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By K. Kar, A. Sreeoath, M. Gautam

"This paper presents results of an experimental investigation of the sampling efficiency of a blunt cylindrical sampler oriented with respect to the oncoming flow. The number of particles sampled by the cylindrical blunt sampler and an isokinetic sampler is measured using the TSI Aerodynamic Particle Sizer. A technique is described to conven the ratio of the particles sampled into the sampling efficiency. The experimental data thus obtained is then compared with the impaction model of Vincent and Mark (1982) with the empirical constant determined from our experiment.. The comparison shows excellent agreement for 0° and 90° orientation.1.0 IntroductionCylindrical dust samplers are widely used in practice to determine the concentration of the airborne particulate matter. The sampler is simply a means to collect particles from the ambient, whose concentration is subsequently measured by some size selective techniques. Gravimetric and optical techniques are the two most commonly used methods to measure the particle sizes. While impactors are used in gravimetric analysis, Aerodynamic Particle Sizer, Aerosizer. Electron microscope, Coulter Counter etc. use the optical method to measure the particle sizes. The Aerodynamic Particle Sizer (APS) and the Aerosizer are the new generation devices which employ the time of flight of particles within intersecting laser beams to determine the particle size.The introduction of the sampler in the free stream disturbs the flow pattern due to two distinct actions of the sampler on the fluid stream: one of them results due to the conformity of the flow to the geometry of the circular cylinder and the second one is caused by the flow into the suction orifice. If the sampler performance is determined by the number of particles entering into the sampler inlet relative to the number of particles present in the free stream, then the particle trajectory outside the sampler and into the inlet is the deterministic factor for the sampling efficiency. The particle trajectory inside the sampler is not important in this case."

Nov 1, 1995

By V. R. Spironello

The Bureau of Mines is conducting studies of the slags related to ferrous technology to evaluate acceptable substitutes for the auxiliary flux, mineral fluorspar, in foundry operations. This work is directed toward the Bureau's goal of minimizing the Nation's dependence on scarce and critical minerals Comparative basic practice cupola (18-inch-ID) trials were made to evaluate a waste material called "used potlining," which contains significant levels of fluorine, sodium, and aluminum in various compounds. Used potlining is recovered from alumina reduction cells after its useful life, and was supplied by the Aluminum Co. of America (Alcoa) to the Bureau for evaluation. The material in the lump and pelletized form (with limestone) provided extremely fluid slags based on visual observation during cupola operation. No adverse effects were found on cupola performance, metal and slag chemistry, the environment, or mechanical properties of the castings produced. Fluorine recovery in the slag was equal to, or higher than, that of fluorspar; fluorine losses to the scrubber water and solids were lower. The acidity of the scrubber Hater was somewhat neutralized. No difference was observed in furnace-refractory attack, as determined by the level of magnesia in the slag and visual inspection. The recovery of sodium in the slag, presumably as the oxide, significantly increased slag fluidity, suggesting that less than equivalent fluorine may be required. There was no contamination of the gray iron by the aluminum from the used potlining. Used potlining was completely satisfactory as a substitute for fluorspar in cupola ironmelting.

Jan 1, 1981

By L. A. Neumeier

The Bureau of Mines evaluated the properties and anisotropy in properties of rolled Zn-Cu and Zn-0.12 pct Ti-Cu alloys with various copper additions to 1.25 pct. The alloys were rolled cold and at various hot-rolling temperatures to reductions as high as 92 pct after breakdown rolling. The properties are extremely sensitive to various combinations of composition, rolling temperature, and rolling reduction, Zn-Cu alloys can develop good creep resistance, but they are inferior in that respect to Zn-Ti-Cu alloys. For alloys either with or without the titanium addition, cold-rolling results in recrystallization of the matrix and rejection of copper from solution, causing poor hardness, tensile, and creep properties, but high ductility. Peak tensile strengths develop when the alloys are rolled in the range 320° to 400° F, Best creep resistance for Zn-Cu alloys requires higher rolling temperatures when copper content is increased. Creep resistance is best for Zn-Ti-Cu alloys with about 0.75 to 1.0 pct CU rolled near 480° F. Some copper is soluble in the TiZn15 phase, which forms into "stringers" during rolling. The possible contributions to creep behavior of factors such as distribution of second-phase particles, grain size, and preferred orientation are discussed.

