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By E. R. Palowitch

Two samples of the Lower Hartshorne (Spadra) bed were collected: A sample of the raw coal with the machine cuttings excluded, and a sample of the machine cuttings exclusively. Analysis of the 5-inch by 200-mesh size fraction of the raw coal, excluding machine cuttings, showed that a product meeting minimum quality specifications could be produced by washing at 1.60 specific gravity, yielding a theoretical 93.7 percent of clean coal. A negligible amount of near-gravity material at the separation gravity indicated an easy washing problem. The sample of machine cuttings had a maximum size of 2 inches and contained about 50 percent ash. Washability tests of the 2-inch by 200-mesh size fraction indicated that a theoretical yield of 30.0 percent of specification-grade coal could be achieved by washing at 1.49 specific gravity. As the machine cuttings represent an estimated 10 percent of the total coal mined, their inclusion in the mine output would increase the theoretical net yield of salable coal by only 3.7 percent. Because the machine cuttings contained a high percentage of sink 1.80 specific-gravity material, they had neither an effect on the separating gravity required to clean the raw coal nor on the difficulty of separation. Gabbing underground versus transporting the cut-tings to the surface for disposal or washing either separately or combined with the raw coal involves a number of practical, economic; and intangible factors; hence, no specific recommendations could be made. A discussion of some of the factors involved in dealing with a similar problem is given by Gandrud and Riley.4

Jan 1, 1962

By George S. Rice

"""To prevent the propagation of mine explosions, the Bureau of Mines, Department of Commerce, recommends rock-dusting all coal mines, except anthracite mines, in every part, whether in damp or dry condition. It also recom¬mends that rock-dust barriers be used to sectionalize the mine as additional defense; but these should not be regarded as a substitute for generalized rock-dusting."" (Mine safety decision, No. 5, April 7, 1927.)The purposes of this circular are to present concisely the requirements for effective rock-dusting of coal mines in order to prevent propagation of mine explosions, and to point out the principal related facts on explosibility of coal dusts and mixed coal-mine dusts, as determined by extensive testing in the Experimental Mine of the Bureau of Mines. study of these principal facts on coal-dust explosibility in conjunction with the recommendations for rock-dusting, should help to make clear to mine operators and others concerned the necessity for systematic rock-dusting in all coal mines except anthracite mines, and the futility of inadequate or sporadic rock dusting.The descriptions of nearly 1000 explosion tests in the Experimental Mine are available in a forth-coming bulletin2 and in earlier publications.3For detailed specifications as to the kind of rock-dust, amount to use, where to be applied, and method of sampling and testing, the reader is referred to Bureau of Mines Serial 26064, and American Engineering Standard Committee ""Recommended American Practice for Rock-Dusting Coal Mines"" quoted in Bureau of Mines Information Circular No. 60305.Summary of Specifications for Rock-Dusting1. Mines to be rock-dustedAll coal mines, except anthracite mines, should be rock-dusted.2. Extent of rock-dustingAll open accessible parts of a coal mine should be rock-dusted, including slopes, entries, cross,-cuts, and rooms, headings and pillar workings to within at least 50 feet of the face.3 Amount of rock-dustingAfter cleaning up the coal dust as thoroughly as practicable, sufficient rock-dust should be used to have the mixture of remaining coal-dust plus the rock-dust in any zone contain 65 per cent or more of inert or noncombustible matter. First dusting may require 3 pounds to 5 pounds per linear foot of passageway.4. When to rock-dust In any zone or section (made by dividing the mine for rock-dusting purposes) when the incombustible content falls to 55 per cent, that section should be re-rock-dusted so as to bring the incombustible content well above 65 per cent."

