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By Carl E. Norman

An investigation of geologic structure on macroscopic, mesoscopic, and microscopic scales was conducted on near-surface igneous and metamorphic rocks in which the existing stress field was determined by in situ methods. A consistent NE-SW orientation of the maximum compressive stress in the horizontal plane at four of five test localities appears due to the intrusion of NW-trending diabase dikes. Structural features at the mesoscopic scale show no consistent directional relationship to determined stress directions. Petrofabric diagrams of open microfractures show preferred orientations, but these are not consistently related to the orientations of larger structural features, such as joints, foliation, or mineralized shear zones. However, at five of six test sites the preferred direction of microfractures occurs nearly perpendicular to the maximum principal stress directions; an anomalous parallel relationship exists at a test site in an intrusive rock body. The results suggest that the open microfracture subfabric may provide a means for gaining information on the directional properties of stress fields. Such information can be obtained from oriented cores taken from holes which exceed the approximate 100-foot depth to which other in situ methods are presently limited.

Jan 1, 1970

By Samuel A. Goldberg

The Federal Coal Mine Health and Safety Act of 1969 delegated to the Bureau of Mines a yearly program of health inspections. Respirable coal mine dust concentrations are measured by Bureau inspectors. Samples of respirable coal mine dust are weighed to determine dust concentration and then analyzed for ash and quartz content. This paper describes the laboratory procedure for determining the percent quartz in the respirable coal mine dust samples.

Jan 1, 1972

By N. E. Hanna

To be authorized for use in coal mines, explosives and blasting devices must pass certain safety tests prescribed in schedule 1F,3/ on the basis of extensive practical and theoretical research by the Explosives Testing Station of the Federal Bureau of Mines. An explosive or blasting device that passes these tests is placed on the active permissible list. As this list is constantly revised, it has been the practice of the Bureau of Mines periodically to publish the names of explosives and blasting devices that have been added to the active list, as well as those that have been transferred to the inactive list; changes in brand names also are reported. This circular covers all permissibles including additions, transfers, and changes made between December 31, 1945,4/ and December 31, 1951.

Jan 1, 1952

By J. Hanslovan, R. H. King

An investigation of the feasibility of shielding low-voltage trailing cables in underground coal mines is described. Both laboratory and under¬ground installation results are presented. The main objective of shielding is to reduce the electrical shock hazard; however, several problems will be encountered by mine operators who install shielded cables. Parameters related to such items as purchasing, splicing, troubleshooting, safety, and reliability are discussed. Some of these problems can be minimized by changes in cable constructions and shuttle-car reeling-device components. Both SH-C and SH-D constructions are considered.

Jan 1, 1979

By George E. Fasching

The Bureau of Mines has developed a pulse counting system with improved energy resolution and having dual channels to process pulses at different rates and a pulse pileup detector for channel selection. Pulse input is delayed until the detector determines if any pulse is so closely followed by a second pulse as to constitute pulse pileup. If no pulse pileup is detected, the slower channel is selected; this clips the pulse to a wide pulse width to retain good energy resolution. If pulse pileup is predicted, the fast channel, with correspondingly shorter pulse width, is selected to improve resolution with respect to time. Output of the two channels is transmitted to a pulse height analyzer for interpretation. The pulse processing system can process count rates above 300,000 counts per second with little loss in energy resolution.

Jan 1, 1974

By Oleg Terichow

Electrophoretic mobility measurements were made by the Bureau of Mines on samples of a Florida phosphate slime to determine the optimum conditions of coagulation and settling in an aluminum sulfate solution. Addition of anthracite to promote mutual coagulation demonstrated the practicability of heterocoagulation by reduction of the repulsive effect of double layers. By proper selection of the electrolyte and its concentration, the reduction of the double layers to a net zero point of charge causes the predominance of Van der Waals' forces of attraction leading to the coagulation and rapid settling of both particle systems, as is predicted by the Derjaguin-Landau-Verwey-Overbeek theory of colloidal stability. Confirmation was found in the microfiltration tests where a modified Carman equation was applied to evaluate the specific filter bed resistance.

