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By E. G. Davis

Large-scale ultrafine grinding tests of a coarse kaolin were made using the Bureau of Mines developed attrition grinding process in continuous open-and closed-circuit systems. A 20-inch diameter attrition grinder, designed and constructed at the Tuscaloosa Laboratory, was used. Studies included single- and multiple-stage open-circuit grinding, and also continuous grinding tests in closed-circuit with a 6-inch-diameter solid bowl centrifuge. Clay feed, containing 9.0 percent minus-2-micrometer esd, was used at fates up to 840 pounds per hour. Multistage grinding tests gave better results than single-stage treatment when equivalent clay feed rates were used. Closed-circuit grinding tests yielded ground products containing slightly more minus-2-micrometer-esd clay than the open-circuit grinding when using the same clay feed. Energy consumption was lower in closed-circuit grinding than in batch or open-circuit grinding. A modified two-stage closed-circuit grinding system gave the best grade of product and amount of minus -2-micrometer-esd clay produced per pound of clay feed. The ground product from this test contained 88.5 percent minus-2-micrometer-esd material and electrical energy consumption was 327 kilowatt-hours per ton of minus-2-micrometer-esd material produced.

Jan 1, 1973

By J. S. Dunning

The objective of this research by the U.S. Bureau of Mines was to determine the effects of AI additions on the sulfidation resistance of Fe-Cr-Ni alloys. A series of Fe-Cr-Ni alloys with and without -additions of 4 pet AI were tested in a wet S vapor atmosphere at 677 C. A study of the morphology and composition of corrosion scales indicated a different corrosion mechanism for AI-free alloys compared with AI-containing alloys. Aluminum-containing alloys formed a compact, tightly adherent layer at the metal-scale interface that reduced corrosion rates by a factor of 3 to 10 compared with that of AI-free alloys. The thin, adherent AI-containing scale limited inward diffusion of 0 and S to the base metal and outward diffusion of Ni from the base metal. Aluminum-containing alloys formed a three-layer scale in oxidizing-S environments, while AI-free alloys formed a less protective two-layer scale.

Jan 1, 1989

By E. C. Baker

Costs of disposing of steel slag are estimated based on the present method and a proposed alternate method for a steel mill in the Pittsburgh area. Estimated cost data were calculated by the Bureau of Mines and do not reflect the investment and operating costs and credits of a specific steel mill and processing plant. The alternate method of steel slag disposal would result in an appreciable cost savings to the mill and concurrently supply the industrial and commercial markets with low-cost, high-quality construction materials.

Jan 1, 1970

By Ellis S. Hertzog, James R. Cudworth

Tremendous interest has been evidenced in the subject of dewatering and drying ooal for the past 10 years, and yet little effort has been made to summarize the literature, at least so far as this country is concerned. Only a few published articles have dealt solely with dewatering and drying coal. In most cases the subject has been discussed briefly, either in general terms or as to specific installations. It is desirable that a compendium be prepared collecting in one place information on the dewatering and drying of coal, the needs for this process in various fields, the available equipment, and the current American practice in regard to it. This work was underta..lten by the :Bureau of Mines in cooperation with the University of Alabama. New coal-washing plants in which various types of dewatering and drying equipment were in operation were visited in-Pennsylvania; Ohio, India...~a~ and Illinois. The dewatering·and drying of coel has .been studied in this coimtry by the Surface Preparation ·Committee of the ·coal Operato~s• Committee of the .American Mining ·Oongress. In GermaIJY .it has received the special attention of the Reichskohlenr·at, and in Great Britain of the Utilization of Fuel Commi-t-tee of the Insti ti.ite of Min"ing Engineers.

Apr 1, 1938

By G. R. Peterson

To determine the availability of aluminum from world bauxite resources, the Bureau of Mines investigated 139 bauxite deposits worldwide and evaluated the potential production of aluminum based on the demonstrated resources of bauxite ore from 91 mines and deposits in 22 market economy countries. The demonstrated resources of the bauxite mines and deposits included in this study represent an in situ resource of 20.2 billion metric tons of bauxite. Total identified bauxite resources in market economy countries amount to roughly 31.9 billion tons. Of the demonstrated resource, some 18.8 billion tons of bauxite considered minable provide a production potential of 3.6 billion tons of primary aluminum. Given the wide geographic distribution of bauxite deposits, stable supplies of bauxite for aluminum production seem assured well into the next century. However, a tight market situation could develop during the 1990's unless the real price of aluminum increases enough to stimulate massive new investments in production capacity, particularly in refining and smelting. This study indicates that a real price of at least $0.85 per pound (in January 1980 dollars) would be necessary to stimulate the required investments and provide a sufficient rate of return on invested capital.

