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By G. S. Scott, G. W. Jones

"INTRODUCTION An important phase of the accident-preventing program of the Bureau Mines is the determination of the explosion hazards of various combustible gases, vapors, and liquids encountered in mining and allied industries and the development of methods of eliminating or mitigating them.Recently, isobutane has become a commercially important raw material in the production of aviation gasoline by the alkylation process. 4/ in which isoparaffins are combined with olefins to give higher molecular weight compounds of branched-chain structure.Because of the anticipated commercial importance of isobutane in industry, it has been deemed necessary to study and determine its general explosion haz¬ards. This report gives its limits of inflammability, minimum ignition temper¬atures, and the amounts of nitrogen and carbon dioxide required to render isobutane-air mixtures noninflammable."

Jun 1, 1947

By L. A. Morley

This report summarizes the work performed on Bureau of Mines Contract J0199106, "Portable Trailing Cables, Splices, and Couplers - Design and Installation Considerations," from May 1, 1979 until December 31, 1981. Splice installations and considerations for the possible use of conductive-rubber shielding in low-voltage trailing cables as well as coupler installations in high-voltage cables were the principal tasks. Flammability measurements on cable components and general testing facilities for mine electrical equipment were secondary tasks. Theoretical and empirical data indicate that conductive rubber with high resistivity values is an unsatisfactory shield design for current-sensing fault detection. Elimination of partial discharge in coupler installations requires meticulous care.

Jan 1, 1982

By Aleksandar D. Bugarski

Three types of uncatalyzed diesel particulate filter (DPF) systems, three types of high-temperature disposable filter elements (DFEs), and one diesel oxidation catalytic converter (DOC) were evaluated in underground mine conditions for their effects on the concentrations and size distributions of diesel aerosols. Those effects were compared with the effects of a standard muffler. The experimental work was conducted directly in an underground environment using a unique diesel laboratory developed in an underground experimental mine. The DPF systems reduced total mass of aerosols in the mine air approximately 10-fold for light-load and 20-fold or more for high-load test conditions. The DFEs offered similar reductions in aerosol mass concentrations. The efficiency of the new DFEs significantly increased with accumulation of operating time and buildup of diesel particulate matter in the porous structure of the filter elements. A single laundering process did not exhibit substantial effects on performance of the filter element. The effectiveness of DPFs and DFEs in removing aerosols by number was strongly influenced by engine operating mode. The concentrations of nucleation mode aerosols in the mine air were found to be substantially higher for both DPFs and DFEs when the engine was operated at high-load modes than at low-load modes. The effects of the DOC on mass and number concentrations of aerosols in mine air were relatively minor when compared to those of the DPF and DFE systems.

Jan 1, 2009

By S. C. Schaefer

Thermodynamic properties of indium oxide (In203) have been studied with a high-temperature galvanic cell employing stabilized zirconia electrolytes. In the temperature range 790° to 1,230° K the free-energy change for the cell reaction 21n(1) + 3Cu20(c) = In203(c) + 6Cu(c) together with the standard free energy of formation of cuprous oxide gives the standard free energy of formation of indium oxide from the elements as ?Gf° = -218.78 + 75.34 X 10-3T ±0.7 kcal/mole. A third-law analysis yields the standard enthalpy of formation: ?Hf°298.15 = -221.5 kcal/mole.

Jan 1, 1971

By Carl Belser

Approximately 30 million pounds of tungsten trioxide in the form of ferberite concentrates have been shipped from Boulder County. Since 1940, the production has varied considerably, being affected by the emergency needs of World War II and the Korean conflict. During World War II, attempts to stimulate production were made by the Metals Reserve Company by stabilizing the price for a specified period, the Reconstruction Finance Corporation by small mining development loans, and the Bureau of Mines and the Geological Survey, who cooperatively explored some of the district by surface and underground core drilling. During the Korean conflict and continuing through the first half of 1954) tungsten production was being stimulated by a Government-gauranteed price and by financial assistance loans under the Defense Production Act of 1950 to qualified operators of properties that have merited exploration. This combined program has increased production in Boulder County from about 1,900 pounds in 1949 to an estimated 383,000 pounds of tungsten trioxide in 1953. The 1953 production came from 67 properties. One of the problems confronting producers is the need for improved beneficiaton methods. Ores from the area have not been amenable to flotation concentration and gravity methods have resulted in poor recovery, often less than 70 percent.

Jan 1, 1955

By E. G. King

Many of the rare-earth oxides are now commercially available in pure form and they have a variety of potential technical uses. Thermodynamic data for these oxides, however, are rather sparse. It is one of the functions of the Bureau of Mines to fill the need for this type of information. This report gives the results of low-temperature heat-capacity and high-temperature heat-content measurements by the Bureau of Mines of lanthanum sesquioxide. The entropy at 298.15° K. was evaluated and heat-content and entropy increments above 298.15° K. were obtained to 1,800° K. The results were combined with the known heat of formation at 298.15° K. to derive heats and free energies of formation at higher temperatures. Sufficient information is now available to permit reliable thermodynamic calculations involving lanthanum sesquioxide within the temperature range 298° to 2,000° K.

