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By S. J. Page, R. A. Jankowski, J. A. Organiscak

The U.S. Bureau of Mines investigated the relationship of bituminous coal seam parameters and the amount of airborne respirable dust generated at longwalls. Dust and coal samples were obtained from 20 longwalls operating in geographically representative coalfields throughout the United States. Statistical analyses of coal seam parameters and airborne respirable dust measurements indicate a likely causal relationship between seam type and respirable dust. Low-ash, high-volatile coal seams were associated with higher airborne respirable dust levels. A negative linear correlation (significant at the 95-pct confidence level) was observed between the seam's ash content and airborne respirable dust, explaining up to 18 pct (R2 = 0.18) of headgate dust level variation and up to 15 pct of tailgate dust level variation. Volatile matter was found to have a positive linear correlation with tailgate dust level, explaining 16 pct of the variation. Further data examination indicates that these relationships with dust are most likely nonlinear, because of improved R2 values over the linear correlations. However, a notable portion of longwall dust production is influenced by other operational parameters, so additional research under more controlled conditions is needed to determine the seam's causative functions.

Jan 1, 1992

By Sidney Speil

In the study of clays and related minerals, the analytical techniques commonly employed in mineral analysis are not always applicable. The X-ray examination of a clay sample usually will show the major constituents, but often minor· clay impurities will not be detected because of line broadening and the similarity of the main lines of clay· mineral diffraction patterns, The petrographic analysis of clay minerals with clay particles as small as a few microns is usually difficult. With still smaller particles, a gross effect often is noted in which a mixture of several constituents gives the appearance of a single constituent with the mean optical-characteristics of the mixture. 3/ The electron microscope has recently been used to study clay particle shapes of various aluminosilicates. 4/ However, this method has not yet been sufficiently explored. The Chemical method in which a mineralogical analysis is calculated from the oxide chemical analysis has been discussed by Wilson 5/ and others, and many of the shortcomings have been pointed out. It should also be recognized that the variable alkali and alkaline earth content of bentonites makes it inaccurate to assign these basic elements arbitrarily to feldspar or mica in any clay that contains appreciable bentonite.

Jul 1, 1944

By L. V. Clark, Arthur La Motte

"INTRODUCTION The U. S. Bureau of Mines in 1930 and 1931 made a study of the properties and characteristics of liquid-oxygen explosives (L.O.X.) at the request of one of the largest users, in order to determine and eliminate the hazards attending its use.This report deals with the examination of absorbents for L.O.X. to (1) determine their most desirable and most undesirable characteristics, (2) to find ways and means of desensitizing absorbents to mechanical shock, and (3) to determine the effect that such desensitization of absorbents has on the explosive Characteristics of L.O.X.ABSORBENT MATERIALS The absorbent used in driving the Simplon Tunnel, the earliest project in which L.O.X. was used, was composed of crude petroleum, soot, and kieselguhr. During the World War, powdered cork, soot, sawdust, powdered straw, or other similar powdered materials were mentioned in the German military instructions for use of ""liquid air"" explosives. At that time the common types of absorbent, materials were compounded ones containing the above ingredients as well as kieselguhr, paraffin, gas oils, charcoal, bituminous coal, etc.Kuryla and Clevenger4 investigated absorbents of the above type and made the following statement concerning them:"

Apr 1, 1932

By Francis J. Kelly

This Bureau of Mines study was made to obtain and present facts concerning the production and marketing of rare-earth metals and thorium in the Central and Southern Rocky Mountains (Arizona, Colorado, New Mexico, Utah, and Wyoming, referred to in this report as the region) and to review the current demand for these elements in the United States. Little or no published information was available on the marketing practices for these commodities. As a result of many inquiries from industry, potential prospectors, and the general public, the various factors of resources, production (present and potential), marketing, and consumption have been investigated, and the results are set forth in this report. Material concerning occurrences and deposits is from published references detailed in the bibliography.

