Search Documents

By P. M. Ambrose

This report describes an accident, which took place in the Chemical Corrosion Laboratory at the College Park, Md., Station of the Federal Bureau of Mines. The accident occurred while Walter L. Acherman, chemist, was performing a routine manipulation during a corrosion experiment involving commercially pure titanium and red-fuming nitric acid. There was a sudden and very violent reaction, and a large quantity of acid was thrown in the face and over the body of Acherman, causing serious injury. L. B. Golden, chief of the Chemical Corrosion Section, was exposed to nitric acid fumes during the ensuing rescue and first-aid operations and died on January 25, 1954. According to the medical report, the direct cause of Mr. Golden's death was pulmonary edema and confluent bronchopneumonia; the contributary cause, was inhalation of fumes from red fuming nitric acid. The following employees of the College Park Station contributed to this report by supplying information on the accident and assisted in the rescue operation: L. B. Golden, chief, Chemical Corrosion Section; T. E. Green, chemist; Robert Warf field, chemist; L. A. DeVivo, laboratory mechanic; D. W. Chalkley, laboratory mechanic; E. H. Neagle, laboratory welder; and R. L. Heath, laboratory general mechanic.

Jan 1, 1955

By Wallace E. Anable

This investigation by the Bureau of Mines was conducted chiefly on Cuban serpentine nickeliferous ores to determine whether these materials would be amenable to direct carbothermic reduction in an electric furnace to produce a low-carbon ferro-nickel. The project was carried out as one of several under a Memorandum of Agreement between the Bureau of Mines and the General Services Administration (Contract GS-OO-B (D)-152l). Two ore samples were received for this investigation. One was a mixture of nickeliferous serpentine from the North Ocujal, South Ocujal, and San Juan claims of the Nicaro Nickel Co. The other sample was a mixture of material from the Ramona and the Lorna Mulo claims of the Cuban Nickel Co. Most of the ore from the Ocujal-San Juan deposits and about 40 percent of the sample from the Ramona-Lorna Mulo deposits were calcined before smelting. The remainder of the sample from the Ramona-Loma Mulo deposits was smelted after drying to about 8 percent moisture. An arc-resistance, selective-reduction smelting technique was employed in these tests. Either bagasse alone or a mixture of bagasse and coke was used for reductants. No flux was used in the furnace charges.

Jan 1, 1957

By C. C. Hwang

The Bureau of Mines made time-dependent calculations to determine the size of a stationary source fire within a ventilated duct (or passage-way) necessary to ignite a combustible duct liner. The objective of this work was to gain more understanding of what occurs in duct fires and to determine critical conditions for ignition and propagation of mine fires. Heat transfer to the combustible surface includes both convective and radiated components, while the heat is conducted into the combustible and reradiated to the surroundings. The combustible is assumed to ignite when the net heat transfer to its surface is sufficient to raise the surface temperature to some minimum temperature, defined as the ignition temperature. A nondimensional parameter, which characterizes the source-fire intensity in the presence of ventilation flow, emerges as a parameter for a criterion of the critical conditions. The results of these calculations indicated that the minimum fire size necessary for ignition increases with the ventilation rate and duct cross section. These results are compared with experimental results obtained from fires in a 0.8-by 0.8-by Il-m-long duct and a full-scale gallery (2.4-by 2.4-by 65-m). Agreement between the theory and the experiment is good.

Jan 1, 1988

By J. D. Spagnola

The Bureau of Mines conducted research to obtain comparative data on the extent of reduction of galena and sphalerite with molecular hydrogen and with hydrogen from the thermal cracking of ammonia and methane at various time intervals. Galena reductions of 95 to 99 percent were obtained with H2 and with decomposed NH3 while reductions of 70 to 80 percent were obtained with cracked CH4? Sphalerite reductions of 99 percent were obtained at 1,000° C with Hz and with decomposed NBs; however, complete volatilization of the free zinc from the remaining concentrate and the subsequent recombination of zinc and sulfur vapors resulted. A promoted iron catalyst brought about a decrease of 100° C in the temperature required for complete decomposition of ammonia. It was found that H2S retards NB3 decomposition and that nitrogen retards the reduction of galena by H2? A mixture of N2 and He in about the same ratio as that obtained by the thermal cracking of NBs gave about 15 percent less reduction of galena than was obtained with decomposed NB3; this indicates that a portion of the hydrogen obtained by NBs decomposition is in an active form.

