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By H. C. Ko

Calorimetric determinations of low-temperature heat capacities and standard enthalpy of formation were made by the Federal Bureau of Mines for basic aluminum sulfite, A1203?2.0S02?5.3H20. The standard values of entropy (S°), enthalpy of formation (?Hf°), and calculated Gibbs energy of formation (?Gf°) at 298.15 K are 85.2±0.1 cal/deg-mole, -943.1±1.2 kcal/mole, and -820.7±1.2 kcal/mole, respectively.

Jan 1, 1976

By G. H. Gronhovd

This report describes the design and initial operation of a slagging gasification pilot plant installed by the Bureau of Mines at the Lignite Research Laboratory, Grand Forks, N. Dak., in 1958-59. The tests covered in this report were conducted over a period of about 2 years, beginning in April 1959. The pilot plant was designed for eventual operation at pressures ranging from 400 to 600 p.s.i.g. (pounds per square inch gage); however, for the preliminary test reported here, the gasifier was fitted with a low-pressure slagging section and operated at atmospheric pressure and at 80 p.s.i.g. The reason for using a low-pressure slagging section for initial operation was to facilitate modifications in design during the development of a reliable slagging procedure.

Jan 1, 1962

By M. S. Seehra, R. S. Pandurangi

"The interaction of amorphous silica particles with several hydrogen bonding agents (H2O,, C2H,OH, C,H,NO) was investigated by monitoring the changes in the bulk and surface IR vibrational modes of silica using photoacoustic spectroscopy, It is argued that the intensity of the silanol band at 3747 cm-1 provides (an inverse) quantitative measure of the interaction of surface groups, along with the shift in the broad hydroxyl band, the interaction following the order C,H,NO > C2H2OH > H2O.The use of IR spectroscopy to study the adsorption on solid surfaces is well documented in the literature,"" For example, hydroxylation of a clean silica surface results in the formation of the free silanol group Si-OH, with a sharp IR band near 3747 cm-1. Further hydroxylation produces a broad band near 3500 cm-1, which is believed to result from various hydrogen-bonded silanol bands leading to a multilayered surface structure of few nm.3-6 Earlier studies had indicated a relationship between the surface silanol band and various chemical activities of silica such as cytotoxicity,7-9 catalysis,10-12 and others.13 Recent studies from our group14-in which the intensity of the silanol band and cytotoxicity of silica, heat-treated at various temperatures up to 1095°C, were investigated-have provided a strong correlation between cytotoxicity and intensity of the silanol band.Coating of silica by PVPNO (polyvinyl-2-pyridine N-oxide with the empirical formula C7H8N0), a strong hydrogen bonding agent, is known to reduce the cytotoxicity of silica, presumably by chemically blocking the silanol groups from phospholipids.15 This interaction of the hydrogen bonding agents with the silica can be studied by IR spectroscopy, and Knozinger16 and Rouxlet and Semples17 have used transmission IR spectroscopy to study the effect of various chemicals on the surface IR modes of silica. However, one of the major disadvantages of transmission IR spectroscopy is that the sample preparation (grinding and mixing with KBr and pelletizing) usually distorts the surface modes (see, e.g., Ref. 14) and there is always a doubt about the effect of the sample preparation on the measured properties, In recent years, photoacoustic (PA) spectroscopy has become the technique of choice for studying the IR spectra of samples in their natural state, since no sample preparation is necessary.18,19 Moreover, according to a recent paper,20 the relative intensity of the surface modes in PA spectroscopy of silica particles is much higher than that in transmission FT-IR spectroscopy. Consequently PA spectroscopy is ideal for studying the surface chemistry, In this work, we have used PA spectroscopy to investigate the interaction of three hydrogen bonding agents (C7H8NO, C2H5OH, and H20) with the silica surface by monitoring changes in the surface IR modes, Our results show that the surface IR modes get perturbed to a larger extent than the bulk IR modes in interaction with the hydrogen bonding agents, Moreover, whereas in the earlier studies, the shift of the broad silanol band near 3500 cm-1 was used as a measure of the interaction with hydrogen bonding agents,16,17 here we show that the relative decrease in the intensity of the sharp silanol band near 3747 cm-1 also serves as a quantitative parameter for the relative surface coverage and surface modification, Details of this work are given below,The Cab-O-Sil samples of silica used here were obtained from the Cabot Corporation of Tuscola, IL, In our earlier studies,14,20 we have shown these particles to be amorphous and about 0.05 am in size, For coverage of these particles with H20 and C2H50H, the following procedure was employed. About 5 mg of silica was mixed with 50 mL of the liquid (H2O or C2H5OH) and refluxed for one hour, The remaining liquid was allowed to evap¬orate to dryness and 1 mg of the treated sample was used to collect the PA spectra. In the case of PVPNO, the amount that binds to Cab-O-Sil is taken from the data on quar"

