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By N. E. Hanna

[Testing explosives for safe use in coal miner ran boon an important factor in preventing mine explosions. In the United States, explosives that have been approved by the Bureau of Mines are called permissible explosives. A purvey of the history of coal mining since permissibility testing welt, instituted some 4 years ago shown that there is no record of a coal-mime explosion caused by permissible explosives when used in a manner prescribed by the Bureau. To maintain the appropriate standards of quality, the Bureau of Mines conducts a series of examinations and tenth on samples of explosives collected in the field. In what is considered the most crucial test, teat 1, the explosives An fired from a steel cannon into a gallery atmosphere containing a mixture of natural gas and air, In another important test, test 4, the explosives charge to fired into a mixture of natural gas, air, and coal diet. To satisfy the permissibility requirements, the explosive must undergo throe gallery teats without igniting gas or coal duet. Other tests also are required for permissibility, but they do not come within the scope of the present paper, which studies the factors affecting the incendivity of explosives when fired into methane, air, and/or coal-dust mixtures. It in believed that a better understanding of the factors will contribute to the development of safer explosives.]

Jan 1, 1954

By L. A. Morley

Volume III of the final report examines the indication versus interruption procedures used on motion-drive power equipment, with emphasis on surface excavators. The report begins with a review of the electromechanical acid conversion used with the Ward-Leonard control system. Protection criteria for the drive-system components are then discussed. Fault sources and fault calculations for both the ac supply source and dc power loop are introduced to assist in discussing indication and interruption procedures. The subject is then expanded to examine the dynamic process of the machine and determine the effects of fault current and position of the machine to allow for an orderly shutdown. With this analysis, possible indication an interruption procedures are given for the four-quadrant duty cycle of excavators. The report concludes by introducing other mining operations that utilize similar motion-drive systems and also static (solid-state) drives and recommends further research in these areas, as well as a more detailed examination of the dynamic fault analysis for excavators.

Jan 1, 1982

By F. S. Wartman

Recent changes in metallurgical practice, particularly those in flotation, have altered greatly the functions of the different units of a copper smelter. Gangue minerals are removed from the feed so much more thoroughly that the reverberatory furnace, once virtually a concentrator in which a low-grade ore was concentrated into a rich matte by virtue of the removal of gangue elements as slag, has become very largely a melting furnace in which the rich flotation concentrates are rendered molten so that they may be converted. Moreover, since the proportion of matte to slag in the reverberatory furnace output is greater than it was formerly, the amount of converter slag returned to the reverberatory for cleaning is, in comparison to the amount of slag actually formed in that furnace, also much larger. In some cases, approximately half of the reverberatory dump slag may have originated in the converter. The increase in the proportion of convertor slag to total slag produced has brought about certain consequences not entirely desirable. Converter slags contain a high percentage of iron and therefore are high in specific gravity and are very basic. A considerable guantity of magnetite, both dissolved and suspended as solid crystals, is always a component, The basic nature of the ordinary converter slag and the presence of the suspended magnetite crystals make impossible the reduction of the copper content of the slag below approximately 1 per cent by even the most prelonged settling, and a re-treating process is necessary. At present, general practice in western copper smelters is to return the converter slag molten to the reverberatory furnace. Here dilution by mixing, with slag formed in the reverberatory furnace and reaction with raw sulphides and siliceous materials in the reverberatory feed reduce the magnetite and increase the silicates to the point necessary for a satisfactory dump slag.

