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By Robert E. Barieau

General expressions for evaluating various thermodynamic properties applicable to the van der Waals equation of state have been derived. These formulas were subsequently used to evaluate various thermodynamic functions in the two-phase region. The results indicate that, for a van der Waals fluid, there is a finite discontinuity in the second derivative of the vapor pressure curve, in the second derivative of the chemical potential or Gibbs free energy at the critical point, and in the heat capacity at constant volume measured at the critical density. Numerical values are tabulated and graphs are presented for all functions calculated.

Jan 1, 1967

By LeRoy D. Loy

The disposal of excess overburden from surface mining can be accomplished by use of a reclamation technique entitled head-of-hollow or valley fill. This report attempts to assess current valley fill regulations and practices, identifies inherent benefits and deficiencies, and develops concepts to enhance fill technology.

Jan 1, 1978

By E. H. Rose

This paper, describing the concentrator practice of the Moctezuma Copper Co., is one of a series being prepared by the Bureau of Mines. The Nacozari concentrator of the Moctezuma Copper Co. (the Mexican subsidiary of the Phelps Dodge Corporation) is located about 75 miles south of Douglas, Ariz., in the Moctezuma District of the State of Sonora. Nacozari is the southern terminus of the Nacozari Railroad, ever which all concentrate is transported to Douglas for smelting.

Jan 1, 1930

By M. Copeland

Phase relations of gadolinium alloyed, up to 40 weight-percent (wt pct), with AISI 304-type stainless steel were established. Body-and face-centered cubic iron-rich solid solution phases and several intermetallic gadolinium-containing compounds of variable composition that approximated the formulas Fe9Gd, Ni7Gd2, Ni3Gd, Fe2Gd, NiGd, and NiGd3 were identified. The intermetallic phases Fe9Gd and Ni7Gd2 were noted to melt at about 1,080° C at about 0 to 2 wt pct gadolinium. The melting temperature of Fe9Gd increased with increas-ing gadolinium content to a plateau at about 1,230°C and 30 wt pct gadolinium, and the melting point of Ni7Gd2 decreased to a plateau at 900° C and 30 wt pct gadolinium where Ni3Gd, NiGd, and Fe2Gd coexist. Body-centered cubic iron solid solution was stable from 1 to 2 wt pct gadolinium to higher contents, 30 wt pct gadolinium or possibly more, and face-centered cubic iron up to 12 wt pct gadolinium below 1,200° C. The stability of these phases above 1,200° C was not resolved except for the mel points. A limited number of fabrication variables as well as mechanical and corrosion properties of alloys containing up to 5 wt pct gadolinium were studied. Equilibrating and forming operations were best conducted at about 940° to 1,080° C. Some variability in the yield and tensile strengths of alloys was noted; however, there was a continual decrease in ductility and impact resistance with increasing gadolinium contents. The resistance of gadolinium alloys to corrosion in water at 354° C was about the same as stainless steel.

Jan 1, 1965

By D. G. Kuehn

Studies were conducted by the Bureau of Mines to determine the positive ions and neutral species produced in glow discharges of gas streams containing 1.0 percent NO in helium, 29 percent dry air in helium, and 1.06 percent NO in N2, Mass spectrographic measurements were conducted for gas pressures from 2.3 to 10.0 torr and dc currents from 10 to 20 mAo Ion species observed included NO+, N2 +, O2 +, N+, and 0+ with lesser amounts of He+, He2+, and N02+. Variations in various ionic and neutral species with discharge duration were interpreted to be consistent with an electrically induced dissociation of NO to produce N2 and O2. No nitrogen oxides were observed to form in glow discharges of the helium-air mixture.

Jan 1, 1975

By A. J. Kraemer

This report on the physical and chemical properties of crude oils of California is one of a series on the producing districts of the United States. It includes a short discussion of results, tabulated data, and individual analyses of California crudes. Analyses of crude oils from the fields of Fresno, Kern, Los Angeles, Orange, and Ventura Counties have been published in Serials 25952 and 26083. The analyses reported in this paper corer samples that were obtained subsequent to the publication of Serials 2535 and 2608. The samples were obtained by members of the San Francisco office of the Bureau of Mines. The collecting of samples was facilitated by the courtesy of representatives of oil companies in California.

Jan 1, 1927

By J. D. Sargent

Selenium might be described as a paradoxical element, being either a metal or a nonmetal, a conductor or nonconductor, amorphous or crystalline, colorant or decolorant, and a hydrogenator or dehydrogenator. Selenium was discovered in 1817 by the Swedish chemist, Berzelius, while studying flue dust from the lead chambers of the sulfuric acid works at Gripsholm, Sweden, The ordinary stable form of selenium is a crystalline, grayish solid with semi-metallic luster. It melts at 217° C., boils at 684.8° C., and has a density of 4.79.

