in two projects at the deposit in 1948 and in drilled 12 holes totaling 1,706.6 feet, examined and sampled the underground workings, excavated by bulldozer and hand, 3,155 linear feet of trenches and collected numerous samples for assay. The best scheelite shown; was found in the underground exposure of the Furniss mine.

Jan 1, 1950

By G. E. McElroy

Economic solutions of problems of mine-ventilation improvement can be found by mathematical analyses of alternative methods of procedure, but, in the case of our older bituminous-coal mines, the airway network is usually so complex that mathematical solutions are too tedious to be practical. Recourse usually is made to extremely costly and uncertain trial-and-error procedures with the existing layout and equipment. The resulting errors often prove costly and sometimes create hazardous conditions. Both the economic and safely aspects of alternative methods of ventilation improvement may be rapidly and cheaply investigation with analogue computers. An electrical analogue computer, designed and built especially for analyzing mine-ventilation-distribution problems, has been placed in service by the Bureau of Mines at its Pittsburgh, Pa., Experiment Station. It is a nonlinear, low-voltage, fluid network analyzer of a type developed by Malcolm S. Mcllroy, professor of electrical engineering at Cornell University. It was designed in close coopera¬tion with Professor Mcllroy and built by the Standard Electric Time Co., Springfield, Mass. It is the seventh unit of this type to be placed in service and the first designed for mine airflow problems. The other six were designed for either water- or gas-distribution analyses. Three are much larger and more expensive units. The largest unit has a capacity of 20 sources, 576 mains, and 180 loads, or regulated-flow paths. The Bureau unit has a capacity of 5 sources, 128 mains, and 48 loads.

Jan 1, 1954

By T. E. Swigart

In the production of oil end gas, engineering methods have been applied less than in any other branch of the oil industry. While refineries, gasoline plants, pipe-line and other transportation systems, and even drilling wells to a great extent, take advantage of engineering skill, the tendency has been to assume that the handling of producing wells is merely a mechanical and routine matter. At present few companies employ engineers to study oil and gas production methods with a view of increasing the general efficiency of recovery, but in vie, of the advancement in other lines of the petroleum industry by the application of engineering principles, does it not seem likely that the production branch may benefit also by engineering studies? Engineering applied to the handling of producing wells falls under two general headings, - first, the efficient handling of wells from the time of their inception in order to obtain the greatest possible ultimate production, and, second, the rehabilitation of old properties that have been handled carelessly in their early lives. To date, the engineering work that has been done on oil production problems falls mostly in the second class. For example, the use of vacuum and the application of compressed air have proved successful in some instances in stimulating wells of low gas pressure. These methods are costly to apply and are adapted to small wells in which the gas is almost exhausted, or in which the original gas pressure is negligible. The experiments described in this paper fall under the first heading, as they were made with an idea of learning toe probable extent to which the gas production of an oil well can be curtailed while gas in the sand is still plentiful, and thus saved for doing work during the later period of a well's life. Because of the scope of the experiments, this paper does not include a discussion of back pressure on flowing wells or for purposes other than cutting down the gas produced with each barrel of oil.

Jan 1, 1922

By A. Z. Dimitroff

An improvised rock- dust disseminator, consisting of a 10-gallon galvanized metal milk can that dispenses rock dust in return air currents by the injection of compressed air has reduced the float dust explosion hazards at the Koehler coal mine, Koehler, N. Mex.

Jan 1, 1965

By Frank E. Cash

Data on the accident experience of the pebble-phosphate industry in Florida for 1930 and 1940 are combined in this report with statistics for the 9-year period 1930-38, inclusive, which were published in Information Circulars 69173/, 69684/, and 71005/. The periodic compilation and publication of such data enable the pebble-phosphate industry, as well as other industries, to consider the relative hazards, compare experience, and thereby help to prevent accidents. ACKOWLEDGMENTS Accident data were furnished by the following operating companies: Amalgamated Phosphate Co., Brewster; American Agricultural Chemical Co., Pierce; Coronet Phosphate Co., Plant City; International Agricultural Corporation, Mulberry; Phosphate Mining Co., Nichols; southern Phosphate Corporation, Bartow; and Swift & Co., Fertilizer Works, Bartow.

