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By J. D. Davis

THE CARBONIZING properties of Chilton-bed coal from Lorado No. 5 mine, HE Logan County, W. Va., were determined by Bureau of Mines-American Gas Association tests at 600°, 700°, 800°, 900°, and 1,000° C. and by expansion tests. Chemical analyses, agglutinating and plasticity tests, and low- and high-temperature assays also were included in the investigation. Blends with low-volatile Pocahontas No. 3 coal were carbonized at. 900° C. The Chilton coal bed lies in the Kanawha, or Upper Pottsville formation of the Pennsylvanian system; the estimated original reserves are nearly 3.2 billion tons. The bed was 39/1 to 57 inches thick in the Lorado No. 5 mine, and the coal was 38 to 57 inches thick. The carbonization sample contained 62.6 percent fixed carbon on the dry, mineral-matter-free, basis, and the heating value on the moist, mineral-matter-free basis was 15,190 B. t. u. per pound; it therefore ranks as high-volatile A bituminous. It contained 1.8 percent moisture, 35.2 percent volatile matter, 57.9 percent fixed carbon, 5.1 percent ash, and 0.7 percent sulfur, as carbonized. The sulfur was largely organic, and the ash softened at 2,630° F. The agglutinating value determined on a silicon carbide-coal mixture of 15:1 was 6.8. In the Gieseler test the coal softened at 327° C., fused at 407° C., attained a maximum fluidity of 5,730 dial divisions per minute at 435° C., and solidified at 487° C. Maximum resistance in the Davis plastometer was 45.5 pound-inches.

Jan 1, 1951

By R. M. S. B. Horta, W. T. Roberts, D. V. Wilson

Evaluation of results obtained by the Harris method for inverse pole figures is discussed. Two existing analyses and a new approach are compared. In the most frequently used analysis, different reflections are accorded equal weight. A second method involves area-weighting of reflections, mainly to take account of nonuniformity of Pole distribution. In the new method, reflections are weighted according to their multiplicity factors. Intensity ratios obtained from a sample of steel sheet by the three methods are compared. INVERSE pole figures offer a convenient method of depicting the proportions of material with various orientations referred to a unique specimen axis. The technique was first applied to fiber textures, but it is now frequently used as a description of texture in sheet metal, the unique axis in this case usually being the sheet normal. The Harris method' for the determination of inverse pole figures has the great merit of simplicity. It suffers certain intrinsic limitations, but provided that these are borne in mind, the results allow useful conclusions to be drawn regarding the effects of texture components on certain mechanical properties. Much thought has been given to alternative methods of texture description, aimed at eliminating the ambiguity in the simpler methods.2"6 Refinements in the method of description are obtained at the price of increasing complexity, and it seems clear that a simple method, such as that of Harris, will continue to find application. The original derivation by Harris1 has been corrected by Morris7 and later by Mueller, Chernock, and Beck.2 Since the latter reference is more accessible, it is referred to more frequently than the work of Morris. Most users of the inverse pole figure method present their results on the basis of the treatment by Mueller et al., and it is the purpose of the present communication to comment on this treatment and to suggest a simple modification to the method of presentation which enhances the meaningfulness of the results. It will be convenient first to summarize the Mueller analysis as follows: The intensity Ihkl of a hkl reflection from a textured specimen is: Ihkl=CI0AL\Fhkl\2NhklPhkl [1] where C is a constant for a given sample I, is the intensity of the incident beam A is an absorption factor. With usual diffrac-tometer geometry and a flat specimen, A is inversely proportional to the density of the specimen. L is the Lorenz polarization factor Fhkl is the structure factor for the hkl reflection Nhkl is the multiplicity factor phkl is the fraction of crystals in the polycrystal-line aggregate with any particular (nkl) plane parallel to the surface. The corresponding equation for a specimen with randomly oriented grains is lR,hkl=CRl°ARL\fnkl\2Nnklk [2] the subscripts R indicating the factors that are different for the random sample, which will, in general, have a density different from that of the textured one. The intensity ratio is hkl , c A Phkl [3] IR,hkl CR AR PR The constants are eliminated by summing over all the measured reflections ^iRMi °R AR PR ljPkkl and from Eqs. [3] and [4] T IR,hkl The only unknown in Eq. [5] is Yj phkl and before this can be evaluated, it is necessary to adopt some form of normalizing procedure. Mueller et al. assume that when a large number, n, of reflections is used, the average value of p as defined by Eq. [6] below will be unity ? = £j**l3l [6] and the final result of their analysis follows: hkl Pkkl = i I&Jf~ [7] ±y* Ihkl ^ in,hki The normalizing procedure used by Mueller et al. involves an unrealistic assumption since it gives equal weight to each of the hkl reflections. Other normalizing procedures can now be examined with a view to selecting a more appropriate one. For an infinite number of reflections, the function p can be averaged over a continuous range of orientations covering the complete solid angle 4p by the integral relation: p =1 jp(a)dQ = l [8] This is the only exact procedure, but in practice a

