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By Francis R. Redfern

Newton's method of solving a nonlinear equation is employed to develop a least-squares acoustic emission source location method in which the spatial residuals of the location equations are minimized. These residuals, related to the distances from the least-squares source location perpendicular to the surfaces described by the location equations, permit location error to be estimated to first order along the spatial axes. The solutions obtained by this method are the best spatial solutions to the location equations in the least-squares sense. Also presented is a procedure by which the geometrical control of a transducer array can be evaluated using the rate of change of source location with fractional velocity change.

Jan 1, 1982

By Wing G. Agnew, John A. Johnson

"INTRODUCTION This paper is one of a series being published by the Bureau of Mines pertaining to an investigation on the use of stemming in metal mines now being conducted at the Mount Weather Testing Adit. Its purpose is to compare the amount of dust and gases produced as a result of blasting charges of dynamite (1) in drill holes, (2) in bombs, and (3) in mud-cap or adobe shots.ACKNOWLEDGMENTSValuable assistance and advice on stemming were given by members of the staff at the Bureau of Mines, as acknowledged in previous publications. 4/TEST PROCEDUREThe results used for comparison in this report are from dust and gas samples taken after blasting (1) four regular test rounds with no stemming, (2) five bomb shots, and (3) two mud-cap or adobe shots."

Dec 1, 1942

By Sumner M. Anderson

ATHOUGH scattered signs of increased activity in the mining industry accompanied an incipient improvement in the overall economic situation during the latter months of 1963, production levels for the year as a whole responded to the general 1962-63 business recession with a 4.2 percent decline. The petroleum industry, active since 1907, did not become a dynamic force in the economy until exploration and drilling contracts were concluded with private companies in 1958 and 1959; on November 15, 1963, having virtually achieved self-sufficiency in petroleum in the preceding year, those contracts were unilaterally annulled. In the field of metallics, the only approach to internal sufficiency-aside from the iron and steel industry that has depended heavily on the importing of basic raw materials-has been in mining, smelting, and refining lead and zinc although iron ore, silver, beryllium, tantalite, and tungsten have been mine production items of economic significance. Reserves of lead, zinc, silver, bismuth, vanadium, and low-grade and metallurgically difficult iron ore-as well as those of beryllium, tantalite, and tungsten which are produced primarily for export-appear to be fairly abundant. The exploration of deposits of copper, cobalt, tin, lithium, gold, manganese and uranium has been undertaken on a relatively small scale, and little precise information is available on the extent of reserves. Argentina is dependent on foreign sources for part of its required iron and steel and, except for lead and zinc, most of its nonferrous metals. Nonmetallies and solid fuels present an exceptionally varied array of production items among which cement had the second largest 1963 output in South America. Borates, bentonite, common clay, diatomite, fluorite, granite, lime, limestone, obsidian, onyx, rhodochrosite, salt, and spodumene ordinarily are produced for export either exclusively or in excess of domestic consumption requirements. Barite, cement, chalk, gypsum, marble, and mica are both exported and imported. Argentina depends entirely or partly on imports for coal and coke, certain special types of clay, mineral abrasives, graphite, magnesite, mineral fertilizers, sulfur, talc, and minerals for construction, the last group being chiefly attributable to convenience of river transport from Uruguay.

Jan 1, 1964

By Janke L. W. Jolly

Owing to an upsurge in export earnings. Cameroon made substantial economic Progress in 1978 and 1979. With a real growth estimated at 6%, the gross domestic product (GDP) for 1979 surpassed $5 billion.2 Crude petroleum production was providing a new potential in 1978 and 1979 for achieving national self-sufficiency. Among other benefits, crude petroleum exports were helping to offset the escalating costs of refined petroleum imports and to reduce the 14% to 17% annual rate of inflation. Over the 4 years prior to 1978, Cameroon's petroleum imports increased by 12.1% in volume annually, while the import cost increased by 24.5% annually to about $105 million. Total export earnings for 1978 were $805 million,3 to which crude petroleum contributed $25.3 million and crude aluminum product exports contributed $25.9 million. Petroleum exports had increased to about $240 million in 1979 and were in third place after coffee and cacao. Total imports for 1978 were valued at nearly $1 billion. The volume of petroleum imports decreased in 1979 to 552,000 tons, compared with 622,000 tons in 1978. The European Economic Community (EEC) countries purchased over 75% of total Cameroonian exports and provided most of the Nation's imports. The United States purchased $12.4 million in petroleum exports from Cameroon in 1978. Domestic consumption of aluminum metal from imported Guinean alumina continued. to grow; thus exports of this metal to France (valued at $2 million in 1978) and Japan

