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By P. M. Brown

The Bureau of Mines is investigating a dewatering technique for coal-clay waste that uses a flocculant, polyethylene oxide (PEO). This flocculant forms strong stable flocs that can be dewatered on a static screen. A field test unit (FTU) using this technique was operated at approximately 400 gal/min, using a waste stream from the flotation circuit of a coal preparation plant. Consolidated coal-clay material con-taining 55 to 60 pct solids was produced when the flotation circuit slurries of 2.7 to 8 pct solids were treated with 0.1 to 0.3 Ib PEO per ton of solids. The FTU was also operated at 64.5 and 87.5 gal/min using a portion of the underflow slurry from the preparation plant's thickener. Consolidated coal-clay material containing 55 to 60 pct solids was produced when the thickener underflow slurries of 19 to 24 pct solids were treated with 0.08 to 0.2 Ib PEO per ton of solids. PED-treated materials continued to dewater when placed in a pit.

Jan 1, 1983

By N. Greninger

The Bureau of Mines examined the possibility of a seasonal variation of respirable dust concentration in U.S. coal mines. The first step was to review company and MSHA-inspector dust samples that had been collected during the past several years in 14 selected mines for compliance purposes. Results indicated severe scatter in data; most standard deviations of the dust concentrations measured in winter and summer months were comparable in magnitude with the mean values of dust concentrations for the seasons. Therefore, a detailed statistical analysis was conducted. At the 90% confidence level, the company samples of three mines had winter means 0.15 to 0.54 mg/m3 higher than the summer means; six mines had negligible seasonal variations; and five mines had winter means that ranged from higher to lower than the summer means. Inspector data, however, were too sparse for analysis. In view of both the low frequency of occurrence of a seasonal effect and its wide scatter in several of the mines, the study was ended with the conclusion that seasonal varia-tion in respirable dust levels, in general, is an insignificant factor.

Jan 1, 1986

By L. C. IlsLey, Charles M. Means

The descriptive rather than the strictly technical meaning of many of the terms and expressions used in the electrical rules is given in order to assist in their interpге- tation . ALIVE . At a potential measurable with a voltmeter and different from that of the earth or another conductor . (Static charges should be determined with an electrostatic voltmeter . This condition may apply to current - carrying parts , to noncurrent - carrying parts and adjacent material where a failure of insulation has taken place , and to objects having stored or static electricity . ) ALTERNATING CURRENT . A current that changes in direction -- positive or negative-- a certain number of times per second , depending upon the number of poles and speed of the generator . AMMETER. An instrument for measuring current , indicating in amperes . AMPERE . A term applied to denote the rate of current flow . ( Analogous to " gallons per minute " in a hydraulic system . ) APPROVED . Accepted as suitable by a competent committee , board , or organization designated by those adopting the rules . ductors . ARMOR . A steel or equivalent metallic covering for one or more electric con- AUTHORIZED PERSON . Anyone commissioned by the official in charge of the mine or his deputies to carry out certain duties incident to the generation , transformation , and distribution or use of electric energy in the mine , such person being one who is competent within the purpose of the rule in which the term is used .

May 1, 1930

By C. W. Huggins

The primary objective of this Bureau of Mines research was to measure the size distribution of respirable quartz collected at metal mines, nonmetal mines, and processing plants to select the best reference standard for use in quantifying quartz in mine and plant dust samples. The secondary objective was to size all the nonquartz particles collected at the same sites. Particle size measurements were made on 29 samples using a scanning electron microscope in the backscatter mode of operation, interfaced with an image analysis system. The Mine Safety and Health Administration, Denver, CO, provided the 29 samples, which were collected at mines and processing plants in 19 states. The accumulated particle size measurements indicate that NBS 1878, minus 5-f.lm Hin-U-Sil, and minus 5-f.lm Supersil would be preferred over Silver Bond B as reference standards for most quantitative determinations by X-ray diffraction and infrared spectrometry. The respirable dust samples collected at sand plants, however, would be better served by a new reference standard having a quartz particle size distribution of approximately 2.2 um, as none of the four existing reference standards matched closely with them. Commercially available NBS 1878 and minus 5-um Hin-U-Sil CQuid be used as reference standards for 28 of the 29 samples studied in this investigation.

Jan 1, 1986

By Douglas A. Elkins

The unique characteristics of plasmas, their current applications, and ongoing research into new applications are described. Major technical and economic problems in application of plasma technology are discussed. Examples of potential applications of plasma in extractive metallurgy are described and evaluated. The report includes a selected bibliography of articles on plasma and related high-temperature technology.