Mar 1, 1992

By Ralph H. Espach

The value of careful fractionation in the manufacture of petroleum products is recognized more and more by petroleum refiners. Recent studies have shown that the quality of the products depends largely on the type of fractionating equipment and on the care used in operating the equipment. For example Rue3 has shown that careful fractionation of pressure distillate will greatly reduce the amount of chemical treatment necessary to produce finished gasoline. The advantages of the combination of pipe still and bubble tower in obtaining good fractionation are well recognized in the petroleum industry. However, the equipment designed in the past has in general been much too large for convenient laboratory use. The present paper describes a continuous-distillation apparatus for the laboratory study of fractionation. This apparatus has given very satisfactory results in the study of different crude oils and petroleum products. A discussion of the theory and action of bubble towers has not been given, as this subject has been discussed previously by Cooke and Rue4. It is believed that the distillation curves of the products obtained from this apparatus show clearly its capabilities.

Jan 1, 1928

By Eugene Fry

The Huber-Rydalch manganese property is in the Erickson mining district of Tooele County, Utah. The district covers the southern part of Simpson Mountains, a block rising abruptly above the surrounding desert floor (fig. 1). The Ruber-Rydalch deposits and other deposits in the Simpson Mountains manganese area were examined by Bureau of Mines engineers during 1940 and 1942 under the strategic minerals program. J. T. Pardee visited the district briefly in 1918. A. E. Granger and A. F. Shride, of the Federal Geological Survey, mapped the geology of the area in 1942 and 1943. The manganese deposits occur as veinlike masses in brecciated fault zones that traverse Cambrian and pre-Cambrian quartzite, quartzite conglomerate, and phyllite. The deposits now exposed near the surface represent the oxidized portions of primary mineralization originally containing rhodochrosite and rhodonite associated with quartz and calcite and small quantities of pyrite, galena, sphalerite, and chalcopyrite. The oxide ore is composed of manganite, pyrolusite, psilomelans, and wad in a gangue of quartz, calcite, and brecciated quartzite.

Jan 1, 1949

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

The panic bars (and associated linkage's and electrical circuitry) that are defined in this document are a machine operator-actuated control for the emergency deenergization of the tram motors on Self-propelled, electric and diesel face equipment; including haulage equipment such as shuttle cars. There are nine basic types of panic bars (and several variations) that are recommended in this document, but all of the panic bars are characteristically of the "fire door" type that is frequently encountered on outside exit doors of many public and soma commercial buildings. It is also the intent of the following panic bar designs that, when emergency brakes are added to the face equipment machinery for which they are required, that they be designed and hooked up so that actuation of the panic bar will result in automatic application of the emergency brakes (immediately following the deenergization of the tram motors). The following panic bar design requirements are a restatement of the proposed requirements defined in the Federal Register, requirements cited in 'Guidelines for the Design and Installation of Devices for Deenergization of Self-Propelled Electric Face Equipment/Automatic Emergency Brakes" by C. E. Lester and J. D. Greenhalgh of MESA, and Bendix recommendations that were formulated as a result of discussions with personnel at the various machine manufacturers and underground coal mines that we surveyed, discussions with G. L. Judy (our consultant), etc:

Jan 1, 1974

The panic bars (and associated linkages and electrical circuitry) that are defined in this document are a machine operator-actuated control for the emergency deenergization of the tram motors on self-propelled, electric and diesel face equipment; including haulage equipment such as shuttle cars. There are nine basic types of panic bars (and several variations) that are recommended in this document, but all of the panic bars are characteristically of the "fire door" type that is frequently encountered on outside exit doors of many public and some commercial buildings. It is also the intent of the following panic bar designs that, when emergency brakes are added to the face equipment machinery for which they are required, that they be designed and hooked up so that actuation of the panic bar will result in automatic application of the emergency brakes (immediately following the deenergization of the tram motors). The following panic bar design requirements are a restatement of the proposed requirements defined in the Federal Register, requirements cited in 'Guidelines for the Design and Installation of Devices for Deenergization of Self-Propelled Electric Face Equipment/ Automatic Emergency Brakes" by C. E. Lester and J. D. Greenhalgh of MESA, and Bendix recommendations that were formulated as a result of discussions with personnel at the various machine manufacturers and underground coal mines that we surveyed, discussions with G. L. Judy (our consultant), etc:

Jan 1, 1974

By B. P. Martinez

In response to a request from the President, the Department of the Interior joined with other agencies in a comprehensive study of the land and water resources of the New England-New York region. As part of this study, chemical engineers of the Bureau of Mines have visited 1,025 mineral-industries plants to inventory the waterborne wastes of mineral origin, discharged by the mineral industries of the New England-New York region. Four-hundred and sixty-two of these plants disposed their wastes to a public sewer of some type, but waste control remains a problem for moat of them. The 1,025 plants are discussed in main industry groups according to their production: Chemical and allied products. Stone, clay, and glass products. Iron and steel and their products (except machinery). Nonferrous metals and their products. Electrical machinery. Machinery (except electrical). Transportation equipment. Miscellaneous mineral industries.

Jan 1, 1956

By Jr. Hazen

Relationships that may exist between assays and sample interval lengths when using unequal sample intervals in mine sampling have been investigated as part of the larger research problem of adapting statistical methods to the analysis of weighted average grades. The theoretical relationship between the amount of difference in the weighted and unweighted average grade of ore and the size of the correlation coefficient between assay value and sample interval length was found to be linear. Numerous examples of actual field sample and assay data, which have been obtained by using unequal sample intervals, are documented, and the differences between weighted and unweighted average grades of ore and the correlation coefficients between assays and sample interval lengths have been computed and plotted on graphs. Differences between these actual field data and the expected theoretical linear relationship are examined. It is hypothesized that the use of unequal sample intervals in mine sampling is, in fact, stratified sampling in a statistical context. The sampler establishes stratification by selecting unequal sample intervals on the basis of differences in lithology, changes in rock type, characteristics of mineralization, or differences in metal content. Statistically} methods currently used in mine sampling, involving unequal sample intervals, fail to consider differences in the inherent variances in grade of ore within the various strata established by using unequal sample intervals. Consequently the strata are sampled with different precision. This difference in precision of sampling between strata may account for much of the deviation between the plotted points representing actual field sampling data and the theoretical linear relationship between the amount of the difference between weighted and unweighted average grade of ore and the size of correlation coefficient between assays and sample interval lengths.

Jan 1, 1966

By Robert W. Smith

The Bureau of Mines is engaged in a systematic evaluation of the thermodynamic properties of combustion gases. These studies are designed to provide basic thermodynamic information of high accuracy, facilitating the theoretical study of flame and combustion phenomena. This report is the fourth of a series4/ presenting results of the study for particular fuel-oxidant systems. These calculations have as their objective the evaluation of the constant pressure flame temperatures of methane-air, propane-air, and ethylene-air mixtures for a range of pressures.

Jan 1, 1953

By Roy L. Grant

The Bureau of Mines investigated the up-and-down method with factorial designs to determine if shorter, and therefore less costly, trial sequences could be used. Although sequences of 50 trials are usually recommended, sequences of 20 trials were arbitrarily chosen for the experiments with permissible coal mine explosives described in this report. These explosives were fired from a cannon pointed into a flammable natural gas-air atmosphere at the Bureau of Mines Explosives Research Center gallery to ascertain their safety properties. The investigation demonstrated that the shorter sequences led to useful conclusions with a reduction in cost of the experimental program.

Jan 1, 1967

By Raymond W. Hiteshue, Sam Friedman, Paul Dobransky, Robert Madden

A hvab coal was carbonized in a closed system at 600 ° C and 40 to 1 , 200 psig to produce a high- Btu gas and char . By retaining the volatiles within the system, it was possible to virtually eliminate production of tars and oils . Depending on pressure and residence time , yields of combustible gases (72 to 92 percent methane ) amounted to 4,000 to 6,000 cubic feet per ton of maf coal and gross heating values of these gases varied from 830 to 960 Btu per cubic foot . Yields of char (maf ) were about 1,600 pounds per ton of maf coal . Increased residence time favored production of gases but reduced their heating values , whereas increase in pressure resulted in somewhat higher heating values and lower production . Similar effects were observed from the carbonization of a low- temperature tar . If these results could be translated to an economical carbonization process for producing high- Btu gas from coal , the demand for coal could be expanded by 40 to 50 million tons per year . Because of large yields of char , a process of this type would obviously have to be integrated with coal - fired power plants . Fortunately , operations could be conducted at essentially atmospheric pressure as product gas under this condition can be obtained in satisfactory yields and with good quality .