Jan 1, 1965

By N. S. Dalal, X. Shi

It has been known for more than a decade that vanadium (V) stimulates the oxidation of NADH by plasma membranes (1) but the underlying mechanism is still not fully understood. This effect has been attributed to a membrane-associated NADH-dependent vanadium (V) oxidoreductase (1). Subsequent studies suggest that vanadium ( V) can accept an electron from fiavoprotein dehydrogenase that oxidizes NADH (2). The phenomenon ofNAD(P)H oxidation coupled to vanadium(V) reduction has also been demonstrated in other biological systems (3-6). A recent electron spin resonance (ESR) study from our laboratory reported on the accumulation of vanadium (IV) duringthe reduction ofvanadate (vanadium(V)) by the ftavoenzymes glutathione reductase (GSSG-R),4 lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase in the presence of NAD(P)H (7). It was concluded therein (7) that these ftavoenzymes function as NAD(P)H-dependent vanadium(V) reductases. More recently, however, Liochev and Fridovich (8) have argued that the ESR data (7) do not demonstrate that the investigated fiavoenzymes act as vanadate reductases. They suggest an alternative mechanism in which the fiavoenzyme simply serves as a generator ofsuperoxide (02) radical, which acts as a propagator of the radical chain reaction leading to NAD(P)H oxidation (9, 10), as summarized below:

Nov 1, 1995

By F. Garcia, J. Cervik

Recent advances in the commercial separation of gases using membranes have renewed interest in the possibility of applying this technology to the recovery of methane ( CH4 ) from mining operations . This Bureau of Mines report briefly reviews the history of the development of membranes for gas separation , the theory of how they work , and their application to the separation of methane from air and associated problems . However , methane -air mixtures are difficult to separate with membranes because the pertinent gas couples , 02 - N2 , 02 - CH4 , and N2 -CH4 , have poor separation characteristics , as indicated by their separation factors of about 3 or less . Even if these separation factors were substantially higher , there is doubt that methane could be recovered economically from the low concentrations in mine ventilation exhaust ( 2 vol pct or less ) . The exhaust pressures are not sufficient for adequate separation . The power cost of compressing the methane recovered . these mixtures would far exceed the value of New discoveries could make separation of gob hole methane - air mixtures practical . These mixtures have much higher concentrations of methane (from 30 to 100 vol pct ) ; however , for safety reasons , be limited to gob gas with 60 vol pct CH4 or more .

Jan 1, 1988

By R. S. Dean

A large metallurgical experiment station at Salt Lake City to house the works of the Bureau of Mines in the intermountain area properly has long been projected. It finally became possible when a Public Works Allotment of $300,000 was set aside for building and equipment. With the new building assured, the Bureau of Mines decided to move the headquarters of its Metallurgical Division from Washington, D. C., to Salt Lake City, Utah. It was felt that this move would simplify they administrative work of the chief engineer of the division, as all stations devoted primarily to metallurgical work are west of the Mississippi. These include Rolla, Mo.; Minneapolis, Minn.; Pullman, Wash.; Reno, Nev.; Berkeley, Calif.; Boulder City, Nev.; and Tucson, Ariz. In addition to these stations will groups, of investigators working on metallurgical problem, are maintained at Pittsburgh, Pa., and College Park, Md. Salt Like City was clearly a more central point for the direction of this scattered work than Washington, D. C. The building (fig. 1, A and B) was designed from general plans worked out by the authors of this paper. Contraction was begun in March of 1939, and by the end of the year the Metallurgical Division had moved, into its now quarters.

Jan 1, 1940

By D. K. Deardorff, Laurance L. Oden, H. Kato, M. I. Copeland

The equilibrium relationship of hafnium and tantalum was studied to facilitate alloy and property investigations . The data obtained are presented graphically as the equilibrium diagram . Alloys were prepared from high - purity components by nonconsumabletungsten- electrode arc melting . Data for the equilibrium diagram were obtained by optical pyrometry , metallography , X- ray diffraction of heat treated specimens , X- ray diffraction using a high- temperature camera , and differential thermal analysis . During the investigations , a casting apparatus was constructed , and the existing melting - point apparatus was improved . The bcc allotrope of hafnium forms a continuous series of solid solutions , called beta , with tantalum which exhibit a minimum melting point at 20 wt pct tantalum and 2,110 ° C. At 24 wt pct tantalum and 1,050 ° C , hafnium- rich beta decomposes in a monotectoid reaction to yield alpha and tantalum- rich beta . The monotectoid isotherm extends from 5.5 to 60 wt pct tantalum . The twophase region , in which hafnium- rich and tantalum- rich beta solid solutions are immiscible , rises to a maximum temperature of 1,265 ° C at 38 wt pct tantalum . The solubility of hafnium in tantalum decreases from 40 wt pct at the monotectoid temperature to 20 wt pct at 750 ° C.

