Search Documents

The use of belt air in underground coal mines has been a continuous discussion since it was first introduced in the Federal Coal Mine Health and Safety Act (Coal Act) of 1969. Although the Coal Act prohibits the use of belt air to ventilate active workings, there were two exceptions prior to the 2004 Final Rule. There have been several major studies/rule-proposals by MSHA since 1985 and the most recent of which is the Technical Study Panel (TSP) established by the Mine Improvement and New Emergency Response (MINER) Act of 2006 to study the use of belt air and related issues. This paper reviews the history of belt air use, its associated controver-sies, and more specifically, the 20 recommendations unanimously approved by the TSP.

Jan 1, 2009

By J. Wickens

Haile Gold Mine is located near Kershaw, South Carolina, approximately 50 miles south of Charlotte, North Carolina. Gold was first discovered at the site in 1827, and the property has been through several operating periods since. The relatively low grade and refractory nature of the deposit has been a challenge for efficient processing since the start of mining on the property. Early processing techniques included gravity separation and barrel chlorination. The last operation employed heap leaching in 1985 through 1992. After being closed and reclaimed for over 20 years, the property is poised to re-open and produce once again. In this chapter of the Mine?s legacy, flotation and ultra-fine grinding will be employed to achieve economic extraction of gold and silver from the pyrite. This paper briefly reviews some of the mine?s history, the metallurgical testing, the flowsheet and discusses design considerations. KEY WORDS: process plant, flash flotation, leaching, SMD, stirred media detritor

Feb 27, 2013

By E. R. Darby

When bronze is melted in open-flame furnaces a considerable amount of slag is formed during the melting operation. This slag may be incidental to the melting practice or it may be formed intentionally by slag-forming constituents added to the furnace charge to provide a covering for the melted metal When this slag is removed from the furnace, it contains, in addition to the free metal carried with it by the skimming operation, a considerable amount of metal as oxide either combined or mechanically mixed with it. By the usual crushing and washing methods this metallic oxide generally goes to the tailings pile, so diluted by other foundry waste that its recovery is economically impossible. If this furnace slag is not inixed with other foundry waste, practically all of the metal oxide as well as the free metal may be recovered by some form of smelting operation. The first side of the problem to be considered is the amount of slag produced. It may not be true that the majority of foundries have no record of the amount of slag made, but it is certainly true that a very great many either have no record or pay little attention to it. Usually the collection of furnace slag for one normal week's run will be sufficient to determine the advisability of its being handled in a different manner from the crushing and concentrating generally employed. If a large representative sample of the accumulation is crushed and concentrated and the recovery compared with the results of a careful assay, it will be found that a large percentage of the total metal content was lost in the washing process. The percentage of loss will be greater than the metallic oxide content, as some free metal in extremely fine particles always is carried away in grains of slag. From such a comparison, it may be determined whether or not the slag should be melted, sold or treated as before. An example of an actual test of this kind is given below. In a foundry melting 50,000 to 80,000 Ib. of bronze per day, a week's accumulation of furnace slag and ladle skimmings amounted to 16,500 1b.—over three times as much as the foundry superintendent estimated before the accumulation was made. Two tons of this material was taken as representative of the lot. This was ground through a thoroughly cleaned ball-mill and concentrated over a Wilfley table. The

In 2004, a total of 741 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). These mines (e.g., potash, gypsum, salt) comprised 5.1% of all operations.

Sep 1, 2007

By E. C. Foster

The project objective of this contract is to design, develop, and demonstrate a dust collecting system for auger head miners, used in coal seams 40 inches or less in height, which will reduce respirable dust below the limits established by the Federal Coal Mine Health and Safety Act of 1969. This system was to be incorporated into 3 Wilcox Mark 20 continuous miner. In order to accomplish this, the objective was divided in three main areas. First: To develop a dust control system which would remove by isolation, respirable dust from the face area and areas where miners work. Second: To develop a dust scrubbing system to remove and collect float dust before the air reaches the return airway. Third: To reduce the overall noise levels to which the miners are exposed.

