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By Roy L. Wilfong

The linear expansion of high-purity oxides of yttrium, cerium, samarium, europium, and dysprosium was determined by the interferometric method for the temperature range 25° to 1,000° C. Single-crystal magnesium oxide and single-crystal aluminum oxide were used as reference materials. The bulk density and crystal form of the nonreference materials also were determined. The coefficients of linear expansion in the range 25° to 1,000° C were found to be 8.10 x 10-6 for yttria, 12.10 x 10-6 for ceria, 10.81 x 10'6 for samaria (monoclinic), 10.35 x 10-6 for europia (monoclinic), and 8.13 x 10-6 for dysprosia, each given in centimeters per centimeter per degree Centigrade. A detailed investigation of the interferometric technique for measuring thermal expansion in this temperature range was made. The interferometer was found to be a precise tool but only when adequate precautions were taken. These precautions are described.

Jan 1, 1963

By David C. Oyler

The Bureau of Mines is cooperating with the U.S. Department of Energy in a directional degasification project at the Emerald mine near Waynesburg, Pa. This project is designed to combine the highly successful underground horizontal degasification technology with surface drilling methods. The objective of this program is to demonstrate that directional drilling can be used as a technique for degasifying coalbeds ahead of mining to reduce the hazards of methane-air explosions in coal mines. The directional hole at the Emerald mine is designed to start vertically and enter the Pittsburgh coalbed horizontally. A 3-inch-pilot hole entered the Pittsburgh coalbed at a vertical depth of 999 feet. The hole will be reamed to 8-3/4 inches in diameter, and 5-1/2-inch casing will be cemented in place. Three individual 3-inch-diameter, 3,000-foot horizontal gas collection holes will be drilled into the coalbed in a "bird foot" pattern. A corehole and vertical dewatering hole have been completed at the anticipated coalbed intercept. The dewatering hole was drilled to 130 feet below the Pittsburgh coalbed, a depth of 900 feet, and 880 feet of 7-inch-OD casing was cemented in place. Seven vertical holes for monitoring the extent and progress of degasification have been drilled within the horizontal drilling area.

Jan 1, 1979

By Irving Hartmann, Edward Thomas

"INTRODUCTION Adoption of rubber-tire shuttle cars underground in conjunction with mobile coal-loading machines has introduced new problems in the control of dust on mine roadways. Where this type of loading and transportation is used, development and extraction are generally rapid, with the result that much coal is spilled from the shuttle cars during normal operation, Coal in the roadways from this source and from sloughing of the ribs is ground to fine dust by the wheels of the 'shuttle cars and by the treads of the loading and mining machines. The coal dust usually is somewhat contaminated by pulverized rock, and the mixture could not be loaded with the run-of-mine coal without undue contamination of the product even if it were cleaned up promptly.The presence of large quantities of fine, loose dust, which is constantly stirred up and kept in suspension in air by the traffic, constitutes a grave explosion hazard, reduces visibility along the roadways, and is physiologically harmful to the workmen who breathe the air. From the operating standpoint the loose material is undesirable along the roadways because it provides poor traction for the trucks and thereby increases wear and power consumption. The dust-explosion hazard could be eliminated or reduced by frequent application of sufficient rock dust on the roadbed; but this would not remedy the other difficulties, and in fact it might intensify them. Where practicable, the most direct and effective safety measure is to clean up and remove promptly all dust that forms and settles on the roadways. Unfortunately, in many cases this procedure is not feasible. A third Suggested remedy is to prevent dispersal of the dust into the air and to promote its consolidation on the floor by wetting the dust particles.During the past few years several mines have used calcium chloride on shuttle-car roadways to allay the dust thereon. When exposed to the' humid atmosphere of the mine this salt absorbs Moisture from the air and deliquesces, and in this way wets the dust on the floor of the roadway. In a survey conducted in coal mines in southern West Virginia and in eastern Kentucky where calcium chloride has been in use, somewhat conflicting re- ports were received regarding the merits of the application, and several operators have abandoned the practice either because of actual or assumed disadvantages. The purpose of the study described in this report was to collect and correlate evidence and, on the basis of experimental data obtained in the field and in laboratory tests, to present a clearer picture of the factors involved in the allaying of dust by use of salts."