Jan 1, 1964

By George S. Rice, J. W. Paull, R. R. Sayers

"Standard rock dust for use in the rock dusting of coal mines might be defined tentatively as powdered mineral, light colored and free of carbonaceous matter and free silica, all of which will pass a 20-mesh screen while 50% of it will pass-through a 200-mesh screen.Such dust may be prepared from limestone, gypsum, anhydrite, or shale free of sand and flint. For the initial rock dusting of the average nongaseous bituminous mines enough standard rock dust should be applied so that the combustible content of the resulting mixture of rook dust with mine dust shall not exceed 45%, a range somewhere between 35% end 45% being the practical objective sought.All entries, slopes or passageways and room necks should be rock dusted.Additional safeguards are:a.,Rockdusting roomsb.,Scattering of dust in vicinity of shots before firing.c.,Placing of barriers in the mouths of panels, cross-entries and other key positions.Redusting becomes necessary whenever the combustible content of the mine dust exceeds the permissible maximum. This should be determined by regular, systematic sampling, followed by a simple analysis of the samples for combustible content. A Bureau of Mines volumeter for measuring the density can be used for the determination of combustible content."

May 1, 1924

By Ellsworth Spencer

Noise induced hearing loss continues to afflict workers in many occupational settings despite longstanding recognition of the problems and well-known methods of prevention and regulations. Sound levels associated with heavy construction equipment range from 80 to 120 dB(A) and power tools commonly used in construction produce sound levels up to 115 dB(A).(1) The focus of this research was to determine the noise exposures of heavy construction equipment operators while documenting the workers’ tasks, (i.e. hauling, moving, and/or pushing construction material). Time-motion studies were performed at the construction sites and were used to correlate the noise dosage with the work performed by equipment operators. The cumulative dose for the operator was then plotted with references to work tasks, to identify the tasks that caused the greatest noise exposure. Three construction sites were studied for this research located in the western Pennsylvania and eastern Ohio areas. The types of construction equipment studied included asphalt pavers, backhoes, bulldozers, compaction equipment, excavators, haul trucks, telehandlers, and wheeled loaders. The results showed that bulldozer operators consistently had the highest noise exposures, ranging from a NIOSH REL (Recommended Exposure Limit) dose of 844% to 25,836% and an OSHA PEL (Permissible Exposure Limit) dose of 139% to 1,397%.

By R. S. Dean

The principle of explosive crushing depends upon the fact that an expandable substance contained within the pores of a solid body will disrupt such a body upon expansion. Such expansion may be obtained by the detonation of an explosive or by the sudden release of pressure of a superheated liquid. That this principle of disruption may be applied to minerals rests on the fact that cracks, cleavage planes, and pores exist in all mineral to an extent hardly conceived possible heretofore. Crushing by this method takes advantage of force applied from within the mineral rather than from forces applied from without. The application of a force from within would appear to be more effective. A consideration of the possibilities of such a method for crushing led to some experimental work of a preliminary nature, the results of which are embodied in this paper. No systematic program was followed in the work and the results are, therefore, not final and far from complete. The success attained so far, with the mediocre apparatus available seems to warrant a preliminary report, with the expressed hope that the work may be carried on as well-outline program covering such phases as have been impossible to investigate at this time.

Jan 1, 1931

By S. M. Shelton, J. B. Zadea, M. M. Fine, T. L. Johnston

"INTRODUCTION The Mayfield manganese property is about 25 miles south of Van Horn, in Jeff Davis County, Tex. The ore deposit is developed by a large open-cut and a small stope.An 8-ton sample was received for testing; it was taker at random from material on the mine dumps and consisted of a mixture of manganese oxides, barite, and siliceous gangue minerals. The manganese occurred largely as hard, massive, crystalline psilomelane, with a small amount of pyrolusite. The gangue minerals consisted of intermixed iron-stained sand stone, quartzite, chalcedony, calcite, quartz, and barite. Chemical analysis showed 8.9 percent manganese, 3.3 percent iron, 38.4 percent silica, 6.6 percent calcium carbonate, 7.1 percent barium, 3.1 percent alumina, 0.09 percent phosphorus 0.01 tungstic oxide, and less than 0.05 percentAnalysis of selected clean pieces of manganese minerals, free of gangue, showed 48.1 percent manganese end 13.4 percent barium, of which only 0.2 percent was present as barium sulfate. This indicated a limit in concentration. Barium was also present in the gangue as a separate mineral, barite (BaSO4), which has approximately the same specific gravity as the manganese oxide."