Jan 1, 1962

By Kenneth O. Bayard, John D. Sullivan

"This repot continues the series of papers being prepared at the Southwest Experiment Station of the Bureau of Mines in cooperation with the department of mining and metallurgy, University of Arizona, on factors involved in the leaching of ores. A list of previous publications is given in the bibliography at the end of this paper.Four factors are essential to the leaching of any copper-bearing ore: (1) A solution that will attack the copper minerals must get into the body of the ore particles; (2) the copper minerals must be dissolved by the solution; (3) the solution containing the dissolved copper must find its way out of the voids of the rocks into the main solution; and (4) the copper in solution must be recovered by some means of precipitation.This paper considers the third step -- the extraction of the water-soluble copper. From leached ores. The usual commercial practice in leaching copper ores consists of: (1) Crushing the ore to pass through a screen with approximately one-quarter or one-third inch openings; (2) charging the crushed ore into a fat; (3) adding, usually by upward percolation, a solution that will attack the copper minerals; and (4) washing the copper-laden solutions out of the ore with solutions weaker in copper than the pregnant solution, and finally with water. A countercurrent system of leaching and washing is usually employed. In some plants the solutions are circulated during leaching and washing, and in others they are not. In some plants the wash solutions are added by upward percolation, while at Chuquicamata the so-called ""piston-displacement"" method of washing is employed.The following condensed resume of the leaching cycle of the plant of the Inspiration Consolidated Copper Co. is given to present to the reader a picture of the steps involved in a typical leaching cycle. This plant was recently described in detail.4 The ore, crushed to pass openings 11/2 inches in diameter, passes over a screen with ¼-inch openings. The undersize from the screen goes to a Dorr howl classifier that removes the primary slime from the circuit. The overflow from the classifier is treated in a slime-leaching plant. The oversize of the ¼-inch screen passes through rolls, where it is crushed to pass a 3/8-inchscreen. The undersize from the 3/8-inch screen join with the coarse material from the classifier, and the combined products become the feed to the leaching vats. There are 13 concrete lead-lined leaching vats. The complete leaching cycle is 13 days. Eight tanks are under acid-iron content at all times; three are being washed, one tank is being filled, and the one is being excavated. The electrolyzed solution from the tank house, to which amount of new acid has been added, is put on the oldest tank of ore under need This solution travels from tank to tank and finally emerges from the newest ore"

Apr 1, 1931

By T. O. Llewellyn

The Bureau of Mines conducted batch-?scale tests on a sample of parphyry copper mill tailings as part of a study to determine the feasibility of rutile recovery from this source. The tailings that were tested contained 0.75 percent titanium dioxide (Ti02), with about two-thirds of the Ti02 values occurring as rutile. Mineralogical studies indicated that about one-half of the Ti02 content could be considered recoverable. Beneficiation studies of the tailings showed that best flotation results were obtained when sulfides and carbonates were removed by bulk flotation prior to rutile flotation. Rutile flotation was most effective when a petroleum sulfonate collector was used in an acid circuit. From this basic method of flotation, two alternative procedures were developed. The first procedure was to size and grind the tailings to minus 200 mesh; deslime the total pulp; and then float the sulfides, carbonates, and rutile. The second procedure was the same, except that it did not include sizing and grinding. Flotation of the sized and ground tailings yielded rutile concentrates containing 43.1 percent Ti02 and 75.7 percent of the recoverable Ti02. Rutile concentrates floated from the tailings that were deslimed but not ground contained only 34.7 percent Ti02 and 69.4 percent of the recoverable Ti02.

Jan 1, 1980

By W. L. Brien, O&apos

Molybdenum alloys with good strength properties at elevated temperatures were produced by the powder metallurgical internal oxidation method previously applied to tungsten and known as oxyreaction strengthening. Commercial molybdenum powders were blended with 0 to 10 pet of a reactive powder, ZrMo2. The effects of composition, blending procedure, and sintering conditions on strength properties at elevated temperatures were studied. Strengthening was attributed to zirconium in solid solution with molybdenum and to the presence of submicrometer particles of Zr02. Several alloys had tensile strength and stress-rupture properties com-parable with those of the best commercial alloys. The maximum tensile strengths obtained were 92 kpsi at 1,200° C and 53 kpsi at 1,316° C. The maximum stress-rupture life at 30 kpsi and 1,200° C was 145 hours.