Jun 1, 1927

By Richard A. Walker

This report describes the development and performance of a multi-level, multi-function Calibration Light Source designed for field-calibration of a group of specific photometers. The Calibration Source is capable of providing ±35% accuracy calibrations at all of the following levels: 0. 05 foot-Lamberts, 6 foot-Lamberts, 6 foot-candles and 20 foot-candles. The Source was found to provide constant light output to within 1% over 50 hours of lamp operation and for line voltage variations of ±25%. It is compact and light-weight (11 pounds), and can be easily transported and used by one man in normal office environments (without requiring a darkroom).

Jan 1, 1976

By R. W. Watson

A belt-wearable self-contained self-rescuer (SCSR) manufactured by the CSE Corp. and designated the "SR-1OO" was evaluated for safety in the underground mine environment by the U.S. Bureau of Mines. The evaluation consisted of laboratory tests on the chemicals contained in the unit and field trials to simulate the mine environment. This report summarizes the test results and compares the results with those from earlier tests with chemical and compressed oxygen self-rescuers. It was concluded that the new SCSR did not pose any different or more severe hazards than the earlier units. In view of the mine-proven safety record of the SCSR's now in service, no reason could be found to disallow use of the belt-wearable unit.

Jan 1, 1991

By T. C. Green

A two-phase program evaluated commercial proximity warning devices and then served to design and develop an automatic electrostatic field strength measurement device with improved performance. The Phase I program consisted of test and evaluation of three commercial proximity warning devices, all of which operate on the principle of electrostatic field intensity measurement for determining proximity to high voltage power lines. Performance testing of these devices utilized full-scale cranes and power line systems and a scale model facility. The evaluation results were reported in the Phase I report entitled "Evaluation of Proximity Warning Devices" dated 22 February 1980. Under the Phase II program, a microproressor-based data acquisition system was designed and developed to collect and measure field strength at distributed points around the crane boom. This unit (referred to as the Distributed Sensor AC Electrometer) measures the field strength about a crane boom using 17 distributed sensors. Keyboard control is provided for the equipment operator. Measured field strength values are displayed on a line printer and recorded on magnetic tape. Laboratory testing of this unit demonstrated performance characteristics and field strength measurement accuracy within the design goals. A Phase III measurements program is proposed using the AC Electrometer to map the field strength contours about power line configurations.

Jan 1, 1981

By R. L. Rough

Photoelastic, wire resistance, and borehole-deformation gages were used to measure the in situ strains when an outcropping Black Hand Sandstone Formation in Hocking State Forest, Hocking County, Ohio, was overcored to stress-relieve the surrounding sandstone. Strains transmitted to the photo-elastic gage did not produce isochromatic patterns suitable for quantitative analysis. Strain readings from the wire resistance gage indicated tensile-strain loading during overcoring; readings from the strain-gage bridges in the borehole-deformation gage indicated compressive-strain relaxation during overcoring. The magnitude and orientation of the computed stress fields obtained from both gages were comparable when the corresponding tensile and compressive elastic moduli were applied. Stresses computed from deformation and resistance gages at depths to 5 feet showed the maximum stresses to range from 1.042 to 2.121 times greater than the minimum stresses. The bearings of principal stresses calculated from the deformation gage readings varied between N 61° E and N 83° E; the wire resistance strain gage bearing computations varied between N 68° E and N 82° E. Measurements of in situ strain in sandstone were shown to have promise but to require further development in field technique that could likely be achieved through experience.

Jan 1, 1971

By M. R. Geer

The ever-increasing need to guard against stream pollution has intensified interest in the problems of handling and disposing of flotation tailing. Therefore, the Bureau of Mines investigated the possibility of using crushed washery refuse to adsorb the free water in thickened flotation tailings on a bench scale and then in a pilot plant because the conventional methods of disposing of coal flotation tailings--impounding them or filtering them so they are dry enough to be conveyed to the refuse dump--are sometimes either impractical because of space limitations or costly because of low filter capacity. Most of the refuse samples tested were of similar mineralogical composition and exhibited similar water retention capability. The amount of crushed refuse required to adsorb the water in a particular tailing was influenced greatly by the fineness of the solids in the tailing and hence the percentage of solids to which it could be thickened. The ratio of crushed refuse to tailing solids required to provide a mixture dry enough to be carried on an inclined conveyor belt varied from 2.4 to 6.4. Several chemical agents that were tested were very effective in turning the free water in tailings into a stable gel. Fly ash also was very effective in adsorbing water.