Jan 1, 1970

By D. A. Rice

As part of its mission, the U.S. Bureau of Mines continues to develop technologies that will enable cost-effective compliance with environmental requirements. To this end, investigations to improve the kinetics of chalcopyrite dissolution by simultaneous grinding-leaching in ferric sulfate solution were conducted using the Bureau-designed turbo mill. The development of such a hydrometallurgical process would provide a nonpolluting alternative to conventional smelter technology. The effects of mill rotational speed and volume percent solids on the leaching time and energy required for copper extraction from chalcopyrite were evaluated. The results of this laboratory study have shown that the simultaneous grinding-leaching of chalcopyrite concentrate using the turbomill is technically feasible with essentially 100 pet extraction of copper being possible at 90° C. An optimal energy consumption of 1,153 kW?h/st of copper leached was found in batch testing with the mill operating at 400 rpm with a slurry containing 35 vol pet chalcopyrite. This energy consumption, while higher than other proposed leaching processes (about 600 kW?h/st), is of the same order of magnitude. Further refinement of the energy requirements would require additional testing using a continuous circuit. Leaching times of less than 1 h, for 80 pct copper extraction, are achievable using the turbomill grind-leach process.

Jan 1, 2010

By K. E. Stanfield

One of the initial projects under the oil-shale research and development phase of the Synthetic Liquid Fuels Act, Public- Law 290, 78th Congress, approved April 5, 1944, was a survey of oil shales of the United States for the selection of a site for an oil-shale demonstration plant. The oil shales were assayed by the conventional Bureau of Mines retort method proposed by Karrick and described by Guthrie in a more recent publication. From previous experience and that had in making these assays, it became evident that the assay method should be modified or replaced by a more satisfactory one. There are several outstanding objections to the Bureau of Mines oil-shale assay method: (1) the oil yields are frequently smaller than those obtained by other types of assay equipment and by commercial retorts; (2) the assayed oil yield represents only a portion of the organic matter in the shale, which under more favorable conditions, may, Jae converted, more completely into oil; (3) the retorting procedure is controlled mainly by trial-and-error methods; and (4) the assay requires approximately 6 hours for completion.

Jan 1, 1949

By W. R. Reed, J. P. Rider

"The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) recently developed a series of models using computational fluid dynamics (CFD) to study airflows and respirable dust distribution associated with a mediumsized surface blasthole drill shroud with a dry dust collector system. Previously run experiments conducted in NIOSH’s full-scale drill shroud laboratory were used to validate the models. The setup values in the CFD models were calculated from experimental data obtained from the drill shroud laboratory and measurements of test material particle size. Subsequent simulation results were compared with the experimental data for several test scenarios, including 0.14 m3/s (300 cfm) and 0.24 m3/s (500 cfm) bailing airflow with 2:1, 3:1 and 4:1 dust collector-tobailing airflow ratios. For the 2:1 and 3:1 ratios, the calculated dust concentrations from the CFD models were within the 95 percent confidence intervals of the experimental data. This paper describes the methodology used to develop the CFD models, to calculate the model input and to validate the models based on the experimental data. Problem regions were identified and revealed by the study. The simulation results could be used for future development of dust control methods for a surface mine blasthole drill shroud. IntroductionIn surface mines, production drilling is an essential process in blasting to fracture the hard rock overburden for removal. During the process, considerable amounts of respirable dust are produced. Past sampling at the shroud area of blasthole drills had documented time-weighted-average respirable dust concentrations ranging from 8.68 to 95.15 mg/m3 (Organiscak and Page, 1995) and 1.04 to 52.30 mg/m3 (Listak and Reed, 2007). These high dust concentrations, which may contain silica, can lead to respirable dust overexposures for the miners working nearby. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is ultimately fatal.Two basic methods are used to control drilling dust: a wet suppression system or a dry collection system (Cecala et al., 2012). Dry drilling techniques using a dust collection system are preferred in rural mining locations where a constant water supply is not available, and in the case of rotary drilling where water is associated with accelerated bit wear due to bearing degradation and hydrogen embrittlement. In addition, dry drilling eliminates freezing-related issues with water in colder climates. Dry dust collectors are highly effective at removing dust, especially the finer material, as long as they are properly operated and maintained (Listak and Reed, 2007; Organiscak and Page, 2005)."

