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By Gary P. Sames

This report discusses some practical applications of a geotechnical investigation conducted by the U.S. Bureau of Mines that can help mine operators meet revised Federal regulations in their roof control plans. The investigation, designed to characterize roof conditions near the coalbed outcrop in drift coal mines in eastern Kentucky, revealed that weathered stress-relief joints near outcrop are crucial ground control factors in the region. The joints' origin and character were determined through underground mapping of many joints in coal mine roof and detailed observations and measurement of joint trends and physical characteristics in widely separated strip mine highwalls and roadcuts. This resulted in an understanding of stress-relief-joint patterns and the effect of various rock types on the intensity of weathering in the joints. That information is used in this report to show how stress-relief joints contribute to roof failure and how, through improved roof support and mine planning, safer roof support plans can be developed.

Jan 1, 1992

By David S. Yantek

A-weighted sound levels around vibrating screens in coal preparation plants often exceed 90 dB(A). The National Institute for Occupational Safety and Health (NIOSH) is actively developing noise controls to reduce noise generated by horizontal vibrating screens. A 121-microphone, 3.5-meter-diameter array was used to perform beamforming to determine locations of significant noise radiation on the screen. Below about 1 kHz, the screen body was found to be the most significant noise source. The beamforming contour maps showed several key locations on the sides of the screen and the feedbox are the most significant contributors. Operating deflection shape (ODS) analysis was used to examine the screen behavior under actual operating conditions. This information is helpful in determining how to modify the screen body to reduce the noise radiated by the screen below 1 kHz. The analysis showed modal vibration patterns on the sides and feed box were the main contributors to noise. The results show several areas on the screen sides and feedbox that can be modified to reduce noise.

Jan 1, 2009

By Edward F. Courtney

Loss of life, loss of sight, crippling injuries, and property damage nearly always result from accidents involving explosives. The severity of such accidents has prompted lawmaking bodies to pass laws concerning the transportation, handling, and use of explosives; manufacturers of explosives publish manuals 'describing explosives and practical methods of handling then; and mining companies and others who use large quantities of explosives publish rules based on actual experience for the guidance of their employees. Careless storage of explosives by thoughtless or incompetent persons, particularly if they are left where children or saboteurs have access 'to them, has led to many serious accidents. Many contractors and mining operators who use explosives are extremely careless about storing them. It is the purpose of this paper to discuss the explosive-handling practices of a large western mining company, which are considered better than most.

Jan 1, 1946

By L. A. Neumeier

Sound experimental ingots of zinc alloys for use as rolling slabs were cast with a specially constructed, semicontinuous casting machine. Nominal alloy compositions of Zn-1.0 percent Cu, Zn-0.12 and 0.36 percent Ti, and Zn-1.0 percent Cu-0.03 to 0.36 percent Ti were cast. This Bureau of Mines study was conducted to evaluate the suitability of the casting procedure for providing stock for rolling into sheet. Microscopic examination of ingot sections revealed structures in which grain size varied from the outer to center ingot zones. Columnar grains present in the center zone of the Zn-1.0 percent Cu ingot were absent in the titanium-containing ingots. The ingots with titanium displayed a finer grain size and eutectic structure in the center ingot zone than in the outer zone; the transition in grain size between the two zones was quite abrupt in some ingots. The overall grain size of the titanium-containing ingots was finer than that of alloys cast by more conventional methods. Chemical analysis revealed that compositional segregation is not a significant factor in the formation of the ingot structure. Microstructural studies of small ingots of similar alloys solidified at slow, fast, and intermediate rates confirmed that the ingot structure in the semicontinuous-cast ingots is related to cooling rate, which is, in turn, related to the particular casting machine design and the influx of cooling water on the withdrawing ingots. Microstructures of thin sheet hot-rolled from slabs of the semicontinuous-cast ingots demonstrated that the ingot structure does not preclude the rolling of sheet having a uniform microstructure. Results of hardness surveys of the semicontinuous-cast ingots demonstrated that copper and titanium exert essentially additive hardening effects in these cast alloys.

Jan 1, 1968

By Peter N. Gabby

A mineral survey of 8,300 acres of the 24,980-acre Burnt Creek Wilderness Study Area (ID 45-12), was conducted by the U.S. Bureau of Mines in 1985 at the request of the Bureau of Land Management. The study area is located in Custer County, ID, 90 miles northwest of Idaho Falls. No mines, claims, or prospects are in the study area. The northern half of the study area and adjacent lands to the north, northeast, and east are or were recently under oil and gas lease, Basalt and latite-andesite of the Challis Volcanics predominate in the study area. Several hundred feet east of the study area is a quarry in talus of Mississippian-age limestone that was used for sized 100-pound rock fill in the Old Dry Creek Reservoir dam. Two samples, one taken at the quarry and the other at a limestone outcrop on East Fork Burnt Creek, have CaC03 content in the range of 90 to 95 percent, and is suitable as the limestone component of Portland cement, However, limestone outside the study area could supply foreseeable demand. Lead- silver mineralization has been observed in Paleozoic carbonate rocks elsewhere in the Lost River Range, but these rocks do not occur in the study area.

