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By W. E. Wallace, V. Robinson, M. F. Keane, V. Vallyathan

"An in vitro study of the biologic responses of surface-modified and native silica and kaolin was made to provide comparative information on the supression of cytotoxicity by pulmonary surfactant. The release of alveolar macrophage cytoplasmic enzyme, lactate dehydrogenase (IDH), and lysosomal enzymes B-N-acetylglocosaminidase (B-NAG) and B-ghucuronidase (B-GLUC) and sheep blood-cell hemolysis were moni¬tored as indicators of cell membrane damage and cytutoxicity. Surface modification of silica and kaolin with dipalmitoyl lecithin (UPI) resulted in complete abrogation of cytotoxicity of both minerals. These findings indicate that surface modification of minerals with different adsorption properties by pulmonary surfactant generally lessens their prompt adverse effects.INTRODUCTIONAcute and chronic silicosis are well-characterized clinical and pathologic entities resulting from the inhalation of crystalline silica (Morgan and Seaton, 1984). Kaolin, a layered aluminosilicate clay frequently mined and used in manufacturing, contains tetrahedral silica alternately layered with alumina octahedra. Kaolin is relatively .inert biologically, and distinctly greater pulmonary burdens are seen in patients with kaolinosis than are seen in patients with silicosis. Crystalline siliea (quartz) induces a significantly greater degree of fibrosis in exposed animals in vivo than does kaolin (Hamilton and Hardy, 1974; Parkes, 1982; Hunter, 1976; Sheers, 1964; Warraki and t-lerant, 1963; Lynch and Mciver, 1954; Lapenas et al., 1984).This difference in pulmonary disease associated with the two types of dust is not reflected by in vitro cytotoxicity as Jetermined by pulmonary macrophage bioassays or erythrocyte hemolysis. Cytotoxicity studies using crystalline silica and kaolin of similar size fractions show comparable bioassay response on a mass basis. These cellular bioassays, therefore, do not correlate with the relative in vivo pathogenicity of silicates."

Jun 1, 1988

By J. W. Horne

The United States Bureau of Mines in cooperation with the State of Colorado at the University of Colorado has conducted experiments to determine the amount and composition of the non-condensable gases evolved when crude shale oil is distilled under pressure. Hydrogen sulphide is one of the components found in the complex mixture of Gases produced by the distillation of shale oil under pressure. This paper deals with the apparatus and method used in determining the amount of hydrogen sulphide evolved in the laboratory experimental cracking stills. The study required a complete extraction of all the hydrogen sulphide from the gas stream after it left the water-cooled distillate condensers and before the gas stream entered the charcoal absorber for removing the light naphtha. In devising the method it was necessary to take into account a constant variation of velocity, pressure, and percentage of sulphide in the total gas stream coming from the still. Ordinarily, the quantitative determination of hydrogen sulphide in gas is made by analyzing small samples taken at regular intervals. This estimation can be accomplished by use of the Bunts gas burette as modified by Tutriler, or by a similar method. In the industries where the flow of gas is constant and of uniform composition, this practice is sufficiently accurate for plant control. For experimental work where many variables have to be taken into consideration, as in the case at band; these methods are not applicable.

Jan 1, 1931

By R. V. Ramani, J. Qin

"In this paper, the results of a research study on airborne dust transport in a full scale simulated longwall face are presented. The simulated longwall face was set up in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines to conduct experiments under controlled conditions. The controlled parameters in the experiments were the dust dispersion rate, dust size distribution, density of the dust, air velocity, and the rate of travel of the dust generating source. The analyses of the experimental results on mass concentrations, particle size distributions, and real-time respirable dust concentrations are discussed. There are definite spatio-temporal trends between the location of the shearer, the concentration at any location in the face, and the dust generation rates. The size-consist and density characteristics of the source dust, the air velocity in the face, and the air leakage into the gobs all affect the concentration. INTRODUCTIONA detailed experimental study on the characteristics of longwall dust cloud in operating longwall faces has been reported by Ramani, Qin, and Jankowski (1991). The study indicated that there are several important factors whose effects on dust transport in longwall faces need to be further investigated. In an operating longwall face, the effect of these parameters could not be easily isolated as control over the affecting parameters is not readily possible. In a simulated longwall face, however, these parameters can be controlled. Therefore, as a follow-up to the field study, a series of controlled experiments were conducted in a full scale simulated longwall face in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines [Qin, 1992]. Specific aspects which were addressed during the experimental design phase included determining the types of samples to be collected, selecting proper instruments to collect these samples, and developing detailed sampling and time-study plans to correlate the dust concentrations with face activities. Two types of dust--anthracite and bituminous--were used. Dust dispersion rate into the air as well as the source dust particle size distribution were documented. Control was exercised over both air velocity at the face and air leakage along the longwall face. During experiments, the dust source was moved to simulate the shearer movement at operating longwall faces. Detailed descriptions of the design of experiments, experimental results, and data analyses follow in the subsequent sections."