Sep 1, 1945

By Clarence O. Babcock

This Bureau of Mines report presents the initial development of a two-dimensional method of analysis for inclusions in plates in which the deformed shape of an open hole and the separate structural behavior of inclusion and plate with hole are used to obtain the stresses and strains in the inclusion only. In this report the solution for a circular inclusion is presented because a direct verification of the results with previous solutions was possible. The numerical results were in exact agreement with those obtained with the equations of Sezawa and Donnell. The equations developed are less complex than those of Sezawa and more general, for a circular inclusion, than those of Donnell. Stresses and strains in the inclusion are in terms of the elastic constants of the inclusion and the plate and the biaxial stress field applied far away. The elastic constants can be all different. An important conclusion from this work is that a difference in Poisson's ratios between inclusion and plate may be as important as a difference in Young's moduli between inclusion and plate in producing the inclusion effect. Many problems in mining and rock mechanics can be treated as inclusion problems. The understanding of inclusion behavior on a physical basis should provide the solutions to some of these problems.

Jan 1, 1974

By L. M. Chan, D. R. Carlson, J. H. Johnson

"This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program.The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.INTRODUCTIONDiesel-powered mining vehicles are gaining Popularity in underground coal mines and are almost universally used in underground non-coal mines due to their mobility, flexibility, and higher productivity. However, noxious gases and particulate matter in diesel engine exhaust are a concern because of the potential for being harmful to the health of miners. Diesel exhaust pollutant concentrations out the tailpipe of a mine vehicle change with time due to engine wear, inadequate maintenance, improper adjustments and other factors. This deterioration in pollutant concentrations, if not properly controlled, may adversely affect the air quality in an underground mine. To provide assurance that a clean and healthful work environment are maintained, a program is needed to identify and repair diesel engines that contribute to poor air quality. Also, earlier detection of deteriorated engines will make preventive maintenance possible, thereby eliminating further deterioration and possibly complete breakdown. Preventive maintenance also increases engine life and equipment availability in production which in turn will result in decreased operating costs."

Nov 1, 1995

By Webster S. Anderson

Bureau of Mines planer mining tests on the phosphate bed of the Douglas mine, near Drummond, Mont., indicated that a competent bed with a Mohs' scale hardness of 3 to 4 cannot be mined economically with the planer. Although planer mining was feasible where the bed was fractured enough for a 4-inch depth of cut to be consistently maintained, the depth of cut in the competent beds at the Douglas mine did not exceed 0.5 inch. Average production rates were 0.15 ton per minute and 9 tons per man-shift.

Jan 1, 1966

By William J. Campbell

The purpose of this investigation by the Federal Bureau of Mines was to design and construct a fluorescent X-ray spectrograph for dynamic rate studies of selective oxidation in molten metals and to establish basic principles for interpretation of data obtained by this method. An X-ray spectrograph was constructed in which the sample holder is a resistance wound furnace; it was operated up to 800° C. in oxidizing atmospheres. No difficulties were experienced with the cooling or heating systems nor with the protective layer of mica around the X-ray tube window, even though the oxidizing surface of the metal is only 0.5 inch from the X-ray tube window, Means are provided for heating under controlled atmospheres for selected time? temperature cycles.

Jan 1, 1961

By Yael Miron

Coal mines that undergo self-heatings, and specifically mines that sustain both floor heave and self-heatings, would benefit from the use of sealants to minimize air ingress to susceptible areas. The U.S. Bureau of Mines (USBM) evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gel. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the USBM Safety Research Coal Mine. Two for-mulations resulted in stable gels that lasted for at least 12 months in the mine. Semicontinuous preparation of gel using an eductor was evaluated and appears feasible. Although guar gum gel is expensive, selective use to prevent heatings in specific areas would be cost-effective, both in terms of productivity and enhanced mine safety.