Jan 1, 1955

By Martin Hertzberg

In this Bureau of Mines study, an equation is derived for the limit burning velocity for divergent, spherical propagation from an ignition kernel of radius, r: (Su)e = ( ) . For flame propagation into a preexisting, stretching velocity gradient of magnitude dv/dx, the limit velocity is (Su)e = (a dv/dx)1/2. These formulations are shown to be equivalent to the fluid dynamic concepts of Damkoh1er, Kar10-vitz, and Markstein. Existing data for the b10woff limits of flames are shown to give excellent agreement with those concepts provided that proper account is taken of two dilution effects: composition dilution caused by entrainment and velocity gradient dilution caused by flow expansion. Approximate flow-field solutions are also derived for the unburned gas motion above an upward propagating, spherical flame kernel in buoyancy-induced flows. It is shown that;, the upward hemisphere propagates toward a stagnation plane in a counterflow configuration involving the balance between the combustion force, which accelerates the cold gas upward, and the buoyancy force that accelerates the cold gas downward. The position of the stagnation plane above the upward propagating hemisphere is related to the ratio of the buoyant velocity, vb, to the burning velocity, Suo Extinction of the upward propagating wave occurs by flame stretch in that counterflow configuration when n = Vb/Su begins to exceed the expansion ratio, Pu/Pb' and the wave is blown off by its own buoyancy-induced flow field.

Jan 1, 1984

By Michael Rieber

Rail cars are referred to as "yellow-balled" when they are sufficiently old or damaged to preclude their efficient operation on long-haul or main line routes. For most coal carrying railroads, their alternative value is salvage. This, however, does not necessarily preclude their effective use, on a limited basis, by small mines located near existing trackage. Because of age, the sizes of these hopper and gondola cars ace currently 50 and 70 tons rather than the 100 tons commonly built at the present time. As a gathering system, yellow-ball rail could provide an alternative, particularly in Kentucky, western Pennsylvania and west Virginia, to coal trucks, conveyor belts and pneumatic pipelines [4, p.17], belts and pneumatic pipelines. Rail service of this type provides a limited alternative to track abondonment, a possible financial return to a railbank [3], a direct contribution to service demand on main lines, and a means by which many small eastern coal mines could retain or regain competitive viability [4]. In terms of energy efficiency, compared to trucking coal, the total direct energy impact (fuel) of yellow-ball rail can be expected to range from 280-990 Btu/ton-mile while that for trucks ranges from 1850-3120 Btu/ton-mile [2].

Jan 1, 1977

By Xintan Chang

MFIRE is a computer simulation program that performs normal ventilation network planning calculations and dynamic transient-state simulation of ventilation networks under a variety of conditions. The program is useful for the analysis of ventilation networks under the influence of natural ventilation, fans, fires, or any combination of these. MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters such as the development of new mine workings or changes in ventilation control structures, external influences (varying outside temperatures), and internal influences (fires). Extensive output enables detailed, quantitative analysis of the effects that the alteration will cause to the ventilation system. The program was developed at Michigan Technological University (MTU), Houghton, MI, with support from the Bureau of Mines. A personal computer (PC) version of the program was completed under contract for the Bureau by MTU. The purpose of this report is to document the installation and use of the PC version of the program MFIRE.

Jan 1, 1990

By R. E. Gray

[The purpose of the study is to investigate cases of subsidence over abandoned mined-out areas of the Pittsburgh Coal identified from published and unpublished sources and to determine through a consideration of the geology, topography, climate, mining activity, and evidence at ground surface, what mechanisms control subsidence .and under what circumstances it takes place. The study wan performed it two phases, the first to identify all documented incidents of subsidence in mined-out areas of the Pittsburgh coal Region; and the second, to study a particular portion of the region in detail, collecting pertinent data relative to the sites within, characterizing roil the nature of the subsidence and its economic consequences, and determining the applicability of the findings to other areas whore similar problems with the collapse of abandoned miner have been encountered.]

Jan 1, 1977

By R. E. Hershey

1. Reserves were estimated for three coal beds: Lantana, Sewanee, and Richland. 2. Known measured and indicated reserves for all beds, based on a minimum thickness of 14 inches and on 1,800 tons per acre-foot of coal in place, are estimated at 34 million short tons as of Januray 1, 1954. Of this total, 15 million short tons represents coal 28 inches and more thick. Areas in the beds were omitted from the estimate because available data relative to the bed characteristics were insufficient to permit making an estimate conforming with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves determined by this investigation.