Apr 1, 1942

By E. G. King

THIRD-LAW entropy data for zirconium-containing compounds are sparse. Kelley a lists entropies at 298° K. for the oxide, tetrachloride, nitride, and silicate, as well as for the metal. The present paper presents heat capacities between 51° and 298° K. and entropies at 298.15° K. for the zirconates of the alkaline-earth metals-calcium, strontium, and barium. The authors believe magnesium zirconate does not exist as a stable compound at room temperature. Entropies of formation from the constituent oxides also are given. MATERIALS The materials used in this investigation were synthesized and analyzed in the Berkeley Laboratory of the Bureau of Mines. Calcium zirconate was prepared by heating an intimate mixture of reagent-grade calcium carbonate and pure zirconia for 30 hours between 1,200° and 1,300° C. and for 32 hours between 1,400° and 1,500° C. As part of the heating schedule, the sample was ground and mixed seven times. Periodic analyses and minor adjustments of composition were made. Analysis of the final product gave 31.19 percent calcium oxide (theoretically 31.28 percent) and 68.67 percent zirconia (theoretically 68.72 percent). The X-ray diffraction pattern agreed with that in the ASTM catalog.

Jan 1, 1960

By L. D. Gehi, A. W. Khair, M. Ahmad

"Bit wear presents problems to mining operations because it affects both productivity and economics. Most bit research deals with energy requirements and energy dissipation mechanics for ideal fragmentation during the cutting process.Mechanical cutting leads to dust generation. Past studies involving dust generation due to bit wear concluded that dust concentrations increased considerably after a 7% bit weight loss: leading researchers recommend that the bits be changed at that point.Bit wear is affected by three factors: machine operating parameters in-situ mining conditions and rock properties. Operating parameters such as the depth of cut tool material spray position and the drum's rotating velocity are very important and have a definite impact on bit wear.During the mining process the amount of rock in coal and the strength of that rock is important as abrasion and adhesion take affect. Diffusive wear or deformation becomes dominant only when the temperatures exceed critical. Temperatures rise as a function of drum velocity rock properties and the cutting tool itself.Miner bit surveyIn this study, 15 mines were surveyed, and of those six responded for nine seams. The survey reflected a wide range of information about coal production and bit consumption from continuous miner sections. Also used bits were collected to get first-hand information to analyze wear."

Nov 1, 1995

By David F. Smith

The American Society for Testing Materials4 has recommended that the melting temperature of potassium chromate be used-for indicating the temperature to which a coal sample should be heated in the standard method of analysis to determine its volatile matter content. The specified temperature is 950± 20° C., the melting point of potassium chromate being noted as 940° C. Le Chatelier5 originally found the melting point to be 975°; later6 he found 9400. According to Shemtschushny7 the melting point is 984°; he also found a transition at 679°. Groschuff8 found the melting point to be 971° and the transition temperature 679°. Amadori9 reports a melting point of 9.78° and a transition point of 666°. The International Critical Tables10 take the melting point as 975°, which is estimated to be correct to two significant figures. In view of the apparent uncertainty existing, it has been though worthwhile to make a careful redetermination of this datum. It is of interest not only to determine the melting point of the pure salt, but also of the commercial product, in order to test its suitability for use as a temperature indicator. The work was suggested by A. C. Fieldner, chief engineer, experiment stations division, U. S. Bureau of Mines.

Jan 1, 1929

By Kenneth H. Johnston

Information and data necessary for research on improving methods of oil recovery from low-permeability reservoirs and for comparison and evaluation of performance of such reservoirs with those producing from more permeable sands were obtained. Core analyses, well logs, production tests, well stimulation techniques, primary and secondary production records, and data on two water-flood projects were examined for wells producing from the Bartlesville sand, West Avant field, Osage County, Okla. Overall recovery from the study area was generally poor with only 9.0 percent of the pore volume recovered to January 1, 1968. Larger fracture treatments (8,000 to 12,000 gal) could have resulted in an increase in primary oil recovery. Secondary recovery by water-flooding accounted for only 1.9 percent of the pore volume because of the inability to control the large volume of injection fluid that escaped from the flood patterns and the excessive volumes of water produced with the oil. Future waterflood development in other low-permeability reservoirs should include the drilling of new input wells, use of injectivity surveys to locate possible natural fracture systems, or zones of high permeability, and control of injection fluids by altering flood patterns and/or plugging of the more permeable zones.