Jan 1, 1974

By E. D. Calvert

The Bureau of Mines, in its effort to promote greater utilization of domestically abundant materials, conducted reasearch on an alternate mold material that has commercial potential for titanium investment casting. Using variations of the conventional lost wax molding process, investment shell molds were formed entirely of fused, calcia-stabilized Zr02 and a Zr02-forming binder. Optimization of binder/slurry properties', stucco grain size and dis¬tribution, and curing practices resulted in a structurally sound investment shell that was distortion free and thermally stable. Small titanium castings, weighing up to 10 pounds, were prepared in unheated molds by both static and centrifugal casting techniques. Microstruc¬tural examination of the castings revealed that mold fill and surface quality were enhanced by centrifugal casting, although good results also were obtained from the statically poured molds. Microstructural and electron microprobe examinations showed that excessive, brittle case formation could be avoided by curing the dried shell molds in air for at least 2 hours at 1,400° C. Increasing curing temperature and time above these levels yielded added bene¬fits. Molds fired in vacuum at 1,500° C for 4 hours yielded castings essen¬tially free of case formation. The tensile properties of as-cast test specimens (no surface conditioning performed) id the chemical composition of representative metal samples showed that castings produced were comparable to Grades C-1 and C-2 unalloyed titanium This indicated that no sifnificant degradation of metal properties resulted from mold/metal interaction.

Jan 1, 1981

By John R. McDonnell

The Valle Vidal Unit comprises 100,000 acres In Taos and Colfax: Counties, New Mexico. The unit was donated to the American public In 1982 by the Pennzoll Co. and is administered by the U.S. Department of Agriculture Forest Service as an addition to the Carson National Forest. During 1990-1991, the Bureau of Mines conducted a mineral Investigation of the unit as authorized by an Interagency Agreement (1987) Intended to assist the Forest Service to incorporate mineral resource data In forest plans. The Bureau reviewed literature and records concerning mineral resources and mining activity, and performed a field examination of mines, prospects, and mineral occurrences in and near the Valle Vidal Unit. The La Belle mining district encompasses most of the western part of the Valle Vidal Unit. The district was most active between 1893 and 1902, after the land grant was opened to prospecting and gold discoveries were reported. The discoveries were low grade, and eventually were abandoned. The Bureau's appraisal of the district determined that lode gold occurs primarily in fissure veins in volcanic rocks, and placer gold occurs In weakly cemented sedimentary rocks and alluvial sediments; but at a grade that is currently considered subeconomic. If the price of gold increases in the future, prospecting and exploration in the area may be renewed, but the activity would likely be limited due to "acquired land status" restrictions, which require mineral leasing and prohibit claim location in the Valle Vidal Unit.

Jan 1, 1992

By George H. Johnson

This report describes the procedures and summarizes the results of an investigation of surface subsidence above caving blocks at the San Manuel mine, San Manuel, Ariz., in order to obtain quantitative information on subsidence and ground movement caused by mining large volumes of ore. This investigation is one part of an overall study of rock mechanics being undertaken by the Bureau of Mines. Attention was given to the improvement of a rapid and precise method of surveying a large number of subsidence pins and cracks in the surface terrain. Photogrammetric methods were used as an adjunct to the triangulation subsidence surveying as well as in ordinary topographic work Maps of various kinds were prepared to show the results obtained. The computation of the survey notes was programed for an electronic digital computer at a saving of time and expense over the use of a desk calculator and trigonometric tables.

Jan 1, 1963

By H. C. Fuller

Rhodonite, a manganese silicate, occurs as an important component of extensive veins in the San Juan district of Colorado. Recent work by the Bureau of Mines has demonstrated that typical ores of the area can be upgraded to about 30-percent manganese content. Because of their siliceous nature, such concentrates require further processing to convert the manganese into more usable forms. The investigation described in this report demonstrates the technical feasibility of producing silicomanganese from a rhodonitic concentrate by electric smelting methods. The rhodonitic concentrate used in the smelting research was prepared by dry high-intensity magnetic separation of ore from the Silver Queen vein. The concentrate contained 29 percent manganese, 2 percent iron, and 41 percent silica. The principal minerals in the concentrate were 35 percent rhodonite, 30 percent rhodochrosite, and 25 percent quartz and chalcedony. Limestone was used as the flux and coal was used as the reductant. These minerals were crushed and screened to minus 1/2-inch plus la-mesh size.

