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By R. B. Anderson

As a part of a Bureau of Mines program on the conversion of coal to liquid and gaseous fuels, the kinetics of the Fischer-Tropsch synthesis on iron catalysts was investigated. Nitrided catalysts were studied at 21.4 atmospheres using feed gases ranging from 2H2+1CO to 0.25H2+1CO, and at 7.8 to 21.4 atmospheres using 1H2+1CO gas. The overall apparent activation energy increased with increasing carbon monoxide content of the feed gas from 19.5 kcal/mole for 2H2+1CO to 23.7 for 0.7H2+1CO. The rate of synthesis with 1H2+1CO feed increased linearly with operating pressure from 7.8 to 21.4 atmospheres. A semifundamental rate equation of the form [r=a'PH2 0.6pco 0.4- ?r0.5PH200.5] was shown to fit the data satisfactorily. The relative usage of hydrogen to carbon monoxide decreased with increasing conversion, passed a minimum, and then increased. Apparently water is the principal primary product and carbon dioxide is produced by subsequent water-gas shift reaction. In another group of experiments water, carbon dioxide, argon, and methane were added to 1H2+1CO feed to a nitrided iron catalyst. Argon and methane were only diluents. Carbon dioxide was a slight inhibitor and water vapor was a strong inhibitor to the rate of synthesis. Water accelerated the water-gas shift and usually increased methane production. Important factors of catalyst geometry in determining rate were found to be particle size and extent of reduction. Apparently the active portion of the catalyst is confined to a layer of 0.01 to 0.02 cm from the external surface of particles. A special solution was made of differential equations relating re¬action at the catalyst surface to diffusion in pores of the catalyst for spherical particles with an active layer surrounding an inert core. The equation derived expressed the experimental data reasonably well. Diffusivities determined by this equation varied from 3 to 24X10-6 cm2/sec; these values are of the same magnitude as observed for the diffusion of gases in liquid. The appendix presents a group of synthesis experiments at pressures of 21.4 to 103 atmospheres. In this range the rate of synthesis on nitrided iron catalysts increased with pressure to the 0.74 to 0.84 power.

Jan 1, 1964

By John C. Cook

Channel sand bodies ("wants" or "cutouts") are deposits of barren, hard sediments which interrupt production and pose safety hazards when encountered in underground coal mining. To locate these costly impediments to mining in advance, from the surface of the ground, the seismic reflection method is recommended. High-resolution (high frequency) techniques for shallow seismic exploration of coal beds have been worked out and are reported here, including a field example. Newly-developed high-frequency, digital recording equipment was used, together with light-weight shot-drilling equipment and a variety of down-hole seismic impulse sources. Techniques for rapid but complete coverage of a coal prospect area with a crew of 2 to 6 men n 2 or 3 vehicles are described in detail.

Jan 1, 1976

By Oswald J. Heinrich

THE origin of spontaneous combustion in collieries is, of course, chiefly due to bad system in laying out the pits, unclean workings, insufficient ventilation, and neglect in damming off works after they are exhausted of the main coal. This is particularly indispensable in the Richmond field, because it is difficult and dangerous here, on account of the inferior roof, to remove the last vestiges of coal ; and we are compelled also to retain all the slates and bands, as far as possible, in the pit, to help fill up, although such material is liable to fire. This, however, can be prevented to a great extent, as mentioned below. I am satisfied that the only system of working this thick coal is by cross-cutting (Querbau, ouvrage & travers) or working in benches, as practiced in France (Creusot, Rive de Gier, St. Etienne), in Silesia (Kiinigsgrube), which I have used as far as it is practicable in an old pit, almost torn to pieces by former workings. Modifications may, of course, be needed, even in the same pit, on account of irregularities in the seam. I am also satisfied for economical reasons (on account of the heavy cost for timbering) that pits here ought to be worked upwards, even if it requires a longer period of time to win the coal, and a greater outlay of capital to commence with. The various saddle-shaped " troubles " making natural minor basins in the main basin aid in the execution of this plan. A pit worked once ought to be worked out clean, given up, and dammed off forever. If sections of proper height are assumed, according to the required amount of production for a certain period of time, they ought to be worked out and filled in as much as possible, dammed off, and ultimately allowed to fill up with water, in order to protect the upper works in future from fire in the gob below. This I consider indispensable, because we may not be able profitably to fill in all the ground. To do so we have to use the waste of the mine, although it is liable to fire in time. In using this stuff, it ought to be surrounded by walls of rock not liable to take fire, laid firmly in clay, the gob being in the middle, and firmly covered and packed with clay on top. In