Nov 1, 2016

By Elgin D. Bell

Within the next, year or two, Western Canada should overtake Mexico and France. to become the worlds second largest producer of elemental sulphur, surpassed only by the United States, By 1965, it should produce about 25% of the world's total elemental production and, about 10% of sulphur produced in all forms. In 1952 Alberta had but one small sulphur recovery plant. By 1962, it had fifteen plants with a total designed capacity of almost 6,000 long tons of sulphur per day and actual production of almost one million long tons per year. This decade of dynamic growth was the result of Alberta's rapidly developing natural gas industry. More particularly it was the result of approval in 1960 to export natural gas in large volumes into the United States. Prior approval to export gas from Alberta to eastern Canada and relatively modest volumes to the U. S. had resulted in the construction of several plants but none were of the scale required to serve the U. S. market.

Jan 1, 1963

By C. P. Mabie

This report summarizes studies by the Bureau of Mines in developing a simple method for estimating the phosphorus pentoxide (P205) content of finely ground sedimentary phosphate ores and beneficiated products. The method used involved leaching, filtration, and precipitation. The Bureau found that measurement of the volume of ammonium phosphomolybdate precipitate obtained from samples containing 16.8 to 37.7 percent P205 and the use of an appropriate calibration curve permitted estimates of percentage of P205 content accurate within ± 1.1 to ± 2.6 percent, respectively, at the 95-percent confidence limits. Incidental to mineral dressing and petrographic investigations of western phosphate ores in 1959, the Bureau of Mines undertook development of a simple process-control method for rapid on-the-spot evaluation of phosphate-mineral recovery. Because of the fine-grained and obscure character of western phosphate ores, chemical, rather than microscopic or petrographic, techniques were investigated. The described method involves acid decomposition of the ore or product, filtration, addition of ammonium molybdate reagent to the filtrate, and centrifuging and measuring the volume of yellow ammonium phosphomolybdate precipitate produced.

Jan 1, 1961

By W. A. Cole

This report covers the preliminary phase of an investigation of some clays and shales and other materials in North and South Dakota to determine the feasibility of lightweight -aggregate manufacture in the two States. The background of the light - weight -aggregate industry, on a national basis, and results of preliminary laboratory testing of samples of North and South Dakota clays and shales from various localities are presented herein. The countrywide search for lightweight aggregates was necessitated toward the end of the 19th century by the change in building design from thick, heavy, load- bearing walls to a framework of structural steel .beams and columns with thin walls, followed shortly by the use of reinforced concrete and structural concrete as materials for the load-supporting frame. Ordinary concrete, with sand and gravel aggregate, weighs about 150 pounds to the cubic foot. A lighter concrete was needed to relieve the dead load and make it possible to construct higher buildings or add stories to existing buildings.

Jan 1, 1954

By H. B. Brunot

On April 26, 1949, the Bureau first approved a machine designed to replace the cycle of cutting, blasting, and loading coal by a single operation. This machine took the coal directly from the solid face and delivered it to transportation equipment. By January 1, 1955, 30 approvals for designs of machines of this type had been granted by the Bureau. In the main, this paper describes briefly the action of the various designs approved as permissible. In addition, the approval number, the date of approval, the voltage of the power supply, the number and character of the explosion-proof accessory parts, the size of the trailing cable, and the overcurrent protection at the outby end of the trailing cable are given for each design. Since no similar information has been published by the Bureau, it is hoped the material in this paper will be valuable in giving the mining public an organized look at the various machines of this nature that have been approved as permissible by the Bureau.