Jan 1, 1983

By Donald W. Mitchell

Certification tests for urethane-foam systems and techniques for apply-ing foam safely in mines are described. Fire hazard from foam exists if flame propagates beyond the ignition source or penetrates the foam. Foam that passes the certification tests can be applied on stoppings, continuous sections of ribs of relatively wide passageways (with no foam on the roof), short sections of roof such as overcasts, roof cavities, and intersections (with no foam on the ribs), and between buntons on one wall of a shaft. Foam on the ribs and adjoining roof presents a fire hazard. Stoppings covered with foam passing the certification tests are resistant to penetration of heat, flame, and smoke than similar stopping without foam. Flame propagation can be arrested by water sprays. Spontaneous ignition of foam can be prevented.

Jan 1, 1966

By William C. Cooley

A review was made of two Russian books and a chapter from a third book dealing with pipeline transport of coal. Emphasis was placed on hydrotransport of coarse coal in underground mines or surface pipelines. The books reviewed were: "Means of Increasing the Effectiveness of Hydrotransport," by V. N. Pokrovskaya (1972), "Parameters and Modes of Hydraulic Transport of Coal" by V. V. Traynis (1970), and the chapter "Calculations of Hydrotransport of Useful Minerals and Waste Rock" from the book "Hydromechanization of Opencast Workings" by G. A. Nurok (1970). All three are unique and useful additions to the world literature on hydrotransport. The Traynis book reveals the development and results of circular wheel stand tests to simulate hydrotransport in horizontal pipes, which is a potentially outstanding contribution to slurry pipeline technology. Graphical data and equations are presented which suggest that headlosses for coarse coal can be predicted with good accuracy for pipe sizes up to 14 inches in diameter. Wheel stands permit tests for pipe wear and lump degradation without recycling coal through pumps. Recommendations are made for wheel stand tests and for correlation of existing data.

Jan 1, 1976

By Max J. Spendlove

This Bureau of Mines publication reviews current recycling trends in the United States. Although near-term prospects are poor for recycling most present wastes, urban refuse is an important exception. Such wastes comprise a mine above ground, and much less processing energy is normally required to recycle the constituents of urban ore than to obtain them in equal amounts from natural raw materials.

Jan 1, 1976

By T. T. Campbell

This report traces the development of techniques for the preparation of high-purity rare-earth metals. Rare-earth metals, excepting samarium, europium, and ytterbium, were prepared by converting their oxides to anhydrous chlorides or fluorides and reducing the rare-earth halides with active metals such as lithium or calcium. High-purity, anhydrous rare-earth chlorides were prepared by dissolving the rare-earth oxides in hydrochloric acid to form hydrated chlorides and by subsequently dehydrating the hydrated salts in the presence of ammonium chloride at temperatures ranging from 70° to 360° C. while under reduced pressure (50 microns to 1 inch Hg). The chlorides were also prepared by direct chlorination of rare-earth oxide-carbon mixtures. Reaction efficiencies in excess of 95 percent were obtained by either method; however, purer chlorides were prepared by the aqueous ammonium chloride conversion method. Purification of yttrium chloride by high-temperature vacuum distillation proved to be an effective method of separating, oxygen-bearing compounds from the chloride. Yttrium metal prepared from purified chloride contained significantly smaller amounts of oxygen (990 p.p.m. oxygen in yttrium metal prepared from raw chloride and 200 p.p.m. in that prepared from distilled chloride).

Jan 1, 1961

By J. M. Singer

Thermal, mechanical, and physical properties of virgin and heat-treated Pittsburgh seam coal were determined as part of a comprehensive study of combustion of monolithic coal block. The information was sought to help characterize pyrolysis and combustion processes in underground coal mine fires but should also prove useful in the study of in situ and surface coal gasifiers. Measured properties include thermal conductivity, specific heat, thermal expansion, density, compressive and tensile strength, porosity, and permeability. The transport property data were obtained (when feasible) in two mutually perpendicular directions of the anisotropic virgin coal material, and coal samples carbonized for 5 hours at temperatures of 350° C, 475° C, 500° C, 650° C, and 850° C. Other coals (Pocahontas No. 3, Sewell, and Illinois No. 6 seams) were investigated for porosity and relative permeability. Interdependence among all properties was evident from the results; however, only a few correlations could be developed owing to inhomogeneity of coal material and specimen variation, which had the effect of reducing the accuracy of measurement and increasing data scatter.

