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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 I. D. Schleicher, L. H. Rorden, F. B. Curry, T. C. Moore

The purpose of this program is to extend electromagnetic (EM) techniques for use in locating miners trapped in mines as deep as 1000 m. A previously developed EM system is considered adequate for use at mines less than 300 m deep where it has a probability of detection of 54%. A system for deep mines must keep underground equipment simple, and use extremely low frequencies (ELF), sensitive receivers, and noise cancellation. The proposed location method, developed by Develco for other applications, is based on vector field measurements from two or more static sensors and computation of source location by iterative techniques. During Phase II, very sensitive search coil sensors were built and used in a separate test to verify the feasibility of atmospheric noise cancellation. A "Breadboard" location system version without cancellation, which is a fieldable test bed to evaluate receiving and location functions, was tested and supplied. Very good results were achieved from the first in-mine test with the transmitter at a depth of 380 m. It is expected the results of this work, and additional evaluation tests in the future, will be used to define the requirements for a prototype operational system.

By George S. Rice

The prevention of coal-mine explosions has been one of the chief purposes of the Bureau of Mines. In facti the first Federal appropriation relating to mining methods, in 1908, authorized the investigation of the causes of mine explosions and the possible methods of preventing them. When that investigation started the mining industry had not determined the real causes of a succession of terrible coal-mine explosions in various countries, culminating in the great disasters at CoulTièl'es, France, and Monongah, W. Va. Coal dust as an agent of widespread explosions had been under suspicion, and watering to allay the dust was recommended by some mining engineers but the watering of coal-mine dust was adopted in comparatively few mines of the United States and Great Britain, and had not been introduced widely in any country except Germany. Rock dusting, another method of preventing explosions of coal dust, was early tested with success by the Bureau of Mines in its fist gallery at Pittsburgh and, beginnig in 1911, at the experimental mine, Bruceton, Pa. Several of the fist publications i of the bureau suggested that rock dust be used in gaseous or dusty bituminous mines, and in 1915 Technical Paper 842 strongly recommended it. Since that time additional tests in the experimental mine have fully confied this :ft judgment.

Jan 1, 1924

By Arthur C. McFarlan

There are two distinct coal fields in Kentucky-the Eastern field constituting a part of the Appalachian coal region and the Western field constituting the southern part of the Eastern Interior region. The outcrop pattern of the State is dominated by the Cincinnati arch. Coal-bearing Pennsylvanian strata occupy a low structural position on either flank, preserved thereby from erosion, which in the past has removed these same beds, though a much thinner succession, from the crest of the arch. General geological relationships are shown in figures 1 and 2. On April 13, 1750, Dr. Thomas Walker discovered the first coal recorded in Kentucky. He entered the State through Cumberland Gap (Cave Gap) and found coal a few miles north.

Jan 1, 1944

By P. A. Cox

The purpose of the initial research performed under this contract was to determine the margins of safety in explosion-proof (XP) enclosures, which were designed and certified according to the current schedule (Schedule 2G). Results from this work provide baseline data on the current schedule, from which a new schedule can be formulated to give equal or greater levels of safety. Results and discoveries in the initial work led to an expansion of the contract to cover, additionally, weld quality in enclosure fabrication, reliability of enclosures with windows and lenses, and performance tests for enclosure qualification. Finite element calculations and hydrostatic tests revealed wide variations in the margins of safety in the enclosures studied; however, only one enclosure had a safety factor which was less than one. Results from a weld quality survey led to the recommendation of AWS Welding Standard D14.4 for the fabrication of XP enclosures. Based on other work, accelerated aging tests were recommended for qualifying plastics and adhesives that are used in some enclosures, and a Structural Performance Test was developed to test enclosure strength for a minimum static pressure of 150 psig.

Jan 1, 1982

By Raymond W. Hiteshue

To aid in designing a continuous system for evaluating processes for converting coal to high-Btu gas] the Bureau of Mines determined the amenability of various coals and a char to hydrogasification at 800° C and 6,000 psig using a molybdenum catalyst. A lignite from Rockdale, Tex., an hvCb coal from Rock Springs, Wyo., a char from the low-temperature carbonization of the latter, an hvAb coal from Pittsburgh, Pa., and an anthracite from Luzerne County, Pa., were selected. Highest yields of gaseous hydrocarbons, 94 pet, based on maf feed, were produced from char, and lowest yields, 67 pct, were obtained from lignite. Hydrocarbon gases contained 82 to 92 pct methane, 8 to 15 pct ethane; and 1 to 3 pct propane.