Jan 1, 1962

By James J. Olson

This report summarizes the results of a review of foreign coal mining literature conducted under the Bureau's Advancing Coal Mining Technology program. In addition to a discussion on the historical development of mechanized longwall systems, and the current state-of-the-art method in Europe, this report summarizes the previous and ongoing Bureau efforts to adapt longwall technology to U.S. conditions. The bibliographic section of this report, divided into major categories such as mine design, face management, roadway development, strata control, powered roof supports, coal winning, conveying, and automation, contains over a thousand individual entries. The purpose of this report is to provide U.S. mining engineers with background information on longwall methodology and equipment developed in foreign countries (principally Europe). The Bureau of Mines, as part of its Advancing Coal Mining Technology program, is funding R&D projects to demonstrate that the longwall mining method, successfully used in the deep mines of Europe, can boost productivity and improve safety in certain U.S. mines.

Jan 1, 1977

By Robert W. Freedman

In the Bureau of Mines study, a filter with a 20-by 20-inch-square cross section was inserted into the exhaust ducting of a 4-stroke-cycle, 90-hp diesel engine, and the efficiency of removal of total particulate was measured gravimetrically as a function of time. Removal efficiencies were close to 90 pct during the main portion of several extended runs employing several combinations of filter beds. Variations in engine load had little effect on collection efficiency. Particle size as measured by a Bureau-developed online instrument centered on 0.07 m based on number count. Removal efficiency increased rather sharply for both larger and smaller particles.

Jan 1, 1979

By Neldon L. Jensen

Although ASARCO Incorporated, the only domestic producer, had terminated copper smelting operations and associated recovery of byproduct arsenic trioxide at Tacoma, WA, in 1985, it shipped small quantities of both trioxide and metal from its remaining stocks in 1986. Imports for consumption of arsenic trioxide increased significantly, owing to increased demand for arsenical wood preservatives and the decrease in domestic shipments of trioxide. Prices remained unchanged throughout the year. Development of gallium arsenide integrated circuits, important in advanced military and commercial electronics circuitry, continued to gain momentum during 1986. Domestic Data Coverage.-Shipments of small amounts of arsenic trioxide and metal from remaining stocks by Asarco were reported voluntarily to the Bureau of Mines.

Jan 1, 1988

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 Paul M. Price

The Mouat mine, Nye, Mont., was reopened in 1953 by the American Chrome Co. under a Defense Minerals Production Administration contract. Operations were terminated in 1961 after completion of the contract. Mining methods employed during this period are described in detail, and cost data are presented by years for 1953 through 1959. Ultramafic rocks of the Stillwater complex in Montana contain the largest domestic resource of chromite, and the Mouat mine has been the largest producer. Mine reserves were estimated in 1960 to be about 4.4 million tons containing 22.5 percent Cr203. The chromite deposits occur as a series of overlapping bands or lenses roughly paralleling the steeply dipping layers of the complex. Only two of the chromite layers have proven to be of economic importance. One layer is 2 to 1.6 feet wide; the other is 3 to 8 feet wide. Shrinkage stoping was generally used throughout the mine, but various methods of ore breaking, scope drawing, chute construction, etc., were tested to improve output and lower costs. Long-hole stoping proved to have limited use. Breasting down benches, developed outward from the center of the stope with air-leg drills, was satisfactory only in wider scopes. At the close of operations, the company had standardized the use of lightweight stopers to advance a flat back by breaking from a centrally located face. Mining costs were reduced 47 percent during 7 years of operation.