Jan 1, 1975

By W. F. Marshall

The effect of engine parameters on exhaust emissions from two diesel engines was studied experimentally. Fuel-injection characteristics and intake air conditions were considered as parameters influencing the emissions. Emphasis was placed on the effect of parameter variations on nitrogen oxide (NOx) emissions, because diesels generally emit very low levels of carbon monoxide (CO) and unburned hydrocarbons. Emissions other than NOx were at lowest levels when the engines were adjusted for best performance. NOx emissions can be diminished somewhat through variation in fuel-injection characteristics, but there generally are penalties in emissions of CO, smoke, and unburned hydrocarbons or in engine performance. Temperature and composition of intake air have a significant effect on NOx emissions. Levels of NOx are reduced by recirculating the exhaust gas or by adding water to the intake air stream. However, the rate of water added or exhaust gas recirculated must be limited to prevent the degradation of engine performance and increased emissions of CO and smoke. At high exhaust recirculation rates, levels of CO and smoke were increased such that it was necessary to derate the engine and also to use a catalytic system for oxidation of CO.

Jan 1, 1971

By R. F. Abernethy

A chemical method of determining microgram quantities of arsenic in coal was investigated by the Bureau of Mines to supplement a semiquantitative spectrographic method of determining arsenic in coal ash. In accordance with a method recommended by the International Organization for Standardization, 1-gram samples of coal are decomposed by wet oxidation with boiling sulfuric acid (H2S04) and nitric acid (HN03) to remove the organic matter. After heating to fumes of SO3 to remove HN03, the arsenic is separated as arsine by the action of zinc in H2S04 solution. The arsine is absorbed in dilute iodine solution in which the arsenic is determined colorimetrically by the molybdenum-blue reaction. Two modifications of the method for obtaining the arsenic in solution, in addition to the wet oxidation method, give satisfactory results. The modifications are (1) furnace ashing with MgO added to the coal, followed by treatment with H2S04, and (2) extraction of arsenic from the coal by dilute HNO3 without ashing. Float-and sink-tests show that arsenic is associated mainly with mineral matter in the three coals examined. High-temperature ashing tests show that very little arsenic is volatilized from coal ash below 1,000° C, but it is virtually all removed from the ash at 1,300° C.

Jan 1, 1968

By Isaac A. Zlochower, Kenneth L. Cashdollar

The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties-from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly "refractory" elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechnic ignitors. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from "-1550K for tin and tungsten powders to "-2800K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures.

By Rollien R. Wells

A REPORT of technological advancements restricted to a specific 12-month period is impractical. Inherent in the nature and development of technology is the element of time; rarely can a new process or product be attributed to a particular year. An overall picture of general trends and pattern changes, however, is indicative of technological growth. This paper presents selected observations and discussions of current metallurgical research and practices in an attempt to develop' such a picture. Of the estimated $16.5 billion spent for research and development in the United States in 1962, at least 80 percent was earmarked for the aircraft, electronics, chemical, and machinery industries. Much of the effort was of the end-use variety and was oriented closely to the national defense and aerospace programs. Only a small fraction of the total research money was directed to studies of the utilization and improvement of metals. Even if the investigations in allied fields such as solid state physics are included, the total research expenditure for metal and mineral materials barely reached $500 million. An additional $200 million was spent by industry and government for development of minerals recovery and processing methods.

Jan 1, 1963

By Leonard J. Prosser, Joseph Cervik, John H. Perry

The Bureau of Mines has developed several techniques for draining methane from coalbeds in advance of mining. Drilling long horizontal holes from an underground location is one such technique, which was successfully demonstrated in the Pittsburgh and Sunnyside Coalbeds. The same technique has now been applied in the Mary Lee Coalbed at Jim Walter Resources, Inc. 's No. 4 Mine, Brookwood, Ala. , where two holes were drilled horizontally--one to a depth of 1,010 feet (308 m) and the other to 540 feet (165 m). The 1,010-foot (3083) hole proved successful in degasifying a portion of the Mary Lee Coalbed. The hole drained methane for 1 year, during which time the initial gas flow of 200,000 ft3/d (5,663 m3/d) declined to 65,000 ft3/d (1,840 m3/d). Total gas production was 40 x lo6 ft3 (1.1 x lo6 m3 ). The gas was of commercial quality, with 98 pct methane and a heat rating of 990 Btu/ft (36.89 Mj/m3). The methane emissions from the faces of the mine section advancing into the degasified zone were reduced by 60 pct. The 540-foot (165-m) hole was terminated prematurely when it became impossible to maintain an open hole. Because of caving, very little gas was drained through this hole.