Jan 1, 1962

By M. C. Irani

This study is a survey of supply and demand for minerals, metals, alloys, and compounds used by the chemical industries in the Ohio River Basin (ORB) area of Ohio, Pennsylvania, and West Virginia during 1967. Data for the study were obtained from completed questionnaires received from chemical manufacturers and from interviews with officials of chemical companies and mineral producers and distributors. The information includes kind, quality, quantity, values, sources, specifications, uses, and methods of transportation. Results of the study show that of the total value of mineral materials consumed by the chemical industry, manufacture of inorganic chemicals consumed 46 percent; fertilizers, 22 percent; and soaps and detergents, 19 percent. Fifteen commodities accounted for 91 percent of the total value of mineral materials consumed. Five of these--phosphates, potash, salt, sulfur, and titanium dioxide--accounted for 59 percent of the total.

Jan 1, 1970

By Todd M. Ruff

The majority of fatalities that occur in road construction work zones in the United States involve a worker being struck by a piece of construction equipment or other vehicle. The Spokane Research Laboratory of the National Institute for Occupational Safety and Health, in cooperation with the Washington State Department of Transportation, is evaluating methods to decrease these accidents. One such method uses devices that assist equipment operators in monitoring blind areas around the equipment to prevent collisions with workers on foot or other objects. Several cameras and sensor systems are available for this application, and a study was conducted to evaluate these systems on various trucks used in road construction and maintenance. Tests were conducted using sanding trucks during the winter months, which allowed researchers to investigate the effectiveness and limitations of various technologies under the most extreme conditions. Tests were also conducted using dump trucks during the warmer months to study the effectiveness of the systems in highway work zones. Results show that many difficulties arise when using camera and sensor systems in cold, snowy climates. And, while the operation of these systems is more reliable during the warmer months, challenges still exist in using them on equipment in crowded work areas.

Jan 1, 2004

By H. G. Miller

The success of any project in which gas is injected into oil-producing sands to increase the current rate or the economic ultimate production of oil or in which surplus gas from oil-producing operations is stored temporarily in reservoir sands that have been wholly or partly depleted of their producible oil depends mainly upon an understanding of the underground movements of oil, water, and injected gas and the ability to control their speed and direction of migration through the reservoir sends. Many operators believe that injected gas always travels up the structure and drives oil to wells structurally higher than the injection wells, because the specific gravity of the injected gas is less than that of the fluid substances in the formation. Consequently, many injection wells are located on the flanks of oil-bearing structures with the idea of utilizing the energy of the injected gas to drive the oil to producing wells higher on the structure. It is true, under certain conditions of pressure and fluid depletion of the reservoir sands that injected gas will move in an up-structure direction, but the theory that injected gas always moves up the structure is based on an erroneous conception of the laws that pertain to the expansion of gases. By definition, "a gas is distinguished by its property of infinite expansion and is limited in volume only by the walls of the vessel which contains it." The expansion of gas that is injected into reservoir sands also is limited by "walls" that surround the space influenced by the injected gas. The walls of the majority of undrilled or virgin oil-bearing reservoirs in California are the impervious shales overlying and underlying the productive strata and the "dams" or effective barriers of edge water around the rims of the reservoirs. When gas is injected into the sands of a producing reservoir, regardless of the location of the injection well on the structure or the degree of depletion of oil from the sands, one of the walls which confine the gas in the structure about the injection well is fluid. This wall will be edge water in a nearly depleted reservoir, where the drainage cones or regions of reduced pressure about injection and producing wells intersect; and, where there is no interference of drainage cones and the injection well is structurally above the edge water, the wall will be oil. In some producing reservoirs bottom water may be the lower wall of the space that confines the gas about injection wells, but the effect of bottom water on limiting the expansion of gas is the same as if the water was not present and impervious formation separated the producing from the underlying nonproducing strata. Therefore, since compressed gas always seeks regions of reduced pressure and its final volume is limited only by formation and fluid barriers and since the force exerted by the gas under pressure is equal in all directions, the course of migration of injected gas in reservoir sands in California and the effect of the gas pressure on fluid movement does not depend necessarily upon the up-structure location of low-pressure regions.