Dec 1, 1996

By Wilbur Duvall

For the past few years the Applied Physics Branch has been investigating, experimentally, the generation and propagation of strain waves in rock. The strain waves are produced by the detonation of a high-velocity explosive placed in a small cavity in the rock. Strain gages mounted in the solid rock surrounding the cavity record the strain pulses propagated away from the source. Numerous strain-wave pulses have been recorded in different rock types for charges of various sizes and at various distances from the charge. Analysis of these records has shown, among other things, that there is associated with the strain wave a characteristic pulse width. This pulse width is dependent on the rock type and the distance from the shot point to the gage, but is apparently independent of the charge size or cavity size. Recent published literature on the generation and propagation of seismic waves indicates that the characteristic frequency of an elastic wave generated by an explosion should be a function of the rock type and the size of the cavity created by the explosion. Also, internal friction in the rock would produce absorption of high-frequency components, which would cause continual change in the shape of the pulse propagated. As the experimental data did not verify the expected change in pulse shape with cavity size, a theoretical investigation of the vibrations associated with a spherical cavity in an elastic medium was undertaken.

Jan 1, 1950

By Shirley F. Colby

Much interest has been shown recently in the possible utilization of dolomite as a source of magnesium metal, a large production of which is deemed essential for national defense. As a result, many inquiries have been received by the Bureau of Mines as to sources of dolomite. This report has been prepared primarily to augment the Bureau's present published information on the occurrence of high-grade dolomite deposits in the United States. To supplement such data, the report also defines dolomite and related rocks and describes their properties and uses. The uses are covered in some detail in Information Circular 6524 entitled "Utilization of Dolomite and High-Magnesium Limestone," published in 1931 but now out of print. All essential data on uses contained in that report have been incorporated herein, and. have: been supplemented by data developed during subsequent years. DEFINITION Dolomite is a mineral composed of calcium end magnesium carbonates combined in equal molecular proportions, expressed by the formula CaMg(C03)2. Dolomitic limestones contain considerable dolomite but also include either

Jan 1, 1941

By Steven J. Page

Responding to the increasing concern for dust control in metal and nonmetal mining, the Bureau of Mines investigated typical dust reduction efficiencies of wet bar cutter machines as they are presently being used in salt mines. Wet bar techniques have previously been used in coal mines, achieving dust reduction efficiencies ranging from 11 to 60 pct. Two different wet bar techniques, namely, the front spray and the water trickle, have been studied as they are currently being used in two salt mines. Preliminary results show that the dust reduction efficiencies have a large variation (0 to 66 pct), as is the case for wet bars used in coal. However, whereas wet bars in coal required 3 to 4 gpm water consumption, wet bars in salt obtained similar efficiencies with only 0.1 to 0.4 gpm. The most reliable data obtained during this study show that the front spray system consistently performs at efficiencies between 41 and 66 pct, with an average of 54 pct. The results indicate that, although wet bar cutter techniques in salt mines are a relatively simple and inexpensive means of dust control with a minimum of water consumption, further investigation should be performed to fully evaluate and optimize wet bar cutter dust reduction efficiencies.

Jan 1, 1980

By Joseph A. Sutton

The prospect of utilizing bacteria in mining and metallurgical processes introduces a new and challenging area of investigation. Elements of bacteriology and metallurgy are discussed in connection with possible areas where biological science might be applied in extractive metallurgy. Bacteria may prove important in the selective separation of metals from ores and metallurgical solutions, the production of sulfur from gypsum or pyrites, and the production of sulfuric acid from elemental sulfur. A series of reports concerning the experimental applications of bacteria on minerals and metallic ores will follow this paper. For several years the Bureau of Mines has been investigating the action of bacteria in the oxidation of sulfide minerals and their potential uses in metallurgical processes. Primary attention has been given to the possible utilization of certain strains of autotrophic bacteria that live in industrial leaching solutions or fractures of mineral outcrops. The purpose of this paper is to acquaint the mining and metallurgical engineer with micro-organisms and some of their possible applications in the field of extractive metallurgy.