Jan 1, 1956

By Davis E. Traut

TiC14, AIC13, and VC14 were coreduced simultaneously via a Kroll-type magnesium reduction to form an alloy sponge as part of a research effort by the Bureau of Mines to produce titanium alloy powder. Reduction tem-peratures of 750°, 850°, and 950° C, a range of chloride feed rates from 34 to 152 Ib/(ft2·h), and crucible diameters of 7-3/4 and 10-1/4 in were tested. Microprobe analyses using a 40-um-diam spot showed no effect on alloy microhomogeneity (distribution of Al and V in the Ti, considered critical as a powder property), due to changes in process variables within these ranges. Statistical analysis of these data for alloy sponge indicated greater variation in the chemical composition (AI and V) than that found in commercial Ti-6Al-4V plate or Plasma Rotating Electrode Process (PREP) powder. Therefore, a one-step approach to pow-der, such as grinding the Ti alloy sponge, would not produce a powder product of acceptable chemical homogeneity. An approach that homoge-nized the sponge, such as with a melting step, would produce an accept-able powder product with respect to chemical homogeneity.

Jan 1, 1987

By G. H. Martindill

Complex chemical and physical changes occurring during carbonization result in a heterogeneous system composed of gaseous, liquid, and solid phases, whose relative proportions and chemical compositions change constantly as temperature increases. Studies in which the participating variables are isolated and controlled should be useful in formulating the mechanism of coal carbonization. The most characteristic property of a coking coal is its ability to form a plastic mass at a certain stage of the carbonization process. During this period it is believed that fluidity of the coal influences the properties of the resultant coke. This report gives results of an investigation by the Federal Bureau of Mines of the influence of the maximum fluidity attained by the charge on the physical quality of the coke or char produced. As a first approach to the problem, researchers investigated high-melting-point pitches, which are relatively simple carbonaceous materials. The plastic properties of these pitches, prepared specially for this work, varied greatly; their fluidities, as measured by the Gieseler plastometer, covered most of the fluidity range characteristic of coking coals. Blending these pitches with increasing pro-portions of fine coke progressively reduced their fluidities. Coal-pitch and coal-coke blends also were treated; their fluidities were varied by changing their blending ratios. The various blends were carbonized in a small-scale carbonizer and the resistance of the carbonized residue (char) to abrasion was determined in a small-scale tumbler test, using the Roga drum.

Jan 1, 1960

By Geoffrey C. Huggins

Diagnostic: tests were performed on a production ST-5A Load-Haul-Dump machine manufactured by Wagner Mining Machinery Company to evaluate and rank order noise sources. The diagnostic evaluation indicated that the major noise sources were the transmission, the engine, and the cooling fan. This phase was followed by implementation of recommended noise control treatments, which included vibration isolation of the transmission, a transmission enclosure, an engine enclosure, and modifications of the inlet to the cooling fan. The final step in the program was an underground operational period which began on 31 August 1976 at the National Gypsum Mine in Shoals, Indiana. The noise control treatments successfully reduced the LHD operator noise exposure by 7 dB(A), thus increasing its allowable operation time by a factor of 2.7. Actual measurements made underground using noise dosimeters have indicated that, during, a typical shift, the noise control treatments have reduced the fractional exposure to an allowable level. The report discusses the mechanical aspects of the LHD, its noise sources, the treatments applied, the final levels achieved, and field experience with the noise-controlled machine.

Jan 1, 1977

By J. P. Hansen

Reducibility tests were run by the Bureau of Mines on an open hearth lump ore and four groups of pellets whose smelting characteristics had been deter-mined previously in the Bureau's experimental blast furnace. When reduction data from various tests were plotted on specially prepared paper l-(l-percent reduction/100)1/3 against time, the plots were linear. The iron-wustite inter-face therefore advances at a constant rate. The rate of the interface advance in mm/min was used as a reducibility index. The reducibility index measured at 900° C, using 0.45 cu ft hydrogen per minute varied inversely with the surface area of the sample. Even with carefully controlled surface areas, how-ever, duplicate reducibility indices varied considerably. When enough tests were run to give a stable mean, the mean reducibility index did correlate with blast furnace production for the four pellet groups. Results indicated that if the interface speed itself were to be used for correlation with blast furnace production, a sample size of about 180 grams of minus 0.742-plus 0.525-inch particles should be used with a test temperature of 900° C and a flow of 0.45 cu ft hydrogen per minute.