Jan 1, 1986

By Dennis R. Dolinar

The danger to personnel, equipment, and pillar structure created by the spalling of a coal rib can be minimized by installing rib bolts. To assure that a configured support system will maintain a coal rib, the U.S. Bureau of Mines developed a rib bolt system based on a nonpreventable failure concept. A statistical equation quantitatively relates the amount of rib retained to the bolt spacing and the width of the spalled material. Laboratory test results show that the equation accurately predicts the amount of material retained and confirm the validity of the support concept. The examination of rib bolting at a coal mine experiencing rib sloughage provides evidence that the effectiveness of the support can be related to the failure pattern of the spalled material. An analysis of roof and roof support reaction to rib sloughage at the mine indicated that the rib sloughage had little effect on roof stability. Although supporting ribs might not affect roof stability, laboratory test results indicate that the material retained by the support can sustain a load up to 20 pct of the intact compressive strength of the material.

Jan 1, 2010

By Oliver A. Dibble

This paper it one of a series being prepared for and published by the United States Bureau of Mines, describing mining methods and costs at clay pits throughout the United States. These papers are designed to disseminate technical information regarding the methods used. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual operators as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. The open-pit recovery of clay for cement plants is a comparatively simple operation in comparison with underground mining of clays; nevertheless, it represents an appreciable factor in the cost of cement manufacture. The following report deals specifically with the methods employed by the Aetna Portland Cement Co., which operates cement mills at Fenton and Bay City, Mich., in recovering clay from their pit at Corunna, Mich., on the Grand Trunk Western Railway.

Jan 1, 1932

By J. B. Littlefield

This study is one of at number conducted to determine the concentration of dust in the air during the complete cycle of operation in wet drilling; information as to various factors connected with, drilling in mining operations is considered to be of definite value in the control and prevention of air dustiness, and it in particularly desirable to ascertain whet features of present-day wet-drilling operations in mine work contribute to dust disease and to remedy deficiencies when they are found.

Jan 1, 1938

The head loss data for coal slurries over a range of concentrations and velocities and the laboratory screen analysis were selected as areas for investigation in the data analysis performed. The analysis resulted in the following: (1) Size distributions for the coal used in the horizontal pipeline tests were fitted to the Rosin - Rammler distribution function. Each of the fits was significant. Corresponding Rosin - Rammler parameters were obtained which were introduced into the regression analysis. (2) A regression equation was obtained which predicts the slurry head loss of 1-inch by 0 coal slurries ranging in volumetric concentration from 20 to 40 percent and line velocities from 1 to 14 feet per second as a function of the square of velocity. The addition of the term for concentration in the regression equation did not contribute significantly c head loss.

Jan 1, 1972

By K. O. Bennington

The thermodynamic properites of petalite (Li2A12Si8O20) were determined by the Bureau of Mines. The enthalpy of formation was determined by hydro-fluoric acid solution calorimetry. The values from the elements and from the oxides are ?Hf°298.15 = 2,335.8 ± 3.0 kcal/mole and ?H°295 (from oxides) = -50.60 ± 1.20 kcal/mole. Low-temperature heat capacities were determined by adiabatic calorimetry from 10.69 to 302.11 K. The derived standard entropy is S°298.15 = 111.0 ± 1 cal/deg-mole. Enthalpy increments above 298 K were measured by copper block calorimetry from 298 K to 1,193.6 K. The various experimental data were combined with other data from the literature to calculate the Gibbs energies of formation and equilibrium constants of formation over the temperature range of the measurements. Tables of enthalpies of formation and Gibbs energies of formation are given as a function of temperature from the elements and constituent oxides. The Gibbs energy of formation is ?G°f298.15 = 2,203.8 kcal/mole.

Jan 1, 1980

By H. K. Sacks

The Bureau of Mines has improved a mine dust incombustibles analyzer originally developed at the Bartlesville Energy Research Center (BERC). This analyzer provides quick, accurate analysis of the percentage of incombustible material present in dust samples taken from mine ribs, roof, and floor so that costly overdusting may be eliminated while still maintaining a proper level of incombustibles. The changes being effected on the present design of the BERC model IV rock dust analyzer should simplify its operation and calibration procedures, resulting in increased accuracy.

Jan 1, 1976

By Jon C. Volkwein

The industrial sand industry has been exploring new techniques to reduce dust. One company was experimenting with adding water during bagging operations to the surface of the hag, and into the product as it flowed into the bag. The Bureau of Mines, using instantaneous dust sampling instruments, measured the effectiveness of three methods of adding water. Results indicated that various types of water sprays applied in carefully controlled amounts could reduce dust up to 50% at worker locations at the bagging machine and inside a railroad boxcar. This report also discusses constraints such as product handling, customer acceptance, cold weather problems, dust collector performance, and other areas.