Jan 1, 1930

By W. W. Adams

"The present world-wide demand for increased production in all branches of essential industry involves a matter of vital concern t persons engaged in the mining industry, namely, the productive capacity of the individual mine employee. This applies particularly to coal-mining, upon which other industries so largely depend.The folded and faulted condition of the coal beds in some countries, as well as the thinness and depth of the seams, the adaptability to the beds of available mining machines and equipment are factors which cannot be overlooked in determining what increase in individual output may be looked for in any given country. This subject, while of fundamental importance, can only be referred to in a paper of this length, the primary object here being merely to present a comparative tatamant of individual output under prevailing conditions.The quantity of coal produced by a miner does not accurately indicate the miner's capacity as a workman, not only because of the natural conditions referred to above that limit his annual output, but also because of human factors which may possibly, however, be controlled, such as the demand for coal, the car supply, use of labor-saving machinery, number of days worked during the year, accidents in the mine, etc. It will, however, be an aid in answering the important question as to how and where the immediate need for coal throughout the world may best be surlier, if we examine the output of the miners in the important coal-producing countries over a period of years.Complete official information for recent years is, for several countries, jacking, particularly for France, Austria, and Prussia, but partial data from unofficial sources may be used to show the individual output of the miners in these countries."

Jul 1, 1920

By G. G. Campbell

Bureau of Mines research to develop an in situ retorting recovery method for oil shale has involved field testing of fracturing techniques for creating fluid-flow paths in impermeable oil shale. Electrolinking, hydraulic fracturing without and with sand propping, and explosive fracturing with a liquid explosive were tested in a 25-ft-square, five-spot pattern. These wells were drilled into oil shale at 50-to 88-ft depths near Rock Springs, Wyo. Results of the fracturing tests were evaluated by injecting air into a test well and measuring flow rates and flow profiles in adjacent test wells before and after each test. To identify points of air entry (location of fractures) in wells, flow profiles were determined by use of inflatable packers and by continuous logging with an airflow probe developed during the fracturing program. Electrolinking and hydraulic fracturing without sand propping were relatively ineffective; hydraulic fracturing with sand propping created horizontal fractures with desirable flow capacity; and fracture flow capacity was significantly increased by detonation of nitro-glycerin displaced in the natural and hydraulically induced fracture systems.

Jan 1, 1970

By F. P. Haver

The Bureau of Mines is developing a leach-electrolysis procedure to produce Special High Grade (SHG) zinc from sulfide concentrate without the generation of sulfur oxide gases. Chlorine-oxygen leaching of the concentrate yields zinc chloride (ZnCI2) which, after purification, is electrolyzed in a fused-salt cell to obtain molten zinc metal and chlorine gas for recycle. This paper describes a laboratory-scale investigation made to develop a procedure for electrowinning zinc metal from ZnC12. Zinc chloride by itself is not a suitable electrolyte because it fumes badly above its melting point and is a poor conductor of electricity. Other salts therefore must be added to prevent fuming and improve the conductivity. Optimum results were obtained with a KC1-LiCl-ZnCl2 bath at 500° C, using a current density of 5 amp/in2 and an electrode spacing of 0.5 inch. Under these conditions, SHG zinc was produced at a current efficiency of 94.3 pct and an energy requirement of 1.16 kwhr/lb. Fused-salt electrowinning eliminates the need to handle and melt cathodes and increases the production of metal per unit cell volume through the use of higher current densities than are possible with aqueous electrolysis.

Jan 1, 1976

By S. A. Matthes

This Bureau of Mines report describes analysis of a copper slag for 13 elements from a single sample solution by flame atomic absorption spectroscopy. Samples are dissolved with 7 ml of an HC1-HF-HN03 (3:1.5:2) mixture in heated plastic pressure vessels. A 1.5-pct boric acid solution is added to dissolve precipitated fluorides and to reduce matrix effects that interfere with atomic absorption analysis. Preparation time is less than 1 hour per batch of 10 samples. Total analysis time is less than 6 person-hours for 130 determinations with an average relative standard deviation of 1.83 pct for the 13 elements. Simple acid standards were used for all determinations. Values obtained by this method are in excellent agreement with values obtained by slower, more costly procedures.

