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By R. A. Hatch

The United States depends mainly on foreign imports, principally India, for an adequate supply of sheet mica suitable for its many uses in the electrical and electronics industries. Sheet mica has, in fact, played an indispensable role in developing these industries,4/ and, in turn, the products of these industries (radio, radar, electric motors, and many others) have become indispensable to the military forces. Because or these conditions, sheet mica in its better qualities long has been classified as a strategic and critical material, and from this stems the wide-spread interest in substitute materials of which synthetic mica is one potential type. The United States Departments of the Navy and the Army entered into a cooperative agreement with the Bureau of Mines in 1947 to study ways and means of synthe-sizing and growing mica crystals. This is one of a series of reports5/ that describe the results of this program.

Jan 1, 1956

By D. A. Douglass

This report describes the tri-n-butyl phosphate extraction of cerium (IV) from a sulfate leach liquor prepared from a bastnaesite concentrate as well as from pure eerie nitrate solutions. The work was done on a laboratory scale using separatory funnels. Extraction from pure cerium solutions entailed no great difficulties; however, extraction from the bastnaesite solution proved more difficult, mainly because of the inhibiting effect of the sulfate ion. Despite this, procedures were developed for obtaining good single-state cerium extraction (95+ percent) and a high-purity product (99+ percent), although the maximization of both cannot be achieved simultaneously. This necessitates a compromise in any extraction scheme.

Jan 1, 1959

By R. Burrell, N .. L. Lapp

"Except for asthma and pulmonary infections, the types of lung disease that have been of immunologic interest the longest are the various mineral pneumoconioses. Because of their chronicity, type of pathology produced, and well-known immunotoxic properties associated with the dusts inciting them, the pneumoconioses have long drawn attention to the possibility that the immune system has not only been modulated but that its effectors have possibly contributed to their pathogenesis. All of the mineral dusts reviewed here have definite immunomodulating properties and act on various cellular and molecular components of the immune system. Further, each has an immunotoxic potential to induce either hypersensitivity (as in the case of beryllium) or other types of immune injury. This article reviews the immunologic aspects of the four major occupational minerals that have an immunologic impact on the lung: asbestos (particularly chrysotile), silica or quartz, beryllium, and coal mine dust.These agents have many things in common, yet each is distinctive. Although the possibility still exists that these mineral particles can adsorb intrinsic tissue antigens or extrinsic organic antigens to their surfaces and initiate immune responses to the adsorbed antigens, only one, beryllium, can act as an antigen itself. Silica is a profound macrophage toxin and thereby exerts many effects on those factors controlled by macrophages. Asbestos has undergone the most immunologic studies resulting in a much dearer picture of how it may contribute to immunopathology. Coal mine dust is the agent about which least is known immunologically, partly because there is no such thing as purified coal mine dust or a standard by which coal mine dust can be defined. Indeed, there are studies that use only the dust from the ground coal itself, whereas other studies use the total dust collected from air samples of a working mine in the belief that other types of dusts (e.g., silica from roof bolt drilling, from sand ground on the rails by cars, and from surface drilling) contribute to the disease (Figs. 1 to 5). This properly is coal mine dust and is poorly characterized. Yet, workers exposed to these dusts share similar reactive characteristics and they may be considered collectively as well as individually."

Mar 1, 1992

The following is a Maintainability Design Checklist for coal mining equipment. The purpose of the checklist is to provide a summary of design review points for the maintainability assessment of new or existing underground equipment. It specifically focuses on the identification of equipment design features, tasks, or procedures that impact equipment downtime, repair costs, labor hours and maintainer skill level requirements. Some checklist points are general in nature. The checklist was designed to be used across all categories of underground equipment. The intent is to draw attention to design features and maintenance procedures that will increase maintainability requirements. You are encouraged to adapt this checklist to site specific or machine specific requirements by: ? Inserting specific performance criteria for various categories of maintenance tasks. For example; all hydraulic lines on a shuttle car should be replaceable in 15 minutes or 25 minutes, etc. ? Adding or deleting checklist items for different categories of equipment. You would include environmental control equipment, for example, on face equipment and not on shuttle cars or man trips. ? Adding additional checklist items based on site or equipment specific maintenance histories or experience, company maintenance standards, or other factors.