Jan 1, 1981

By H. Robert Ensminger

The Belizean economy had an estimated annual growth of about 3.4% over that of 1986. Economic growth during the 2 previous years was slower and was characterized by a negative trade balance. The gross domestic product (GDP) was an estimated $200 millioni2 in current dollars. Limited natural resources and scarce finances continued to make the Government's task a difficult one. Belize and China signed an economic cooperation agreement in April under which the Chinese Government is to provide technical assistance, a cash grant of $60.000, and a long-term, interest-free loan of approximately $1.5 million. In May, it was reported that gold was discovered in a remote area of the Maya Mountains in western Belize. An estimated unassayed value of $400 million has been placed on the deposit by one of its discoverers. However, the government in Belmopan has played down the discovery. Two U.S. oil companies. Seahawk Oil International of California and Alston Oil Co. of Texas, were granted licenses to explore for oil. Seahawk Oil will explore a large area of the Orange and Corozal Districts, while Alston Oil will prospect a 90,000-acre area of the western Cayo District. Another U.S. oil company, Pecten Oil Co., recently completed seismic studies off-shore of Belize City. Pecten Oil has made plans to start drilling in 1988.

Jan 1, 1989

By U. E. Brown

This papery describing the mining methods employed by the Bunker Hill and Sullivan Mining and Concentrating Co. at Kellogg, Idaho, is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the United States. The Bunker Hill and Sullivan mines are situated in the western part of the Coeur d'Alene district at Kellogg, Shoshone County, Idaho. The mines were discovered during the summer of 1885 and except for two short periods of labor trouble, between 1890 and 1900, have been in continuous operation. About 575 men are employed at the mine. The production is about 1,400 tons of lead-silver ore per day. This is treated in the company's concentrator and smelter at Kellogg.

Jan 1, 1931

By N. S. Dalal, X. Shi, V. Vallyathan

"INTRODUCTIONThis paper summarizes our recent investigations of the potential role of silicon-oxygen based free radical species in the biochemical mechanism of the lung injury caused by the inhalation of freshly fractured silica. The impetus for this study came from the following observations. Inhalation of crystalline silica is associated with the development of acute and chronic silicosis. Chronic silicosis is characterized by the development of sharply marked concentric fibrotic nodules in the lung. This occurs over a period of several decades with the development of progressive respiratory impairment. In contrast, acute silicosis is manifested by the filling of the alveoli with an amorphous lipoproteinaceous exudate within a short period after exposure, and rapid development of respiratory disability often leading to fatality. Most studies on the pathogenesis of silicosis have focused on the elucidation of cellular mechanisms of cell injury and the development of chronic silicosis. Because pulmonary responses to crystalline silica are distinctly different for · the acute and chronic silicosis, we hypothesized that the acute response is associated with some unique properties of ·freshly formed silica particle surfaces, due to the formation of some reactive chemical species caused by the rupturing or the silicon-oxygen bonds. In occupations involving drilling, tunneling and sandblasting operations acute silicosis can be correlated with this unique surface reactivity of silica. The formation or reactive species was demonstrated, using electron spin resonance (ESR) spectroscopy (Dalal et al., 1986; Fuibini et al., 1987; Hochstrasser and Antononi, 1972). Grinding of quartz crystals under ultra high vacuum (10-10 torr) leads to the formation of Si- and SiO• radicals and these radicals are quenched by exposure to air and other gases (Hochstrasser and Antonini, 1972). ESR signals have also been reported from micronized quartz samples that were evacuated at 413 K (Bolls et al., 1983). In order to find a more direct relationship of such radicals to acute silicosis, we made ESR measurements on quartz dusts freshly ground in ambient air and found- that indeed grinding under ambient environment leads to the formation of the Si• and SiO• type of radicals which decay on storing the dusts in air or in biological buffers (Dalai et al., 1986; Vallyathan et al., 1988). The Si• and SiO radical formation on grinding has also been reported by Fubini et al. (1987). In addition, we recently found that •OH radicals are generated in aqueous suspensions of freshly ground quartz (Dalai et al., 1988; Shi et al., 1988; Vallyathan et al., 1988). We have subsequently carried out detailed cytotoxicity and biological assays on freshly made as well as aged quartz dusts. As summarized below, the results provide new insight into the biochemical mechanism of acute silicosis."

