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By J. H. Holden, C. C. Shale, G. R. Strimbeck, W. S. Bowie

Electrical characteristics of positive corona are presented for air in a 2 - in - diam electrostatic precipitator operating under dynamic conditions at temperatures of 600 ° to 1,500 ° F and pressures of 0 to 80 psig . Results show that current - voltage relationships depend solely on air density . Comparison of data on positive corona with previously published data on negative corona demonstrates a higher sparkover voltage and a wider range of operability for positive corona at temperatures above 375 ° F. The possibility of achieving higher voltages with positive polarity as indicated by these experiments implies several advantages for the use of positive corona in precipitators to allow better removal of suspended material from hot gases . Based on the physics of an ion in an electrical field , a theoretical equation is derived to define current - voltage characteristics of positive corona in terms of air density . Constants for the equation are evaluated from Calculated current - voltage values at different air densities agree reasonably well with experimental data .

Jan 1, 1964

By R. Karl Zipf, Z. T. Bieniawski

"A set of fracture profile photomicrographs is presented for fractures generated under mixed mode loading of the Pittsburgh coal. The fractal dimension is used· to characterize the irregularity of these profiles and a tentative relationship is presented between the fractal dimension and the fracture toughness. Surface roughness appears to depend solely on the stress intensity and no other dependence was observed with fracture loading mode, loading rate· or specimen orientation. Observations of crack bifurcations.in fracture profiles can indicate crack growth direction whereas direct surface observations generally cannot in materials such as rock and coal.1 INTRODUCTIONThe production of fine fragments of material as a result of some loading event occurs in many industrial processes. In crushing and grinding, the efficient production of fine fragments is the desired end result; .however, in coal cutting, the production of fine fragments may lead to high levels of respirable dust in the immediate atmosphere with the danger of human lung diseases. Two of the most important sources of fragments in the 1 to 10 micron size range during a cutting process are 1) severe crushing in a zone near the loading tool and 2) subsequent shearing along major crack surfaces that form the larger fragments during material reduction. These and other sources of fine fragments generation are discussed by Roepke (1984) and Zipf and Bieniawski (1986). The physical character of the nearly created major crack surfaces is believed to have a strong influence on the amount of fine fragment generation that occurs during subsequent shearing movement. When the major large fragments initially form, they are ""locked"" in place by the irregular character of the new fracture surface. Only after some relative motion has occurred between fragments are they actually liberated, and the net result is the formation of additional fine fragments. The fine fragmentation is not necessarily limited to the shearing of high points from the macrocrack surf ace since material remaining in the wake of the crack tip is damaged to a substantial depth below the actual crack surface."

Aug 31, 1989

By R. T. DeWoody, W. C. Miller, W. Chester

Studies were made to determine the effect of the shape of a pneumaticrock- drill exhaust muffler on its efficiency, and the origin and reduction of exit noise from the mufflers. Tests of mufflers of three different shapes proved that the shape is not critical and that a muffler could be incorporated into the shell of the drill. Petal diffusers are beneficial in reducing exit noise but add another projection to the machine. Increasing the number of exit openings while maintaining the same area of exit opening has a markedly beneficial effect on the exit noise and appears to be the most satisfactory treatment.

Jan 1, 1964

By Helen W. Lang

This report describes a monitoring system applied by the Bureau of Mines to provide rapid, continuous determination of the main constituents of exhaust gas during the Bureau's approval schedule testing of diesel engines for under-ground use. Commercially available continuous analyzers with strip chart readout are employed for nitric oxide (mass spectrometric), carbon dioxide (nondispersive infrared), methane (NDIR), carbon monoxide (NDIR), and oxygen (polarographic). Good correlation is obtained between the continuous instrumental results and those obtained by batch chemical and gas chromatographic methods.

Jan 1, 1969

By W. K. Kleysteuber

This report covers the design and testing of a novel bulk materials conveying device by the Bureau of Mines. The transport concept of the device is to create a traveling wave with a steep front so that the bulk material slides and cascades down the front of the wave with some horizontal motion. Ideally, the front should act like a continuous chute. The concept of moving bulk materials along a belt without any forward movement of the belt itself was demonstrated. The conclusions reached were that the mechanism as designed could not overcome the inherent major disadvantages that would make the undulatory conveyor suitable for practical applications.

