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By K. O. Bennington

The thermodynamic properties of synthetic acmite, NaFe3+Si206, were determined by the Bureau of Mines. The enthalpy of formation was determined by hydrofluoric acid solution calorimetry. The values of the standard enthalpy of formation at 298.15 K, ?Hf°298.15, from the elements and from the oxides, ?H°298.15, are ?Hf°298.15 = -615.87 ±0.71 kcal/mole, ?H°298.15 (from oxides) = -32.08 ±0.53 kcal/mole. Various experimental data were combined with other data from the literature to calculate all the related thermodynamic properties in the range of 298 to 1,263 K. The standard Gibbs energy of formation is ?Gf°298.15 = -575.8 kcal/mole.

Jan 1, 1981

By Tobias W. Goodman, George N. Aul, Joseph Cervik

The Bureau of Mines conducted research to degasify a virgin block of coal in the Beckley Coalbed using long horizontal holes drilled in an array from the bottom of a ventilation air shaft. Eight horizontal holes and an in situ pressure hole were drilled in a radial pattern to depths ranging from 418 to 910 ft (127 to 277 m) and 205 ft (62 m), respectively. The investigation showed the shaft was in a basin saturated with water, which resulted in low gas flows from holes. The in situ pressure at 200 ft (61 m) into the coalbed was 79 psig (544.6 KN/m2). The aver- age gas and water flows for the eight holes were 94,100 ft3/day (2,665 m3/day) and 13 gal/min (49.3 l/min) . After 514 days of degasification, 18.7 million ft3 (0.53 million m3) of gas had been drained. Methane face emissions, which were measured as a section advanced toward the shaft, were reduced about 77 pct, emphasizing the value of drainage by this technique. All holes were grouted before the area around the shaft was mined.

Jan 1, 1982

By Howard C. Turnage, Dana T. Updyke, Wayne C. Muhler

The objective of this project was to develop technical data and evaluate performance and utility of leaky feeder communications systems currently used in North American underground mines. The desired information was obtained principally through on-site surveys. Altogether, six of the seven mining companies known to be using leaky feeder communications were visited. This report covers the findings of these surveys. In addition, the report provides a brief background summary of mine communications, a technical discussion of leaky feeder systems, and conclusions and recommendations based on the results of the survey.

Jan 6, 1980

By H. P. Hermance

The Ore Hill zinc-lead mine in Grafton County, N. H., was investigated by the Bureau of Mines from March to July 1943 and from August to October 1944. Fourteen holes with an aggregate bore of 4,899 feet were diamond-drilled, the old workings were unwatered and sampled to an inclined depth of 250 feet, and the tailings dumps were surveyed and sampled. The deposit at the Ore Hill mine comprises a bedding-plane vein of massive sphalerite and galena with subordinate chalcopyrite and pyrite in a series of interbedded metasedimentary and metavolcanic schists about one-quarter mile east of their contact with the intrusive Baker Pond gneiss. The property was first opened about 1850 and was active at times to 1914. Production records are not available, but the output is believed to have been considerable. In 1944, leasers recovered a marketable mica product from mica schist from the dumps and certain outcrops. This report describes the work performed in the Bureau's investigation and presents the data obtained.

Jan 1, 1948

By R. Hogg

"The basic population balance models for agglomeration processes are reviewed and procedures are described for extending their applicability to systems with size-dependent rate constants and to the formation and growth of porous agglomerates from rigid, solid particles. Simplified procedures for the further extension of the models to include simultaneous agglomerate growth and breakage arc also described. IntroductionThe association of small particles into clusters or agglomerates is a significant factor in many facets of particle processing. Agglomeration processes are widely used to facilitate handling, storage and utilization of fine powders. Processes such as coagulation or flocculation are used to aid solid-fluid separation in dispersed particulate systems. Agglomeration also occurs as an accompaniment, often unwanted, to other particulate processing operations such as fine grinding, mixing and blending, transport and flow.Reliable agglomeration models are needed for improved understanding of the processes in general and of the complex role of numerous, interacting variables as well as for direct application to the design and control of industrial processes such as flocculation, granulation and pelletization. Ideally, the models should account for the primary forces responsible for agglomerate ·formation and growth, the effects of external forces on process dynamics, the development of agglomerate structure and its role in the process itself, and the effects of concurrent processes such as structure modification (e.g. compaction) and agglomerate breakage or degradation.In its most general form, the process of agglomeration involves taking discrete, independent particles, bringing them into contact with one another, promoting (or allowing) interparticle adhesion to occur and then causing structure rearrangement, usually under the action of external forces. The relative importance of these steps varies with the nature of the particulate system being agglomerated and with the kinds of agglomerates being produced. Coagulation or flocculation of particles dispersed in fluids is generally dominated by the contact and adhesion steps. In the granulation of powders, on the other hand, particles are already in contact so that structure rearrangement is the principal step."