Jan 1, 1981

By Gloria L. Walker

The Bureau of Mines Information and Analysis Directorate collects worldwide data on virtually every commercially important non fuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Information and Analysis activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1990

By H. J. Fissan, G. Ananth, K. Rubow, V. Marple

"INTRODUCTION Over the past several years a new type of cascade impactor that utilizes small nozzle diameters (micro-orifice nozzles) has been under development (Kuhlmey et al., 1981; Marple et al., 1981). The small nozzle dimensions allow for particles to be collected as small as 0.024 µm aerodynamic diameter on the last stage of the impactor. To obtain a reasonable flow rate of 30 I min - i through the impactor, a large number of nozzles (up to 2000) are required per stage.Furthermore, by locating the nozzles of multi-nozzle stages in a prescribed manner (described in detail by Marple et al., 1981) and rotating the impaction plates relative to the nozzle plates, uniform deposits can be achieved on the impaction plates. As described by Marple et al. (1981), the advantages of a uniform deposit impactor over the conventional impactor that collects particles only beneath stationary nozzles are: (1) maximum use of the impaction substrate surface, reducing both particle bounce (if substrates are greased) and tare weights of the substrates (if particle mass is measured gravimetrically); (2) deposited particles can be analyzed for elemental composition by X-ray fluorescence (Dzubay and Rieke!, 1978); and (3) the pressure in the impactor can be kept relatively high compared to low pressure impactors that depend on a large slip correction to achieve small particle collection (some types of particles may evaporate at low pressures). The work described in this paper investigates two additional advantages of a uniform deposit impactor. These are: (1) the possibility of collecting two separate deposits at one time on one stage for two types of analysis techniques, and (2) the possibility of utilizing piezoelectric quartz crystal impaction plates more effectively by eliminating the deposit location sensitivity nature of the crystals (Schulze-Frohlich, 1981 ).MICRO-ORIFICE UNIFORM DEPOSIT IMPACTOR (MOUDI)A photograph of an eight-stage MOUDI is shown in Fig. 1. Each stage body of the impactor supports the impaction plate for the stage above and the nozzle plate for the stage below as shown in Fig. 2. By rotating alternate stage bodies, while holding the other stage bodies stationary, the impaction plates (or nozzle plates) will be rotated relative to the nozzle plates (or impaction plates).Rotation of the alternate stage bodies is achieved by gears on these bodies that mesh with gears on an electrically driven drive shaft of a rotating mechanism (Fig. 1 ). The alternate stage bodies are restrained from rotation by pins that rest on the drive shaft."

Mar 1, 1989

By W. H. Young

PRODUCTION of bituminous coal and lignite increased substantially in 1963 compared with 1962 figures. The major items of production, consumption, exports, and productivity increased. However, certain key items declined. For the fourth year there was no upward trend in mechanization; the percentage of total tonnage mechanically loaded remained the same as in the 3 previous years and the percentage of total tonnage mechanically cleaned was smaller than in the previous year. Furthermore, the percentage of total production mined by stripping and by augers increased. Most significant was the continued decline in average value and employment. Production.-The output of bituminous coal and lignite in the United States in 1963--459 million tons-was 9 percent greater than the 422 million tons produced in 1962. Production was greater in 1963, largely because of expanded consumption by the electric utilities and an increase in exports.

Jan 1, 1964

By Charles W. Huggins

DEVELOPMENT of the electron microscope has permitted man to examine many small objects that could not be resolved by the light micro-scope. Diffraction, spherical aberration, and chromatic aberration are the main factors that limit resolution to about two-tenths micron with the light microscope. No matter how perfectly a light microscope is constructed and operated, it cannot possibly resolve points separated by less than two-tenths micron. Rapid development following World War II has produced many electron microscopes capable of 20 A resolution. Fibrous inorganic minerals are well suited for electron microscopic study. Many micrographs of chrysotile have been published, but electron microscopic study of the amphiboles has been somewhat neglected. New techniques in sample preparation have simplified the study of fibrous material. Ultrasonic energy has been very helpful in sample dispersion. This publication contains a representative group of electron micrographs of natural inorganic fibers that have industrial value. These fibers commonly are referred to as the asbestiform minerals. The Bureau hopes that the knowledge gained through electron microscopy and other scientific study of the natural inorganic crystalline fibers eventually will lead to the production of synthetic fibers that will satisfy the requirements of industry.