Jan 1, 1963

By William S. Sanner

A demonstrated reserve base (DRB) of bituminous coal suitable for cokemaking has been estimated based on the latest published information on U.S. coal reserves. Bureau of Mines analyses of raw coalbed samples were used to classify the coals as low-, medium-, and high-volatile bituminous and grade them as premium, marginal, and latent coking coals. Coal rank was used as the basis for identifying coking coals, and ash and sulfur content were used to determine coking coal grade. The demonstrated reserve base of coking coal for the entire United States is 162.67 billion tons. However, only 18.96 billion tons are premium (metallurgical) grade, and between 80 and 99 percent occurs in the Eastern States. The demonstrated reserve base of marginal-grade coking coal is 31.3 billion tons; more than half the marginal reserve base is in the Eastern States, and most of the medium- and low-volatile marginal coals are in the Eastern States. The Eastern and Midwestern States contain most of the latent-grade DRB of 112.4 billion tons; most (106.6 billion tons) is high-volatile coal, and 98 percent of the medium- and low-volatile latent coals occur in the Eastern States. Based on the worst assumption, which assumes that only premium-grade coals are used for cokemaking, the DRB for high-volatile coal would suffice for 127 years, the medium-volatile coal for 80 years, and the low-volatile coal for 83 years.

Jan 1, 1979

By R. G. Peluso

Methods and results of studies to determine friction and shock losses encountered in auxiliary face ventilation systems utilizing flexible, spiral-reinforced ventilation tubing are presented. The results, tabulated in graphic form, simplify fan selection and enable mine operators to design adequate auxiliary ventilation systems. Problem illustrates the use of graphs.

Jan 1, 1968

By F. S. Crawford

"After many years of safety activity in the United States in one form or another it becomes increasingly evident to those in contact with safety work that to achieve continuous good results in accident prevention there must be an aggressive organization behind the safety movement at each mine with fairly definite plan and policy. A study of the methods used by various companies and the results they have attained will be of value to the common cause of safety promotion.A study has been made of the safety records of the Menominee iron range in the Lake Superior district, and of data from the county mine inspector's report. Several companies on this iron range that have attained a certain measure of success in their work of accident prevention have given data, and a summary of their safety methods is presented.The Menominee iron range of Michigan lies in the southern portion of the upper peninsula of Michigan, bordering on Wisconsin. It consists of two main. divisions--the West Menominee Range, situated in Iron County in the vicinity of Iron River and Crystal Palls, and the East Menominee range situated in Dickinson County in the neighborhood or iron Mountain, Mich. The mines about Iron River and Crystal Falls are peculiarly subject to fires in a carbonaceous, sulphur-bearing black slate which appears in the footwall. This gives considerable trouble because fires in this material start from spontaneous heating. The methods of mining are top slicing and open stoping, working on benches along the sides of the stopes. The character of the ground varies from medium Soft ore to relatively hard ore which permits open stoping. Approximately one-third of the operating mines are equipped with a fan for main mechanical ventilation. The remainder are ventilated by natural draft. The East Menominee range is the older, top slicing having been used there for a number of years, and the timber mats have boon well developed. In common with all districts, some companies pay more attention to safety than others, although, those which do riot have the best records do pay some attention to safety.During the past three years the annual production per man employed has remained about constant, but in many mines a general decrease is shown in the accident record. The variation in the results attained can be ascribed mainly to the earnestness with which accident-prevention work is pursued, essentially regardless of the method of mining used. This is shown to be generally true, because the record indicates a steady decrease in one mine with an active safety department, while in adjoining mines with the same kind of ground and method of mining but where not such intensive attention has been paid to safety work, the accident record is high."

Oct 1, 1931

By L. J. Froisland

Water classification and heavy-media sink-float methods were investigated for concentrating metallic junk automobile shredder rejects initially upgraded to about 75-percent metal content in an air elutriation system. An 8-inch-diameter water elutriation column with a feed capacity of 2.7 tons per hour was constructed and operated. The results obtained were compared with those produced by sink-float methods. Tests made on duplicate samples of an intermediate-grade metal product were successful in upgrading the metal con-tent from 75 percent to 98.7 and 99.1 percent with respective recoveries of 95.5 and 98.9 percent for the water classification and sink-float procedures. Tentative flowsheets for treating junk auto shredder rejects are outlined.

Jan 1, 1972