Mar 1, 1992

Objective: To improve the effectiveness of dust collector capture on surface mine drills.

Oct 1, 2005

By D. Harrington

"In at least three out of every four working faces in metal mines there is no attempt made to cause air circulation other than by use of compressed air, and in at least nine cases out of ten the compressed air is released merely by opening, or partly opening, the valve and allowing the compressed air to escape through open air hose used to convey the compressed air to the drilling machines. Usually no blowers are in use during periods of drilling, as the exhaust from the drill provides cool, comparatively fresh air for the driller; however, in some instances, the compressed-air line is provided with a tea connection, which permits taking air for the drill from one side of the tee, and air for ventilation through a separate hose used as a blower, simultaneously with drilling.Table 1 contains temperature and humidity data as to compressed-air blowers from open end of air hose at 36 working places in eleven metal mines of four States, embracing the mining of gold, silver, copper, lead and zinc ores, and at horizons ranging from 500 feet below the surface to as low as 4900 feet.It is noticed that the ordinary air surrounding the worker at the face gives an average wet bulb temperature of 81.7° F. for the 36 working faces, with 84.7° F. dry bulb and 87.2 per cent relative humidity. The average wet bulb tem¬perature of 36 readings at these working faces of compressed air at the end of the,hose as the air issues from the hose was 67.4° F., or 14.3 degrees lower than the average wet bulb readings of the air of the working places; however, the average dry bulb temperature of the 36 readings of compressed air as it issued from the end of the hose was 79.7° F., or only 5 degrees less than that of the general air (84.7°); the relative humidity was 51.1 per cent as against 87.2 per cent for the surrounding air. Readings were taken in five raises, seven crosscuts, ten drifts and 14 stopes.It will be noted that the velocity or movement of the general atmosphere at each of the entire 36 working faces, was found to be practically imperceptible; this might readily be inferred since compressed air is rarely used on blowers if there is adequate circulation of the general air of the place. Where rook temperatures could be obtained readily, they are shown; it is noticeable that the dry bulb temperature of the air of the working place varies little from the rock temperature, and that the dry bulb temperature of the compressed air as it issues from end of air hose varies only a few degrees from the temperature of the surrounding rock; in some instances the dry bulb temperature of the compressed air as it issued from the end of the air hose was higher than the rock temperature or the dry bulb temperature of the surrounding air."

May 1, 1921

By Robert H. Ridgway

This circular outlines salient facts regarding the manganese-ore industry in the United States and the world. It is founded chiefly upon published information available in the literature of the subject. The Bureau of Mines has in its files additional, more detailed data upon many of the topics presented very briefly here, and will endeavor to assist the mineral industries and public by giving further information in response to individual inquiries. The Bureau will welcome comments, criticisms, and contributions of data that may assist in making later additions of this circular more accurate, or in developing more fully its mineral files pertaining to manganese. In reporting the production of manganese-bearing ores in the United States the following classification has been adopted by the Bureau of Mines: (1) Metallurgical-grade ores, under which have been classified manganese ores containing 35 percent or more of manganese used in the manufacture of iron and steel, ferruginous manganese ore containing 10 to 35 percent of manganese, manganiferous iron ore containing 5 to 10 percent of manganese, and manganiferous zinc residuum; (2) battery ore; (3) fluxing ores, under which are classified ores that may contain a few ounces of silver and are rich enough in manganese to make them valuable chiefly for fluxing purposes in nonferrous smelters; and (4) miscellaneous ores, under which are classified the ores shipped to brick manufacturers, glass makers, and manufacturers of manganese chemicals.

Jan 1, 1933

By D. W. Frommer, L. Bonicatto, M. M. Fine

A mineral - dressing investigation was conducted to demonstrate the ability of an anionic silica - flotation process to produce high- grade concentrates from submarginal iron ores of the western Mesabi and Menominee ranges . Commercially available equipment and reagents were used . Samples from the Menominee range were exclusively from the Groveland , Mich . , mine and contained hematite as the chief iron - bearing mineral . Bench- scale investigations established that the anionic silica flotation method can function effectively on a variety of undeslimed ores . Continuous tests completed on one Mesabi semitaconite ore and on Groveland mill feed , have verified the validity of the bench research . The Mesabi samples yielded a concentrate containing 60.3 percent Fe and 6.0 percent Sio with an accompanying iron unit recovery at 90.5 percent . Iron recoveries from the mill feed ranged from 79.0 to 87.4 percent .