Jan 1, 1959

By N. S. Dalal, B. Jafari, F. H. Y. Green, M. M. Suryan, V. Vallyathan

"Freshly ground and aged anthracite and bituminous coal samples were investigated by electron spin resonance (ESR) spectroscopy to detect the presence, concentration and reactivity of free radicals. Freshly ground anthracite coal produced greater concentration of free radicals than the bituminous coal, and the radical reactivity was also greater for the anthracite. The reactivity of the newly produced free radicals in the anthracite dust correlated with the dust's toxicity. Furthermore similar coal-based free radicals were detected in the lung tissue of autopsied coal miners, suggestive of persistent reactivity by the embedded coal dust leading to the progressive disease process. Results of the studies on the severity of coal workers' pneumoconiosis (CWP) and free radical concentration m lung tissue support this hypothesis.INTRODUCTIONCOAL WORKERS' PNEUMOCONIOSIS (CWP) has been an important topic of concern to miners, mining engineers, epidemiologists and medical researchers for decades. It is well known that the prevalence and severity of CWP differ markedly between different regions and mines despite comparable exposures to respirable dust (REISNER and RoBOCK, 1977; HURLEY et al., 1979). These variations in pathogenicity of coal mine dusts can only partially be explained by differences in the mineral composition and by rank of coal (CHRISTIAN and NELSON, 1978; CHRISTIAN et al., 1979; HATCH et al., 1980). Cytotoxity studies on mammalian cells do not correspond well with the human disease pattern (CHRISTIAN and NELSON, 1978; CHRISTIAN et al., 1979; HATCH et al.,1980; VALL YA THAN et al., 1988). For example, while epidemiological studies of coal miners (REISNER and ROBECK, 1977; HURLEY et al., 1979) indicate that the prevalence of CWP correlates roughly with the rank of coal, such correlation has not yet been established in biological studies, despite considerable effort (CHRISTIAN and NELSON, 1978; CHRISTIAN et al., 1979; HATCH et al., 1980). In order to help resolve this apparent paradox we have undertaken a systematic study to evaluate whether any correlation exists between the concentration of free radicals present in fresh or aged coal dusts from two well-characterized U.S. coals. This study was also prompted in part by observations reported in the literature that organic free radicals can be formed on the surface of freshly fractured coals (LEBEDEV et al., 1978; DULIBA and CLARKSON, 1984). In particular, ARTEMOV and REZNIK (1980) noted that the decay lifetimes and, hence, the reactivity of the organic free radicals formed on crushing Russian coals, .depended"

Jan 1, 1989

By C. G. Kirkpatrick

Analysis of the data produced by a wide-band, sensitive, horizontal, biaxial motion sensor has revealed several distinctive patterns before, during, and after a roof fall. The signals prior to the roof fall are similar in spectra, but one thousand times larger in amplitude, than those after the roof fall. Immediately preceding the roof fall, by two to twelve hours, five events occurred which were larger in amplitude and lower in frequency than even the large pre-roof fall background signals. An interpretation of these events is offered.

Jan 1, 1979

By Richard F. Hewlett

Use of digital computers makes possible a more efficient and complete analysis of data from a mineral deposit . This computer program was written and used during an investigation into the efficiency of methods of computing grade and tonnage of ore , wherein it was necessary to make repeated computations involving different combinations of data . This investigation was part of a continuing program of sampling methods research at the Bureau's Denver Mining Research Center.2-4 This program is designed to compute tonnage and average grade for 40 cutoff grades using either the statistical or polygonal methods . tational rate is from 200 ( input bound ) to 1,400 assays per minute , depending on the use of either individual ( one assay per card ) assay- interval length or

Jan 1, 1963

By N. S. Dalal, X. Shi

"With a view of elucidating the role of glutathione (GSH) in the biochemical pathways of the chromate-exposure related carcinogenesis, we carried out electron spin resonance (ESR) spectroscopic investigations of the chromate-GSH redox reactions. The ESR measurements, employing spin-traps, provide evidence for the involvement of the glutathione (GS•) radical, as well as an isolable Cr(V)-glutathione intermediate. These results indicater a new mechanism for the reduction of chromate by GSH in cellular environment and help understand the (unexpected increase in Cr(VI)-induced DNA strand breaks at elevated GSH levels.We report here indirect electron spin resonance (EGR evidence for the involvement of the glutathionyl (GS) radical and direct evidence for a Cr(V) intermediate in the reactions of glutathione ¬(GSH) with chromate for the first time.. This work was undertaken to clarify the biochemical pathway of the reduction of chromate by GSH, since this reduction process is thought to be a critical step in the pathogenesis of the chromate-exposure related carcinogenesis. This follows from the literature reports which show that (a) Cr(VI)compounds have been proven to be carcinogens in laboratory animals as well as in human studies2-4, (b) Cr(VI) and not Cr(III) compounds are mutagenic 5-7, (c) Cr(VI) and not Cr(III) compounds can penetrate cell membranes 8.9 (d) the final state of Cr(VI) in cellular reductions is Cr(III)', (e) by itself chromate (or Cr(VI)) cannot be directly mutagenic since Cr(VI) is known not to interact with isolated DNA under physiological conditions 10, suggesting the significance of Cr(VI).reduction processes. One of the major reductants in cellular environments is thought to be the GSH, both outside and inside the ce11s 11-13. Other evidence for the role of GSH in the chromate toxicity is seen from recent studies showing that exposure of hamster cells to non-toxic levels of added selenite increases the levels' of GSH as well as the Cr(VI)-induced DNA strand beaks 14, and thatsuch DNA strand breaks in hepatocytes also change in direct proportion to their GSH content 15,16. These observations wereinterpreted as implying that the reduction of chromate by GSH, to some reactive intermediate is an important step in the chromatecarcinogenicity 15,16. The following reaction steps were,suggested 15, 16"