Jan 1, 2000

By R. Hogg, T. F. Dumm

"Abstract - With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are used as dispersing agents, and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and subsieve particle size analysis of the specific gravity fractions, a complete size specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as -10 µm.IntroductionTraditional gravity separation techniques such as jigging, heavy media and water-only cyclones, shaking tables, etc., have been used to remove impurities from coal ranging in size from about 15.cm (6 ln.) to about 150 µm (100 mesh). The coal washabilty or float-and sink technique ls a well-established procedure for determining the optimum extent to which a coal can be cleaned by such physical separation methods. Because of the desire to recover even finer coal fractions by gravity separation techniques, there is a need to extend the coal washabillty analysis into the ultrafine range. The purpose of this paper ls to describe some of the significant factors that influence fine particle specific gravity separation. Washability analyses have been performed on three ultrafine ( <10 µm) coal samples representing three general mining districts in Pennsylvania. Results of these analyses indicate that the washabillty technique can be successfully applied to ultrafine particles when proper care ls taken."

Jan 1, 1988

By J. C. Gerdeen

A new analytical model for the shear stiffness at a joint of the fully-grouted resin roofbolt is developed using the Theory of Elasticity and an analogy to a beam on an elastic foundation, Gerdeen [2]. The model developed in this study treats the elastic foundation modulus of the resin as being composed of both an elastic rock and an elastic resin. All previous attempts have neglected the elasticity of the rock and treated only the resin. A three dimensional finite element model of the bolt-resin-rock system is developed also and comparisons are made between the predictions made by it and the analytical solution. It is found that the agreement between the two representations ranges between 1.2% and 10.5%, with the greater differences being observed for systems of very large or very small bolt diameters and resin annulus thicknesses. Since such configurations are not the rule in practice parameter studies are performed using the analytical solution with the finite element solution being used as a check. For a 0.75 in. bolt, a resin annulus thickness of 0.1375 in., a resin with E = 7 x 105 psi and -1) = 0.210, and a rock of modulus E = 6.8 x 106 psi and V = 0.159 the shear stiffness is found to be 1.220 x 106 lb,/in, from the analytical solution and 1.245 x 106 lb,/in, from the finite element model. Applying the finite element model to the problem of the axial stiffness of the fully-grouted resin roofbolt a value of 6.002 x 106 lb./in. is obtained which proves to be at least 50% higher than any of the now existing analytical predictions.

Jan 1, 1976

By C. E. Julihn

In the fall of 1933 a new discovery of gold was made in the old Mojave mining district of California about 70 miles north of Los Angeles. It led to mining operations that have surpassed in their results all reasonable expectations and are of exceptional promise for the future. In less than 3 years, exploration has opened up a number of veins, from some of which a substantial amount of high-grade ore has been shipped, while a large tonnage of milling ore has been disclosed. Two mills, operating on ore averaging better than $12 a ton, will probably produce more than a million dollars worth of gold in 1936, and a considerable increase of their output in the following year is anticipated. While continuance of these operations for a number of years is already assured by ample reserves of ore, future discoveries of still other veins are reasonably possible, as occurrence of gold throughout the volcanic rocks of the district is widespread and the veins now being mined showed little to attract attention at the surface.

Jan 1, 1937

By Lloyd A. Morley

A guide to the development and use of an APL computer program for the analysis of load-flow problems is presented. The program is designed to provide an interactive method of load-flow study to improve underground coal mine electrical system design and safety. The theoretical basis for load-flow analysis is discussed, along with per-unit calculations which facilitate computation. Specific input/output, execution and network modification procedures are presented for using the APL program. In addition, typical results are given for examples taken from power system analysis literature.