Jan 1, 1980

By J. Baicker

A two-inch diameter probe containing an intrinsic germanium detector, a canister-type solid cryogen cooling system, cooled FET preamplifier, linear amplifier, high voltage supply, analog-digital converter, microprocessor, buffer memory, bidirectional cable link, and all power supplies has been designed, assembled and tested. A surface support vehicle was designed, built and outfitted. A mini-computer system was constructed and preliminary software developed and tested. A special handling system for a Cf-252 neutron source was designed and has been ordered. The entire system (less the neutron source) is ready for its first field tests. Lab description of the system is presented.

Jan 1, 1978

By Jr. Joyce

This report describes sulfatization of nickeliferous laterites from Puerto Rico and the Philippines for recovery of water-soluble nickel and cobalt sulfates. Temperatures ranging from 665 C to 710 C and a 10-percent sulfur dioxide-air reaction gas were employed during batch-roasting tests and during continuous countercurrent treatment in a 2-inch-diameter shaft furnace. A maximum of 69 percent of the nickel and 76 percent of the cobalt were recovered from one sample of Puerto Rican laterite, and a maximum of 96 percent of the nickel and 91 percent of the cobalt were recovered from the Philippine laterite.

Jan 1, 1965

By N. S. Dalal, X. Shi

"Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(Vl) by glutathione redtuctase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(Vl). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals.C(Vl) compounds have been found to exert serious toxic and carcinogenic effects on humans and animals (1-3). In contrast, most Cr(III) compounds are relatively nontoxic, noncarcinogenic, and nonmutagenic (1,4). Cr(VI) and Cr(III) oxidation states are different in their metabolic pathways: Cr(VI) , ions are rapidly transported across cellular membrane (1,4,5), while Cr[III) moieties do not easily penetrate cells and are not oxidized by cellular constituents (!). Since it is known that the reduction of Cr(VI) ion is required for its reaction with DNA (1), the molecular mechanisms for the intracellular Cr(Vl) reduction has been the focus of current studies but the details are still not understood.Earlier studies on the mechanism of Cr(Vl) reduction include those on the reduction of Cr(VIJ by glutathione (GSH) .0,6-8), ascorbic acid (9), glucose (10), lactose (IO), galacturonic acid (11), microsome (12), and mitochondrial electron transport chain complexes (13). These studies have shown that the Cr(VI) reduction involves the formation of Cr(V)-containing species which are often considered to be the toxic form of chromium. Thus far, however, no information is· available on the subsequent fate of those biologically formed Cr(V) species, in particular employing well defined biochemical systems. In this context, we report here our investigations of the reduction of Cr(VI) by glutathione reductase (GSSG-R). This enzyme was selected because it is ubiquitously present in cellular systems and it has been postulated to be involved in the Cr(VI) reduction (14-17) but the underlying mechanism has not been clarified. We find that the reduction proces·s involves not only Cr(V) but also ·OH radicals. We further investigate the reactivity of Cr(V) and find that it catalyzes generation of OH radical from H2O 2 through a Fenton-like reaction. The role of ·OH in Cr(VI) carcinogenicity is suggested from this study."

Jan 1, 1989

By Paul T. Allsman

This paper describes metal- mining practices at the Harrington -Hickory lead - silver - zinc mine at Milford , Beaver County , Utah . The operations of the Harrington-Hickory incorporate a number of features that should prove of interest and value to other operators of small mines . These features include employee participation in profits , a well- laid -out electrical system, adequate financing , a well - balanced equipment and supply inventory , a well - organized system of bookkeeping , adequate roads , and good management . As crude ore is shipped directly to smelters and mills in the Salt Lake Valley , close attention is paid to see that the ore is segregated by classes and treated where it can bring the greatest not return . A combination of these features has resulted in maintaining relatively low costs, considering the grade and size of ore shoots at a time , during and following the war , when equipment , supplies , and labor were costly and difficult to obtain . The period covered in this report includes two war years and two years following , from April 1, 1944 to June 30 , 1947 .