Jan 1, 1974

By R. V. Ramani, R. Bhaskar

"While the National Academy of Sciences has stated that gravimetric sampling technology for compliance purposes is adequate, research into various aspects of respirable dust control require data on many other parameters of airborne dust. These, in turn, have created the need to use many instruments, other than personal gravimetric samplers, in mi ne environments for dust measurement. There is a need to evaluate the performance of these instruments under conditions of potential use.As part of research in the Generic Technology Center for Respirable Dust, cascade impactors, gravimetric personal samplers and gravimetric samplers collecting dust using isokinetic sampling principles were employed for dust measurements under identical conditions in a mine airway. During the course of the experiments, 8-stage cascade impactors and gravimetric samplers drawing air isokinetically were located in the center of a mine airway at various stations. Two types of data were examined - concentration of dust and size distribution of the dust collected in the samplers. The data show that the amount of dust collected by an impactor is less than half the amount collected isokinetically. The size distributions of the dusts collected from the two instruments, though comparable, show a consistent difference in median diameters. The cause for this bias is examined.The paper presents and discusses the results of the tests, including the concentrations and size distributions obtained from the two instruments for different experimental conditions. There is a need to document the performance of various dust measuring devices in mine airflow conditions.INTRODUCTIONThe sampling of airborne dust in mines can be done for several purposes. Traditionally, dust sampling has been restricted to the gravimetric measurement of airborne respirable dust to comply with the regulations governing the mining industry. Instruments such as the MRE gravimetric sampler, and personal gravimetric samplers that have collection characteristics similar to the human respiratory system have been in use for the last two decades. Presently available instrumentation for the purpose of regulation have been considered adequate by the Committee on the Measurement and Control of Respirable Dust in Mines (National Academy of Sciences, 1980),"

Jan 1, 1989

By William W. Elmer

This paper, describing the mining method at the Black Butte quicksilver mine, is one of a series of papers being prepared by the U. S. Bureau of Mines on mining practices, methods, and costs in the various districts of the United States. It is presented to show the mining practice and costs in the successful treatment of low-grade quicksilver deposits. The operation discussed is an excellent example of w1-pat can be done in working a limited tonnage of low-grade ore under sound management. The Black Butte mine is situated at Black Butte, Lane County, in the southern part of the State of Oregon, 17-1/2 miles from Cottage Grove -- a station on the Siskiyou branch of the Southern Pacific Co. The Black Butte mining district lies in the foothills of the Calapooia Mountain Range, which connects with the Cascade Range on the east and with the Coast Range on the west. The elevation at '.lie reduction plant is 1,000 feet above sea level. The apex of Black Butte Mountain, or which the mine is situated, has an elevation of 2,700 feet. The district possesses exceptional natural facilities infrequently met with elsewhere for the mining and reduction of cinnabar ores. Several factors which contribute to the unusually low mining costs are:

Jan 1, 1930

By L. Mark Irwin, R. A. Marsyla

The objective of this laboratory investigation was to develop a mattesmelting process for the recovery of copper from industrial smelter dusts . Experimentation was conducted on three samples of Cottrell precipitator dust from a northern Michigan smelter with variations in the following conditions : Temperature , charge composition , pelletization , and moisture content . Based on chemical analyses of the furnace slags , poorest recovery of copper was effected in smelting dry charges regardless of composition . Some improvement was noted with uniformly moistened charges and still more with pelletized (but dry) mixes , but best results were obtained from smelting moist , self - fluxing pellets . Under favorable conditions , experiments yielded furnace slags with an average copper content of only 0.15 percent , which is well below that of industrial copper reverberatory slags .

Jan 1, 1963

By H. S. Caldwell

Molten zinc, condensed from zinc vapor, was used by the Federal Bureau of Mines to leach aluminum from an aluminum-silicon alloy made by carbothermic reduction of silicious aluminum ores. Zinc requirements were minimized by re-fluxing condensed zinc in a low-pressure, Soxhlet-type distillation unit. The minimum ratio of zinc used to aluminum in the crude alloy was approximately 2:1. When the system pressure was reduced from atmospheric pressure to 100 microns or less, the rate of aluminum extraction increased by a factor of 20. Leaching rates were much higher when the zinc vapor was condensed directly on the crude alloy than when molten zinc was passed over the alloy in the absence of appreciable zinc vapors. Observations indicated higher extraction efficiencies from crude alloys containing greater amounts of iron. Complete extraction was obtained with negligible loss of zinc. Assuming complete removal of zinc, the aluminum products will contain 1 to 6 percent silicon and about 0.5 percent iron plus titanium. The leached crude-alloy residue is a highly friable spongelike material containing about 80 percent silicon, several percent iron and titanium, with the remainder aluminum. This extraction method has been patented (Patent 2,810,637) and assigned to the Government. Research and development investigations are continuing at the College Park Metallurgy Research Center.