Jan 1, 1961

By Robert E. Meredith, Thomas T. Campbell

An investigation was undertaken to examine the feasibility of employing low- temperature nonaqueous baths for electrodepositing some of the refractory metals of the ferroalloy group . To date , such metals as tungsten , molybdenum , and vanadium have been produced only by high - temperature processes that are technically difficult and sometimes cumbersome in operation . Deposition studies were performed in a wide variety of organic solvents , including amides , ammonia derivatives , ketones , polyhydroxy alcohols , and ethers . Compounds prepared and used as solutes included the chloride and bromide salts of vanadium , tungsten , and molybdenum . Studies were conducted over a temperature range of 20 ° to 200 ° C under inert atmosphere . Conductivity and current potential data were obtained for all baths that contained reasonable solute concentrations . Qualitative solubility data were obtained for compounds of ferroalloy metals in a variety of solvents . In general , all solutes showed low solubility in ethers and ketones but reasonable solubility ( in excess of 20 grams per liter ) in alcohols , amides , and ammonia derivatives . No successful metallic deposits that would encourage further study were obtained with any of the systems that were examined .

Jan 1, 1963

By C. A. Herbert

"The Bureau of Mines for a number of years has conducted experiments at its experimental mine near Bruceton, Pennsylvania, on the explosibility of coal dust, with particular reference to dust explosions in coal mines, and the knowledge so rained may well be applied to the handling of coal dust at industrial plants and elsewhere.Powdered coal is coming into use more and more as a fuel, and the dangers incident to its use should be recognized and guarded against, as a number of accidents have occurred in recent years due to ignorance of this danger or to carelessness.Within the past three years two very serious accidents, under almost identical circumstances, have occurred on the surface at two different coal mines in Southeastern Iowa, due in each case to the sudden ignition of a cloud of fine coal dust.The first accident resulted in the burning of six men, three of them fatally; the second burned eleven; three men died as a result of their burns.The mines in the Southeastern part of Iowa, where these two disasters occurred, are operating in a thin coal bed averaging about three feet in thickness, and are worked on the long-wall advancing system similar to that of Northern Illinois.The miners in this section are paid on a screened coal basis; in other words, receive no pay for the fine coal. As a result they use forks in loading the coal into the mine cars, and naturally a considerable quantity of coal is left along the roadways. Subsequently this fine coal, together with the roof rock that is taken down to give sufficient height on the roadways, is loaded into cars and dumped in piles on the surface. This roof rock is a block, oily shale and the contribution of fine coal and oil shale gives ample combustible material to thoroughly burn the rock as it is dumped."

Jul 1, 1923

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

"An important activity of the Bureau of Mines is the promotion of safety in mining and industry. In connection with these activities, the Bureau determines the explosion hazards of combustible gases, liquids, and solids and investigates means by which explosions may be eliminated or reduced in violence.The limits of inflammability and ignition temperature of combustible gases, vapors, and solids are of practical importance because such materials can be manufactured, transported, and used with greater safety, provided the range of concentrations and temperatures that cause explosions are known.Many organic compounds, which until a few year ago were merely laboratory curiosities, are now being manufactured in large quantities owing to the national emergency, particularly those chemicals entering into the manufacture of synthetic rubber, a product that is playing a major role in the Government program of national defense. This re Jolt gives results relative to the limits of inflammability of styrene and its ignition temperature in air and oxygen. This combustible liquid is now used extensively in the manufacture of synthetic rubber."

Mar 1, 1942

By Kris Chatrathi, John E. Going, Kenneth L. Cashdollar

Two types of flammability limits have been measured for various dusts in the Fike 1-m3 (1000-L) chamber and in the Pittsburgh Research Laboratory (PRL) 20-L chamber. The first limit is the minimum explosible concentration (MEC), which was measured at several ignition energies. In addition to the three dusts studied previously (bituminous coal, anthracite coal, and gilsonite), this work continues the effort by adding three additional dusts: RoRo93, lycopodium, and iron powder. These materials were chosen to extend the testing to non-coal materials as well as to a metallic dust. The new MEC data corroborate the previous observations that very strong ignitors can overdrive the ignition in the smaller 20-L chamber. Recommendations are given in regard to appropriate ignition energies to be used in the two chambers. The study also considered the other limiting component, oxygen. Limiting oxygen concentration (LOC) testing was performed in the same 20-L and 1-m3 vessels for gilsonite, bituminous coal, RoRo93, and aluminum dusts. The objective was to establish the protocol for testing at different volumes. A limited investigation was made into overdriving in the 20-L vessel. The LOC results tended to show slightly lower results for the smaller test volume. The results indicated that overdriving could occur and that ignition energies of 2.5 kJ in the 20-L vessel would yield comparable results to those in the 1- m3 vessel using 10.0 kJ. The studies also illustrate the importance of dust concentration on LOC determinations.