Jan 1, 1941

By Stephen D. Cramer

The objective of the present studies was to develop thick adherent and coherent coatings of platinum and palladium on refractory metals and other substrates of industrial and engineering importance. Existing platinum and palladium electrolytes were modified to make them suitable for the electrodeposition of thick deposits. The optimum operating conditions for these electrolytes were established. Pretreatment procedures for columbium, copper, graphite, molybdenum, nickel, stainless steel, tantalum, titanium, tungsten, vanadium, and zirconium substrates were studied. New pretreatment procedures for columbium, molybdenum, stainless steel, tantalum, tungsten, and nickel were developed. The internal stress and hardness of selected electrodeposits were measured. The effects of heat treatment upon the properties of electrodeposits were studied.

Jan 1, 1967

By E. C. Lane

This report presents the results of the Bureau of Mines' twenty-first semiannual survey of motor gasoline marketed in the United States. The 12 cities in which samples were collected have teen chosen as representative of the more important marketing territories, as it is obviously impractical to obtain a sample of every gasoline sold in the entire country. The survey reveals that the motor gasoline which is being marketed in the United States this winter is decidedly more volatile than that sold a year ago. Samples from all cities show a decided improvement in volatility except those from Laramie, Wyo., which show a small decrease in volatility.

Jan 1, 1930

By Jack R. Woodyard

Scientists at the U.S. Bureau of Mines are studying iron aluminides as possible substitutes for stainless steels to reduce the Nation's dependence on imported strategic and critical materials. In a Bureau investigation on the mechanical properties of Fe-28Al, it was found that the material's machining properties were significantly improved at slow tool and feed speeds. Machining techniques normally used for brittle materials failed or were costly. Further experiments using a 5-in (12.7-cm) mill cutter with carbide inserts, operating dry at minimum machining speeds, produced visually smooth sample surfaces with no tool damage. As a result of these experiments and a review of published data on hydrogen embrittlement of iron aluminide under tension, non-water-based (e.g., sulfur-based) lubricants were chosen for production machining. Four-flute, 3/4-in (19-mm) carbide end mills were used at slow speed under lubrication. This latter procedure reduced tool wear and breakage by a factor of 2. Machined surfaces and specimen cross sections were analyzed by scanning electron microscopy to detect microcracking. Tensile tests gave the expected yield and ultimate strengths, indicating that no degradation by low-speed machining occurred. This study extends this work to show that the alloy can be machined at higher speeds using high-speed steel end mills, and that water-soluble cutting oil is a suitable lubricant and coolant.

Jan 1, 2010

By John R. Benham

In 1979 and 1980, the U.S. Bureau of Mines and U.S. Geological Survey conducted a mineral survey of the 20,500 acre Black Butte RARE II area (No. 5102) in the Los Padres National Forest (fig. 1). The work by the Bureau of Mines indicates that the potential tor mineral resources in the area is low. Samples of outcrops and stream channels contained no economic minerals. A mercury deposit near a granodiorite-sedimentary rock contact occurs 2 mi northeast of the study area, but similar deposits have not been discovered within the area. Geothermal potential exists near Tassajara Hot Springs, but no thermal springs occur in the area; nor have oil, gas, or coal resources been found.

Jan 1, 1982

By Cleo G. Rall

The value of brine analyses in the study of petroleum-engineering problems was recognized early in the history of petroleum. The Bureau of Mines before 1928 had indicated in several reports.3/ ways in which analyses might be used. Because of the confusion resulting from attempts to correlate the work of different chemists using greatly varying methods of analysis and systems of computation and expression of results, a paper presenting the methods used by the Bureau of Mines was prepared and published in 1928. This system of determining the characteristic constituents of oil-field waters and of calculating and reporting results has been widely adopted by the petroleum industry. The earliest and most obvious use of water analyses is determination of the source of water infiltrating into petroleum and natural-gas wells. For this purpose it is necessary that an analysis of the connate water of the formation from which the oil is produced be available and that an analysis of the contaminated water be made. By comparing these analyses with those of connate waters from formations higher in the structure, the formation from which the infiltrating water comes may be identified.

Jan 1, 1953

By Leonard P. Vitt

This report details the work done to provide the U.S. Bureau of Mines with a customized Wireless Ground Monitor Wireless Ground Monitor was modified as follows: 1. A voltage regulator was added to prevent false trips with line voltage variations. 2. A Ground Wire Trap was designed to eliminate problems with parallel paths and provide spark suppression. 3. A three phase filter was designed to reduce 60 Hz leakage current. 4. A portable tester was designed to permit complete test of installed systems. 5. The design was modified to insure trip with an open ground wire in the event of a failure of any one semi-conductor component.