Jan 1, 1968

By J. Dean Warner

In 1984, as part of a project to evaluate Alaskan occurrences of certain critical and strategic minerals, the Bureau of Mines investigated a columbium-bearing regolith on upper Idaho Gulch, near Tofty, AK. The regolith is derived from weathering of a dolomitic marble and consists mostly of iron oxide minerals with accessory apatite, zircon, xenotime, rutile, monazite, and the columbium minerals aeschynite, columbite, and ilmenorutile. Two regolith lenses contain 340,000 lb of columbium resources at an average grade of 0.07 pct. Calculated composite concentrates from two regolith samples (approximately 200 lb each) contained 53 and 57 pct of the columbium at grades of 0.97 and 0.86 pct, respectively. In each case the grade could be improved to 1.1 pct Cb with a sacrifice of 9-pct recovery. The regolith's mineralogy, trace-element geochemistry, and similarity to descriptions of other columbium-enriched regoliths suggest that the underlying marble may be a carbonatite. The lack of associated alkalic igneous rocks and the stratiform nature of the regolith, however, may be interpreted as evidence for sedimentary origin of the marble. The marble and regolith are a lode source for some of the minerals in the Idaho Gulch placer deposit.

Jan 1, 1986

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

D.2 Principal Types of Coating A Sodium Silicate Sodium silicate is a good fire retarder when freshly applied, but it loses its effectiveness if the relative humidity is at all high, thus exposure to a relative humidity exceeding 65 percent causes a serious decrease in the effectiveness after only one month. In fire, sodium silicate swells to a frothy mass (intumescence) which hardens and insulates the wood against heat. This property is destroyed by exposure to moisture. Manufacturers of many of the proprietary paints containing silicates state that their products have overcome this difficulty The reagent may be applied alone, or, better, in a mixture with lime-water and common salt, or with inert fillers such as kaolin or asbestos. B Ammonium Phosphate Strong solutions (25 to 35 percent) of monammonium phosphate or diammonium phosphate give good protection. Two or three coats of hot solution should be applied either with a large flat brush or an ordinary paint spray gun The solution should be applied as hot as possible, as this improved penetration, and it should be the aim of the operator to apply 4 lbs of reagent, i e , one gallon of 33 percent solution to every 100 square feet of surface

Jan 1, 1976

By Jr. Dubaniewicz, Gregory M. Green, Kenneth L. Cashdollar

Laser-based instruments are used in areas where coal dust ignition presents a safety hazard. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory ~NIOSH, PRL! is conducting a study to help determine when an optical beam may be considered a potential ignition source in underground coal mines or coal storage facilities. Researchers conducted experiments to determine threshold igniting powers for Pittsburgh seam bituminous coal dust clouds using an 803 nm continuous wave laser. For fine sized coal dust dispersed in air, concentrations ranging from 600 to 2000 g/m3 were the most easily ignited. A heated layer of coal dust that deposited on the fiber tip during dispersion ignited the dust clouds. Minimum observed igniting powers for laser beams delivered by 200, 400, and 800 mm core fiber optic cables and directed into coal dust clouds were 2.0, 3.0, and 5.0 W, respectively. Threshold igniting power was proportional to beam diameter, and threshold igniting power density decreased with larger fiber diameters. Ignition delay times averaged 0.6 s and did not vary significantly with laser power under initially turbulent test conditions and with flammable targets. Comparisons are made with the results of other researchers.

By Peter G. Kovalchik, Lawrence W. Scott, Thomas H. Dubaniewicz, Frank T. Duda

Overheating of electric cables on shuttle cars has long been recognized as a cause of premature insulation failure leading to shock and electrocution. Use of cable reels on shuttle cars can cause excessive heat build up which, in turn, causes the cable insulation to soften and become easily damaged This heat-softened insulation reduces the life of the cable. Repeated cycling of a cable in this manner can cause premature aging of the insulation; it becomes bridle, cracks and allows electrical leakage paths to farm. These leakage paths provide the opportunity for shock and electrocution to occur if miners come in contact with the damaged section of cable. It is imperative that cable operating temperatures be maintained at safe thermal limits. This paper discusses a research project conducted by the National Institute for Occupational Safety and Health, Pittsburgh Research Center to determine dynamically the conductor temperature of reeled shuttle car cables using fiber optics technology. The research portrays typical shuttle car loading cycles (both current and time cycles). Root-mean-square current loading is calculated based on the results. The thrust of this effort is to provide the scientific basis for ampacity derating factors specifically for mine machinery using reeled cables This information will reduce the probability of electrical hazards from reeled cables