Jan 1, 1979

By H. B. Hill

The discovery of the Oklahoma City field and its rapid development into one of the major oil-producing districts is an outstanding epoch in the history of the petroleum industry not only of Oklahoma but also of the United States. The relatively great depth to which the wells were drilled and the large initial production of high-gravity oil are of special significance. The field has boon under proration almost from the time that its development began, and many new production problems have developed out of the changed conditions of operation. The discovery well was first tested in December 1928 at a depth of 6,402 feet, with an initial production of 4,847 barrels of 38,5.° A.P.I. gravity oil, and several months later was, completed at a depth of 6,624 feet, The large initial production, the high pressure, and the large gas volume in the different horizons of the discovery well suggested the potential possibilities of gas and oil, production in formations of Pennsylvanian and pre-Pennsylvanian age.

Jan 1, 1933

By W. R. Crane

Recent papers on support of roof and top rock in mines representing present practice in so far as it hits been described by engineers in all of the principal mining countries, cover a relatively aide range of topics. The papers abstracted herein include such subjects as the testing of materials of support, failure and movement of rock above workings, effect of excessive pressures on rock masses, axed the application in mines of timber, metal, concrete, packing, and filling support. It is not within the scope of this paper to present a logical and orderly discussion of the elements of support and their application to conditions influenced by the material worked or the method of mining. Only the essential facts of a paper appear in the abstracts, the idea being to give a fairly clear picture of the behavior of various types of support under brows conditions and to put into concise form important information concerning present practice, modifications of practice, and the trend toward new practice. With such valuable facts from others experience made readily available, it Is hoped that the engineer with particular and often trying problems may obtain suggestions that will be immediately helpful.

Jan 1, 1932

By C. A. Herbert

Information Circular 6746 reviewed the fatalities in Indiana coal mines. for the fiscal year October 1, 1951 to September 30, 1933. Since then Indiana has changed its fiscal year to the period July 1 to June 30, but as most statistical data on accidents are arranged according to calendar years, the data in this paper are for the last 3 months of 1932 and the calendar year 1933, rather than for the new Indiana fiscal year. Tables 1 and 2 list the fatalities in Indiana coal mines3/ by cause and occupation for the last 3 months of 1932 and for the calendar year 1933. The fatalities for the small wagon mines employing fewer than 10 men are separated from those employing 10 or more men to call attention to the ex- tremely high fatality rate in small mines, largely because the State mining law does not apply to them nor do they come under the jurisdiction of the Indiana mine inspectors; as a result health and safety conditions are ex- tremely bad. During the last 3 months of 1932, 5 (approximately 42 percent of the total) fatalities occurred in the small mines, while for the calendar year 1933, 12 (approximately 32 percent) of the fatalities occurred in them. The Indiana Division of Mines and Kining estimates that these small mines have an annual production of approximately 325,000 tons, or about 4.5 percent of the total coal-mine production of the State. In other words, for these small mines the fatality rate per tons mined during 1933 was about 10 times as great as for the mines employing 10 or more men. Another lamentable feature in connection with the fatalities in small mines is that very few carry any compensation insurance and the owners are not worth enough financially for dependents of victims to collect anything under the common law; as a result, the dependents of those killed usually are left penniless and subjects of public charity.

Feb 1, 1935

By H. B. Salisbury

As a part of a research program designed to help minimize national requirements for new mineral commodities by maximizing recovery of metals from domestic secondary resources, the Bureau of Mines investigated the development of economic methods for recovering copper and associated metals from complex electronic scrap. Three types were selected for research: (1) multiple-pin plugs and connectors, (2) obsolete aircraft radio assemblies, and (3) the magnetic fraction of shredded electronic scrap furnished by the Bureau's Avondale Research Center. The plugs and connectors, after incineration to remove plastic components and melting, yielded a brittle ingot, as did the internal portion of the radio assemblies. The brittle ingots were ground to minus 35-mesh for processing, and the magnetic material was used in the as-received condition. A process using pretreated or raw scrap as a copper precipitant in various concentrations of acidulated copper sulfate solution was developed as a means of effecting an initial separation and upgrading in the form of high-grade cement copper containing all or most of the precious metals.

Jan 1, 1981

By R. R. Wells

As a part of the strategic mineral program, examining engineers of the Bureau of Mines collected samples several manganese properties in Colorado. As all of the ores were too low-grade to be acceptable to manufacturers of ferromanganese, beneficiation studies were required .to determine the amenability of the ores to concentration. Manganese in the form of impregnations in sedimentary beds is found in the Denver plains area a few miles east of the Rocky Mountain front. Deposits are reported to occur intermittently over a distance of more than 200 miles. The manganese oxides occur in beds of conglomerate or arkosic sand, generally accompanied by limonite. The Manganese and iron oxides,, however, usually are found in separate layers. Three samples were submitted for beneficiation tests, two samples from Buckley Field bombing Yang, Arapahoe County, and one from near Franktown, Douglas County.