Jan 1, 1976

By C. P. Fang, V. A. Marple, K. L. Rubow, P. H. McMurry

"It has been known for some time that sizes of aqueous particles may be affected by flow-induced relative humidity (RH) changes. The RH of air flowing through an impactor decreases as a result of pressure drop through the impactor and increases because of aerodynamic cooling within the high-speed jets, as illustrated in Figure 1. Because the sizes of aqueous particles depend on RH, the impaction stage on which such particles are collected may be different from the stage where they ought to be col¬lected, based on the particle size at the sampler inlet.Fuchs (1980) reviewed literature on water vapor condensation in impactors. The reviewed impactors operated at jet velocities of 100-250 m/s. Particle size increases ow¬ing to water vapor condensation were found in all cases. In one case (Khorguani et al., 1970), it was found that very small droplets (Dp <_ 0.02 um) containing sodium chloride and silver iodide were collected in an impactor with a cut point of 0.32 µm and a jet velocity of 100 m/s. Fuchs believed that such particles could not be captured in an impactor without having been enlarged by condensation. Winkler (1974) sampled at¬mospheric dust with a rectangular nozzle impactor that had a nozzle cross section of 0.3 x 15 mm, a cut size of 0.4 um, and an average jet velocity of 100 m/s. No adhesive was used on the impaction plate. The collection efficiency increased as air humidity was increased from 20% to 100%. The effect was especially noticeable in the increased collection efficiency for hygroscopic particles, and was attributed to condensation.Extensive theoretical and experimental research work on the distortion of the particle size distributions in impactors was done by Biswas and coworkers (1985, 1987). The impactors employed in the study were a low-pressure impactor with high jet velocity stages (Hering et al., 1978, 1979) and a conventional six-stage impactor, Sierra's model 226, operated in the incompressible regime. Ammonium sulfate aerosols were chosen for the study. In the low-pressure impactor, an orifice operating at a Mach number of 1 causes a sudden pressure drop, significantly reducing the RH in the next two stages (stages 5 and 6). This results in a 0.15-um diameter ammonium sulfate droplet shrinking to about 0.07 um at stage 5 when the inlet RH is 95%. In stage 7, the tempera¬ture drop is considerable because the jet speed is sonic. For an inlet RH of 95%, a 0.03 um droplet grows to about 0.06 um. However, the same size droplet at an inlet RH of 25% grows to only 0.04 um. For the Sierra model 226 cascade impactor that is operated with a Mach number of 0.27 at the last stage (stage VI), it was found that for an inlet RH of about 67%, particle growth would occur in stage VI. At 80% RH, both stages V and VI were affected. Biswas et al. (1987) stated that Mach number alone does not determine the size biasing; the type of aerosol, the inlet conditions, the temperature and pressure ratio, and the impactor geometry (throat length, jet-to-plate distance, etc.) must be considered for each stage in evaluating the distortion of the particle size distribution."

Mar 1, 1992

By Friedel. Michael J.

The U.S. Bureau of Mines investigated acoustic emission (AE) and the Kaiser effect in six types of rock: St. Cloud gray granodiorite, Barre granite, Dresser basalt, Salem limestone, Berea sandstone, and a volcanic tuff. AE signatures were used for interpreting the rock deformation stage and for indicating mechanisms of failure in uniaxial compression. The research demonstrated the advantages of using the volumetric stress-strain curve, as opposed to the more conventional uniaxial curve, for correlating AE response signatures with deformation stages and fracture processes in the rock. Standardized experimental procedures were used for the AE monitoring. The Kaiser effect was shown to be capable of determining prestress levels to within a few percentage points in uniaxial compression tests. Also, prestress memory was shown to be retained in the rock for periods of up to at least. 5 months, the maximum period of testing. The Kaiser effect AE technology holds promise for providing a comparatively inexpensive and less complex method for examihing stress history in rock. However, since the conftning stress has a pronounced influence on the Kaiser effect, it must be considered in developing technology for determining peak fteld stresses based on the Kaiser effect.

Jan 1, 1990

By E. C. Lane

This paper is the second report of the results of the United States Bureau of Mines twenty-third semiannual survey of motor fuel marketed in the United States. The first paper, reporting data relating to gravity, vapor pressure, and distillation range of the samples, was published as Report of Investigations 31293. A third and concluding paper giving the results of other tests will be published as soon as these tests have been completed. The present paper deals with the data of the twenty-third semiannual survey presented in accordance with the revised specifications for United States Government motor gasoline. The sample numbers used are identical with those used in Report of Investigations 3129, with additional data included for copper strip corrosion (method 530.22).4 and sulphur content by the lamp method.5 Three hundred and twelve samples were collected and analyzed in this survey. Two hundred and seven samples were competitive-price gasolines and one hundred and five samples were premium-price motor fuels.6

Jan 1, 1931