Jan 1, 1956

By Anthony D. Szpak

The purpose of this program was to demonstrate the feasibility of Illuminating various types of underground coal mining machinery as required by the Federal Coal Mine Illumination Standards Part 75.1719 to 75.1719-4 Code of Federal Regulations Title 30. Nine various machines were illuminated and the illumination systems were evaluated for a 3 month period of operation. Factors evaluated were ease of implementation, reliability, ease of maintenance, acceptance by mine workers and operators, Illumination degradation and durability.

Jan 1, 1981

By Robert M. Jimeson

The competitive market potential for solvent refined coal is estimated. Market advantages of solvent refined coal are enumerated. Markets are possible in combustion, railroad locomotion, and carbon electrodes. The combustion characteristics are consistent with expected air pollution restrictions on the emission of sulfur and particulate matter. A market potential of sufficient size exists to support the initiation of solvent refining in the United States. The market analysis should help fuel producers determine the advisability of their undertaking the solvent refining of coal.

Jan 1, 1969

By Rexford D. Singer

The purpose of this study was to evaluate the current literature on the use of calcium chloride and ligninsulfonates as dust suppressants with respect to potential adverse effects on health or the environment. Calcium chloride poses little internal hazard to man and animals, but toxicity to vegetation in and around the area of application should be expected. The effects, however, should be considerably less than those observed from using calcium chloride as a road deicer. Except for trout, ligninsulfonates seem to pose little direct systemic toxicity problems in aquatic organisms, animals and man or any problem with local vegetation. Because of a greater volume of information on its use and effects, calcium chloride is recommended over ligninsulfonates.

Jan 1, 1982

By Amy Anderson

The Silica (SME) Technology has been utilized on three separate projects focusing upon the stabilization of mercury-contaminated materials: at the Mother Lode Mine in Oregon, the Sulfur Bank Mercury Mine in California and at a former chloralkali plant in British Columbia. Each of the projects relied primarily on the results collected via EPA Method 1311 TCLP, with additional tests such as SPLP, humidity cell tests and other supporting tests employed as well. Both technical and economic performance of the silica-based technology was evaluated as well as that of competing technologies in some cases. Results established that in each of the three projects an SME chemical dosage rate of 3% chemical by weight of soil/sludge was the optimal ratio required to achieve project treatment objectives, TCLP test results exhibited a reduction in the leachable mercury from the treated materials ranging between 75% and 99% as compared to untreated material, satisfying the technical objectives for each project, Project costs ranged from $l5.00 - $18.26 per metric ton.

Jan 1, 2003

By Eric Pirard

Theoretical studies carried out on shape analysis supply mathematical tools to analyze the influence of grain shapes on ore beneficiation. In the case of statistic images like those encountered in applied mineralogy parametrical and harmonical analysis methods are used. It is important that the shape parameters are adapted to the specific processes involved in ore beneficiation, while remaining easy to manipulate. The inertia parameters are considered in the scope of granulometric and gravimetric processes It appears that they are able to distinguish between the resulting products where very popular shape parameters are not. The measured statistics are analyzed through discriminant analysis procedures in order to estimate the importance of morphological differentiation and the aptitude of shape parameters to account for this.

Jan 1, 1989

By O. H. Metzger

This is one of a series of papers being published by the Bureau of Mines on mining areas and districts in the Western states. It describes mining and milling practices in the vicinity of Wickenburg in Maricopa and Yavapai Counties, Ariz. ACKNOWLEDGMENTS The author acknowledges the aid and cooperation of the operators of the mines visited. Reports of geologists and engineers who previously visited the area were drawn upon freely. Individual acknowledgments are made in the text.