Jan 1, 1964

By J. E. Matta

The methane gas emitted from coal samples collected from the conveyor belts dumping into silos was measured by the Bureau of Mines. Approximately 50 pct of the total gas desorbed into a sealed can within 1 week was released during the first 24 hours. No simple correlation between the gassiness of the coal stored and the methane concentration in the silo open space above the coal was found. This was probably because the gassier coals were stored in open-top Silos, which were better ventilated. Although the methane concentration in the open space above the coal pile was less than 1 pct for all 34 silos investigated, a methane measurement in the coal pile showed that high methane concentrations can exist. The methane released in the pile appears to accumulate and not liberate freely into the open space above the coal pile. Probably this gas is released during reclaiming operations, but further research is required to substantiate this claim.

Jan 1, 1978

By A. F. Baker

Laboratory flotation of synthetic coal-pyrite mixtures and high-pyritic-sulfur coal indicated that ferric chloride (FeCl3), aluminum chloride (AIC13), chromium chloride (CrCl3), and cupric sulfate (CuSO4) are potential pyrite depressants. For each metal salt there appeared to be a range of pH values and optimum concentration for selectively depressing pyrite in coal flotation. Pyrite was depressed in the pH range from 4.5 to 7.0 with ferric chloride, from 5.8 to 7.0 with aluminum chloride, from 6.4 to 7.1 with chromium chloride, and from 6.4 to 7.4 with cupric sulfate. Best separation of pyrite from coal was achieved in flotation solutions containing from 2 X 10-5 to 5 x 10-5 mole/ liter of each salt. In solutions containing excess salt concentrations, coal was also depressed. These Bureau of Mines tests demonstrated on a laboratory scale that, in solutions containing 4 X 10-5 mole/liter ferric chloride and from 1 x 10-4 to 2 x 10-4 mole/liter sodium hydroxide, the pyritic sulfur content of a Lower Freeport bed coal sample could be reduced from about 2.51 percent to less than 0.60 percent with recoveries of over 83 percent. The depression of pyrite appears to be due to the adsorption of positively charged colloidal metal hydroxide at the pyrite-solution interface. This hypothesis is supported by zeta potential determinations which showed that suspended coal and pyrite particles in solutions containing metal salts are positively charged in the pH range where depression occurs.

Jan 1, 1971

By R. B. Schluter

The objective of this Bureau of Mines investigation was to determine the effects of adding manganese compounds and ores to iron ore pellets. Manganese dioxide, carbonate, sulfate and chloride, plus six manganiferous ores from the Minnesota Cuyuna Range were tested as additives to increase the manganese content of iron ore pellets. One to 5 percent manganese, as a compound or ore, was added to five magnetite concentrates and one hematite concentrate. These concentrates were ballad, indurated (1,300° C), and tested for reducibility. Manganese sulfate and chloride were unsatisfactory additives causing cracking and degradation of the pellets during reduction. Manganese dioxide, carbonate, and the ores were satisfactory additives. The additives increased pellet compression strengths with a corresponding loss of reducibility, as compared to the pellets without manganese additions. The changes in compression strengths and reducibility were caused by the formation of Jacobite spinel and slag within the pellets. However, when the induration temperature was lowered from 1,300° to 1,200° C the reducibility and compression strengths were comparable to the pellets without manganese additions indurated at 1,300° C.

Jan 1, 1974

By Max L. Glenn

As part of its goal to minimize requirements for mineral commodities through conservation and substitution, the Bureau of Mines conducted research to develop molybdenum as a potential substitute for superalloys containing the strategic and critical materials, nickel, chromium, and cobalt. Since molybdenum requires protection from oxidation at high temperatures, several complex oxides of the spinel and perovskite structure were investigated to determine which possessed the greatest potential for use as oxidation-barrier coatings. Two spinels (MgCr204 and MgA1204) and five perovskites (BaHfO3, YCrO3, NdCrO3, BaZrO3, and LaCrO3) were selected for testing. Various high-temperature prop¬erties that are important for oxidation-resistant coatings were examined, including diffusion rates of oxygen and molybdenum, recession (vaporization) rates, hardness, erosion resistance, sinterability, reactivity with molybdenum, and ease of application. From the evaluation of high-temperature properties, two spinels (MgCr204 and MgA1204) stand above the other oxides as possible coatings for molybdenum. However, laboratory coatings of MgCr204 at 1,360° C (2,480° F) are equivalent or inferior to currently available MoSi2 coatings; laboratory coatings of MgA1204 may be comparable under limited conditions to currently available MoSi2 coatings at the same temperature.