Jan 1, 1968

By A. T. Sweet, G. Douglas Gardner

"INTRODUCTION In the ammonium sulfate process for the production of alumina from clay,,3/ the clay is baked with amonium sulfate at about 400ºC. to form anhydrous ammonium alum and free ammonia or ammonium carbonate. The alum is leached from the baked product with water and circulating liquors and is purified by recrystallization. Aluminum hydroxide is precipitated by treating thus alum the alum the ammonia or ammonium carbonate from the baking step. Ammonium sulfate is recovered from the filtrate for reuse, and the aluminum hydroxide precipitate is calcined to produce high-purity alumina. In this process, as in other acid processes for the production of alumina, 4/ a large part of the iron in the clay is extracted. The iron tends to build up in the leach liquors and contaminate the crystals, so that its elimination is one of the most important problems in the process. A number of large clay deposits occur in the Western States. Those that have boon explored most extensively 5/contain an average of 24 to 30 percent available A12O3 and 2 to 8 percent available Fe2O3. 6/ The available Fe2O3 content of various other clays ranges from less than I percent to more than 20 percent. The available Al2O3 or Fe2O3 is usually 90 to 98 percent of the total but may be much less. In generals the iron content bears no fixed relation to the alumina content and may vary widely within a given deposit."

Jan 1, 1948

By A. J. Barry

Two methods of testing anchorages of headed expansion-type mine roof bolts were investigated by the Federal Bureau of Mines to determine whether they are acceptable for general use. In both methods a load was applied to a tightened bolt with a hydraulic jack. A total of 80 tests, 40 using each method, was conducted in 4 test areas in 3 commercial coal mines. Electric resistance strain gages were used in all tests to indicate true bolt load as the bolt was tightened and when an additional load was applied with the hydraulic jack. The results indicate that: 1. The relationship between the true bolt load and the jack load will vary according to the test method until the two loads become equal. The bolt load-jack load relationship below this point can be determined only with strain gages. 2. The point at which the two loads become equal can be estimated by noting the load when the hardened washer becomes loose in one method, and when the bearing plate becomes loose from the roof in the other. It also can be approximated for either method of testing by noting the load when the first abrupt change in the slope of the jack load-bolt displacement curve occurs. 3. The anchorage characteristics of the test bolt can be determined from the data obtained from either method by examining the slope of the jack load-bolt displacement curve above the point at which the true bolt load is equal to the jack load.

Jan 1, 1960

By P. M. Gruzensky

A survey of the literature has been made covering the extraction of bismuth from raw materials, its separation from lead, and its subsequent refining. The use of aqueous, nonaqueous, and fused electrolytes in electrolytic refining is reviewed. This literature survey has been prepared preliminary to some proposed investigations concerning the electrometallurgy of bismuth, and, although an effort has been made to cover a majority of the applicable references, a critical review was not attempted and no assertion is made that this manuscript is exhaustive in nature. Titles of publications in parenthesis are translations from the language in which the reference was originally published.

Jan 1, 1954

By F. D. DeVaney

Manganese-bearing deposits f the Leadville, Colo., district are of two distinct types. Manganosiderite, a combined or intimately mixed ferrous and manganous carbonate, occurs in unaltered zones as the predominant mineral. From 50 feet below the surface to as deep as 900 feet, psilomelane and wad, both black manganese oxide minerals, are found in intimate contact with hematite and limonite. A typical analysis of the black oxide ore shows 20.08 percent Fe, 18.64 percent Mn, 15.91 percent insoluble, 14.91 percent moisture, 0.94 percent Zn, and 2.13 percent Pb. A considerable tonnage of the oxide ore has been mined for production of spiegeleisen and for other purposes.