Jan 1, 1961

By R. W. METCALF, A. G. Charles, F. M. SHORE

To furnish the information frequently requested by producers and suppliers as to the fuel requirements of the Federal Government , the Bureau of Mines , with the cooperation of the consuming departments and establishments , has collected the data herein , showing the Government's fuel consumption during the fiscal year ended June 30 , 1930. The following tables show the quantities and kinds of fuels consumed by the Federal Government in each of its departments and their principal branches , in each State , and in Alaska , Hawaii , Panama Canal Zone , Porto Rico , and the Virgin Islands . The separate departments and establishments were asked to supply information for each Federal building or other plant and , as to vessel fuel , the amount loaded at each port of supply . Fuels consumed in internal combustion engines are not included . The report does not include fuels used by Post Offices of the fourth class , since their fuels are not purchased by the Federal Government but are covered by an allowance in each case for light and heat . In some cases the data supplied represent receipts , which are approximately equivalent to consumption . The present study is believed to be the first effort to bring together the data representing the Government's requirements for the various fuels which it consumes . Figures showing the coal consumed by the Federal Government were gathered for the year 1922. These data are shown in an article by O. P. Hood and R. H. Kudlich of the Bureau of Mines , contributed as a chapter to " Industrial Coal ; Purchase , Delivery and Storage , " published by the American Engineering Council . The figures of coal consumption presented herewith are approximately comparable with those published for 1922 , a relatively small difference being due to the fact that the 1922 figures include the Philippine Islands and all other territory in which any coal was consumed by the Government . At the present time , the only data on Government fuel consumption that are published regularly are those compiled by E. B. Swanson , chief economist of the petroleum economics division of the Bureau of Mines . These are published annually by the Bureau of Mines in " Sources and Distribution of Major Petroleum Products , Atlantic Coast States , " and by the bureau in cooperation with the American Petroleum Institute in the annual " National Survey of Fuel Oil Distribution . " It is believed that the data herewith will prove of interest and value to the fuel industries as well as to Government consumers and that it will also afford a basis for measuring future trends in the use of the various fuels by the Federal Government . Figures showing the quantities of the various kinds of fuels consumed by each of the executive departments and independent establishments , are given in Table 1. It should be noted that when one organization procures and delivers fuel to be consumed by other branches

Apr 1, 1932

By John E. Shelton

Flotation tests were conducted on two samples of copper-nickel-bearing ore from the Harriman area near Rockport, Maine. The samples were taken by Roland F. Beers, Inc., for tests in cooperation with the Federal Bureau of Mines. One sample, analyzing 0.38 percent copper and 0.71 percent nickel, was essentially a disseminated pyrrhotite in hypersthene. Pentlandite, chalcopyrite, pyrite, and millerite were intimately associated with the pyrrhotite. Locked series flotation tests on this sample showed that 87.4 and 73.4 percent of the copper and nickel, respectively, could be recovered in a bulk concentrate that analyzed 3.47 percent copper and 5.34 percent nickel. The copper-and nickel-bearing minerals were collected with sulfhydric collectors in an alkaline circuit. Cleaning the concentrate three times with the addition of pH regulators was sufficient to attain the previously stated grades. The second sample had analyses of 0.31 percent copper and 0.85 percent nickel; talc and hypersthene were the main gangue minerals. Bulk sulfide flotation, made while depressing the talc, resulted in a concentrate that analyzed 2.33 percent copper and 4.70 percent nickel at recoveries of 70.0 and 54.4 percent, respectively. Flotation of the talc followed by bulk sulfide flotation resulted in a nickel content greater than 5 percent. A locked-series test showed that 60.7 percent of the copper and 73.7 percent of the nickel could be recovered at grades of 1.29 and 4.85 percent, respectively.

Jan 1, 1961

By J. R. Hauger, P. A. Romans, W. J. Niebuhr

With suitable instrumentation and techniques it is possible to determine the presence of tantalum in columbium to 20 ppm . This paper discusses the selection of X- ray spectrographic instrumentation and describes a technique for accomplishing the low level determination of tantalum . An ion- exchange method of separating tantalum from columbium is also described .