Jan 1, 1932

By B. J. Moore

This publication contains analyses and related source data for 352 natural gas samples from wells and pipelines in 18 States and 5 foreign countries. All of the samples were obtained and analyzed during calendar year 1974 as a part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economics. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4862 and 576.3 The results of the investigation of the occurrences of helium are published annually to make the information available as soon as possible to the gas industry and the public in general. Sixteen previous publications have presented the results of 10,479 gas analyses prior to 1974. The first three, Bulletins 486,4 576,5 and 617,6 contain analyses and related source data on

Jan 1, 1975

By William Seymour, L. D. Schmidt, J. W. Myers, W. T. Reid

"This investigation was conducted by the Bureau of Mines as part of a program of the Solid Fuels Administration to encourage the utilization of anthracite fines, the objective being to determine the practicability of using anthracite fines in the manufacture of packagedThe experimental loss of packaged fuel covered by this report were made at a commercial plant using the Glenn Smith process and ordinarily making packaged fuel from Pocahontas screenings. These lots included several made from straight antimacite mines and others made from various blends of anthracite fines with four different bituminous coals. In all cases an asphalt binder was used. Determinations of the physical properties and the cobustion characteristics o the various samples of packaged fuel were made by the. Bureau of Mines at the Central Experiment Station.The physical tests indicated that a packaged fuel of sufficient strength for ordinary handling can be made from straight anthracite coal or from a wide variety of blends of anthracite fixes with bitunimous coal, using asphaltic binder. However the combustion tests indicated that packaged fuel made from anthracite alone tended to crumble excessively during burning and that as much as 30 to 50 percent of a caking coal may be required In the mixture to produce a block having satisfactory combustion characteristics.The authors wish to acknowledge the. splendid cooperation of Messrs. H. W. Kelly, J. L. Mooney and C. H. Stoss of Columbus, Ohio, who were chiefly responsible for obtaining the materials and making all the arrangements necessary for the production of the packaged fuel for testing.Thanks are due to the officials of Carnegie Institute of Technology for the use of their Olsen. Testing Machine and to H. M. Cooper and W. A. Selvig of the Bureau of Mines for analyses and tests."

May 1, 1946

By Thomas Fraser

"INTRODUCTION The Santa River Valley of northern Peru contains extensive deposits of a good-grade anthracite that offer one of the most accessible sources of solid-fuel supply for South America. This region is served by the narrow-gage railroad of the Corporation Peruana del Santa, which taps the coal fields along the Chuquicara River and terminates at the port of Chimbote, where facilities have been provided for loading coal into ocean-going vessels.This Government-sponsored corporation is prosecuting a vigorous program of development in this region, envisaging an intensively industrialized area around Chimbot Bay, fueled and powered by the anthracite of the upper valley and a hydroelectric generating plant now being constructed in the Cahn del Fate, where the Santa River has cut through the coastal range of the Andes.This development also includes the construction of extensive irrigation works to greatly expand agricultural production in the valley and thus estab¬lish the basis for a prosperous, well-balanced, industrial and agricultural community. It is hardly necessary to point out the importance of the local anthracite-mining industry to this general plan.At the invitation of the Peruvian Government, through the agency of David Dasso, chairman of Corpoacion Peruana del Santa, a technical mission was sent to Peru in March, April, and May 1945 to examine these coals and assist the corporation in promoting preparation of the coal for most effective use in the contemplated expansion of industry and trade."

Feb 1, 1948

Papers presented at a U.S. Bureau of Mines (USBM) technology transfer seminar describe the causes of violent material failure in U.S. mines, measurement techniques for monitoring events that result in violent failure, and mitigation techniques for controlling failure. Specific factors contributing to violent failure are identified on the basis of geotechnical monitoring in 16 U.S. hard-rock and coal mines and on statistical analyses of 172 coal bump events. New monitoring and analysis techniques developed as tools for assessing violent failure; geotomographic methods that provide new capabilities for the study of material failure and stress changes over large areas; and seismic methods for determining source locations, calculating energy release, and determining source mechanisms are described. Fair correlations have been established among seismic parameters, elastic stresses, face support load, and violent events. USBM studies have identified the advantages using both yielding and stable pillars for coal bump control. A computer program has been developed as an aid for selecting room-and-pillar layouts. The practical aspects of implementing a destressing program is outlined for coal mines, while the importance of mine orientation and timely support installation in controlling buckling-type failure is identified for hard-rock mines.

Jan 1, 1995

By S. M. Runke

The purpose of the work described in this publication was to determine, on a pilot-plant scale, the practicability of concentrating low-grade bauxite deposits to render them suitable for the extraction of alumina. In 1941, when it became apparent that the United States might soon be drawn into war, the government, through its various agencies and bureaus, began to stimulate and increase production from domestic reserves of bauxite, which is the principal raw material for the production of aluminum. This activity, which was centered in Arkansas, where 95 percent of the domestic reserve is situated, reached peak production when enemy submarine warfare greatly hindered imports from foreign sources. During this period the average domestic production in Arkansas rose from approximately 300,000 long wet tons to something over 6,000,000 tons in 1943.