Jan 1, 1988

By B. Z. Zhong, T. Ong, W. E. Wallace, W. Z. Whong, Z. W. Gu, M. J. Keane

"Abstract-Diesel emission particles (DEP) from an engine operating on the Federal Test Procedure VDC were dispersed in an aqueous mixture of dipalmitoyl lecithin (DPL). a major component of pulmonary surfactant and saline and were tested for genotoxicity using the unscheduled DNA synthesis (UDS) assay with autoradiography techniques in cultured Chinese hamster lung cells. A DEP sample from the same source was dispersed in dimethyl sulphoxide (DMSO) and subjected to the same assay. Both dispersions (in DPL and DMSO) were found to induce UDS in a dose-related manner. After separation of the sample into supernatant and sediment fractions. the activity of the DEP sample was found to reside in the supernatant fraction for the DMSO-dispersed sample; and in the sedimentary fraction for the surfactant-dispersed sample. These findings further indicate that genotoxic activity associated with DEP inhaled into the lung may become bioavailable through the dispersion properties of pulmonary surfactant components.INTRODUCTIONTHE mutagenicity of diesel emission particles (DEP) has been studied intensively (LEWTAS and WILLIAMS, 1986). Carcinogenic effects of diesel exhaust in exposed animals have been reviewed (NIOSH, 1988) and an evaluation of carcinogenic risks to humans from diesel engine exhausts has been published (IARC, 1989). Using components of pulmonary surfactant such as dipalmitoyl lecithin (D PL), dipalmitoyl phosphatidylethanolamine (DPPE) or dipalmitoyl phosphatidic acid (DPPA) dispersed in physiological saline, we have previously shown that diesel soots express mutagenic activities in the Salmonella histidine reversion assay system and in the sister chromatid exchange assay using the cultured Chinese hamster lung (V79) cells. Mutagenic activity of diesel soots dispersed in DPL, DPPE and DPPA was quantitatively comparable to and in some cases greater than, the activity expressed by an equal mass of soot extracted by dichloromethane-dimethyl sulphoxide (DCM-DMSO) (WALLACE et al., 1989).Unscheduled DNA synthesis (UDS) is accepted and frequently included, as one of the tests in the battery of assays used to assess carcinogenic-mutagenic potential -of chemicals (MITCHELL et al., 1983). In this study, induction of UDS in V79 cells by DEP, dispersed in the major component of pulmonary surfactant DPL, was carried out. The purpose of this study is to validate the suggestion generated from our previous work that mutagens associated with inhaled particles may be dispersed or solubilized in the phospholipid component of pulmonary surfactant and become active in such a phase (WALLACE er al., 1989) and to test the fractionated DEP sample using UDS assay for a more complete evaluation of its genotoxicity."

Dec 1, 1995

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 Foster Fraas

Calculations based on data related to the electrostatic precipitator illustrate the variation in the electric forces on a particle with change in position in the ionized field. The feeble forces in some separators are explained by the low field intensity at midpoint locations between the electrodes. When the particles are in contact with the exterior surface of a rotating cylindrical electrode, a high field intensity at the electrode surface combined with the image charge results in large electric forces. The permissible feed velocity increases as the square root of the electrode diameter, providing high values in efficiency and feed rate capacity, particularly in surface-to-mass ratio separations such as are encountered in secondary materials recycling operations.