Jan 1, 1964

By Kenneth R. Farley

The Bureau of Mines developed a rapid and accurate flame photometric procedure for determining cesium and rubidium in ores and in products associated with the extractive metallurgy of these elements. The effect of associated ions is neutralized by addition of buffer solution; alkali metal effects are neutralized by parallel analyses made on standard solutions similar in composition to the sample being studied. The overall accuracy of the method is within 2.5 pct of the amount of cesium or rubidium present; the range from 1 to 25 pct is the most accurate.

Jan 1, 1966

By K. K. Kelley, L. B. Pankratz

The heat contents of four silicate minerals -- akermanite , cordierite , gehlenite , and merwinite --were measured from 298 ° to around 1,700 ° K by the dropping method . The results were compiled into tabular and equation forms suitable for thermodynamic calculations . The heat contents of these compounds are nearly additive with respect to their constituent oxides .

Jan 1, 1964

By K. K. Kelley, L. B. Pankratz, W. W. Weller

Mullite is a substance of prime importance in ceramic technology . Despite this fact , its thermodynamic properties have received little attention . A Bureau of Mines literature survey disclosed the absence of lowtemperature heat capacity data , the absence of an experimental entropy value for 298.15 ° K , and the lack of heat content data beyond the temperature range from 298° to 576 ° K. Data supplied in this Bureau report fill these gaps in the thermodynamic knowledge of mullite . According to equilibrium phase studies of Aramaki and Roy ,3 the mullite phase melts congruently at 2,123 ± 15 ° K , and the equilibrium crystallinephase composition extends from Al Si2013 to Al6.8 Si₂ Q4.2 . The results in this report are for the stoichiometric composition , Al Si¿Qз . • Heat capacity measurements were made over the temperature range from 50 ° to 298 ° K , and the entropy at 298.15 ° K was evaluated . Heat content measurements covered the temperature range from 298 ° to 1,800 ° K. Heat content

Jan 1, 1963

By D. J. Judy, D. J. Rabovsky, W. H. Pailes, V. Castranova, K. Van Dyke, J. Rabovsky, N. A. Sapola, M. McPeek

"Platelet activating factor (PAF) can be released from pneumocytes following exposure to occupational dust (Am. Rev. Respir. Dis. 135:83, 1987). In addition, PAF has been shown to induce pulmonary inflammation, edema, and bronchoconstriction (Hosp. Prac. 19, 67, 1983). This investigation reports the effects of PAF on the properties of three types of cells found in the lung. PAF (1-100, K1/2 = 2.5 pH) caused depolarization of neutrophils as well as generation of chemiluminescence and secretion of hydrogen peroxide. These responses were dependent on the presence of extracellular sodium. However, PAF did not alter oxygen consumption of neutrophils. Although PAF (10 uM) caused depolarization of alveolar macrophages, no stimulation of chemiluminestence, superoxide secretion, or oxygen consumption was observed. However, PAF (10 uM). did potentiate chemiluminescence and superoxide secretion in response to zymosan (2 mg/ml) by 55% and 36%, respectively. In addition, PAF (10-90 uM) caused aggregation of alveolar macrophages. PAF (2-10 uM) also caused depolarization of type II cells, but did not affect membrane integrity or oxygen consumption. However, PAF (10-18 PM) enhanced the activities of two distinct forms of cytochrome P-450 in type II cells and caused aggregation of type II cells at PAF doses above 18 uM. These data indicate that PAF can affect the secretory activity of pulmonary phagocytes and the ability• of type II cells to detoxify foreign compounds (Bureau of Mines Grant - G1175142).INTRODUCTIONPlatelet activating factor (PAF) is a glycerophospholipid (1-0-alkyl-2-acetylsn-glycerol-3-phosphoryl choline) which has been shown to Mediate a broad range of biological activities (1-3). Its pulmonary actions include contraction of pulmonary tissue (4), secretion of leukotrienes from leukocytes (5), airway constriction (6), pulmonary edema (7), and enhanced migration of neutrophils into the airspaces of the lungs (8,9).PAF can be released from several different cell types, such as, basophils, neutrophils and alveolar macrophages, in response to a variety of particulates or membrane stimulants which include zymosan, calcium ionophore, phorbol esters, chemotactic agents, and endotoxin (10-13). Therefore, PAP may play an important role in the development of pneumoconioses by mediating pulmonary responses of lung cells to a variety of occupational dusts. To investigate this possibility, we determined the effects of PAF on several physiological parameters of neutrophils, alveolar macrophages, and alveolar type II epithelial cells."