Jan 1, 2010

By J. B. Gayle

The Bureau of Mines sole-heated oven has been used for studying coal expansion for some 20 years. During the period before 1940 emphasis was placed on studies of the mechanism of coal expansion and the effects of variations in operating conditions on the results. Since 1940 emphasis has shifted to a survey of the expansion properties of various coking coals. Because additional information concerning a number of unsolved problems in connection with the earlier studies appeared highly desirable, this investigation of the use of sole-heated ovens for studying coal expansion was undertaken. The principal findings, in order of their discussion in the text, may be summarized as follows. 1. Expansion results for binary blends of coking coals exhibit nonadditive behavior, both positive and negative deviations from additive behavior being noted, depending on the particular coals tested. Additive behavior can be achieved, however, either by charging the blend components in separate layers (which indicates that the observed phenomena are not characteristic of the particular expansion oven used) or by testing relatively coarse sizes of coal (which suggests that the effects of crushing on the expansion properties of coking coals may be even more complex than is generally recognized).

Jan 1, 1959

By Allan F. Smith

The Bureau of Mines studied toxic products produced by burning eight fire-resistant mines conveyor belts, a brattice cloth, and an electrical cable insulation obtained from laboratory-scale burning experiments under various air-flow conditions. Generally, CO product concentrations for most materials were noticeably higher then the NO2 and HC1 levels that were measured; also, no phosgene was detected. However, several of the fire-resistant belt samples yielded HC1 concentrations that were above the reported lethal level for 1/2 to 1-hour exposures, although these data were limited to flow conditions where air dilution effects were small; the belt materials that showed this behavior included samples of polyvinyl chloride, styrene butadiene, styrene butadiene blends, and a British neoprene which yielded the greatest amount of toxic vapor. In addition, some results are presented on the phosphoric acid concentrations that may be produced from the decomposition of ammonium dihydrogen phosphate when dispersed on a burning coalbed.

Jan 1, 1973

By Edwin C. Reeder

This is one of a series of papers dealing with mining methods and costs prepared under the sponsorship of end in cooperation with the United States Bureau of Mines. The mining methods described in this paper are those used in one of the large mines producing fluorspar in the Kentucky-Illinois fluorspar field, located in southern Illinois and western Kentucky on the Ohio River. The occurrence of ore and the methods of wining are similar to those in other mines in the district; therefore information regarding methods and the results obtained should be of interest. Improvements in methods have been made as experience developed the need of them. The trine is situated at Rosiclare, Ill., on the Illinois Central Railroad, and shipments are also made b r barge on the Ohio River.

Jan 1, 1930

The current procedure for measuring the concentration of respirable coal mine dust is as follows. Each filter is preweighed by the filter manufacturer to ±0.1 mg. Following sampling with the Coal Mine Dust Personal Sample Unit (CPSU) at 2.0 L/min, the filter with coal mine dust is sent to MSHA for weighing. The current MSHA procedure for weighing respirable dust samples uses a Mettler Model AE163 analytical balance in conjunction with an automatic weighing system with a precision of ±0.02 mg [Tomb 19901. Each balance is calibrated twice per day. Quality control for the automatic weighing system includes the systematic weighing of one in eight filters on a second Mettler AE163 balance. Tolerance is set at ±0.1 mg between the two weighings of the same sample. Weights are truncated at the 0.1 mg level (e.g., 3.457 mg is truncated to 3.4 mg) [Bowman et al. 19851. The difference of the two truncated weights is then recorded as the weight of coal dust deposited. The respirable concentration (mg/m3) is computed by multiplying by a correction equal to 1.38 and dividing by the volume of air sampled (2.0 L/min x sampling time [min]).

Jan 1, 1997

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

Airborne respirable dust surveys were conducted at six surface coal mines to investigate the effectiveness of dust control methods used on rotary rock drills and bulldozers. Dust controls commonly used on drills include a dry dust collection system, exhausting from a shrouded area around the collared hole, and an enclosed drill operator cab, filtering airborne dust from the cab. Bulldozers are also typically equipped with an enclosed operator cab as a dust control measure. Airborne respirable dust sampling was conducted near each equipment's source of generation and inside its enclosed cab. Silica analysis was performed on the dust samples to determine the percent silica content in the dust generated at the six mining operations. An additional eight- month follow-up of dust sampling was also conducted in the enclosed operator cabs of several rock drills and bulldozers. Data were analyzed for long-term variability of accepted control methods to abate dust and silica levels. The highwall rock drill was the major and most variable dust source as compared to the bulldozer, generating dust levels, on average, one order of magnitude higher than dust levels of the bulldozer. Four of the six drills surveyed had dust containment and capture problems at the shrouded drill table above the lple. Repairs or modifications to three of the drill dust collection systems were shown to reduce dust levels by more that 50% next to the shrouded drill table. The enclosed operator cabs provided more than 90% and more than 40% lower dust levels than at the dust source for the drill and bulldozer, respectively. Long-term sampling of several of these highwall drills and bulldozers showed that the dust levels in the drill cabs were frequently higher than 0.2 mg/m3 and more variable than in the bulldozers. The bulldozer dust levels were frequently below 0.2 mg/m). Future research should focus on improving some of the deficiencies present in the drill's primary dust collection system, and developing quality control methods to ensure the integrity of enclosed cab protection for equipment operators.