Jan 1, 1977

By M. H. Stanczyk

The Bureau of Mines made bench-scale laboratory tests on a sample of typical Florida phosphate slime to determine alumina and phosphate extractions obtainable by agitation leaching, by baking and curing, and by a leach-electrolysis scheme. Recovery of mineral values from leached slime pulps by resin-in-pulp ion exchange contact and the reaction of the leached pulps to filtration, flocculation, and settling were also investigated. The best extractions of alumina and phosphate were obtained by (l) agitation leaching with sulfuric, hydrochloric, or nitric acid at an elevated temperature or (2) curing or baking the slime with sulfuric acid. Alumina extractions ranged from 80.8 to 90.0 percent and phosphate extractions ranged from 93.3 to 98.4 percent when the slime was leached at 90° C with sulfuric, hydrochloric, or nitric acids. Baking the slime with sulfuric acid at 200° C for 4 hours yielded an alumina extraction of 92.3 percent and a phosphate extraction of 97.0 percent, whereas curing with sulfuric acid at 100° C for 24 hours gave slightly higher alumina and phosphate extractions. Flocculation and settling properties of the slime were virtually unaffected in all cases. Filter area requirements, although somewhat improved as compared to untreated slime, remained relatively high. The lowest filter area requirement obtained was 44 square feet per ton of dry solids treated per day. Contacting leached slime pulps with ion exchange resins depleted the leach pulps of solubilized values; however, the filtration and settling properties of the barren pulps were unaffected. A leach-electrolysis scheme resulted in some concentration of solubilized phosphorus, but the method showed little promise of being commercially feasible.

Jan 1, 1966

By Phillip N. Yasnowsky

This Bureau of Mines report examines the percentage depletion allowance rate structure in relation to several criteria that are indicative of U.S. mineral import dependence. These criteria are the minerals considered as strategic and critical for stockpiling purposes, the ratio of reserves to forecast cumulative demand (1976-2000) for selected minerals, and the U.S. net import reliance as a percentage of apparent consumption (1978), also for selected minerals in general, it was Found that there does exist a direct, although not perfect, relationship between the percentage depletion allowance rates and the degree of import dependence as indicated by these three criteria. The higher percentage rates tend to he associated with those minerals for which the United States is, or will likely he, heavily dependent on foreign sources. In addition, a basic discussion of the mineral depletion allowance is provided, including numerical examples illustrating the computation of the allowance under several assumptions. Also, the percentage depletion allowance rates for individual minerals are tabulated.

Jan 1, 1980

Although alternating-current (a.-c.) power systems and equipment have been used in coal mining for many years, most mines in the United States are powered mainly by direct current (d.-c.). There are several logical reasons for this, but the use of d.-c, equipment is, in most instances, a direct outgrowth of the original practice of using such power for haulage systems. For traction equipment such as the electric trolley locomotive the d.-c. motor has ideal operating characteristics, and thus it has been widely used for haulage locomotive service. The first efforts at electrification of coal mines started with the haulage system and from there branched out to include the many types of electrically powered mining machinery used in the industry today.

Jan 1, 1960

By William W. Adams

A new record in accident prevention was made by the metal-mining a industry of the United States in 1938, as signalized by a lower fatality rate than in any previous year. The rate was less than half as high as in 1911, the earliest year for which figures are available. A good safety record was also established in the prevention of nonfatal injuries, as the injury rate was lower than in any other years except 1931 to 1935, a 5-year period notable for its unusually low injury rates. Employment was more limited in 1938 than in 1937, both in number of men employed and total number of man-hours worked. The number of workdays per man also was smaller than in 1937. Operating companies reported that 7,233 mines were active in 1938 or some part of the year and that the total number of men employed was 103,027. This figure represents the summation of the average number of men employed as reported by the companies, the average for each mine being that for the period during which the mine was active. The number of employees at all mines in 1938 was 15,402 less than in 1937. Reports covering all mines indicated a total of 188 million man-hours worked during the year, or 21 percent less than the nearly 240 million man-hours worked in 1937. In the performance of this work accidents occurred that resulted in the death of 156 employees and the injury of 1.2,722, each injured employee being disabled for more than the remainder of the clay on which he was hurt.. The fatality rate for 1938 was 0.83 per million man-hours worked, which was 9 percent more favorable than the rate of 0.91 for 1937. Nonfatal injuries occurred at the rate of 67.61 per million man-hours worked, an improvement of 10 percent compared with the injury rate of 75.37 for 1937.