Jan 1, 1970

By Kenneth L. Rubow, Virgil A. Marple

"INTRODUCTION Respirable dust is defined as the dust which penetrates to the alveolated regions of the lungs. Due to the size selective nature of the particle removal mechanisms in the nasal passages and lung airways, criteria defining respirable particles must be a function of the particle size. Three criteria defining respirable particle penetration are shown in Figure 1. These criteria have been defined by the British Medical Research Council (BMRC), the American Conference of Governmental Industrial Hygienists (ACGIH) and German TBF 50-11 (1).The quantity of respirable particles in an aerosol can be measured by use of two-stage samplers. The first stage consists of a particle preclassifier with penetration characteristics corresponding to one of the respirable penetration curves in Figure 1. The large nonrespirable dust particles are removed from the airstream in the preclassifier and the smaller respirable dust particles pass on to some device which can measure their concentration (the respirable dust concentration).Instrumentation for the measurement of respirable coal mine dust has been limited by the severe conditions existing within the coal mine. The conditions of particular importance are the methane atmosphere, high humidity, and the general non-laboratory type environment. The most severe of these conditions is the methane atmosphere since any electronic or electric powered instrumentation must be intrinsically safe to operate in such an atmosphere.In spite of the difficulty of sampling respirable dust within the mines, many instruments have been developed for in mine use. Although these instruments operate under a variety of principles they generally fall within two categories: personal samplers and area samplers.A personal sampler is worn by the mines while he is performing his duties in the mine. These devices are generally small, light weight and require little power so as not to interfere with the miner's ability to work."

Jan 1, 1988

By Michael G. Zabetakis, Israel Liebman, Henry E. Perlee

Flammability studies conducted to date on stratified methane - air and pentane - air mixtures in air indicate that location and extent of a flammable layer are affected by molecular diffusion , gas motion , and propagation of flame . In initially quiescent mixtures , the lower limit - of - flammability zone may be determined by assuming molecular diffusion alone governs mixing rate . The upper limit - of - flammability zone can be predicted in this manner only for stratified layers with small concentration gradients ( less than 0.2 volumepercent per inch ) ; where large concentration gradients are encountered ( for example , as much as 30 volume - percent per inch ) , the initial - mixture methane concentrations that yield flammable mixtures are larger than anticipated . Flames propagating through heterogeneous quiescent methane - air atmospheres in the direction of the concentration gradient exhibit flame speeds at any point that corresponds to the flame speed of the homogeneous gas mixture having the same gas composition as that of the point in the heterogeneous system . In flowing mixtures with large concentration gradients , the degree of mixing prior to ignition does not appear to affect the flame velocity and emitted radiation appreciably in a 6.5 - ft - diameter gallery .

Jan 1, 1964

Develop a more efficient method of testing the integrity of in-situ leach mining operations. The Problems For economic and environ-mental reasons, in-situ leaching operations must be sure that wells do not leak. Loss of solution in large quantities can be expensive in itself, and if such losses result in pollution the costs can be even higher. Wells are usually tested for leaks by sealing them with packers, pressurizing them and monitoring the pressure drop. However, many commercially-available packers are designed to be used in steel-cased wells rather than the fiberglass-or plastic-cased wells used for in-situ mining. These packers are heavy, cumbersome, expensive, and often leak. In addition, commonly used well-integrity-test systems require lengthy test periods and drill rigs or hoist trucks with rigid pipes must be used to run the packers in and out of the well. The Bureau of Mines has developed a mobile, self-contained leak-testing system that is faster, uses trailer-mounted equipment that can be operated by one person, and features a new inflatable packer.

Jan 1, 1985

By W. H. Lewis

This Bureau of Mines report and its companion report (Information Circular 9073) have been prepared as a complete reference on underground coal mine lighting. This report discusses system design criteria and procedures, data and specifications to aid in selection of suitable mine lighting hardware, and guidelines for system installation and maintenance. Topics include light measuring techniques and instruments, illumination regulations for underground coal mine environments and equipment, lamps and ballasts, available mine lighting hardware, design and evaluation of coal mine illumination systems, and installation and maintenance of a mine lighting system.

Jan 1, 1986

By J. G. Stuart, A. W. Cipkins, R. H. Thompson

Preliminary safe distances for blasting wiring from typical electromagnetic sources are presented. The distances are for underground coal mines and electromagnetic sources in the frequency range below 10 MHz. The distances are based on measurements performed at 3 locations in each of 3 coal mines. The measurement apparatus, measurement procedure, measurement results and the rationale used in the calculation of the safe distances are all described. The safe distances presented are dependent on the measurement results and their interpretation. More measurements are clearly necessary to establish the validity of the suggested distances.

Jan 1, 1985

By John S. Dunning

This paper is one of a series describing methods and costs of recovering sand and gravel from deposits in the United States and deals directly with the operations of the Atlas Sand, Gravel and Stone Co. at Farmington, Conn. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent local expenditures only and not total production costs. It is recognized that publication of total costs might in some instances cause embarasement to individual producers, as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations may ensue.