By Douglas A. Donato

This Information Circular presents the MULSIM/PC system of numerical modeling computer programs developed by the U.S. Bureau of Mines. This system consists of four programs: PREMUL, the preprocessor or mesh generator; MULSIM/PC, the actual numerical modeling program (number cruncher); MUL3D, a three-dimensional postprocessor; and MUL2D, a two-dimensional postprocessor. These programs were specifically designed to operate on IBM-compatible (MS-DOS-based) personal computers for easy transfer of this technology to the mining industry and academia. MULSIM/PC uses a subvariation of the boundary-element method, namely, the displacement-discontinuity technique, for linear-elastic geomechanical analysis of mine plans in one or two parallel underground tabular deposits. Results calculated by this technique include stresses and displacements as they relate to changing mine geometries and materials. In addition to describing the MULSIM/PC program and its features, and providing a detailed example model, this report also documents the associated preprocessing and postprocessing programs that are part of the MULSIM/PC system. User's guides for all the programs are contained in the appendixes following the main report.

Jan 1, 1992

By I. Iwasaki

In recent years the rapid depletion of high-grade iron ores and the demand by blast furnace operators for increasingly low-silica ores have stimulated interest in flotation studies of low-grade iron ores, such as wash-ore tailings and oxidized taconites. Four processes have been reported for the flotation separation of these iron ores--anionic and cationic collection of the iron oxides, cationic collection of siliceous gangue, and anionic collection of activated siliceous gangue (5).5/ The effectiveness of any one method, however, depends largely on the mineralogical composition and on the physical structure of the sample; hence, a comprehensive study of the floatability of the individual minerals occurring in these materials is essential. A review of the literature shows that the floatability of hematite and magnetite has been frequently investigated, whereas very little corresponding information is available for goethite, or for its more earthy form, limonite, both of which are abundant in the Mesabi and Cuyuna ores (19). The purpose of this investigation was to formulate general information on the floatability of goethite. Vacuum flotation, contact angle measurement, and simplified flotation tests using a modified Hallimond tube were used. The experimental results were correlated with the electrokinetic properties of goethite as determined by streaming potential measurement. The results were used to interpret the batch flotation tests made on an artificial mixture of quartz and goethite.

Jan 1, 1960

By Arnold F. Stalder

The measurement of various gas concentrations in the atmosphere at a particular location has become a problem of considerable importance. Levels that need to be monitored vary from the range of percent for constituents such as oxygen to parts per million levels for gases like nitrogen dioxide. In particular, mine air can become contaminated with noxious or toxic gases from several sources: fires within the mine, diesel-powered equipment, and explosive sources. The contaminants that result are carbon monoxide (CO), carbon dioxide (CO2), and oxides of nitrogen (NO and NO2). Additionally, oxygen (O2) may be depleted. Thus, the workman can be exposed to potentially toxic or asphyxiating atmospheres. A device was needed that will continuously monitor the mine air in working areas and provide warning of hazardous atmospheres. The Mine Air Monitor was conceived as being a portable, rugged instrument capable of measuring the concentration of the various atmospheric constituents in the mine environment. The unit was to provide both warning signals and quantitative measurements when hazardous contaminants existed at too high a level, or when the oxygen was being depleted. The initial concept involved optical sensors for all of the contaminating gases to be measured, namely CO, CO2, CH4, and NO2, and an electrochemical cell to monitor O2. When the explosion proof requirements of Schedule 2-G made the concept appear to be unfeasible from the standpoint of weight and portability, the program was redirected and a three channel monitor employing electrochemical sensors was adopted. In this case the gases to be monitored were O2, CO and NO2. The remainder of the program was oriented towards obtaining good, commercially available lectrochemical sensors for the above gases, testing them, reducing deficiencies noted during these tests, and making the necessary modifications to integrate the three sensors into a Mine Air Monitor suitable for the mine environment.