Jan 1, 1974

Andesites are a major source of aggregate for much of the North Island of New Zealand. There are regional differences with respect to some important properties of the andesites. Some are reactive with cement and are designated as potentially deleterious or deleterious by the concrete industry. Other andesites, particularly those that are slightly altered or weathered, have rather high Plasticity or Clay Indices and perform poorly in road construction.   The performance of the andesites has been investigated and can be shown to be determined by: +        the chemistry of the rock which in turn determines the chemistry of the glass in the rock; +        the presence of large amounts of groundmass glass in the rock; and +        the nature of the superimposed alteration processes. Environment of extrusion and how rapidly the rock has been cooled or chilled are also important as they determine the fabric of the rock and how much glass will be present in the rock.   There are three main types of alteration that affect the quality of the aggregate: 1.   hydrothermal alteration, 2.   late magmatic alteration associated with the devitrification of glass, and 3.   weathering.   Each of these alteration types produces different alteration minerals. In fresh andesites the devitrification of glass has an important affect on the rockÆs properties. The Taranaki andesites are shown to have unusually (in comparison with other North Island andesites) high Na2O contents, held in the groundmass glass, which is the fundamental reason for the high alkali û silica reactivity of these andesites.

Jan 1, 2005

By Patrick J. Doig

The Lewis Street CSO Tunnel is an important element in the efforts of the Metropolitan Government of Nashville and Davidson County (Metro) to improve the treatment of waste-water in the area. The tunnel is approximately 1,675m (5,500ft) long with a finished diameter of 2,600mm(102inches). 116m (380ft) of tunnel was constructed in soil with the balance being in lime-stone rock. Excavation was with a 3,700 mm (12ft) diameter Jarva hydraulic shield in soil and a Jarva Mark 12 TBM in rock. The permanent lining of the tunnel comprised concrete pipe with steel end-rings and a vinyl liner. This paper describes the construction of the project with particular emphasis on the excavation and lining of the tunnel.

Jan 1, 1997

By W. S. Hargratt

THE present era of exploitation of the Little Long Lac and Sturgeon River areas commenced in 1925, when Beardmore Gold Mines started development of what is now the property of Northern Empire Mines. A shaft was sunk in 1927-28 and a very limited amount of underground work was carried out, following which the property was shut down. It remained idle until 1932, when Empire Star Mines, a Delaware Company, optioned the property. This Company formed the Northern Empire Mines Company, Limited, to operate the mine, and immediately instigated an aggressive programme of surface and underground development. By the summer of 1933, sufficient ore was indicated to justify the installation of a small mill. The decision was also reached to bring in electric power. A power-line was built from Hydro, the Ontario Power Commission's development on the Nipigon river, to the mine, a distance of approximately 50 miles. This work was entirely financed by Northern Empire Mines. Mill construction was commenced in October, 1933, and completed by March, 1934, thus making this mine the first producer in this district.

Jan 1, 1940

By Patiño E

Bioleaching is an established technology for the pre-treatment of refractory gold ores and concentrates and the leaching of whole ore copper heaps. In many cases, it offers economic, environmental and technical advantages over pressure oxidation and roasting. However for bioleaching to compete successfully with others pre-treatment processes it needs to be optimized with regard to the parameters that affect the bioleaching reactions and the growth of the microorganism involved. In this sense, this paper focus on the thermodynamic approach applied in bioleaching through of the definition of the growth system and it is thermodynamics analysis, the effect of heat production and energy dissipation on growth and thermodynamic analysis of growth kinetics and the effect of nonstandard conditions.