Jan 1, 1982

By Maria I. De Rosa

This report analyzes mine fires for all U.S. underground and surface coal mining categories by state and2-year time periods during 1990–1999. Risk rate values are derived, and ignition source, methods of fire detection and suppression, and other variables are examined. The data were derived from Mine Safety and Health Administration (MSHA) mine fire accident publications and verbal communications with mine personnel. The analysis will provide the National Institute for Occupational Safety and Health, MSHA, and the mining industry with a better understanding of the causes and hazards associated with mine fires and will form a basis for future fire research programs.

Jan 9, 2004

By Joseph Cervik, J. H. Perkins

The Bureau of Mines has conducted desorption work on fine coal particles at near atmospheric pressure. An apparatus has been developed that uses a capacitance manometer to measure desorption of methane from coal particles up to 2 inches in diameter and pressures up to 1,000 psi. This will make it possible to duplicate the desorption process as it occurs in its natural under- ground environment.

Aug 1, 1970

By Douglas Talley

This report describes a 4-inch diameter borehole probe which contains a low light level TV camera, magnetic compass, light illumination source, bottom/water detector sensor and a pointing angle sensor. The camera viewing angle is at a right angle to the probe's body. All data from the sensor is multiplexed into the closed circuit camera video for transmission on a single 50 ohm coaxial cable to a surface control unit. Likewise control of the probe's power, zoom lens, focus, panning and aperture is accomplished via a down-link multiplexed on the same cable.

Jan 9, 1984

By Noel N. Moebs

The Bureau of Mines conducted five reconnaissance magnetometer traverses across a small abandoned chromite mine in the State Line district of Pennsylvania and Maryland to determine the geophysical response of the area. The results indicate that more extensive geophysical surveys of the region might establish some worthwhile guidelines for chromite exploration. While chromite only rarely can be detected directly by magnetic methods, there is a possibility that geophysical signatures in the adjacent host rock could provide some guidelines for further exploration. Prior to 1875, all the chromite produced in the United States came from the State Line district, and the potential for discovering additional podiform deposits could be significant. Virtually no state-of-the-art geuphysical or geochemical studies have been conducted in this district since World War II and sizable areas remain undeveloped and suitable for exploration. While the results reported in this paper are not supported by drilling, it may encourage others to investigate the area more fully for improved methods of detecting subsurface podiform chromite deposits. New theories on the emplacement of ophiolites also could contribute to an assessment of the chromite potential of the serpentinite belt.

Jan 1, 1991

By Paul T. Allsman

This paper gives the cost and describes the mining of 55 tons of nickel-bearing rock by hand methods from a prospect in southern Nevada, June 15, 1937, by the Mining Division of the Bureau of Mines. The geology, mineralogy, and problems related to future development also are discussed briefly. The main object was to obtain a 55-ton sample within the limited period during which funds were available; little time was available to make a first-hand detailed study of the possibility of commercial ore deposits being found. The sample was desired by the Metallurgical Division of the Bureau for experimental purposes at the Electro-Metallurgical Station at Boulder City, Nev. The term "ore" is used loosely in the following discussion to designate dike material containing nickel and copper, without consideration of its commercial value. ACKNOLEDGMENTS Material concerning the geology and mineralogy of the prospect and district as obtained from Geological Survey publications by Bancroft3/and Longwell4/.

Jan 1, 1938

By R. V. Ramani, R. Bhaskar

"The spatial distribution of airborne dusts, deposition of dust in the airway, as well as the effect of airflow velocity and particle density on dust behavior in mine airways were studied in a set of experiments performed in a mine airway under controlled conditions. Considerable deposition of dust near the source was indicated. Pronounced effects due to velocity were observed in ambient dust concentration and deposition along the mine airway, both in the respirable and the total size ranges. Cross-sectional concentration measurements indicate an increase in concentration from the roof to the floor. The average cross-sectional concentration is about 75% of the concentration in the center of the airway.IntroductionA number of studies have been performed since the early 1950s on the behavior of dust in mine air (Bradshaw and Godbert, 1954; Dawes and Slack, 1954; Bradshaw et al., 1954; Hall, 1955-56; Reinhardt, 1971; Ford, 1971; Courtney et al., 1982). While the experimental data available from these studies are indeed useful in understanding dust cloud behavior in a specific situation, no generalized conclusions can be drawn because of the lack of data on parameters such as flow velocity, size distribution of the source dust, and particle density. These change from mine to mine or even within the same mine. The present study is aimed at providing a better understanding of the temporal and spatial behavior of dust particles in underground mine airways (National Academy ofSciences, 1980). The characteristics studied encompassed airborne concentrations and floor depositions over the entire size range as well as the respirable size range. The experimental results in this paper are intended to complement a mathematical model developed to predict ambient concentration and deposition of airborne dust in mine airways (Bhaskar and Ramani, 1986)."