Apr 1, 1949

By W. W. Adams

Reports received by the Bureau of Mines, Department of Commerce, from State mine inspectors, for November, 1930, showed that 219 men were killed in the coal mines of the United States during the month, an increase of 25 over the previous month and 33 over November, 1929. On the other hand the production of coal decreased, the output of 43,329,000 tons in November being 8,397,000 tons less than in October and 9,005,000 tons less than in November a year ago. The larger number of fatalities accompanied by a smaller output of coal resulted in a higher death rate4 per million tons in November than in the same month last year or in October, 1930. The November rate was 5.05, as compared with 3.55 for November, 1929 and 3.75 for October, 1930. The increase in the rate for the industry as a whole was chargeable entirely to bituminous mines,, as the anthracite mines had fewer fatalities in November than in either of the previous months to which reference has been made. Reports for bituminous mines alone 'allowed that accidents at class of mines resulted in a death rate of 5.12, based on 195 fatalities and a production of 38,122,000 tons. This rate indicated an increase of 55 per cent over the rate for October, of the same year, and 72 per cent over the rate for November, 1929. The October record was 146 fatalities and 44,150,000 tons, and that for November a year ago was 138 deaths and a production of 46,514,000 tons. Twenty-four deaths occurred at anthracite mines in November, 1970: the output of coal was 5,207,000 tons, hence the rate was 4.61 per million tons. During the corresponding month a year ago there were 48 deaths and 5,820,000 tons of coal produced, which indicated a death rate of 8.25. In October, 1930, the death rate was o.34; based on 48 deaths and 7,576,000 tons.

Jan 1, 1930

By A. C. Rice

Aminopolyacetic acid chelating agents were added to separatory-funnel-scale solvent-extraction systems to determine the effect on separating rare-earth elements. Average values for separation factors between adjacent elements obtained with Primene JM-T2 increase 36 percent when EDTA is added to the aqueous phase. Adding HEDTA or DCTA also improves separation factors for certain rare-earth elements. Percentage of extraction and the separation factors exhibit marked sensitivity to concentrations of amine, chelating agent, and hydrogen ion. The chelating agents improved separation in Primene JM-T, BHDA, and Primene 81-R extraction systems.

Jan 1, 1963

By G. R. Hopkins

The petroleum-refining industry established a. new record in fuel effieciency at refineries in 1936, when 597,000 B. t. u. of heat mere required to refine a barrel of crude oil, compared with an average of 615,000 B. t. u. in 1935 (see fig. 1). The principal factor in the 'indicated gain in fuel efficiency at refineries in 1936 was an increase in crude runs of 11 percent over 1935. A large part of the heat utilized at refineries is consumed elsewhere than under stills, or in ways quite independent of crude-oil distillation. In other words, as the operating ratio ( crude runs divided by capacity) for re- fineries increases toward tine maximum of 100 percent, the fuel requirements show progressively smaller increases and the average B. t. u. consumption per barrel of crude refined declines.

Jan 1, 1938

By E. H. Denny

Colorado coal-mine fatalities, which have gradually decreased since 1914, have shown a marked decline since 1924. Data on coal-mine fatalities in Colorado published by the U. S. Bureau of Mines5 indicate that the deaths per thousand 300-day workers have decreased from 9.13 in 114 to 6.14 in 1926, and that the deaths per million tons produced have decreased from 9.18 in 1914 to 4.98 in 1926. Table 1 gives fatality rates in Colorado and in the United States from 1914 to 1926 inclusive. [ ]

Jan 1, 1929

By Phillip R. Moyle

In 1985 the U.S. Bureau of Mines evaluated the mineral resources of the Sheep Creek West Wilderness Study Area (ID-111-36A), Owyhee County, ID, for the U.S. Bureau of Land Management. The Wilderness Study Area consists of 11,680 acres centered approximately 20 miles south of Grasmere, 10. It contains no mines, claims, or prospects. No mineral resources were identified; however, a geode occurrence within and adjacent to the Wilderness Study Area, and minor amounts of placer gold along Sheep Creek, may be of interest to rorkhounds and recreational gold panners.