Jan 1, 1938

By A Giblett, B Putland

This paper provides a simple guiding framework for grinding circuit optimisation, focussing on common themes in past optimisation success stories, the conditions for success and techniques that can be employed to identify and define opportunities. Many significant grinding circuit improvements have been reported for operating plants, based on recurring themes such as the optimisation of mill feed size, mill liner design, process control, critical size, grinding media and classification. The paper condenses these experiences into a set of simple questions for the operator to ask, and provides guidance towards identifying and achieving the optimisation goals.CITATION:Giblett, A and Putland, B, 2018. The basics of grinding circuit optimisation, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 129–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Robert W. Metcalf

The feldspars are a series of related aluminum silicates containing varying proportions of potash, soda, rind lime; smaller amounts of other minerals arc likely to be present as impurities. They comprise three principal types: Potash spars, microline and orthoclase (KA12Si208); soda feldspar or albite (NaA1Si308); and soda-lime e (plagioclase) fellspars. The last-named is an intermediate group ranging from albite through oligoclase, andesine, labradorite, and bytownite to anorthite or line feldspar (CnA12Si2O8), Minor varieties are barium feldspar or celsian and a potash-barium feldspar. Perthite is a mixture of orthoclase end albite in alternate layers. Graphic granite or "corduroy spar" is an intergrowth of feldspar and quartz characteristically in the ratio of 3:1. Cornwall stone is a natural mixture of feldspar, quartz, end kaolinite imported in former years in sizable quantity from Cornwall, England. (A similar synthetic mixture, including some fluorspar, has been blended and marketed in the United States as "Carolina stone".)

Jan 1, 1941

By R. B. Ngenda

The ?Kolwezi Zinc Plant?, in French ?Usines à Zinc de Kolwezi? (UZK), has produced about 910 000 dry metric tons of residues during the hydrometallurgical treatment of calcines from sulphide zinc concentrates. The zinc hydro plant residues contain on average 19.47% Zn, 2.7% Cu, 2.1% Pb, 26.6% Fe, 0.12% Cd, 0.39% As, 157ppm Ag, 447.8 ppm Ga, 475.4 ppm Ge, etc. This material was dumped in five ponds in the vicinity of the plant. The high Fe content in the ore concentrates induced important conversion of some of zinc and copper into ferrites during the roasting process. Those ferrites are very stable compounds, which are difficult to leach with dilute sulphuric acid solution. Therefore, they mainly report to the leaching residues. Hot leaching has been successfully applied to the treatment of zinc hydro plant residues. The method, however, presents the disadvantage of simultaneously dissolving iron(Fe). It is then necessary to remove an important iron quantity from solution prior to zinc and other metals recovery.

Jan 1, 2009

With a total value to date of well over $200,000.000.00 for its ore production, the Tintic mining district, which is about 100 miles southwest of Salt Lake City, ranks as one of the three main ore producing areas of Utah. In it are located the biggest silver mines of the country, silver having been the chief metal produced in the camp since its start. Tintic's silver production to date has a total value of over $1 00,000,000, approximately half of the value of the camp's ore production, the balance being roughly divided among lead, gold and copper. Discovery of the camp was made in the late sixties. Lack of transportation and ore reduction facilities delayed extensive development of the area for nearly a decade. In recent years Tintic's ore production has ranged from 350,000 to 400,000 tons annually. In 1924 the camp produced one-eighth of the silver produced in the nation with an output of 7,729,700 ounces. Its lead production was 77,765,000 pounds and its gold production 26,285 ounces.

Jan 1, 1925

Ok Tedi Mining Limited has recently completed the first phase of a trial to compare the performance of D26B Krebs cyclones in different configurations to the new Warman 650 mm CAVEX cyclones. From 1992, rougher flotation feed size has increased from the target d80 grind size of 150 ¦m with increasing SAG mill throughput. At high SAG mill throughput, operators have difficulty maintaining the target cyclone feed pressure and must increase the cyclone feed density, thus resulting in a coarsening of the cyclone split. Warman International have developed the CAVEX high capacity cyclone. The new CAVEX cyclones, when compared to the Krebs units appear to:produce a measurable increase in volumetric flow for the same pressure drop; maintain or decrease the proportion of coarse particles reporting to overflow; and lower the overflow density. In all plant trials to-date, the CAVEX cyclones appear to be superior to the standard Ok Tedi Krebs cyclones. Further testwork is planned to evaluate modified Krebs cyclones (with recent design improvements) against the CAVEX cyclones.

Jan 1, 2000