Jan 1, 1941

By M. M. Fine

A preliminary mineral-dressing study of five samples of East Texas limonitic brown iron ores was conducted as part of the Bureau of Mines program to develop and extend domestic resources of iron ore. The samples were considered to be typical of ore currently being mined and beneficiated by the Lone Star Steel Co. and Sheffield Steel Co. The objective of the research was to investigate those mineral-dressing unit operations that might recover some of the fine iron lost in current industrial wastes or perhaps improve the recoveries when applied to the ores as well. Since current industrial beneficiation practice yields a washed limonite analyzing 41 to 45 percent iron, higher grade concentrates were not sought in this laboratory study. Laboratory investigation included washing and sizing, reduction roasting, and subsequent magnetic separation of the finely ground roasted materials. The results showed that laboratory recoveries of over 80 percent of the iron were possible, for the ores investigated, at concentrate grades comparable to those expected from cur-rent industrial beneficiation practice. ACKNOWLEDGMENTS Acknowledgment is made to the Lone Star Steel Co. and Sheffield Steel Co. for supplying the brown iron-ore samples on which this research was conducted.

Jan 1, 1956

By T. W. Smelser

This Bureau of Mines report presents a review of underground testing, test results, and design guidelines of steel-fiber-reinforced concrete (SFC) mine support (cribbing) developed at the Spokane Research Center. The objective of the work was to verify, in field applications, the performance, economics, and acceptance by the mining industry of the SFC supports and establish design guidelines for their use underground. Results indicate superior performance, favorable economics, and enthusiastic acceptance by the mining industry.

Jan 1, 1983

By Henry E. Hilliard

The production, use, and emission of vanadium in the United States has been traced for the year 1991. Consumption was 3,300 tons2, exports 1,285 tons, and imports 2,013 tons. About 98% of production was used in metallurgy; the remainder was consumed in chemicals, including catalysts. Total emissions to the environment in 1991 were estimated at about 3,100 tons, including emissions due to the combustion of coal and petroleum products. Emissions resulting from the production of ferrovanadium were 130 tons, and emissions from the production of steel about 6 tons. Dissipative losses, defined as losses that occurred during use or as a result of wear, were estimated to be no more than 3 tons. Disposal losses were estimated to be about 4,600 tons. Most of these losses were steel products that contained 0.1% or less vanadium and mayor may not have been recycled. When these products are recycled by the steel industry, vanadium ends up in the steelmaking slag and does not return to vanadium use cycle. Worldwide emissions due to anthropogenic and natural sources were briefly reviewed. It was concluded that industrial emissions were about three times greater than emissions from natural sources.

Jan 1, 1994

A maximum acceptable level of 2 mg/m3 of respirable coal mine dust in active mine workings was established, effective January 1, 1973, under the Federal Coal Mine Health and Safety Act of 1969. It is generally agreed that, as a result, coal mines in the United States are significantly less dusty than they were a decade ago. For example, operators of underground mining machines were exposed to between 3.9 and 6.5 mg/m3 of respirable coal mine dust during 1968-69; now they are exposed to between 1.3 and 1.8 mg/m3. Also, the incidence of underground sections cited for exceeding acceptable levels of respirable coal mine dust decreased during 1976-78, and the vast majority of all working sections are now in compliance. This improvement is very substantial by world standards. It must be regarded as a creditable accomplishment by the coal mine operators, federal agencies, and mine workers involved. Most of the improvement has been brought about by the use of existing technology to control, suppress, and collect respirable coal mine dust. Research and development by the Bureau of Mines has contributed significantly to the accomplishment by improving the methods for sampling, control, suppression, and collection.