Jan 1, 1933

By R. Duncan Gardner

This paper describing the mining practice at the Harmony mine, Baker, daho, is one of a series being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts in the United States. About 150 tons of copper ore containing 4 per cent copper, 0.001 ounce gold, and 0.1 ounce silver, is being produced daily from the Harmony mine by the shrinkage method of mining. The ore is taken by an aerial tramway 1/3 mile long to the mill, where it is concentrated. The concentrate is shipped 8 miles by truck to the railroad and thence by rail to Utah for smelting.

Jan 1, 1930

By C. W. Owings

"PURPOSE OF REPORTThe safety and efficacy of permissible storage—battery gathering locomotives are becoming recognized more and more in coal mines. The great mobility of this type of haulage equipment is due to the fact that no trolley wire and bonding of rails are needed; hence wherever there is track and adequate ventilation to dilute properly any dangerous gases, the storage—battery gathering locomotive may go. As coal near the outcrop or the surface is mined out, coal farther from the outcrop or deeper in the ground must be mined, and gassiness of the coal bed often increases under these conditions. The use of electrical equip¬ment capable of giving off arcs or sparks while operating near or at the coal faces constitutes a serious explosion hazard. Often, it is uneconomical or impracticable to use animal haulage, and locomotives must be employed. The operator should consider the safest and most economical unit; permissible equipment is the answer to this problem, and storage—battery locomotives are the only permissible electric haulage units.A comparison of permissible storage—battery locomotives with cable—reel locomotives of the latest enclosed ""explosion—tested"" type has been made at the Keystone No. 1 mine of the Houston Collieries Co., at Keys one, W. Va. The information and data contained in this publication were obtained by the writer during an inspection of haulage at this mine.ACKNOWLEDGMENTSThe writer is indebted to P. C. Thomas, vice president and general manager, the Koppers Coal Co., operator of the Keystone mines, who granted permission for making the study. W. A. Wilson, general superintendent, Houston Collieries Co., arranged for the investigation and for obtaining the data. C. E. Zuspan, chief electrical inspector, and J. C. Newman, division electrical inspector, accompanied the writer underground and assisted materially in obtaining information and data upon the haulage methods and performance of the locomotives. The assistance or general mine Foreman Pierman and of mine foreman White is gratefully acknowledged."

Aug 1, 1931

By M. M. Tilman

The purpose of this investigation was to determine the effects of small amounts of cobalt in nickel on the tensile properties and hardness of representative types of austenitic stainless steels . Cobalt substitutions for nickel up to 2 weight - percent were made in types 302 and 309 stainless steels . Data were obtained at room temperature for tensile strength , yield strength , percentage elongation , percentage reduction in area , and hardness . In type 302 steels , tensile strength and hardness increased with increased percentages of cobalt , percentage elongation and reduction in area decreased , and yield strength showed little change . Property changes were largely due to the reduction of nickel content rather than to the addition of cobalt . In type 309 steels , only minor variations were observed for the properties investigated ; the effects of the relatively snall cobalt substitutions and nickel reductions were somewhat reduced by the higher total alloy content .

Jan 1, 1964

By P. D. Kovscek

High-pressure streams of water, known as water jets, can be used to improve the cutting efficiency of mechanical bits. During prior testing by the Bureau of Mines, the cutting performance of a longwall shearer, equipped for water-jet-assisted cutting, was evaluated. The performance of the shearer did not improve while using water jet assist because the pressure of the water delivered to the rock surface was inadequate. The study, described in this report, resulted in a determination of the major cause of water pressure loss on the shearer, and an evaluation of the techniques for increasing the water pressure at the rock surface. The results show that the major pressure loss, which occurred between the nozzle and rock surface, is directly affected by the amount of fluid turbulence that develops just upstream from the nozzle. Preventing a sudden change in the direction of the flow channel can increase the stagnation pressure as much as 400 pct. Smoothing the surface of the flow channel in the shearer bit block would increase the stagnation pressure delivered to the rock surface by 35 pet.

Jan 1, 1989

By John H. Soulé

"INTRODUCTION Spodumene and lepidolite were shipped from the Harding pegmatite deposit, Taos County, N. Mex., in the period from 1930 to 1930. Tantalum minerals were noted as early as 1924 and described in 1931 3/ but no tantalum ore was shipped until 1942. The deposit was mapped and studied by geologists of the Federal Geological Survey and engineers of the Bureau of Mines late in 1942 and early in 1943, and a Bureau of Minus exploratory project was carried out in 1943. 4/ Thu following report presents the results of that project.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Minos has as its primary objective the more effective utilization of our mineral resources to the end that they make the greates possible contribution to national security and economy. It i the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lovell B. Moor, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallugiical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, Assistant Director."