Jan 1, 1961

By Heine Kenworthy

In 1930 the Shenandoah-Dives Mining Co. near Silverton, Colo., put into operation a newly erected, 300-ton selective flotation plant to mill complex ores from its nearby mine. The operation was a steady producer and was enlarged to treat 600 to 800 tons a day. In 1942 the company opened and started milling an area in the mine containing semioxidized ore. The valuable mineral. Content of this ore was considerably higher than in the straight sulfide ore previously handled alone. The mixture of clean sulfide and semi-oxidized ore was difficult to treat; consequently tailing losses, especially with respect to lead, were high. A. few years later, in order to study the possibilities, of obtaining higher recoveries by a modification of the mill flow sheet, a 1,200-pound sample of mill feed, taken over a period of several days by the company, was submitted to the Mississippi Valley Experiment Station for testing. Although this sample proved to contain more than twice as much lead as the average yearly mill feed, the same problem of recovering the oxidized values were present.

Jan 1, 1948

By J. J. Hoeppner

Accurate determination of moisture in coals of various ranks has long been a subject of intensive investigation. Excellent reviews of methods developed over many years are given by Brown (9)4/ and, with experimental comparisons, by Goodman, Gomez, and Parry (11). As pointed out in these and other writings, one of the principal difficulties in assigning absolute merit to one or another procedure is the multiplicity of conditions under which water may exist in coal and the difficulties involved in obtaining sharp separation and distinction between these classes. Gauger (10) states: Water recoverable from coal is obtained from the following sources: (1) Decomposition of organic molecules (sometimes called combined water), (2) surface adsorbed water, (3) capillary condensed water, (4) dissolved water, and (5) water of hydration of inorganic constituents of the coal.

Jan 1, 1956

By Michael E. Henderson

The U.S. Bureau of Mines (BOM) constructed the Hydraulic Transport Research Facility (HTRF) to investigate the hydraulic parameters relating to the transport of coarse coal. To achieve these goals in a timely and efficient manner, the Bureau contracted to Boeing Services International (BSI) the responsibility of operating the HTRF and providing technical support. This data report is a summary of the testing and data results for the period 22 November to 10 December 1982. The testing covered herein is for coarse 2-in by 0 (minus 50 mm) Pittsburgh Seam coal in a 6-in (150 mm) pipeline, at velocities ranging from 5 to 20 ft/s (1.5 to 6.1 m/s) and at concentrations ranging from 15 to 45 pct by weight.

Jan 1, 1986

By F. F. Aplan

"The material known as coal has a highly variable composition. As a consequence, coals show a great variation in their physical and chemical properties as a function of coal rank. The situation is further complicated because the preparation engineer must deal with raw coal, as mined. This is an assemblage of coal, upwards of 30% mineral matter and, typically, several percent pyrite. The kind and amount of the mineral constituents is also highly variable from source to source. A knowledge of coal rank and source location, and the kind and amount of associated impurities, is the first step in evaluating the response of a raw coal to preparation procedures. The raw coal must first be characterized before information from one source can be extrapolated to that of another.INTRODUCTIONCoal is a black or brownish-black combustible solid, derived from a heterogeneous mixture of plant remains and associated mineral matter that have undergone chemical and physical metamorphic changes by biological and geological processes without free access to air. It is composed principally of carbon, hydrogen and oxygen with lesser amounts of nitrogen and sulfur. 'Its exact chemical and physical nature has remained poorly defined, because the term 'coal' refers to a broad range of coalified solids ranging in rank from anthracite to a variety of bituminous coals of differing volatile matter content, sub-bituminous coals, and ending with lignite and brown coals. The variation in chemical and physical properties through these ranks is massive. In summary, Luckie's (1988) assertion is apropos: ""There is no such thing as coal; there are coals"". The coal preparation engineer, and, most especially, those scientists and engineers from other disciplines wishing to work with coal, must constantly keep this admonition in mind because what is true for one coal seam is often not directly applicable to another."