Jan 1, 1964

By J. E. Doo1ey

To process and use the heavy ends of petroleum effectively, the development of suitable separation and characterization procedures not currently available was required. A systematic procedure was developed by the Bureau of Mines using such techniques as isothermal and molecular distillation, chemical treatment, silica-alumina gel chromatography, gel permeation chromatography, and spectrometry. Using these techniques, the Bureau achieved a detailed separation and characterization of a 370° to 535° C distillate from Gach Saran, Iran, crude oil. Such a systematic procedure and the semiquantitative data resulting therefrom should be of value in selecting feedstocks and in optimizing petroleum processing operations.

Jan 1, 1973

By William E. Bruce

The Bureau of Mines performed drill calibration tests on two industrial percussive drills of 2-5/8- and 3-1/2-inch piston diameters to determine operating characteristics for their use in conjunction with penetration rate data in developing drillability equations and furthering the knowledge of percussive drills. The use of a linear velocity transducer for measuring piston velocities and application of its instrumentation are described. Data presented include relationships between maximum piston velocity and feed air pressure other results confirm the theory or data of previous investigators, and some comparisons are made with the performance prediction formulas of other investigators.

Jan 1, 1969

By R. P. Bush

The U.S. Bureau of Mines performed Cu exchange capacity (CuEe) tests on Ca and Na mont-morillonites and attapulgite clays. Mathematical models were developed from the data that the CuEe's are derived from for each clay as a function of pH, Cu concentration, and the concentrations of metal ions, which compete with Cu for exchange sites. An analysis was made of the impact of competing ions on Cu losses due to ion exchange. The results show that the CuEC's of clays, and hence Cu losses, are decreased by the presence of competing ions, and that AI and Mg have the largest impact of those cat-ions normally present in Cu leaching solutions.

Jan 1, 2010

By Kenneth J. Miller

To determine the effectiveness of the many new flocculants available to the coal industry 20 of these reagents were evaluated treating slurry feeds to four refuse thickeners. Settling rates and supernatant liquid clarities were determined for each of the flocculants on the four slurries, and zeta potential measurements of the slurry solids were made. The test results showed that the flocculants provided comparable results when judged categorically as anionic, nonionic, or cattonic. It was also apparent that control of zeta potential insures maximum benefit from a flocculant.

Jan 1, 1968

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By J. F. Barkley

Field tests were made on the rate of corrosion of 30 materials used in air preheaters under regular operating conditions, and the buildup of deposits was observed. Twenty-three materials were tested with coal as the fuel on an underfeed stoker and seven with oil, including a short period with pulverized coal as fuel, The plant equipment is described, and pertinent plant operating data are tabulated. Figures 17 and 19 (pp. 24 and 27) give the results of corrosion tests on the uncoated metal test specimens. The information obtained from these tests follows the general pattern described in Bureau of Mines Report of Investigations 4996, Corrosion and Deposits in Regenerative Air Preheaters. The deposits were similar, and the corrosion rates of Cor-Ten and Mayari-R steel (previously found to be essentially the same at the Harding Street Station using coal) continued to show little difference at the Marion Generating Station using principally oil. The one high-alloy steel tested, type 321, showed a much higher corrosion rate than the low-alloy steel, Cor-Ten.

Jan 1, 1959

By R. M. Santmyers

Umber and sienna, like ocher, are naturally occurring mineral pig- ments composed largely of clay permeated with hydrated iron (ferric oxide), but they differ from ocher in that they also contain hydrated manganese oxide. The presence of manganese accounts for their browner color. In addition to silica and alumina (clay) and the coloring oxides of iron and manganese, these pigments often contain lime, barium, and other metallic salts as impurities. Sienna most nearly approaches ocher in chemical composition, and the chief distinction is its physical character. It grades into ocher with de- creasing iron content and into umber with increasing manganese content. Sienna is translucent rather than opaque and is more of a stain than a pigment; as the iron oxide content is rather high (often 60 to 80 per cent), the color is strong and rich and varies from pure brown to reddish brown. This pigment raw sienna, terra di Siena, and Italian earth. is known under several names: Burnt sienna is a pigment of an orange-brown tint made by cautionsly calcining raw sienna. It is divided into two grades; American, and Italian burnt sienna. American burnt sienna is a reddish-brown pigment containing from 25 to 60 per cent iron oxide (Fe2O3). One grade, found in Pennsylvania, analyses as high as 80 per cent and is mown as double strength sienna. Italian burnt sienna is a pigment generally containing more iron than the American product, averaging 60 to 75 per cent iron oxide.3 American pig- ments of the same iron content differ materially in shade, having a Havana- brown color, whereas the Italian is more of a maroon. Italian siennas when tinted with 20 per cent of white, show a bluish tint, whereas American siennas yield a brownish or yellowish hue. Raw umber, also known as Turkey umber, Levant umber, and terra ombra, is a greenish to yellowish brown siliceous and ferruginous earth, containing a considerable proportion of one or other of the higher oxides of manganese, Mng04 and MnO2." It is similar in many respects to raw sienna except that it is much coarser and contains more manganese oxide. All umbers contain over 5 per cent of manganese dioxide. Like sienna, umber is a permanent pigment, not being injured by light or by impure atmospheres. Burnt umber (velvet brown, chestnut brown, etc.), results from the calcination of raw umber. The color is much richer and warmer than that of the raw umber. The colors are equally permanent and can be used in conjunc- tion with all other durable pigments.