Jan 1, 1969

By Henry E. Blake

Defluorination studies on refractory fluoride - bearing compounds and minerals , particularly on partly defluorinated residues from high - temperature pyrohydrolysis , required a dependable and reasonably accurate analyticalcontrol method for the analysis of fluorine . The difficulty in liberating fluorine from the fluorides of metallic elements such as aluminum, zirconium , and rare earths by steam- distillation can be largely overcome if the distillation is made from a sulfuric - phosphoric acid solution of a sodium carbonate fusion of the sample material and if the distillation temperature is maintained at about 155 ° C. The data presented in this paper show that liberation of fluorine by this method is more complete and proceeds more rapidly than by usual distillations from perchloric or sulfuric acid alone or a mixture of phosphoric and perchloric acids . Fluorine in amounts ranging up to about 140 mg can be recovered by collecting only about 300 ml of distillate . Determination of fluoride in the distillate is made by the usual thorium nitrate titration .

Jan 1, 1963

By Howard P. Hamlin, John W. Sweeney

Shales from 14 locations in Indiana were sampled , tested , and evaluated to determine feasibility of producing lightweight aggregates by rotary - kiln and sintering methods . Sampling procedures and the geology of the significant shale units are discussed . Preliminary testing was conducted in a muffle furnace , and continuous tests were made in a 16 - inch by 14 - foot rotary kiln . The aggregate weighed 37.0 to 47.2 pounds per cubic foot . Concrete cubes employing the aggregate were tested to determine the qualities of the concrete . Compressive strength of the concrete using seven bags of cement per cubic yard , after autoclave curing for 6 hours , ranged from 3,600 to 5,850 pounds per square inch . Four samples made suitable lightweight aggregate in the laboratory rotary kiln . Four samples tested by sintering methods made unsatisfactory aggregate .

Jan 1, 1965

By W. J. Boone, Will E. DeVaney, Lowell Stroud

This report is the fifth in a series presenting equilibrium vapor - liquid data for helium- bearing natural gases . It covers a 0.41 - mole - percent - helium natural gas that may be processed in the Department of the Interior's longrange helium conservation program . A Bureau of Mines phase equilibrium apparatus was used to obtain 139 samples of equilibrium vapor and liquid phases at 85 experimental conditions at temperatures from 0 ° to -299 ° F and at pressures from 100 to 500 psia . An appendix covers phase data at 100 , 200 , and 300 psia and at temperatures from -125 ° to -275 ° F for the dehydrated gas containing its original concentration ( 0.2 mole - percent ) of carbon dioxide , and the effect of a preliminary hydrocarbon trap upon subsequent vapor - liquid compositions .

Jan 1, 1964

By L. D. Schmidt, H. G. Graham

Several processes for the production of ultra-clean coal for electrode carbon were developed in Germany prior to and during World War II . These processes have been investigated since the end of the war by the British and U. S. Government missions . As the reports of the investigations are not readily available to the public , it is the purpose of this paper to present the information which has been obtained regarding the methods by which ultraclean coal was produced . Almost all the ultra-clean coal was used in the manufacture of electrodes for the production of aluminum and magnesium . Standard raw materials for making these electrodes are pitch coke and petroleum coke , which are nearly ashless . The inclusion of ash in the electrode carbon results in lowered efficiency and impure metal from the reduction process . Petroleum coke and pitch coke were in very short supply in Germany during the war , so that it was necessary to augment the supply with carbon produced from coal . In the emergency , methods were developed to clean coal which had never before been economically feasible . However , a demand for nearly ash-free coal might develop in the United States if a shortage of petroleum coke were to occur at the same time as a strong demand for light metals . Other uses of ultraclean coal are in direct hydrogenation of coal , in production of activated carbon, and for special fuels . Specifications for electrode carbon are rather severe owing to the necessity for producing pure metal . Maximum amounts of impurities allowable in American practice are as follows : Total ash , 1.0 percent ( in finished coke , 0.7 percent ) Silica , 0.08 percent Ca or Na, or their sum , 0.12 percent Sulfur , 2.0 percent Ba , Ni , Cr , Mn , Co , and V are objectionable in very small amounts . The most important process for ultra cleaning of coal in Germany was froth flotation . Froth flotation had been used widely there to process washery -water sludges and to recover coking coal from high - ash fines . Its use was indicated , therefore , when the demand for ultra low-ash coal arose . In two plants the coal cleaned by froth flotation was treated with acid or caustic to lower further the ash content . Another process used on an industrial scale was that of dissolving the coal substance in the middle oil from direct hydrogenation of coal under controlled pressure and temperature . The resulting paste was heated, filtered , and the oil distilled off . The residue was a low-ash organic material that could be carbonized for electrode carbon or could be hydrogenated directly . Several other processes had been developed to the laboratory or pilot - plant stage but had never been used on a commercial scale . These processes included cleaning by centrifugal action , cleaning by electrostatic action , and cleaning by forming a paste with oil in water . The coal-preparation plants at the Carl Alexander mine , Augusta Viktoria mine , and Kőenigin Elisabeth mine are described in Bureau of Mines Information Circular 7389 : " Coal Preparation Practice in Western Germany" , by Thomas . Fraser and M. G. Driessen . Most of the special equipment used at these plants is described in the above publication .