Sep 12, 2005

By David Sprott, Patrick Andrieux

In 1990 the Noranda Technology Centre commenced a project to develop an interactive three-dimensional blast design system using a commercial computer-aided drafting and design package (CADD). The objective was to alleviate the blast engineer from the tedious and time consuming blast layout and design functions normally done by hand. This would allow more time for optimizing blast designs through assessing multiple options. Since several blast design software "tools" already existed at Noranda, the need arose to integrate all the applications into one overall system that shared one common database. The result is BLASTCAD.

Jan 1, 1991

By Christopher Cloete Uys, Luis Manuel Poinha Valentim

The purpose of this workshop is to describe and demonstrate the use of SPEEDWAVE, a high speed data recorder, its VOD enhancements, and the software which binds the system together. The system was designed by TLC Sohware, SOUTH AFRICA. TLC is a company spedalising in the solution of engineering problems, using computertechnology as a base. TLC was founded in 1987, and has since been involved in many different.measurement, control, simulation and modelling projects. Wth respect to the blasting industry, TLC has, in conjunction with AECI South Africa/ICI, developed a tunnel mining design aid, a ring blasting design aid, a multkhannel seismograph and a laser surveying program. In 1989, TLC designed and built the BA800. a microcomputer-based high speed recorder. These recorders are still in use and are producing valuable results. Based on improved technology and with the field experience of the BA800, TLC has designed and developed the data recorder SPEEDWWE.

Jan 1, 1995

By M. N. H. Khan

CSIRO has been experimenting with supersonic flows as a method of rapidly quenching metallic vapours. Cooling rates above 106 °C/s have been achieved. The supersonic flow conditions are achieved by adiabatic expansion of the vapour through a Laval nozzle into a vacuum chamber. This paper will describe the basic physics of the process, outlining computer fluid dynamic (CFD) modelling of flow in the nozzle, the effects of different flow conditions on the condensation process and discuss the practical design issues associated with operating supersonic nozzles. Results obtained from a CFD model of the nozzle, which compared two methods of incorporating condensation, showed that inclusion of condensation substantially changes the conditions in the nozzle. Most noticeably, the effect of condensation produces a region in the nozzle where the temperature remains almost constant.

Jan 1, 2006

THOSE MARKED THUS * ARE MEMBERS, MARKED THUS t ARE ASSOCIATES THESE SIGNS DOUBLED INDICATE LIFE MEMBERS AND ASSOCIATES RESPECTIVELY THE FIGURES AT THE END OF THE ADDRESS INDICATE THE YEAR OF ELECTION HEAVY FACED TYPE SIGNIFIES HONORARY MEMBERSHIP ` *AARONS, JULIAN B , Mine Supt, The Boulder Deep Levels, Ltd , Boulder, Western Australia, '05 *ABADIE, EMILE R, Cons and Min Engr, 1004 James Flood Bldg, San Francisco, Cal '76 *ABBE, CLEVELAND, JR, GeOl Aid, U S Geological Survey, Washington, D C '00 *ABBOTT, AI ARTHUR, Cerro de Pasco Mining CO , Cerro de Pasco, Peru, So America '95 *ABBOTT, ARTHUR V , Electrical Engr , Westinghouse, Church, Kerr & CO , 8 Bridge St, New York, N Y '82 *ABBOTT, CLARENCE E, Chief Min Engr, Care Fayal Mine, Eveleth, Minn '04

Jan 1, 1910

By Murali M. Gadde

Welded wire mesh is the most commonly used skin control technique in the United States underground coal mines. Currently, selection of the mesh is based on trial and error rather than any rigorous design methodology. Several factors affect a wire mesh?s performance including the amount of rock material to be supported and how the load is distributed, wire gauge, aperture size, grade of steel, weld strength, bolting pattern and sheet size. Although the best way to choose the mesh is to conduct full-scale physical load tests, because of the limitations on the number of variables that can be considered in such tests and the requirement of an elaborate test set-up, it may not always be possible to use this option. An alternative would be to use numerical modeling to study the load-deformation behavior of a wire mesh. In addition to providing a very detailed stress, strain distribution in the entire mesh, the advantage of this approach is the ease with which parametric studies can be conducted. In this paper it is shown that the load-deformation curves generated by nonlinear numerical models match closely with laboratory derived ones. Then, based on parametric studies, design guidelines are developed to choose the mesh appropriate for different loading conditions. The modeling studies also bring forth the limitations of the current lab studies. For example, under some conditions it was noticed that the small sheet size considered in lab tests would produce higher mesh deformations than a full-size one used in actual practice.