Jan 1, 1988

By T. M. Ruff

A prototype mucking machine designed to operate in narrow-vein stopes was developed by Foster-Miller, Inc., Waltham, MA, under contract with the U.S. Bureau of Mines. The machine, called a compact loader-trammer, or minimucker, was designed to replace slusher muckers in narrow-vein underground mines. The minimucker is a six-wheel-drive, skid-steered, load-haul-dump (LHD) machine that loads muck at the front with a novel slide-bucket system and ejects it out the rear so that the machine does not have to be turned around. To correct deficiencies of the tether-remote-control system, a computer-based, radio-remote-control system was retrofitted to the minimucker. Initial tests indicated a need to assist the operator in guiding the machine in narrow stopes. An automatic guidance system that used ultrasonic ranging sensors and a wall-following algorithm was installed. Additional tests in a simulated test stope showed that these changes improved the operation of the minimucker. The design and functions of the minimucker and its computer-based, remote-control system are reviewed, and an ultrasonic-sensor-based guidance system is described.

Jan 1, 2010

By A. L. Pierce

This paper describing the mining practice at the Spring Hill mine of the Montana Mines Corporation, Helena, Mont., is one of a series issued by the Bureau of Mines on mining methods and costs in various districts. Its purpose is to summarize improved methods whereby lower costs have recently been obtained. These improvements are principally the adoption of a modified sublevel stoping method of mining the use of grizzlies underground improvements in haulage, and rage bonuses. The Sprint Hill, Trine is situated in Grizzly Gulch, 3 miles southwest of the city of Helena. Helena is on the links of the Northern Pacific and the Great Northern Railways; and the East Helena smelter of the American Smelting and Refining Co. to which the concentrates from the mine are shipped, is but 6 miles east of Helena. The mine is probing 150 to 200 tons of gold ore per day, with an underground crew of about 40 men.

Jan 1, 1931

By V. A. Nieberlein

Problems of design involving the high-temperature characteristics of materials of construction have focused attention on tungsten, the metal with the highest melting point. To study the properties of this metal a method was needed to produce tungsten of high purity easily and consistently. The Bureau of Mines has made tungsten metal in massive form on a laboratory scale by hydrogen reduction of tungsten hexafluoride (WF6). Metal made in this manner had a purity of 99.99 percent or better, with reference to all detectable impurities, including gases. The process tolerated a wide variation in operating conditions, and the results with respect to total impurities as low as 0.01 percent were reproducible.

Jan 1, 1959

By Michael R. Grubbs

The Bureau of Mines is currently developing methods for reclaiming the metal and mineral values contained in unburned urban refuse. One important phase of this research deals with recovering Mastic from shredded refuse using in electrodynamic separation process. The results of this study have indicated that mixed plastic concentrates analyzing 99.4 percent plastic can be consistently recovered from the light material fraction of shredded refuse, leaving a mixed paper traction analyzing 99.9 percent paper. Recovery of the plastic exceeds 99 percent.

Jan 1, 1972

By Van H. Manning

EXPLOSIVES RESEARCH. As the physical laboratories of the explosives section of the Pitts- burgh experiment station were equipped for testing the physical properties of explosives, both the Army and Navy Departments for many years had requested the Bureau of Mines to make such tests. Chemical control of the physical tests through analyses, heat tests, analyses of gaseous products of combustion, and sand tests was exer- cised through the explosives chemical laboratory. Often an investigation was cooperative between two laboratories. The explosives chemical laboratory also aided the work of the Ex- plosives Regulation both by chemical tests and investigation of acci- dents in explosives plants. COOPERATIVE WORK FOR ARMY AND NAVY DEPARTMENTS. The explosives chemical laboratory devised, at the request of the Bureau of Ordnance of the Navy, a more economical method of making hexanitrodiphenylamine. This problem was assigned to the Bureau of Mines by Dr. C. E. Munroe, chairman of the committee on explosives of the National Research Council, acting as the depart- ment of science and research of the Council of National Defense. Before the United States entered the war the following reports of investigations were submitted to the Army or the Navy: 1. Report of sensitiveness and relative efficiency of TNT and ammonium picrate, dated February 6, 1913, undertaken at the re- quest of the Chief of Ordnance. 2. Report of tests and examination of two samples of TNT and one of TNA for the Ordnance Department of the Army, dated August 5, 1915, was undertaken at the request of commanding officer, Frankford Arsenal. 3. Report of tests for sensitiveness to detonation of mercury ful- minate of 21 samples of TNT crystallized from various solvents, for the Bureau of Ordnance, Navy Department, dated June 17, 1916. 4. Report of tests of two samples of mercury fulminate for Frank- ford Arsenal, dated December 2, 1916, undertaken at the request of the commanding officer, Frankford Arsenal. After the United States entered the war the following reports of investigations were submitted: 5. Report of pendulum friction and large impact tests on two samples of "sodatol" and two samples of "amatol." The final report was dated July 20, 1918; and the preliminary report, May 15, 1918. This investigation was undertaken at the request of the Ordnance

Jan 1, 1919