By R F. Hoeberling

"The use of ground penetrating radar (GPR) for geological purposes has been underway for almost two decades. The commercial need for a versatile GPR that can rapidly identify buried objects andunderground voids has been recognized and is an area of research that has already proved useful for several geological activities. Several types of GPR endeavors have been reported in the literature, including exploration of placer deposits (Davis, et al. 1985) and heavy metals (Hammond and Sprenke, 1991), improving oil recovery (Witterholt and Kretzschmar, 1984), investigating coal seams (Coon, et al., 1981), stratigraphic survey (Fisher, et al. 1992), Lunar soils characterization (Olhoeft, et al. 1975 and Strangway, et al. 1977), characterization of rock around mine tunnels (Cook, 1985), location of old mine workings (Scaife, et al., 1992), location of abandoned gas wells in coal seams (Kemerait, 1992) and survey of hazardous waste burial areas (Horton, et al., 1981). Coal seammapping has been developed using a related continuous wave, phase discrimination technique (Stolarczyk, 1990). As the technology for the radar equipment and the onsite computational power has increased, many new applications have become feasible. This article will describe the present status of the GPR technology and indicate some of the exciting possibilities for nearterm prototypes now being constructed."

Jan 1, 1994

By Victoria Vaccarezza, Corby Anderson

The demand for rare earth elements for everyday technology and applications has initiated much research into the extraction and recovery of these rare earth elements. An otherwise unknown group of minerals, eudialyte is a zircon silicate consisting of rare earth oxides (REO), contained in a unique mineral structure and represented by a complex chemical formula. Research into extraction and recovery of rare earth elements involves various beneficiation and hydrometallurgical techniques. The goal of beneficiation being to efficiently liberate and upgrade the REO content, followed by hydrometallurgy to extract the desired elements. This overview will discuss previous research on treating eudialyte group minerals via different mineral processing and extraction techniques.

CORPORATE SOCIAL RESPONSIBILITY CSR is about how companies manage the business processes to produce an overall positive impact on society. - Indentured work, sexual slavery, fair trade, organic growing, business ethics, environmental issues, ?Right to know -Right to decide?, AIDS activism, civil society - Balancing stakeholder issues - Government responses Who are the bad guys? Where are the threats?

May 1, 2010

By M. Botz

For leach solutions containing primarily free cyanide, the silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method significantly over-estimates the concentration of free cyanide and under-estimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric titration method for determining WAD cyanide that overcomes issues with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to fully release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, accurate WAD cyanide measurements were achieved using the MP-WAD method. Analyses obtained with the new method were found to be within about ±10% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.

Feb 27, 2013

Jan 1, 1968

By S. L. Karunakaran

Selection of an appropriate foundation system requires great skill and ingenuity on the part of the designer. Certain guidelines for choosing between a pile and raft foundation are presented. A number of methods are available for estimating the capacity of piles, giving a wide range of values for the theoretical load carrying capacity. A few aspects to be taken into account while arriving at an appropriate theoretical capacity are discussed. The effect of fluctuation of water table level on the pile capacity and method of accounting for this factor on the pile capacity obtained through initial load test are also discussed. A case study presents a comparison between the estimated values of capacity of piles and the values obtained through the initial load test.

Jan 1, 1996

By G. Auld

"A simple method is presented whereby the additional quantity and static pressure necessary to compensate for ventilation duct leakage may be estimated using the circular reference functions of modern spreadsheets. Favourable comparisons have been made to the National Coal Board (United Kingdom) design charts and to a case study analysis. IntroductionIn mining, most ducted systems are applied to the development of access tunnels, and most of these systems leak to some extent. When the ventilation duct fails to deliver the required quantity of air to the work place, there is a significant contribution to the development costs, either directly or indirectly.Directly — More air and more pressure are required to compensate for the leakage, more capital development (ventilation shafts, parallel drives) are required because ventilation systems cannot push the fresh air far enough, and longer re-entry times to ensure toxic blast fumes to be diluted.Indirectly — There is a reduction in productivity because of the inclement atmospheric conditions, and/or closure of development ends because of unacceptable atmospheric conditions at the working place. This has been exacerbated over the last few decades because of the increased use of diesel equipment of ever increasing power, and the more stringent Occupational Health and Safety requirements demanding more air flow per kilowatt of diesel power.The leakage from a duct must, therefore, be reliably estimated in order to assess the effectiveness and construction of the system; assess the effectiveness of the maintenance or repair of the duct; appreciate the cost of the leakage, and therefore apply effective maintenance and installation procedures; and engineer safer, healthier and more cost-effective ventilation systems."