Jan 1, 1940

In 2005, a total of 739 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). These mines (e.g., potash, gypsum, salt) comprised 5.0% of all operations. ? Mines producing common clay comprised 26.9% (n=199) of all nonmetal mining operations. ? Nonmetal mining operations were located in all states and territories except Alaska, Delaware, Hawaii, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands.

Jan 1, 2008

By Stanley A. Feitler

This Bureau of Mines report deals principally with the resources and economic aspects of feldspar in the United States east of the Mississippi River. Although in a strict sense, all phases of the feldspar industry affect its economic structure, emphasis in this study is on supply, demand, and marketing. Although feldspar was originally mined for use in the manufacture of pottery and other ceramics, the glass industry, which began to use feldspar in the mid-1920's, now consumes more than half of the annual output. Most mining is open cut, and the methods used are similar to those used in mining crushed b stone. Excess plant capacity has been chronic, and production is usually about 30 percent of capacity fur the industry as a whole. Since 1947, feldspar consumption has grown more slowly than the average for all U.S. industry. This has fostered intense competition, especially for the glass market. Prices have not kept pace with inflation, and profits are small. The trend of consumption through 1970 for glass feldspar is expected to be upward; less rapid in consumption of ceramic feldspar is anticipated.

Jan 1, 1967

By Robert N. Roby

Deposits of iron ore in Judith Basin County, Mont., generally referred to as the Running Wolf deposits, were examined by an engineer of the Bureau of Mines in August 1942. During the Summer of 1943 the Federal Geological Survey made a reconnaissance survey of, the Running Wolf Iron district and also made a detailed study and a topographic and geological map of the eastern end of the district. Two deposits of iron ore at the eastern end of the district were trenched and drilled by the Bureau of Mines during the fall and winter of 1943-44, This report presents the factual data obtained from the trenching and drilling' operations. The iron deposits of thy Running Wolf district are accessible from Stanford, Mont., by 14 to 16 miles of county highway and 2 to 3 miles of rough mountain road or trails (see fig. 1). No shipments of ore have been made from of these deposits. The ore is a replacement of Madison limestone at the contact with syenite porphyry. The contact can be traced for about 6 miles in a general northwest direction. 'At least five. deposits occur along this contact.

Jan 1, 1949

Prier to the date of this contract, Ocean Energy had developed and demonstrated a high efficiency fluorescent caplamp which operated from a standard 4 volt miner's caplamp battery. This unit produced about five times the light output of the standard incandescent miner's caplamp. The Company believed that the major market for this unique caplamp was in the industrial and municipal applications. Because of the additional safety requirements for coal mining use, and in conjunction with the much smaller market in the mining industry, the additional expense and difficulty of modifying this caplamp to comply with the Federal and State coal mine regulations were not considered at that time. Recognizing the potential of this lamp for improving illumination conditions for underground coal mining, the US Bureau of Mines contracted with Ocean Energy to make the required modifications to this lamp to bring it into compliance with the Federal and State of Pennsylvania regulations, and thereby, make this lamp available to the anthracite and bituminous coal mining industry. At the outset of the contract, the injection molds for the caplamp housing were being completed, and only prototype, hand fabricated, units were available for tests. The Bureau evaluated these prototype units and formulated a performance specification for the miner's version. Light level and distribution, weight, size, angle of tilt, and operating duration were all specified. In addition, it was required that the caplamp be com¬patible with existin charging equipment at the mines and that the final design be in full compliance with MESA Schedule 6D and he ultimately approved by MESA, Approval and Testing, as well as by the Pennsylvania Bureau of Deep Mine Safety. The scope of this contract covered the modifications required to achieve these objectives. It was agreed by the Bureau that all rights to the lamp, including design, material combinations, circuitry, etc. would remain with Ocean Energy. The charger/adapter system and components, which were developed under contract funds, are disclosed hero and become public knowledge and property. Patent applications have been filed by Ocean Energy to protect the mechanical and electrical design aspects of the lamp. It should be noted that this report contains details, designs and data which may be covered by one or more Ocean Energy patent applications, and disclosure herein is made only to provide better understanding of the contract results.