Jan 1, 1988

By Henry Kreisinger, John Blizard

This preliminary statement presents some of the results of tests carried out at the Lakeside Station of the Milwaukee Electric Railway and Light Co. , by the fuel section of the U. S. Bureau of Mines , in cooperation with the research department of the Combustion Engineering Corporation of New York . The object of these tests was to determine the thermal efficiency , ease of operation , and other particulars of a boiler equipped with specially designed furnace and burners for burning powdered coal . The boiler tested haş 13380 square feet of heating surface , and is one of eight boilers equipped with the Lopulco powdered coal system supplying steam to two 20,000 -Kw . steam turbines in the largest power house burning powdered coal . Twenty- six tests were run at rates of heat transference varying from 4000 to 8000 B.t.u. per square foot of boiler heating surface , and the mean thermal efficiency attained was about 84 per cent , based on the gross calorific value of the fuel as fired . The efficiency varied little with the rate of steaming , and its high value is accounted for by the small loss from incomplete combustion and the small amount of excess air which varied from 5 to 36 per cent . The coal burned had a gross calorific value of about 11500 to 12800 B.t.u. per pound , contained 2 to 5 per cent moisture , 33 to 36 per cent volatile matter and 9 to 13 per cent ash, and was so ground thaf 89 to 95 per cent would pass through a 100- mesh sieve . The ash had a softening point of 2150 to 2450 degrees F. , but did not fuse together at the bottom of the furnace because it was partly protected from the flame radiation by means of a series of water tubes connected to the boiler which were placed between the fumace bottom and the flame, ..

Jan 1, 1923

By A. J. Barry

This report presents observations made by Bureau engineers regarding hydraulic-powered roof supports that are currently being used or have been used on nearly all operating longwalls in the United States, A comparative summary of specifications for various types of powered supports with a brief description of the mine conditions has been compiled to enable mining engineers and mine operators to readily evaluate the differences in design data. Some of the support data furnished in the field may vary from those listed in manufacturers' brochures because of the trend to customize various support components to meet specific mine conditions. A method of estimating support requirements for different assumed operating conditions is presented. Similar computations for specific mine conditions may be used to make preliminary estimates of support requirements.

Jan 1, 1969

By E. Morrice

High-purity neodymium, praseodymium, and didymium (a cerium-free mixture of light rare-earth elements) were prepared by electrolysis of the oxides in a medium consisting of the respective rare-earth fluorides and lithium fluoride. The metals were electrodeposited in the liquid state and collected as nodules on a skull of frozen electrolyte. Cells were operated from 1,000° to 1,100° C. The requisite temperature was maintained by passing alternating and direct currents through the bath. Graphite was used for the anodes and tungsten for the cathode. The metal products contained <0.02 percent each carbon and oxygen and <0.025 percent tungsten as major impurities. Analysis of typical didymium metal nodules showed an approximately twofold enrichment in neodymium and praseodymium over their respective concentrations in the cell feed. The lanthanum content of the metal was about one-half its content in the oxide.

Jan 1, 1967

By H. C. Fuller

Depletion of iron ore in the Nation&apos;s large deposits has directed attention to other sources. One of these is the titaniferous iron ore of the Iron Mountain, Wyo., area. Tests were made to determine the feasibility of smelting this ore, which contains about 20 percent titanium dioxide (Ti02), in an electric-arc furnace to produce pig iron. Initial tests, which were made in a 30-pound-capacity induction furnace, demonstrated that the iron could be easily reduced to metal and that limestone was a suitable and effective flux. Larger scale tests then were made in a 50-pound-capacity electric-arc furnace to obtain the more detailed information necessary for the planned continuous operation of a still larger arc furnace. The principal facts determined by preliminary batch-smelting studies were that (1) 9 pounds of limestone flux was required for each 100 pounds of ore smelted, (2) expensive coke was not required because coal proved to be a satisfactory reductant (near stoichiometric carbon was optimum), and (3) overreduction, which produced a viscous slag, must be avoided.

Jan 1, 1961