Jan 1, 1952

By E. F. Ferrell

Electrowon molybdenum powders and a commercial hydrogen-reduced powder, all with different minor impurities, were investigated by the Bureau of Mines with respect to inherent properties, to fabrication techniques, and to proper-ties of the fabricated sheet. Compared with the commercial hydrogen-reduced powder, the electrowon powders had a larger particle size, a greater flow rate, a higher apparent density, and a lower oxygen content. Sheet materials prepared from the two types of powders showed similar mechanical properties, under the same conditions of heat treatments, except for low-temperature ductility. Yield strengths varied with carbon content, heat treatment, and test temperature.

Jan 1, 1970

By Gary P. Sames

This U.S. Bureau of Mines study was conducted in eastern Kentucky drift mines as part of an ongoing research program to characterize the outcrop barrier zone. "Hillseams" were identified as the dominant geologic cause of roof instability unique to the outcrop barrier zone, with many roof fall injuries and fatalities attributed to them. Hillseam is the eastern Kentucky miners term for weather-enlarged tension joints that occur in shallow mine overburden where surface slopes are steep. Hillseams are most conspicuous within 200 ft laterally of a coalbed outcrop and under 300 ft or less of overburden. Hillseams form by stress relief, and therefore tend to parallel topographic contours and ridges. They can intersect at various angles, especially under the nose of a ridge, and create massive blocks or wedges of roof prone to failure. Examples of hillseams are described in both outcrop and in coal mine roof to establish their geologic character and contribution to roof failure.

Jan 1, 1989

By Albert E. Long

During the summer and fall of 1948 the Bureau of Mines, in cooperation with the U. S. Geological Survey, conducted 6xperiments in diamond core drilling in the Phosphoria formation in southeastern Idaho and southwestern Wyoming. Nearly all of the diamond core drilling in the Phosphoria formation has been done by mining companies interested in finding and developing phosphate-bearing beds amenable to stripping. The recovery of sludge; and enough core (usually 30 to 60 percent) to identify certain marker beds produced by current drilling practices meets both the primary requirement of mining companies in determining depth of overburden and their secondary need to determine the phosphate content of relatively thick minable units whose general composition and nature are already fairly well established.

Jan 1, 1949

By Florence L. Feicht, H. H. Schrenk, Carlton E. Brown

This report describes the dropping - mercury electrode , its use in analysis , and the procedure of the Health Division of the Bureau of Mines in determining lead , cadmium , and zinc . The dropping - mercury electrode or polarograph is an electrolytic device , one electrode of which consists of mercury issuing in small drops from a capillary tube . Such electrodes have been in existence for more than 50 years, but they were not used for analytical purposes until about 1922.6/ Developments since have been rapid , especially in Czechoslovakia , Germany , Italy, and Japan and more recently in the United States . A recent bibliography / contains references to, 825 articles issued from 1903 through 1940. In 1939 Kolthoff and Lingane presented the first comprehensive critical review, in English , of the device and its use in analysis . They have recently issued a book on the same subject. Similar information also is included in a recent book10/ by Kolthoff and Laitinen . Much of the information in this and the two following sections on this device and its use in analysis was obtained from these three publications . The use of the dropping - mercury electrode in analysis is based upon the fact that the kind and amount of electro - reducible and electro - oxidizable constituents in solution can be determined from the current -voltage relationships revealed by this electrode or electrolytic device .

May 1, 1942

By Shirley F. Colby

Much interest has been shown recently in the possible utilization of dolomite as a source of magnesium metal, a large production of which is deemed essential for national defense. As a result, many inquiries have been received by the Bureau of Mines as to sources of dolomite. This report has been prepared primarily to augment the Bureau's present published information on the occurrence of high-grade dolomite deposits in the United States. To supplement such data, the report also defines dolomite and related rocks and describes their properties and uses. The uses are covered in some detail in Information Circular 6524 entitled "Utilization of Dolomite and High-Magnesium Limestone," published in 1931 but now out of print. All essential data on uses contained in that report have been incorporated herein, and. have: been supplemented by data developed during subsequent years. DEFINITION Dolomite is a mineral composed of calcium end magnesium carbonates combined in equal molecular proportions, expressed by the formula CaMg(C03)2. Dolomitic limestones contain considerable dolomite but also include either

Jan 1, 1941