Oct 1, 1948

By L. B. Pankratz

High-temperature heat contents were measured for two praseodymium oxides and three terbium oxides. There were: Pr2O3 (298° to 1,600° K), PrO1.833 (298° to 1,050° K), Tb2O3 (298° to 1,600° K), TbO1.719 (298° to 880° K), and TbO1.812 (298° to 850° K). With the exception of PrOl.833, all results were regular. PrO1.833 had a small thermal anomaly at 760° K with an extra absorption of 380 cal/mole. The measured heat content values, tabulated smooth heat contents, and entropy increments are reported. Heat content equations were derived.

Jan 1, 1966

By A. B. Hooker, L. C. IlsLey

"Field inspections and data relative to the use of rubber—sheathed trailing cables in mines show that much cable is ruined or its probable life shortened by being overheated in service.The length of cable required to make connection from a source of supply to a machine at the face workings may be 100 to 500 feet. As a rule, the cable is carried on a reel and unreeled as required; and thus in most cases some of the cable is not removed from the reel. The overheating generally occurs in that part of the cable which is left on the reel.Factors that determine the heating of trailing cables are:1. The size of the conductors in the cable.2. The maximum energy to be supplied through the cable, based upon the horsepower of the motor and the degree to which the motor is loaded.3. The voltage of the supply and the variation of the voltage at the receiving4. The time length of current flow and whether continuous or intermittent.5. The kind of current (direct or alternating).6. The amount of cable left on the reel.7. The type of cable used.8. The kind of reel used.In connection with an investigation of the general performance of rubber—sheathed trailing cables, the Bureau of Mines has made a limited study of some of these factors, including the following points:"

Jul 1, 1931

By Seth C. Schaefer

The Bureau of mines investigated thermodynamic properties of MnSO4 and 2CdO CdSO4 to obtain basic thermodynamic data applicable to the treatment of mineral concentrates during roasting and sintering processes. Standard Gibbs energies of formation were determined with high-temperature galvanic cells using stabilized Zr02 as the electrolyte. Potential measurements were obtained from the cells?

Jan 1, 1983

Commodities statistics and other information are available through the following three systems: Internet Access: To acccess the USBM Gopher server on Internet, connect to: gopher.usbm.gov port 70, using gopher client software. Or contact the Systems Administrator for technical questions: Matt Klevemann, 412-892-6499 (klevemmc@miner.usbm.gov) These USBM materials are available on Internet, with more to come in the future: Publications and other research findings, including this bimonthly publications list, newsletters, tech transfer updates, enviromental technology research, health and safety information. USBM software products Media materials and speeches. Mines Data: Computer bulletin board. Log on via modem through 202/501-0373, or call 202/501-0406 for technical assistance. Mines FaxBack: Return fax service. 1. Use the touch-tone handset attached to your fax machine's telephone jack. (ISDN [digital] telephones cannot be used with fax machines.) 2. Dial 202/219-3644. 3. Listen to the menu options and punch in the number of your selection, using the touch-tone telephone. 4. After completing your selection, press the start button on your fax machine.

Jan 1, 1995

By C. C. Furnas

Despite the fact that a great many industrial processes depend on efficient contact between a gas stream and a bed of broken solids for their operation, the data in the literature are very meager. Several investigations3 have been undertaken, but the work has been limited in scope and application. BUREAU OF MINES PROGRAM OF RESEARCH For the past 10 years the United States Bureau of Mines has been engaged in research with the object of formulating a more or less complete quantitative theory of the workings of the iron blast furnace. Obviously, in order to do this one of the essentials is to have considerable definite information on the laws of gas flow through beds of broken solids. This report in a brief summary of the experimental work on the problem which has been done at the North Central Experiment Station. The complete report with more detailed tabulation of the data and explanations of the experimental procedure is in process of publication in the form of a bulletin.

Jan 1, 1928

By M. J. Kovalik, D. E. Wolfson, F. Fischler

Plastometric tests were made to determine the maximum thickness of the plastic layer for different U.S. coals . The effect of test variables on the maximum thickness of the plastic layer was studied . The values for the maximum thickness of the plastic layer were found to be related to the Gieseler maximum fluidity , plastic temperature range , free swelling index , and other plastic properties of coals . Only a general relationship was observed between the plastometric parameters obtained in these tests and the coking properties of coal .