Jan 1, 1974

By Doug Tesarik

The study of neutrinos?particles infinitesimally smaller than atoms?would be significantly advanced if a deep underground facility were available that would filter out unwanted cosmic radiation. Encouraging progress has been made in satisfying the criteria for such a facility with the selection of the Homestake Mine in Lead, SD, by the National Underground Laboratory Committee as the recommended site for a National Underground Science Laboratory (NUSL). The Homestake Mine is America?s oldest and deepest underground mine, and its well-maintained infrastructure to depths of 2438 m below the surface makes the mine an excellent site for such a laboratory. The investigation reported here is an initial study of the stability of the first of the proposed chambers. A cylindrical room with a dome-shaped roof and floor was analyzed in three dimensions using the finite-difference program FLAC3D. The results were compared to recommended support requirements based on Barton?s Tunneling Quality Index, Q. Based on model results and observations from previous mining studies, large rooms with 50-m roof spans can be constructed and will remain stable at 2141 m below the surface in the Poorman Formation when the rock is reinforced with cable bolts. Construction may be possible at lower levels in the Yates Formation if more extensive laboratory strength tests confirm initial results.

Jan 1, 2002

By Sidney Katell

An estimated capital investment of $76,499,800 will be required for a plant designed and built to produce 90 million standard cubic feet per day (std.c.f.d.) of synthetic pipeline gas through Lurgi gasification of bituminous char. This investment figure does not include the pretreatment plant, the cost of which is assumed to be reflected in the cost of the char fed to the gasification system. Shift conversion, C02 removal, and methanation are required after gasification in the Lurgi unit to make a gas suitable for pipeline transmission. Capital investment data are based upon equipment costs, January 1959. Based on a 90-percent or 330-day operating year, the operating cost before profit and Federal taxes with the char price as a variable will amount to the following: [ ]

Jan 1, 1959

Determine the appropriate spacing and alarm levels for carbon monoxide and smoke sensors used for fire detection in underground coal mine conveyor belt entries. Background Fire represents one of the most severe hazards in underground coal mines. Early-warning fire detection in underground coal mines is essential to successfully implement and execute evacuation and control measures. Both carbon monoxide (CO) and smoke sensors have the ability to provide reliable early-warning capability, provided that they are spaced properly and set at the appropriate alarm levels. The U.S. Bureau of Mines conducted a series of large-scale experiments where a small coal fire was used to ignite a conveyor belt at air velocities of 0.76 to 6.1 m/s. The test configuration was purposely designed to model a worst-case fire scenario for fires that develop within conveyor belt entries in underground coal mines. During the tests, CO and smoke levels were continuously measured to determine alarm times and alarm levels as the fire intensity progressed. The data from these tests indicated that for a given sensor spacing, the time to reach a preset alarm threshold depends upon the belt entry air velocity and cross-sectional area. Analysis of this data resulted in the equations and nomographs for CO and smoke sensor spacing, and alarm levels contained in Bureau of Mines RI 9380, "Fire Detection for Conveyor Belt Entries."

Jan 1, 1993

By John J. Henn

An evaluation is presented for an ammonium sulfate leaching process designed to extract manganese from Cuyuna, Minn., and Aroostook, Maine, deposits. In this process the manganese and iron in the ore are reduced to MnO and Fe 3 0 4 in a shaft furnace; the reduced ore is then leached with ammonium sulfate solution forming soluble manganous sulfate while leaving most of the iron undissolved. After filtration, the manganese and some impurities are precipitated from solution as carbonates which are then pelletized and calcined to form a product composed mainly of Mn3O4. The plants are designed to produce 100 tons per day of manganese contained in a product that is suitable for the production of ferromanganese. A byproduct credit, together with the extra processing cost, is included for the Cuyuna ore processing plants because Fe2O3 may be recovered for use in blast furnaces. The estimated operating costs per ton of manganese, excluding income taxes and return on investment, are: [ ] The process with or without byproduct recovery, when treating Cuyuna or Aroostook ores, is not economically competitive with ores available at $71.43 per ton of contained manganese.

Jan 1, 1968