Mar 1, 1989

By W. E. Wallace, V. Robinson, M. F. Keane, V. Vallyathan

"An in vitro study of the biologic responses of surface-modified and native silica and kaolin was made to provide comparative information on the supression of cytotoxicity by pulmonary surfactant. The release of alveolar macrophage cytoplasmic enzyme, lactate dehydrogenase (IDH), and lysosomal enzymes B-N-acetylglocosaminidase (B-NAG) and B-ghucuronidase (B-GLUC) and sheep blood-cell hemolysis were moni¬tored as indicators of cell membrane damage and cytutoxicity. Surface modification of silica and kaolin with dipalmitoyl lecithin (UPI) resulted in complete abrogation of cytotoxicity of both minerals. These findings indicate that surface modification of minerals with different adsorption properties by pulmonary surfactant generally lessens their prompt adverse effects.INTRODUCTIONAcute and chronic silicosis are well-characterized clinical and pathologic entities resulting from the inhalation of crystalline silica (Morgan and Seaton, 1984). Kaolin, a layered aluminosilicate clay frequently mined and used in manufacturing, contains tetrahedral silica alternately layered with alumina octahedra. Kaolin is relatively .inert biologically, and distinctly greater pulmonary burdens are seen in patients with kaolinosis than are seen in patients with silicosis. Crystalline siliea (quartz) induces a significantly greater degree of fibrosis in exposed animals in vivo than does kaolin (Hamilton and Hardy, 1974; Parkes, 1982; Hunter, 1976; Sheers, 1964; Warraki and t-lerant, 1963; Lynch and Mciver, 1954; Lapenas et al., 1984).This difference in pulmonary disease associated with the two types of dust is not reflected by in vitro cytotoxicity as Jetermined by pulmonary macrophage bioassays or erythrocyte hemolysis. Cytotoxicity studies using crystalline silica and kaolin of similar size fractions show comparable bioassay response on a mass basis. These cellular bioassays, therefore, do not correlate with the relative in vivo pathogenicity of silicates."

Jun 1, 1988

By Yael Miron

Ammonium nitrate-fuel oil (AN-FO) mixtures are used as blasting agents in mining pyrite-bearing ores. The temperature of these ores can increase by the continuous, though at times slow, oxidation weathering of the pyrites. At elevated temperatures, AN-FO reacts exothermally with pyrite, and the reaction becomes self-sustained at 120° C ± 10° C. The Bureau of Mines has conducted an investigation to determine the reactivity of mixtures of AN-FO with pyrite containing ferrous sulfate. The results of tests in a heated vessel simulating a hot borehole demonstrate that small amounts of ferrous sulfate, a major product of pyrite weathering, initiate a self-sustained exothermic reaction with AN-FO at 80° C. Five pct by weight of urea was found sufficient to prevent a reaction among the three ingredients, at least within the limits of the test, which reached 180° C. Smaller amounts of urea and of potassium oxalate slowed down the reaction and delayed its onset to higher temperatures, but did not prevent it.

Jan 1, 1979

By Paul E. Loustaunau, Devah Galloway, Catherine Wetherby

This report describes a project in which Development of a Supervisory and Management Training Program for the Underground Coal Mining Industry was developed and evaluated. The project was carried out in two phases. The first phase was a research effort to develop specifications for the program. The second phase was a development and evaluation effort. In the second phase, training programs for first-line supervisors (section foremen) and for middle managers (mine/shift foremen and mine superintendents) were prepared in accordance with the specifications and evaluated by members of the industry. This report describes the project and presents the conclusions drawn there from.

Jan 5, 1983