Jan 1, 1964

By Arnold B. Hubbard

This report describes a method of concentrating the insoluble organic material (kerogen) in a rich Colorado oil shale without any apparent alteration of its original chemical form. The method involved treating finely pulverized shale with dilute acetic acid at room temperature to remove the carbonates, which act as a cementing agent for the shale, and cause the shale particles to partly disintegrate into the organic and inorganic components. The acid-treated shale then was centrifuged in different liquid mediums ranging from 1.4 to 1.15 gravity to effect a mechanical separation. From a Colorado oil shale containing 48.0 percent ash, kerogen concentrates containing 43.3 to 8.7 percent ash were obtained. The carbon:hydrogen ratios of the kerogen in the original shale and the different concentrates were essentially the same. The oil:kerogen ratios calculated from Fischer assays of the above samples were essentially the same, regardless of the organic or inorganic contents. This was also true of the assay water:kerogen ratios of the same samples. These data indicate that no significant change occurred in the kerogen during the concentration process.

Jan 1, 1952

By H. H. Schrenk, F. E. Griffith

"The increase in tunneling operations that requires working under pressures greater than that of ordinary atmosphere has raised the question of the use and possible limitations of respiratory protective devices under such unusual conditions. As little, if any, information is available, there is need for a comprehensive study of this subject before specific recommendations can be made. In the absence of such data it seems desirable to make a few preliminary observations regarding the problems associated with wearing respiratory protective devices under increased air pressures.Two distinct problems must be considered--the mechanics of the apparatus used under such conditions and the physiological effects of increased pressures on wearers of respiratory apparatus. This report is confined to the use of oxygen breathing-apparatus and gas masks under pressure.ACKNOWLEDGMENTSThe data presented were obtained at the Queens Midtown Tunnel under construction at the east end of 42d Street, New York City, during a study of compressed-air illness conducted by the Bureau of Mines in cooperation with the United States Public Health. Service and the New York City Tunnel Authority.Grateful acknowledgment for cooperation and the use of facilities is made to Dr. R. R. Sayers and his associates, particularly Dr. J. W. Crosson (who acted as observer during the oxygen breathing apparatus tests), of the Division of Industrial Hyiene, National Institute of Health; to the Port of New York Authority, through Dr. Edward Levy; end to the contractors, through Doctor Emery."

Jan 1, 1940

By A. J. Forney

Recent experiments used catalysts of plate assemblies in synthesizing high-Btu gas and gasoline indirectly from coal. A gas with a heating value of 925 to 943 Bt-: per cubic foot has been prod u la the hot-gas-recycle pilot plant from synthesis gas (3H2+100) with lathe turnings used as catalyst in the first reactor, and assemblies of parallel sprayed plats of nickel in the second. Solid plates made of Raney nickel, and steel and aluminum plates sprayed with Raney nickel or nickel oxide were tested. Those catalysts had very low resistance to gas flow; 90 percent lower than nickel granules used in previous experiments. In a single stage of synthesis thee nickel plates were only partially successful. Although the heating values of the product gas ranged from 856 to 941 Btu per cubic foot, the carbon monoxide content of he gas was above 0.1 percent. Both steel and wrought turnings were tested in single-stage synthesis, but the conversion of hydrogen and carbon monoxide was too low to attain the desired heating value of 900 Btu per cubic foot in the product gas. Assemblies of plates thermally sprayed with fusel iron were tried in an experiment to make gasoline. A gasoline yield of 52 percent (of the hydro¬carbons produced) was obtained using a 1H2-10O feed These sprayed assemblies were in service for 1,500 hours, the longest that this type of catalyst has been used. When a second reactor containing Raney nickel catalyst was added in series with the first reactor, complete utilization of the feed gas was obtained because in addition to the liquid product, a high-Btu gas with a heating value of 800 Btu per cubic foot was made.

Jan 1, 1965

By Richard J. Kline

The underground mining industry is presently using the fluid network analyzer and digital computer to analyze ventilation systems. The availability of the digital computer and ventilation programs to mining companies has escalated its use, permitting the design and modification of new or existing mine ventilation systems to be projected completely and thoroughly with consistent precision. Because the analog computer has been analyzing ventilation systems accurately for many years, a comparison of the analog and digital methods was warranted. This report summarizes a detailed comparison for one mine, based on parallel analyses by the two computer systems.

Jan 1, 1972

By F. S. LOTT

Publication of the Bureau of Mines annual surveys of the capacity of petroleum refineries in the United States was suspended after the entry of the United States into World War II . The last published survey was that of January 1 , 1941 , released in April 1941 as Information Circular 7161 . The purpose of this publication is to provide comparable information with respect to crude - oil and cracking capacity on January 1 , 1947. No attempt is made at this time to bridge the gap in annual statistical series from the date of the last published survey to the present one . However , complete summary tables will be included in the succeeding survey for January 1 , 1948 .

Mar 1, 1948