Jan 1, 1980

By Richard D. Miller

This Bureau of Mines publication contains analyses and related source data for 224 natural as samples from 18 States. Of the total, 191 sam¬ples were collected during calendar year 1981. The remaining 33 samples were collected during previous years, but releases, granting permission to publish were not received until 1981. All samples were obtained and analyzed as part of Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by the mass spectrometer and special helium apparatus described previously (1-2).3 The results of the investigation of the occurrences of helium are published annually to make the information available as soon as possible to the gas industry and the general public. Twenty-five publications have presented the results of 12,827 gas analyses made prior to 1981. The first three bulletins (1-3) contain analyses and related data on 5,218 gas samples collected from 1917 through 1960; these bulletins have been supplemented annually by information circulars (4-17, 19-24) containing 7,609 analyses of samples collected since 1960.

Jan 1, 1982

By John Paul Gries

During World. War II, when the curtailment of imports led to an unprecedented demand for domestic mica, beryl, spodumene, and other pegmatite minerals, the Bureau of Mines and the Geological Survey entered upon a program designed to expedite mining of these minerals from the Black Hills area of South Dakota. The program involved napping, sampling, and drilling of many pegmatite dikes in the southern portion of the Black Hills and beneficiation conducted in the field and in the Bureau of Mines laboratories at Rapid City, S. Dak., Rolla, Mo., Salt Lake City, Utah, and College Park, Md. This report describes the occurrence and sampling of the Beecher No. 2 pegmatite, which was investigated as part of the general pegmatite study in South Dakota. Investigation of the Beecher No. 2 pegmatite was started on November 20, 1943, and terminated in the spring of 1944. During this period, the Bureau of Mines took a series of trench samples across the pegmatite at the surface for grain-count studies and chemical analyses. The Geological Survey mapped the geology of the deposit after it was exposed by trenching and stripping.

Jan 1, 1950

By Paul S. Schopf

The results of an experimental investigation into the possible use of medium energy acoustic fields (130 to 140 dB) to precipitate 1 to 10 micron particles is presented. The aerosol was produced with a LeMer generator using oleic acid and nitrogen. The sound field was a sinusoidal standing wave field in an acrylic tube, with light transmission data used for concentration determination. The results showed collection efficiencies of up to 80% on 2 micron particles with a residence time of 11.8 seconds at a sound pressure level of 139 dB re 2x10-5 N/m2. A discussion of the possible turbulent mechanism is made, as well as review and comparison with others? work.

Jan 1, 1972

By J. M. Kuchta

The Bureau of Mines investigated four simulated coal gob fires to obtain a more reliable data base for defining the state of a sealed mine fire and to evaluate the performance of various fire detectors. The fires were conducted in a multiple-entry section of the Bruceton Experimental Mine by heating 4,000 to 21,000 pounds of rubblized bituminous coal to ignition and monitoring the temperature, gas emissions, and smoke under ventilated and sealed combustion conditions. Product gas concentrations depended upon the coal bed size, coal temperature, heating rate, and oxygen concentration or ventilating condition but varied little after the fires were sealed. Expressions are given that define the temporal variation of CO and O2 after sealing when the coal temperature decreased rapidly. The CO/C02 ratio is a more sensitive fire indicator than the CO/?02 ratio, although the latter is universally used for detecting the incipient state of a coal fire. In comparison, the Jones-Trlckett ratio [ CO2 + ¾ CO ? ¼ H2 ?O2] is less reliable for this purpose. The best detector for determining the state of a mine fire after it has been sealed was a prototype submicrometer smoke particulate sensor. Limitations of the various detector systems are also discussed.

Jan 1, 1982