Dec 1, 1946

By E. P. Youngman

The mining law of May 16, 1884, is still the basic mining legislation in Smeden. To satisfy a demand for a revision of the entire mining law, special commissions have been at work for a number of years; but present indications are that the work will require several more years for its completion. The changes contemplated would affect mainly the relations between the nine operator and the landemer, as the present law, according to general opinion, tends unduly to jeopardize the landowner's right in favor of the miner. The socialist party desires additional changes, especially in the direction of giving more direct control of the industry to the State, a control that it now seems to exercise through individual agreements with mining companies. Its control of the Lapland iron mines comes through its sharing the ownership with the Luossavaara-iirunavaara Altb. In this instance, the Government should be Considered as a private commercial body, since the agreement with the company

Apr 1, 1933

By Hiram C. Draper

The Mining Division of the Bureau of Mines, in cooperation with the Obstacle and Demolition Branch, Engineer Research and Development Laboratories, Department of the Army, undertook some extensive tests to determine the effectiveness and limitations of using standard demolition-type shaped charges in underground Mining. The tests proved the shaped charge has no practical application in the functions of mining covered by this report. At an approximate cost of 0 per foot hole plus spall produced by the most efficient single shots with the M3 shaped charge, the cost is over 20 times that of producing a better hole with a rock drill. The concussion would prohibit its use in many mines, and the excess carbon monoxide gas liberated by the pontolite explosive would be an additional hazard when used underground.

Jan 1, 1948

By W. L. Parker, W. A. Selvig

"Introduction.Powdered or pulverized coal is extensively used as a fuel, the total annual consumption*** in the United States being about 12.000,000 tons, and growing steadily. As the coal is usually pulverized so that 70 per cent or more parses through a 200-mesh sieve, it presents difficulties in sieving, because such finely divided material tends to clog the meshes. A fineness test is desirable in order to judge the efficiency of the pulverizing apparatus, and as an indication of the particle size of the coal being burned.Committee D-5 on Coal and Coke, American Society for Testing Materials, has recognized the desirability' of a standard method for determination of fineness of powdered coal. The Bureau of Mines, in co-operation with this Committee, conducted sieving tests on two standard samples of powdered coal, which are described in this paper. As a result of this work a method for making fineness tests, by band sieving, is recommended as a standard method, while a rapid method, by machine sieving, is given for routine tests.Outline of Investigation.Preliminary trial tests were made by the bureau and tentative methods were formulated for making the sieving tests both by band and by machine.Each of two samples of powdered coal was carefully mixed, and portions were sent to the twelve laboratories mentioned later. These were requested to make duplicate sieving tests on the two standard samples, by the hand-sieving and machine-sieving methods, and to follow the tentative procedure exactly as outlined. All of the laboratories made sieving tests by hand shaking and eight of them made tests by machine shaking."

Nov 1, 1923

By T. J. Ballard

The Conrad Hill mine vas first opened as a gold mine about 182 and has been operated at various times since then. The Bureau of Mines, as part of the strategic minerals program, mapped and sampled the accessible mine workings. The work failed to reveal appreciable copper values or evidence of additional ore deposits.

Jan 1, 1948

By H. O. Poppleton, F. E. Block

This investigation was made to develop a method of preparing high - purity thorium metal in quantities up to 20 kilograms per batch . Several methods for the preparation , purification , and reduction of thorium tetrachloride are discussed . Thorium tetrachloride was prepared by chlorination of decomposed thorium nitrate or oxalate with carbon tetrachloride or phosgene . tion of the crude tetrachloride was achieved by multiple distillations or by filtration of the molten chloride . It was found that high - purity thorium metal could be prepared by sodium reduction of thorium tetrachloride if chloride of sufficient purity were available . Byproduct salts and excess reductant were removed by vacuum distillation , and the resultant thorium metal sponge was consolidated by consumable - electrode or fixed - electrode arc melting . It was demonstrated that metal prepared by this method could be fabricated into bar , rod , or sheet , at room temperature .

Jan 1, 1964

By Phillip N. Yasnowsky

This Bureau of Mines report examines the percentage depletion allowance rate structure in relation to several criteria that are indicative of U.S. mineral import dependence. These criteria are the minerals considered as strategic and critical for stockpiling purposes, the ratio of reserves to forecast cumulative demand (1976-2000) for selected minerals, and the U.S. net import reliance as a percentage of apparent consumption (1978), also for selected minerals in general, it was Found that there does exist a direct, although not perfect, relationship between the percentage depletion allowance rates and the degree of import dependence as indicated by these three criteria. The higher percentage rates tend to he associated with those minerals for which the United States is, or will likely he, heavily dependent on foreign sources. In addition, a basic discussion of the mineral depletion allowance is provided, including numerical examples illustrating the computation of the allowance under several assumptions. Also, the percentage depletion allowance rates for individual minerals are tabulated.

Jan 1, 1980