Jan 1, 1986

By C. M. Mason

The current Bureau of Mines active list of permissible explosives includes 95 brands. Twelve are gelatinous and the rest are the more commonly used granular ammonium nitrate type. The list of permissible blasting devices comprises five Cardox models.

Jan 1, 1968

By R. V. Ramani, W. Miola

"A relationship exists between the quartz contents in the underground coal nine airborne dust samples and those in the coal and host rocks that are mined [17, 18, 19] The prescribed method for quartz analysis in respirable airborne coal dust samples is the MSHA P-7 method. Accurate quartz analysis procedures are needed for bulk samples in order to predict the potential quartz content in airborne nine dust, which in turn will aid the design of quartz dust control procedures during mining. thereby reducing the airborne quartz dust in underground atmospheres. The requirements of this method are that the amount of quartz is the sample be less than 250ug, and the total sample weight less than 2,500 ug. Unlike with airborne dust samples, there are no limitations to the available mass of bulk samples. However, these are no standard procedures for the preparation of bulk samples for scanning or prescribed methods for quartz analysis. The NIOSH and MSHA methods are certified for roped* dust and the acceptance of these methods for bulk samples assumes that the bulk samples will be reduced to the conditions specified for respirable dust samples. An alternative method is X-ray diffraction, which provides higher average quartz values than those obtained from P-7 method for the same samples.An investigation was carried out to determine the optimal procedure for preparing the bulk samples for the IR and XRD analyses. In this paper, the investigations on the effects of calibration, particle sizes, matrix composition, interferrous, and behavior of the filter substances on IR, XRD and FTIR results are presented. The error introduced by the presence of kaolinite and a new sample asking procedure to reduce it are discussed. The problems experienced with conventional sample holders for scanning were eliminated with the design and development of a new hollow sample holder. Quantitative comparison of quartz determinations by IR, XRD and MR methods on coal, roof and floor rocks, and airborne dust samples are presented. The important factors affecting the results of quartz analysis methods are: 1) bulk sample preparation for obtaining representative and homogeneous analysis samples: 2) particle size distributions of the analysis samples and calibration standards; 3) qualitative matrix composition of the analysis sample; 4) matching calibration standards to analysis sample; 5) substrates for sample deposition during analysis sample preparation; 6) procedures for analysis sample mounting; 7) selection of proper portions of she response profile for insanity measurement; and 8) interferences of spurious phases with the critical analyses. The recommendations of this study are important to enable comparisons and interpretations of analysis and research results."

Nov 1, 1995

By Robert C. Johnson

Single crystal whiskers of ZrO2 and TiO2 were grown by solution and crystallization of these oxides in molten baths. Mixtures of Na2B407 and LiC1 were the most suitable growth media for zirconia. Sodium borate alone and Na2CO3 plus SiO2 were best suited for titania. The solubilities of zirconia and titania in molten sodium borate were determined, Whether zirconia whiskers were dendritic or nondendritic depended on the temperature used. The best single crystal whiskers were grown below 1,100° C. Titania whiskers always grew as single crystals. The tensile strengths of zirconia and titania whiskers were about 15,000 psi and 50,000 psi, respectively. Modulus of rupture was about 49,000 psi for zirconia whiskers and 75,000 psi for titania whiskers. Chemical analyses showed the zirconia and titania whiskers to be pure. The zirconia and titania whiskers were shown by X-ray analysis to be, respectively, baddeleyite and rutile.

Jan 1, 1965

By Emery Chilton, Charles Taylor, Mark Senk, Linda McWilliams

Three-axis ultrasonic anemometers are used to study airflow in the NIOSH ventilation gallery where ventilation in an underground mine is simulated. In this study, performance characteristics of this anemometer are evaluated and the effects of sensor orientation and sampler location on flow readings are examined. The study results provide guidelines for more effective use of the ultrasonic anemometers in the ventilation gallery.