Jan 1, 1975

By D. A. Larson

The Bureau of Mines conducted basic experiments to study the process of crack propagation with a wedge indenter. The work was conducted under plane stress conditions in a hard, brittle limestone. The purpose of these experiments was to first gain an understanding of the basic crack propagation process under a sharp indenter, and second, to determine how the crack propagation process could be used to improve mechanical fragmentation systems. Three methods of rock fracture with the wedge indenter were investigated in this program. These were the confined indentation tests, the unconfined splitting tests, and the edge chipping tests. The confined indention tests represent worst case conditions for crack growth and formed the lower bound on fracture efficiency. The unconfined splitting tests represented best case conditions and fixed the upper bound of fracture efficiency. The edge chipping tests represented an idealized fragmentation process based exclusively upon the highly efficient fracture propagation process. Edge chipping achieved a specific energy of 25 in lb f/in3 compared to conventional drag cutters, which required a specific energy of at least 2,385 in·lb f/in3? Thus edge chipping is up to 100 times more efficient than conventional drag cutting. Because of these promising results, more work is planned with the fracture propagation process in three dimensions.

Jan 1, 1987

By R. W. Lewis

Spectrochemical procedures were developed using dc arc excitation for the determination, in parts per million, of 18 impurity elements in electrorefined beryllium and high-purity beryllium oxide. The metal samples were dissolved in dilute hydrochloric acid, evaporated to dryness, and converted to the oxide in a muffle furnace at 900° C. Germanium oxide was added as an internal standard for the determination of 15 of the elements, copper oxide for boron and molybdenum, and neodymium oxide for calcium. The average coefficient of variation was 11 percent with the exception of copper, which averaged about 43 percent.

Jan 1, 1962

By J. Bruce Clemmer

[Gypsum is one of the most important nonmetallic c minerals, as is indicated by the fact that the United States consumed approximately 3,500,000 tons of natural and calcined gypsum in 1937. The building trades were the largest users required 2,520,000 tons of calcine for production of plaster, wall board, tiles, block, and various other insulating and building materials. The glass and ceramic industries and other manufacturers required an additional 126,000 tons. The balance was used in the uncalcined condition as retarder in Portland cement and or agricultural purposes.]

Jan 1, 1941

By Launa Mallett, Charles Vaught, Jr. Brnich

This paper introduces a technique for incorporating employee participation into the prevention component of a contingency plan. Companies sometimes focus so much energy on response that they forget to put resources into the basics of emergency prevention. The training program discussed here was designed to make employees part of the prevention system. Examples of training materials from the program are provided, a sample method for introducing risk assessment to employees is shown, and a strategy to address limited training time using short videos is explained. Methods for tailoring the training to any worksite and for specific risks are also included. The program is being designed and tested by the Pittsburgh Research Laboratory/NIOSH and employees of an underground coal mine. Examples are taken from the implementation of the program at the mine during the summer and fall of 1998. Results of the program evaluation and lessons learned during the implementation are discussed.

By Joseph Grumer

Reported fiscal year 1973 studies of fires and explosions seek to develop capabilities during mining operations to detect and quench ignitions of gas in the face area, to detect and quench by means of passive or triggered barriers explosions propagating in rock-dusted coal dust, and to detect incipient fires early enough for easy extinguishment. Research discussed includes minimum air velocities to lift coal or rock dusts, surveys to determine adequacy of rock dusting, chemical agents to quench gas or coal dust explosions and their relative efficacies, spectra radiated by explosions, and nozzle sprays of extinguishants.

Jan 1, 1973