Sep 1, 1931

By J. L. Shultz

Mass spectrometric analyses were obtained for naphthalene and anthracene oils, heavy creosote, and three fractions of a pitch. The average molecular weight, aromaticity, and mean structural unit were determined for each fraction. The investigation of these fractions of coal tar has resulted in semiquantitative data for 38 structural types and carbon number distribution data for their alkyl derivatives. The molecular weights of 10 of these structural types indicate ring systems not previously reported in products from high-temperature carbonization of coal. Two of these structures are poly-nuclear aromatic hydrocarbons, two are oxygen-containing compounds, one contains sulfur, and five are nitrogen-containing compounds.

Jan 1, 1967

By E. W. Dean

A previous report of the Bureau of Mines* has supplied data for the physical and chemical properties of samples of crude petroleum produced in the eastern fields of the United States. It was issued as a preliminary chapter of a bulletin which is to cover the results of a survey of the entire country. The present report is a second preliminary chapter including figures that are available for the producing fields of the Rocky Mountain district. Work is being continued. with a series of samples from the States of Kansas and Oklahoma which will be described in a third preliminary chapter, to appear at a subsequent date. Acknowledgments. The obtaining of samples was rendered possible through the courtesy of representatives of a number of producing and refining companies operating in the Rocky Mountain district. The Bureau hereby acknowledges its appreciation of the hearty spirit of cooperation that was universally encountered.

Jan 1, 1921

By N. S. Dalal, X. N. Hu, X. Shi, V. Vallyathan

"Although silicosis has been studied extensively, the mechanism is still not fully understood. Experiments do provide evidence that the actions of unique properties of silica surface on the cell membrane are the starting point of silicotic processes. This paper summarizes literature on chemical properties of silica surface, and the effect of particle size on silica toxicity. This paper also discusses the ways in which silica dusts are thought to interact with the cell membrane, with emphasis on freshness, hydrogen bonding, and free-radical interactions.INTRODUCTIONSilicosis is a debilitating pulmonary disease that afflicts persons (miners, foundry workers, ceramic workers, heavy construction workers, etc.) who chronically inhale silica-containing dusts (Schepers, 1960; Silicosis and Silicate Disease Committee, 1988). Since silica is second only to oxygen in weight percentage of the earth's crust (about 28%) and is found in an enormous diversity of minerals, it is natural that silicosis is one of the major industrial health hazards all over the world. Although silicosis has. been studied extensively, the mechanism by which the dusts exert their toxic actions on cells and the processes by which these actions progress to fibrogenesis are still poorly understood. The biological characteristics of the dusts are largely unknown, although it is suggested that the dust size, shape, surface charge, roughness, surface chemical composition, trace metal content, and crystallinity; dose of silica in the ambient air of the workplace; duration of exposure; genetic variation in exposed subjects; personal respiratory patterns; and presence of any coexisting disease (such as tuberculosis or rheumatoid arthritis) all influence the expression of silicosis (Koskinen et al., 1983; Noweir et al., 1980; Raask and Schilling, 1980; Reiser and Last, 1979; Thorne et al., 1985; Wolff et al., 1981). The actual biochemical mechanisms through which these factors operate are still unclear. However, the experiments do provide evidence that the actions of certain unique properties of silica surface on the cell membrane are the starting point of the silicotic process (Allison et al., 1966; Allison and Harrow, 1971; Bateman et al., 1982; Marks, 1957; Parazzi et al., 1968; Reiser and Last, 1979; Summerton et al., 1977). This article summarizes literature on chemical properties of silica dusts and how silica dusts are thought to interact with the cell membrane, with emphasis on hydrogen bonding and free-radical interactions."

Jan 1, 1989