Jan 1, 1989

Between 1985-1986, the Bureau of Mines reviewed the mining history and minerals information for areas in and near the San Isabel National Forest to appraise the mineral resources present and determine the types of deposits, and their location in the Forest, that could be mined economically if sufficient demand and metal prices existed. The two major metallic deposit-types that are of national mineral resource significance within the Forest are stockwork- molybdenum (with tungsten and tin) and carbonate-replacement zinc-lead-silver deposits. Historically, small gold placers, gold-quartz veins, silver-quartz veins, skarn iron and copper deposits, volcanogenic copper-zinc-precious metal deposits, and base- and precious-metal veins have been mined. Barite, carbonate rocks, gypsum, other non-metallic deposits, and pegmatites, have also been mined. Sand and gravel, present in large volumes, occurs along and has been mined outside the Forest along the upper Arkansas River valley. Turquoise and gemstones are present in small amounts and are of interest to collectors and jewelers. Geologically, sediment-hosted uranium and copper are present in small occurrences but no resources have been identified. Geothermal resources are related to the Rio Grande rift which parallels the central part of the Forest. Four hot spring areas are present - two of these are within the Forest. Because of the low power requirements of the region, and the presence of other generating facilities, these geothermal resources have had only limited local use. Evaluation of mine models that may be found in the region show that base-metal deposits require a high precious-metal component to be economic. Although molybdenum can be produced at economically competitive prices, there is little demand for the product. Capital costs to start new molybdenum mines would be very high and it is not likely that new mines will be put into production in the near future.

Jan 1, 1989

By Foster Fraas

This Bureau of Mines report describes a method for separating minerals at magnetic susceptibilities within the diamagnetic susceptibility range. The maximum feed rate varies directly with the square root of the lower limit of permissible susceptibility, while the lower limit of permissible susceptibility varies inversely as the square of the magnetic field strength. Minerals may be separated at particle sizes smaller than possible on conventional dry-type magnetic separators.

Jan 1, 1969

By Stephen D. Hill

The Bureau of Mines devised and constructed a modified Knudsen effusion apparatus, permitting a constant measure of the weight of effusing vapor, to determine the equilibrium vapor pressure of metal halides at temperatures up to 1,200° K and over the pressure range 10-5 to 10-2 torr. The reliability of the apparatus was established by determining the vapor pressure of potassium chloride. After correcting for partial dimerization of the vapor, data obtained on solid KCl between 750° and 950° K can be expressed by the following equation:

Jan 1, 1966

After nine years of negotiations, the U.N. Conference on the Law of the Sea approved a Law of the Sea Treaty text in April. Israel, Turkey, the United States and Venezuela voted against the text and 17 other nations including Belgium, the Netherlands, Italy, the Soviet Union, the United Kingdom and West Germany abstained. These nations still have the option of joining the treaty when it is opened for signing in December. However, the Reagan Administration has stated that several provisions of the deep seabed mining portion of the text are unacceptable and it seems unlikely that the United States, at least, will change its position. ALUMINUM Reynolds Metals Co. has criticized an Oregon state plan to relax air pollution standards for aluminum plants. The company feels that relaxation of the rules does not go far enough. Reynolds officials say that they have spent about $31 million at their Troutdale plant for state-of-the-art pollution control equipment, and if they are required to make the pollution reductions called for in the 1986 rules, Reynolds would be forced to close the 40-year-old plant.

Jan 1, 1982

By T. M. Garland

This report presents a Bureau of Mines assessment of crude oil and associated gas production and reserves that would result from different drilling efforts in the lower or contiguous 48 States during the 1972-85 period. The drilling effort was based upon five growth rate assumptions from the 1971 level. Additions to crude oil reserves were computed for nine cases resulting from the use of three equations for findings per foot drilled and three constant revision factors. The results indicate that the United States will not become self-sufficient in crude oil production by 1985 and also illustrate the lead time required to reverse the decline in oil production. Discussion is limited to three of the nine cases to provide high, intermediate, and low results. More emphasis is on the intermediate case because it is indicative of the most probable trends. The methodology and statistical data are included in the appendices.

Jan 1, 1974

By Arno C. Fieldner

Coal for coke production is fundamentally necessary for the manufacture of pig iron , and pig iron must be had for making steel - a vital element in our modern industrial economy . In both World Wars , special effort by Government and industry was required to meet the emergency of greatly increased demands . In the first World War , lack of coke - oven capacity , rather than lack of coking coals , was the principal problem ; but in the second World War both oven capacity and coking -coal mining capacity were pushed to the utmost . Because of inadequate supply , it became necessary to allocate a part of the production of these coals from other fuel use to coke production . This was done by the Solid Fuels Administration . These experiences raised a question , during and after the war, as to the nature and amount of the minable reserves of coking coal suitable for the manufacture of metallurgical coke ; and to what extent the lower -rank and lowergrade coals could be utilized by improving preparation and by appropriately blonding different coals . Obviously , much investigation and research are required to find answers to these questions . Somo work was done by Governmental and industrial agencies during the war , and , fortunately , more has been undertaken since the close of It is the purpose of this paper to review briefly our fuel reserves , with special reference to coking coal , and to discuss the problems of utiliz . ing progressively poorer coking coals as the reserves of high - quality coals approach depletion .