Jan 1, 2006

By Maria José Santos Lima

A pesquisa e o desenvolvimento de Materiais nanoestruturados vêm crescendo significativamente nos últimos anos. Estes materiais apresentam propriedades significativamente modificadas em comparação às dos materiais convencionais, devido às dimensões extremamente reduzidas dos cristalitos. O carbeto de Tântalo (TaC) é um material extremamente duro, apresentando elevada dureza, elevado ponto de fusão, elevada estabilidade química, boa resistência ao ataque químico e choque térmico e excelente resistência à oxidação e corrosão. Desta forma este trabalho teve como objetivo a obtenção de TaC nanoestruturado a partir do precursor tris(oxalato)oxitantalato de amônio hidratado, através de reação gás-sólido a baixa temperatura (1.000°C) e curto tempo de reação. Os materiais obtidos foram caracterizados através de difração de Raios-X (DRX), Refinamento Rietveld, Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Infravermelho (espectroscopia IV), Termogravimétrica (TG). Através das analises de DRX e do refinamento Reitiveld para o TaC com S = 1,1584 observou-se a formação do carbeto de tântalo puro com estrutura cúbica e tamanho médio de cristalitos na ordem de 12,5 nanômetros.

Aug 7, 2018

By F. Warnaars

Historically, this area produced gold and silver from many well-known vein deposits, like Tayoltita, Topia, and San Jose de Gracia. Modern exploration identified three categories of deposits: 1) low grade porphyry golds in shallow level dacite porphyries; 2) batholith-related deposits; and 3) those formed in volcanic sequences of Late Cretaceous to Late Tertiary. At least four porphyry golds have been identified, of which Metates is best known. These are formed by and within daciteporphyries, associated hydrothermal breccias and sometimes within surrounding meta sediments. Their ages are from mid-Cretaceous to Early Tertiary. Precious metal deposits associated with batholiths occur as veins, contact haloes in meta sediments or volcanics, skarns, tectonic breccias, hydrothermal tourmaline breccias, dacite dikes or as disseminated or stockwork deposits such as La Fortuna.Several new gold discoveries were made in older EarlyTertiary Volcanic Sequences and in the younger Tertiary volcanics within prominent structures exceeding 3 to 5 km in lengths. Some of these are open-pittable but most have to be mined by underground methods.

Jan 1, 1999

By G. H. Lewis, C. L. Krcil, N. S. Harding, D. E. Havekotte

Introduction Limestone injection work was completed in a 440-kW (1.5-million Btu per hour) pilot-scale combustor in preparation for a 50,000-kg/h (110,000-lb per hour) industrial steam boiler limestone injection test program. The main objectives were to: (1) identify the important variables that affect sulfur capture, (2) determine the maximum SO2 removal, and (3) determine the effect of limestone addition on furnace operability and heat transfer. A more detailed report is given by Lewis et al. (1985). The test program was divided into two phases. The objectives of Phase I were to determine the important variables that affect SO2 reduction and to investigate the effect of limestone addition on combustor operation and heat transfer surfaces. The objective of Phase II was to determine, using only the important variables identified during Phase I, the conditions that resulted in the greatest sulfur dioxide reduction. Phase I Test program Using one limestone, five variables were identified as having an effect on SO2 reduction. These are noted with their respective ranges: heat release rate [103 to 166 kW/m3 (10,000 to 16,000 Btu per hour-cu ft)], Ca/S molar ratio (0 to 3), flue gas oxygen concentration (3% to 5%), additive particle size [90% -150 µm (-100 mesh) and 90% -45 µm (-325 mesh)], and burner stoichiometry (SR = 0.75 and >1.15). A 2.3% sulfur northern West Virginia coal, pulverized to a nominal grind of 70% -75 µm (-200 mesh), was burned for the tests. The limestone used was obtained from a Maysville, KY, quarry and contained 51.75% (wt) CaO. An 11-run statistically designed program (plus three duplicates) was used to screen the five variables. The effect of limestone injection on the combustor heat transfer surfaces was determined by comparing the heat transfer rates through a slag panel and fouling probes during periods with and without limestone injection. Combustor operation was determined by noting any operating problems that occurred during the tests. Test procedure After furnace wall temperatures had stabilized at operating conditions, heat transfer surfaces (slag panel and fouling probes) and the convection section were blown clean, and a four-hour test was begun. The