By Jack C. White

Studies were made to determine the character and distribution of the copper lost in copper mill tailings. Acid soluble (oxide) and acid insoluble (sulfide) copper were determined for heavy-liquid sink and float products of screen-sized fractions from 12 copper mill tailings. In most of the tailings studied, the coarse-size fractions are higher in copper grade than the respective bulk tailings, high in sulfide copper, and low in oxide copper. Oxide copper occurs predominantly in the minus 325-mesh "slimes." Microscopic examination of heavy-liquid sink products indicated that recovery of liberated copper sulfide minerals is complete in most mills, and that copper minerals not being recovered are locked with gangue particles. Additional copper could probably be recovered from most tailings by size classification, scavenger froth flotation of the coarse fraction, and regrinding of the concentrate to achieve liberation of the locked sulfides.

Jan 1, 1971

By Sam S. Taylor

[The discovery of many oil fields in Illinois since 1936 and their rapid development have brought tine problem of brine disposal to the foreground in that State. The ultimate magnitude of the is not yet known, but already it is great enough to warrant technical investigation. The Bureau of Mines, therefore, has made a general survey of the methods of handling oil-field brines in Illinois and has studied in detail three subsurfaces disposal systems.]

Jan 1, 1940

By Joseph E. Matta, John C. LaScola, Fred N. Kissell

The Bureau of Mines investigated coal storage silos to determine how gassy coal must be for methane accumulations in a silo to become hazardous and where such accumulations are likely to occur. Methane concentrations were measured in the open space above the stored coal pile, in the pile, and in the reclaiming area. No methane layering was found in closed-top silos. Reclaiming areas were as gassy as the top part of the silos. Coal samples were collected from the conveyors entering the silos in order to assess the gassiness of the coal. No simple correlation was found between the gassiness of the coal stored and the measured methane concentrations. However, at mines where the average 24-hour gas emission from the conveyor belt samples was 14 ft3/ton or more, fans or open tops were used. It appears that a large fraction of the methane released during storage remains in the void space between the coal particles.

Jan 1, 1981

By Liming Yuan

In order to reduce fire hazards caused by spontaneous combustion in longwall gob areas, a computational fluid dynamics (CFD) study is being conducted by National Institute for Occupational Safety and Health (NIOSH) to simulate the spontaneous heating of coal in longwall gob areas. A CFD model was first developed to model the spontaneous heating process in a two longwall panel district using a bleeder ventilation system with a stationary longwall face. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous combustion studies. Heat generated from coal oxidation is dissipated by convection and conduction, while oxygen and oxidation products are transported by convection and diffusion. CFD simulations were then conducted to model the spontaneous heating in longwall gob area with a bleederless ventilation system. A single longwall panel with a bleederless ventilation system was simulated. The effect of gob permeability on the spontaneous heating was also investigated.

Jan 1, 2009

By A. B. Hooker, P. G. Guest, E. J. Gleim

"From time to time the United States Bureau of Mines has received reports of gas explosions alleged to have been caused by correctly assembled flame safety lamps. In most of the mines where the explosions occurred the lamp was in use at a working face where the velocity of the ventilating current would be relatively low. The inference has been that the lamp was correctly assembled but that the gauze became sufficiently overheated to ignite the surrounding atmosphere.As part of its routine investigation of flame safety lamps the Bureau of Mines subjects each lamp to a test in still and moving atmospheres to determine its safety. Heretofore, as long as the lam, successfully passed this and other tests no determinations as to the margin between success and failure were made; hence, in attempting to answer inquiries concerning the reported explosions it was found desirable to be able to give actual gauze temperatures as a measure of the comparative safety of lamps under various conditions. The previous laboratory tests of flame lamps in still mixtures were made in a chamber or ""gallery"" of relatively small volume where the lamps might have been subject more or less to the smothering effect of the combustion products. It was therefore decided to make a special series of tests to obtain the gauze temperatures of both bonneted and unbonneted lamps in still and low velocity mixtures, using a larger gallery to offset any smothering effect.These tests are believed to represent the first attempt at measuring gauze temperatures by means of themocouples. The results will not only be of interest but will also be helpful to many in determining the status of flame safety lamps relative to gas ignitions in mines."