Jan 1, 1979

By D. Hinton, M. McCawley, R. C. Lantz, F. Pisano, C. Stanley

"INTRODUCTION Aerosols (5 um have not been shown to be consistently generated and characterized in inhalation chambers. Particle deposition in the lungs however may occur with particles as large as 25 um(1). Therefore, in order to closely simulate the atmosphere of an underground coal mine where the distribution is bimodal, with modes at S and 15 um (2), particles much greater than <1 um must be characterized for uniform mixing and size distribution within these chambers. The Hazelton Animal Exposure Chamber has been chosen because it has been best characterized for smaller particles (<1 um) (3), and is the major type used by most inhalation toxicology institutes such as Lovelace Inhalation Toxicology Institute and Battelle Northwest Laboratory.BACKGROUNDPreviously published studies on the inhalation of solid aerosols have attempted to characterize the distrition of particles of <2 um in diameter. There are no published reports of extensive work characterizing either the size distribution of particles <1 um or the concentration throughout the exposure chamber (Table 1).Table 1 shows the variability and sizes of several aerosols <1 um in diameter used in five previous chamber studies.Discussion of Previous StudiesThe study done by Bauermash, Bryan, Dickinson, and Burke (4)stated two major concerns in the development of the 6.5 ft. diameter chamber. The first was that a quantity of animals could be exposed to the same concentration regardless of the location of the animal, and second was that the chamber could be easily cleaned and decontaminated. The solution to the first concern required a circular chamber with the contamination air entering the chamber somewhere along the central axis. The animals could then be changed during exposure time so that each animal was exposed throughout the total volume."

Jun 1, 1988

By R. V. Lundquist

Aeration in water slurries and controlled drying of manganous hydroxide produced from dithionate leaching of Artillery Peak manganese ores from Arizona were investigated by the Bureau of Mines at its Electrometallurgical Experiment Station, Boulder City, Nev., to determine whether a simple process could be developed for converting this product into a battery-grade manganese dioxide. The properties of manganese dioxide prepared by the thermal decomposition of manganous nitrate were investigated also. Manganese dioxide suitable for use in batteries was not obtained from the dithionate leach product, but some of the factors controlling its oxidation were isolated. Aging of manganous hydroxide was of major importance in retarding its oxidation by aeration. Sodium hydroxide and sodium silicate promoted oxidation by drying. Optimum quantities were about 0.85 mol of sodium hydroxide and 0.2 mol of sodium silicate per mol of manganese, and drying temperatures of 200° C. produced yields of manganese dioxide up to 90 percent of the manganese present. Higher temperatures and concentrations of reagents carried oxidation of manganese beyond its tetravalent state.

Jan 1, 1957

By John Nagy

The effect of low percentages of methane (0 to 5 pet.) in an air atmosphere on spark initiated explosions of coal dust was investigated. With low dust concentrations (0.1 to 0.4 oz./cu, ft.), small amounts of methane increase the explosion pressure; with larger dust concentrations (0.5 to 2.0 oz./cu. ft.), small amounts of methane decrease the explosion pressure. The rate of pressure rise of a coal dust explosion increases with increase in methane concentration; about 3 to 4 pct. further addition of methane yields a decrease in the rate of pressure rise. Convection currents created by the air or gas blast used to disperse dust produce an increase in explosion pressure and rate of pressure rise. The minimum explosive concentration of the coal dust decreases about linearly as the concentration of methane increases from 0 to 5 pct. The explosion pressure increases linearly as the initial pressure within the chamber increases. Similarities between coal dust and methane explosions are indicated, INTRODUCTION During coal mining, methane occluded in coal or adjoining strata is liberated into the mine atmosphere,4 Normally, the methane is diluted and swept away by the ventilating air. Under some conditions, through accidental disruption of the ventilation system, sudden outburst, or because insufficient fresh air is supplied to a working place, low percentages of methane may be present during mining operations. If it is permitted to accumulate, methane itself presents an explosion hazard; its limits of explosibility arc approximately 5 and 15 pct. The effect of low percentages of methane on the explosibility of coal dust was studied to provide a broader understanding of the hazards of ignition and explosion and thus to facilitate development of control

Jan 1, 1961