Jan 12, 1986

By Pratt Rogers, Aaron Young

Digital transformation (DT) is the process by which entities adapt themselves to modern technology. As digital technology becomes more prevalent (automation, cameras, sensors, touchscreens, artificial intelligence, etc.), there will be increased pressure on companies to leverage it for additional gains. For many companies in the mining industry, this will involve overcoming a steep learning curve. Furthermore, as the long-term success of the mining industry is dependent on a labor force with new skills (data management, analytics, digital literacy, etc.), new curriculum will need to be appended to the mining engineering discipline. This paper considers the mining industry’s need for DT. Then, it presents a three-part review of the foundational components of the DT process–ubiquitous data, connectivity, and decision making. Finally, it provides a discussion on the future of DT in mining as well as a research direction, which identifies the need of academia to provide support for mining companies in the form of both research and the education of digitally literate, dynamically capable mining engineers into the coming decades.

By John R. Reeves

The principal oil aha.le in Indiana ie known as the New Al'baZ\Y shale. It 11 ot Devonian age, and ia usually correlated with, although not certainly of the 1ame age a,, the Antrim shale of northern Michiga.. the Ohio shale of Ohio, and the Chattanooga shale ot Kentucky. Termescae • a."ld Georgia. The nqtmal thickneaa of the formation 1n Indiana 1e a.bout 100 faet, ltbough 1n the region of its out­ cro;l the tall th!::kne,111 io rarely exposed because cf the general d:.p of the strata, which is 11 about 30 feet per mile to the west. With the exception ot thin local pha1e1, the entire thickness is oil shale,

Aug 1, 1922

By L. Dubourg, H. Habibi, D. Rasmussen

The combination of laser welding with Gas Metal Arc Welding (GMA W) forms the hybrid laser-OMA W welding. This process is an attractive tool with a high potential in welding lightweight structures, especially for aluminum alloys. For five years, this technology has increasingly attracted interest in both, industry (aeronautics, automobile, metal industries producing large structures) and academia (universities and research centers). Hybrid laser-OMA W welding process is generally accepted for its robustness, efficiency and flexibility. Coupling of a deep-penetrating laser beam with the heat and molten metal feeding of GMA W significantly expands the original welding application range of lasers. Its main advantages compared to the two individual components are deep and stable weld penetration, gap-bridging ability improvement, low distortion and easy filler metal addition. Hybrid welding allows a much wider groove tolerance compared to laser welding, especially for aluminum welding. Moreover, the reduction in distortion decreases the post-welding rectification needed and makes the assembly easier. In addition, if metallurgical factors are critical, the weld composition can be balanced with filler metal, decreasing the hot cracking susceptibility of some aluminum alloys. The combination of these two welding processes can also improve the weld bead shape quality (including the elimination of undercut), possibly reduce the porosity and increase the welding speed. This article reviews the recent works about the laser-OMA W hybrid welding of aluminum alloys. After a brief presentation on the interaction mechanisms between a laser beam and an electric arc, the paper depicts the typical welding parameters and experimental methods along with their characteristics.

Jan 1, 2006