Jan 1, 1949

General economic conditions continued to improve in the second quarter of 1984 as real gross national product advanced at an annual rate of 7.5 percent (table 1). This followed an even larger first quarter annual rate increase of 10.1 percent. The slower second quarter growth was greeted as a sign that the economy is not over-heating. The signs of slowed growth in some sectors suggest that the recovery may continue well into 1985 without the inflation symptomatic of a rapid recovery. Most of the slowdown in growth was absorbed by business inventories, personal consumption of durable goods, and residential fixed investment. Business inventories grew by only 68 percent as much as in the first quarter, personal consumption for durable goods grew by 58 percent of the first quarter rate, and residential fixed investment slowed to only 44 percent of the first quarter growth. Sectors with accelerated growth in the second quarter included personal consumption of nondurable goods and of services, which increased at annual rates of 9.6 percent and 3.8 percent, respectively, and Federal purchases of goods and services, which increased at an annual rate of 47.9 percent.

Jan 1, 1984

Significantly increase the amount of fresh air that sweeps the face in front of a continuous mining ma-chine, in order to prevent methane gas buildup. Approach Water sprays are mounted along the sides of a continuous miner and behind the cutter head to help push ventilating air along the required path, and prevent its short circuiting. How It Works A continuous miner is fitted with two sets of water sprays, one of which is used at a time. The set of sprays shown in the diagram, helps move the ventilating air forward along the left side of the miner and across the cutter drum from left to right. That air is then drawn into the exhaust air passageway located along

Jan 1, 1978

By J. D. Davis

THIS REPORT gives results of an investi¬gation of the carbonizing properties of coals from Pittsburgh bed, Jamison No. 9 mine, Marion County, W. Va., and from Upper Freeport bed, Bull Run No. 1 mine, Preston County, W. Va. The study included Bureau of Mines-American Gas Association tests at 800° and 900° C. and various chemical and physical tests designed to evaluate the plastic, expanding, and agglutinating properties of coal. A blend of each coal was carbonized in the 500-pound slot oven. The carbonization sample of Pittsburgh coal contained 2.7 percent moisture, 35.8 percent volatile matter, 54.4 percent fixed carbon, 7.1 percent ash, and 0.9 percent sulfur. It contained 60.9 percent fixed carbon on the dry, mineral-matter-free basis and had a heating value of 14,780 B. t. u. per pound on the moist, mineral-matter-free basis. It therefore ranks as high-volatile A bituminous and was blended with low-volatile Pocahontas No. 3 coal. Upper Freeport coal contained 2.8 percent moisture, 27.7 percent volatile matter, 60.9 percent fixed carbon, 8.6 percent ash, and 1.0 percent sulfur, as carbonized. It contained 69.5 percent fixed carbon on the dry, mineral-matter-free basis and therefore ranks as medium-volatile bituminous. It was blended with high-volatile A Pittsburgh coal from Allegheny County Pa.

Jan 1, 1952

By R. S. Dean

In addition to the normal work and that pertaining to strategic minerals, the Metallurgical Division has been made responsible for carrying on major investigations in the development of processes&apos; for the treatment of low-grade domestic manganese ores that heretofore have failed to yield products suitable for the preparation of ferromanganese, an alloy essential to every ton of steel produced. These investigations are particularly important at this time because of their part in tucking this country self-sufficient with regard to manganese when the stock-piled ore becomes e exhausted and as foreign shipments of ferro-grade ore are cut off. The results indicate that there is a good probability of accomplishing this objective, while at the same time conservation may be promoted through the use of normally useless material from the large, low-grade ore deposits.

Jan 1, 1941

By Robert L. Frantz

This report is a part of the project "Study of the Human Factors Aspects of an Automated Continuous Mining Section". The report covers three phases: Phase I Assessment of the Impact of the Automation Technology on Mining Health and Safety. Phase II Estimation of the Cost-Effectiveness and Productivity of Automation. Phase III Prediction of the Psychological and Organizational Impacts of Automated Mining, The investigation determines that the automation of a continuous mining section will improve the health and safety of the miner, increase productivity and decrease mining costs, result in a more attractive and desirable working environment, and result in a greater rate of return on capital investment.

Jan 1, 1977

By George T. Faust

The petrographic microscope plays an important role in the mineral dressing of nonmetallic materials. Petrographers and mineral technologists have evinced an interest in the technique developed, specifically, for mineral-dressing problems. The following dissertation makes the informa¬tion more generally available. ACKNOWLEDGMENTS The authors are indebted to O. C. Ralston, chief engineer, Nonmetals Division, and to Will H. Coghill, supervising engineer of the Southern Experiment Station for a critical reading of the manuscript. They are also indebted to their colleagues for technical information obtained in the course of cooperative work, in particular to J. B. Clemmer for the use of the data on fluorite.

Jan 1, 1940