Jan 1, 1966

By R. E. Head

[Recent investigations at the Intermountain Experiment Station of the Bureau of Mines at Salt Lake City indicate that metallurgists have given little attention to the occurrence of jarosite minerals in the oxidized ores of lead and silver. These investigations have also emphasized the importance of lowing when these minerals occur in the oxidized ores, especially those containing lead, silver, and gold, as their presence is a material factor in selecting a suitable kind of treatment. Since the question of the occurrence of jarosites in oxidized ores has come to the attention of the Bureau of Mines, investigation has indicated that plumbojarosite and argentojarosite are quite common. These two minerals appear to be widely distributed and probably escaped recognition by persons who had attempted to treat certain oxidized lead ores in which the jarosite minerals represented a material portion of the metal content. Consideration of the physical characteristics of the jarosites also indicates that in many cases failure to treat some of the oxidized lead ores with success has been directly due to the fact that the greater portion of their lead and silver content was present as plumbojarosite and argentojarosite. The data and the description of these minerals given in the body of this paper indicate that attempts to recover lead and silver from ores in which appreciable amounts of too metals occur is plumbojarosite and. argentojarosite would be unsuccessful if confined to gravity methods of concentration. There are undoubtedly considerable tonnage of oxidize lead ores in the various mining regions of this and other countries, and it is quite probable tat in some of these ores the metal content of lead and silver may be largely anglesite (lead sulphate) and cerussite (lead carbonate) but that they will also contain cerargyrite (silver chloride), argentojarosite, and plumbojarosite. The treatment of such ores therefore presents an important problem, since a product is discarded from]

Jan 1, 1928

By G. L. Hundley

The Bureau of Mines has devised a procedure to recover chromium chemicals from concentrates derived from low-grade domestic chromites. These domestic chromites contain silicon and aluminum impurities at levels that are too high to permit processing by present industrial processes. The Bureau procedure consists of reacting chromite with molten NaOH under oxidizing conditions to form sodium chromate (Na2Cr04)' The reaction product is leached with methanol to recover the majority of the unreacted NaOH, then with water to extract the Na2Cr04 and the remainder of the NaOH. The Na2Cr04 product is recovered by evaporative crystallization from the aqueous solution. This report presents laboratory results of studies to determine the optimum leaching conditions for the reaction products of several domestic chromite concentrates. Results of solution purification and crystallization studies are also presented. The concentrates are from a variety of sources including the Stillwater Complex in Montana, Red Bluff Bay and the Kenai Peninsula in Alaska, and a Ni-Co laterite from southern Oregon. Sodium chromate crystals were produced that contained less than 0.01 pct NaOH.

Jan 1, 1988

By C. C. Merrill

The Bureau of Mines beneficiated the wastes generated by commercial titanium chlorination operations to reclaim metal values and reduce the problem of disposing of solid wastes. A water leach solubilized about 40 percent of the dry weight and over 75 percent of the metallic impurities. The residue from the water leach was rich in titanium dioxide and carbon; it was combined with rutile and recycled to a laboratory chlorinator. The contained carbon was used in lieu of part of the coke requirement.

Jan 1, 1969

By R. H. Reist, R. D. Dey, V. Castranova, J. P. Durham, Y. Rojanasakul

"Silicosis is a fibrotic pulmonary disease produced by inhalation of silica-containing dusts (Peters, 1986). Chronic silicosis may develop 20-40 years after initial exposure to crystalline silica, and the disease may progress from a simple to a complicated form. Few symptoms are evident in simple silicosis with pulmonary function being relatively normal. However, chest radiographs reveal small rounded ·opacities in the upper lobes of the lungs. These silicotic nodules consist of collagen arranged in a distinctive circular pattern. As fibrotic changes become more severe, the disease progresses to complicated silicosis (progressive massive fibrosis). Complicated silicosis is associated with shortness of breath and decreases in pulmonary function characteristic ofrestrictive lung disease. Chest x rays reveal numerous large silicotic nodules which may be associated with scar emphysema. Several mechanisms have been proposed to explain the cellular events which result in silica-induced lung damage and fibrosis (Lapp and Castranova, 1993). They include: ( l) direct cytotoxicity of silica, (2) activation of oxidant and enzyme release from alveolar macrophages, (3) recruitment and activation of polymorphonuclear leukocytes, and (4) stimulation of fibroblast proliferation and collagen synthesis.Tetrandrine is a bisbenzylisoquinoline alkaloid derived from the Chinese herb Radix Stephania tetrandra. It has a molecular weight of 622.73 and an empirical formula of C38H420 6N2. The chemical structure of tetrandrine has been published previously by our laboratory (Castranova et al., 1991 a). Its structure is characterized by methoxy groups at C7 and C12 , uncharged nitrogens at N2 and N’2 and two 17-carbon ring members connected by a double oxygen bridge between Ca-C7 and C11-C12. Tetrandrine has been shown to reduce both silica-induced fibrosis and the elevation of lung collagen content in rats (Huang et al .. 1981; Yu et al., 1983; ldel, 1987). Furthermore, tetrandrine has been used as an antifibrotic agent in Chinese clinical trials (Li et al.. 1981 ). Preliminary results suggest that administration of tetrandrine to patients with silicosis results in substantial improvement of symptoms, increases in diffusion capacity, and decreases in the size of shadows on lung x rays."

Nov 1, 1995