Mar 1, 1950

By R. L. Grant

An investigation was undertaken by the Bureau of Mines to determine the relationship between freespace and ignition probability for borehole shots. A series of experiments was concluded which covered six freespace conditions for a pemissible explosive in a 3/4-inch borehole and encompassed some 700 shots. The results were analyzed statistically. From the analysis of variance, it was concluded that the freespace means were different and that this conclusion is not impaired by possible differences in the explosives used. Within the limitation of this experiment, a definite relationship was found between the freespace and the ignition probability. Specifically, the incendivity increases with increased freespace up to a maximum; beyond this maximum there is some indication of decreasing incendivity. Further investigations are in progress to establish whether the effects of freespace on ignition probability reported here are applicable to the large test gallery, INTRODUCTION A borehole loaded with an explosive charge is a common feature of the routine gallery tests for determining the permissibility of coal-mine explosives, of Experimental Coal-Mine shots, and of the small steel cannon shots used in connection with certain research programs on the ignition of firedamp (6, 10).6/ The question of the interrelationship of freespace, weight of charge, and ignition probability of the methane-air atmosphere has been raised

Jan 1, 1959

By W. W. Adams

Three hundred and twenty-eight mines and quarries, representing 36 States, took part in the twelfth yearly accident-prevention contest conducted by the United States Bureau of Mines and known as the National Safety Competition. Four underground mines and one open-cut mine (which represents the quarry and open-cut mine group), each the leader in its group, were awarded the ?Sentinels of Safety? trophy. Relative standing in the contest" was determined by the number of days lost from accidents in proportion to the total number of man-hours worked. Since 1925, when the National Safety Competition was inaugurated, an increasing interest has been taken in it by mining and quarrying companies as a means of stimulating mine and quarry safety by competition among similar plants. Each participating plant can, on a basis of its standing and record in the contest, determine to what extent its safety program is succeeding or to what extent it needs strengthening. With this information, each company that has a low standing in the contest can intensify its safety-promotion efforts the following year to obtain a? lower rate and possibly win the trophy or achieve honorable mention in the competition. Except for 1929, the National Safety Competition of 1936 represented more man-hours of employment than any other year since the yearly contests began.

Jan 1, 1937

By E. W. GOODWIN, V. F. Parry, J. B. Goodman, L. D. Schmidt, J. D. Davis, A. C. Fieldner, W. S. Landers, J. L. ELDER

The Heliopore process is essentially an arrangement that uses the waste heat in the exhaust gas of an internal - combustion engine to carbonize coal (noncaking ) or lignite . The gases distilled from the coal furnish fuel for the internal - combustion engine , which drives an electric generator . Thus the main products of the plant are electricity and char . A flow diagram illustrating the principles of operation of the Heliopore process is given in figure 1. The primary equipment consists of a carbonizing retort , gas cooling and scrubbing equipment, a gas storage holder, and an engine to burn the gaseous carbonization products . Coal is charged into the top of the retort while the hot gases from the engine travel upward through special ducts in the retort countercurrent to the coal flow . The hot gases never come into direct contact with the coal . Char is discharged at the bottom of the retort and hot gases at the top . The gaseous products resulting from carbonization of the coal are drawn off by an exhauster through the condensing and scrubbing equipment to take out tar and liquor , then to a gas holder , and finally are burned in a gas engine . The gas engine drives an electric generator and the engine exhaust gases are returned to the retort to carbonize coal . The entire process was intended to be continuous and self - sustaining, and to use coal as the only fuel . The plant may be said to be a large - scale pilot plant in that , although it is of full commercial size , its main purpose is to provide data for the design of others of its type . The installation tested had a daily throughput of about 4 tons of coal . Figures 2 , 3 , and 4 picture some details of the plant and equipment used in the experimental testing . Further details of the equipment and engineering drawings of the castings are shown in figures 8 to 22 in the Appendix .

Dec 1, 1943

By David S. Brown

What troubles me so often about debates over the environment, which I have heard since I entered government in the late 1960's, is that the issues are so often presented as a false dilemma--the either-or fallacy in logic. The either-or fallacy allows only two possible choices: Either protect the environment or exploit it. In reality, however, there may be a few more options. The diverse, often competing, values that the Earth offers require us to weigh and balance those options through a range of policy options. A quality environment and economic growth and opportunity are not mutually exclusive. First, let me acknowledge that I support a set of resource values recognized in U.S. laws and deemed important down through history for the success of free, progressive, and secure societies: the importance of access to raw materials. Increasingly, however, mineral raw materials have been viewed at best as not particularly relevant to a sophisticated, technologic society, and at worst monstrously destructive of our natural environment. Both perceptions, in my judgment, are wrong.

Jan 1, 1989