Feb 1, 1929

By K. Kar, M. Gautam, J. T. Jurewicz

The 10-mm Dorr-Oliver cyclone has been widely used as a personal sampler for size selective sampling of particles within the respirable range (Dp < 10 gm). Because of their inertia, the particles are unable to follow the swirling flow (outer vortex) within the cyclone. The particles migrate to the bottom of the cyclone, depending on their size, and get trapped into the inner vortex which leads to an eventual blow-off from the top of the cyclone. By measuring the size distribution of the particles in the free stream and in the collected sample, the aspiration efficiency of the cyclone can be calculated. Velocity difference between the free stream and sampling velocity. Inlet orientation, particle impaction and deposition, particle inertia and free stream turbulence result in the departure of the aspiration efficiency from unity and this, in turn, leads to inlet bias. Although the effect of inlet bias on sampling efficiency has been investigated in past, the results lack detailed information and show only some general trend. In this effort, a systematic, in-depth experimental work on the effect of inlet bias on the sampling efficiency has been undertaken using non-intrusive Laser Doppler Anemometry (LDA), Aerodynamic Particle Sizer (APS) and impactors.

Mar 1, 1992

By John L. Morning

Although faced with a slowdown in the world economy, continued inflation, and rising costs, the mining industry exceeded its 1974 raw mineral production value of $55.1 billion by 13%. The increase was due to value increases in the production of fuels and nonmetals; metals reported a decrease in value. Of 23 metals produced, 14 showed value increases; of 44 non-metals produced, 26 reported value in-creases. Because of increasing costs and depletion of high-grade reserves, the mining industry continued to rely on new technologies to maintain its profit margins. In the surface mining sector, the development of new tools and equipment played a large part in increasing production and maintaining this goal. Some of the types of equipment developed were instrumentation for control of pit slope stability, shovel power transmissions, electric wheel trucks, and single-flight conveyor systems.

Jan 1, 1977

By J. J. Hoeppner

Accurate determination of moisture in coals of various ranks has long been a subject of intensive investigation. Excellent reviews of methods developed over many years are given by Brown (9)4/ and, with experimental comparisons, by Goodman, Gomez, and Parry (11). As pointed out in these and other writings, one of the principal difficulties in assigning absolute merit to one or another procedure is the multiplicity of conditions under which water may exist in coal and the difficulties involved in obtaining sharp separation and distinction between these classes. Gauger (10) states: Water recoverable from coal is obtained from the following sources: (1) Decomposition of organic molecules (sometimes called combined water), (2) surface adsorbed water, (3) capillary condensed water, (4) dissolved water, and (5) water of hydration of inorganic constituents of the coal.

Jan 1, 1956

"One of the functions of the United States Bureau of Mines is to investigate the ability of electrical mining equipment to operate in a gassy mine without danger of igniting explosive atmospheres. To accomplish this purpose, tests are made in which mixtures of gas and air are ignited in the equipment while it is surrounded by explosive atmospheres of the same composition. In such tests, records of pressures developed by the internal ex-plosions are obtained and observations are made of any flames, sparks, or smoke which may issue from bearings and joints. Occasionally the explosion pressures in a mining machine rheostat or a compartment of some other machine reach a value which is judged to be excessive or abnormal.A number of factors are known to influence the explosion pressures, and both German and. British investigators have irate extensive research on their effects. Much of this work had been done with artificial compartment which certain conditions could c held, constant while others were being varied. The U. S. Bureau of Mines has not made any research on a scale to compare with that of the British or German investigators; however, special studies have been necessary from time to time to determine the cause and remedy for high pressures obtained in the routine test of some piece of mining machinery. Thus it has been possible to verify some of tee theories established on a purely experimental oasis by practical tests of machines as actually built for mine use.Some of the factors determined the pressure that will result when an explosive mixture in a compartment or connected compartment is ignited are: (1) The volume of explosive mixture ignited, (2) the percentage of as in the mixture, (3) the amount of coal-dust in the compartment or compartments, (4) the degree of movement or turbulence of the mixture at the time of ignition, (6) tightness of the joints and bearings, (6) the size of opening between, compartments, (7) the distance between the point of ignition and openings, and (8) the cooling, effect of surfaces and of material inclosed in the compartments."

Dec 1, 1929