Jan 1, 1971

By Robert H. Essenhigh

A stirred reactor (SR) combustion system has been developed to gather information on the mechanisms of ignition and flame propagation of coal dust under conditions similar to those found in coal dust explosion flames. The prime scaling variable considered in this study is that of rapid particle heating (between 105 and 106°K/sec) which is accomplished by means of turbulent mixing during combustion. The SR combustors tested in this study have consisted basically of spheres hollowed in the centers of refractory housings. Coal and air mixtures have been injected into the spherical combustion chambers through a single jet, two opposed jets or four opposed jets. The diameters of the jets have ranged from 0.63 to 0.22 cm. The volumes of the combustion chambers have ranged from 1.0 to 0.2 liters. The reactors have been equipped with thermocouples embedded in the combustion chamber wall as well as a thermocouple located in the exhaust gas stream. In the latter versions of the SR, provisions were made for both solid sampling and gas sampling of the reactant stream exiting from the combustion chamber. Experiments have been carried out using pulverized bituminous coal. The coal has been reacted in an SR in mixtures of air and air/nitrogen. These experiments have provided information on the mode of ignition of the coal as well as yielding information on the kinetics of coal pyrolysis through the use of SR theory. Ash tests performed on the reacted samples collected from the SR indicated that the majority of the values of weight loss percentage were between 60 and 70 percent. The percentages of weight loss were relatively unaffected by changes in temperature which varied between 1100 and 1700°K and by changes in residence time which varied between 10 and 20 millisec. Volatile matter tests performed on the samples indicated that the volatile matter left in the char ranged from 3 to 20 percent of the original content. By assuming that all the mass loss was due solely to pyrolysis with no combustion occurring at the particle surface, Q-factors for each test have been calculated. The results of these calculations indicate an average value of Q equal to 1.88. This finding shows that the majority of mass loss can be attributed to pyrolysis. The fact that the extent of reaction varies only slightly over the range of test conditions has been examined in the context of the two component hypothesis of coal constitution. This approach leads to the conclusion that the reaction of the "easily evolved" component VMI is extremely rapid and that the majority of it is removed from the coal in times less than the residence time in the system. This means that the volatile residue remaining in the char can be considered to consist of component II, VMII. If the mass fraction of VMI = 0, then an activation energy of 18.0 kcal is obtained for the pyrolysis reaction. If the mass fraction is assumed to be 0.75, the activation energy increases to 31.2 kcal.

Jan 1, 1978

By R. L. Andrews

The Bureau of Mines investigated means of electrodepositing iridium to form thick coatings suitable for the protection of such metals as tungsten and molybdenum, which oxidize rapidly at high temperatures. Using a fused sodium cyanide bath, thick, adherent, and coherent deposits of iridium up to 15 mils thick were plated on tungsten and molybdenum substrates at 600° C and current densities of 10 to 100 ma/cm2. Limited oxidation testing of molybdenum encapsulated with pure iridium indicates that the coating may offer protection to approximately l,000° C in flowing air, but that at higher temperatures, the volatility of its oxide limits use of pure iridium. Alloy coatings of iridium with platinum, palladium, and rhodium up to 4 mils thick were formed from a fused sodium cyanide electrolyte; because their oxides are less volatile, these alloys may protect substrates at higher temperatures. Deposits made from aqueous electrolytes either had very low rates of deposition or were highly stressed and cracked when heavy deposits were made.

Jan 1, 1967

By Sol Weller

The Fischer-Tropsch synthesis consists of the formation of long-chain hydrocarbons by passage of carbon monoxide-hydrogen mixtures over metal catalysts, usually based on iron, cobalt, nickel, or ruthenium, at temperatures in the range 180°-300° C., and at pressures of 1-15 atmospheres. Although the reaction has been known and studied for more than 20 years, the mechanism by which it occurs is still poorly understood. One approach to understanding is to consider the effect upon the course of the synthesis of variations in each of the important operating variables. Consideration of the experimental data pertaining to these variables may suggest an over-all picture describing the synthesis - a picture which, in turn, would have to be consistent with all the known facts. The first part of this paper will be concerned with such a consideration of operating variables; the second portion will discuss recent work pertaining to the role of metal carbides as intermediates in the synthesis.

Jan 1, 1949

By F. N. Kissell

The applicability of the "direct method" for determining the methane content of virgin coalbeds was tested. Preliminary results indicate that the direct method, when applied to exploration cores, can be successfully used to estimate coalbed gas content and also approximately predict the total gas emission from a prospective mine located in the coalbed at the exploration site.

Jan 1, 1973

By Leonard Obert

A triaxial procedure is described for measuring the modulus of elasticity and Possion's ratio of stress relief cores , that is , the concentric hole cores obtained by the overcoring technique . The elastic constant determinations can be made at stress levels comparable with those encountered in underground mining . The results from tests on an aluminum alloy calibration specimen and four rock specimens are included .

Jan 1, 1964