Jan 1, 2002

By J. D. Bliss

The discovery that triggered the current gold rush in southeastern Peru was made in about 1975 along the Rio Madre de Dios in Madre de Dios Department (Fig. 1). About 5000 to 10,000 miners (called chichiqueros) were working in the area as of 1990. Placer mining is the principal source of revenue for people living along the Rio Inambari and west of Puerto Maldonado. As in past gold rushes, working and living condition are harsh. Supplies are expensive, and the area has poor access compared with other areas in Peru. Food, fuel and all mining supplies are trucked over dirt roads from Cuzco, a three-to-five-day trip (Fig. 1). Some material also comes from Brazil. Many placers have a similar life cycle, beginning with small-volume mining (surface or underground). At the end of this small-scale mining, the placer is exhausted or it has a sufficient volume of gravel high enough in gold grade to be worked by large-volume methods, which lead to exhaustion of the resource. The level of maturity of a placer can be determined from its gold grade. The amount of gold production from large-volume mining can be predicted, given detailed, cumulative gold-production data on placer deposits during small-scale mining (Bliss et al., 1987). Using this general model, the authors analyzed the placers in the Rio Madre de Dios area. Small-volume mining Most placer mining in the Rio Madre de Dios area is in alluvial deposits either in or bordering the major rivers. Locally, some placer mining is in terrace deposits above the rivers. All minerals (including the subsoil) in Peru belong to the state. However, a mining claim (denuncia) is easily obtained for mineral exploitation. It is separate from property ownership.

Jan 1, 1992

By S. Hamilton

Borates are essential to life, and to many products that are essential to an acceptable standard of living. They occur naturally in seawater at an average concentration of five milligrams of boron per liter. Fresh water lakes, rivers, streams and ground water generally have concentrations of about one milligram boron per liter. Borates are also present in soil at concentrations ranging from 0.1 to three milligrams of boron per kilogram. Because most of that boron is locked into insoluble minerals, clay or organic matter, boron deficiency is more widespread than boron enrichment. Borates evaporate into the atmosphere from seawater, rain, snow and hot springs. In rain and snow, natural boron concentrations range from 0.002 and 0.1 milligrams boron per liter. All told, boron moves through the atmosphere at a rate of 5 Mt to 7 Mt/a (5.5 million to 7.7 million stpy).

Jan 1, 2005

By S. Paul Singh

Rock is a heterogeneous medium, a fact often ignored during blast design. In reality, the rock mass characteristics have a controlling influence on the outcome of a blast. If the optimum blasting results are to be achieved over a range of rock mass conditions, it is prudent to understand the role played by the geological features of a rock mass in producing overbreak around the periphery of an excavation. The field work was performed in a drift located in a geologically dominant rock mass and also included observations and assessment of blast damage at several operating mines. The blast damage was estimated on the basis of the half cast factor. The effect of rock strength, rock quality designation, orientation , frequency and aperture of joints, number and thickness of layers and hydrogeological conditions on blast damage has been described.

Jan 1, 2000

By Didier Kasongo NYEMBWE

The paper circumscribes the base metal casting industry in Southern Africa. It essentially consists in the founding of copper and zinc alloys. The challenge related to the scarcity and the unaffordable quality patterns and dies faced by the industry is discussed. New manufacturing technologies for foundry tooling called Rapid Prototyping that can possibly be used to alleviate the above mentioned challenge are then presented and their benefits assessed.

Jan 1, 2007

Book Reviews M. J. Jones(ed.). Geological, mining and metallurgical sampling London, The Institution of Mining and Metallurgy, 1974. 268 pp. £8. Spooner, J., et al. (eds.). 1974 miningannual review, London, The Mining Journal Limited, June 1974. 506 pp. £14,25 (including annual subscription to Mining Journal and Mining Magazine). J. H. Quilliam et al. (eds.). The ventilation of South African ~old mines. Johannesburg, Mine Ventilation Society of South Africa, 1974. 488 pp. RI0,00. The Hans Merensky Foundation As announced in a recent brochure, the 25-year-old Hans Merensky Trust has been converted to The Hans Merensky Foundation, its main objective being 'to promote and assist in the development of the resources of the Republic of South Africa and neighbouring territories articularly such natural resources as soil, water, minerals, flora and fauna-and to promote the health and welfare of the inhabitants; more specifically by research, experiment and demonstration and through the correlation and application of scientific knowledge'. Applications for S.A.I.M.M. membership and transfer Please note that new application and transfer forms have been issued.

Jan 11, 1974

Executive SCOTT TURNER, Chairman FREDERICK M. BECKET JOHN A. MATHEWS H. A. GUESS WILLIAM WRAITH Finance HENRY KRUMB, Chairman PAUL D. MERICA ROBERT E. TALLY Admissions JOHN M. LovEJOY, Chairman GEORGE D. BARRON ERLE V. DAVELER WILLIAM H. BASSETT W. D. B. MOTTER, JR. Alternates HENRY B. FERNALD F. JULIUS Polls AMOR F. KEENE

Jan 1, 1932

Jan 1, 1967

By M. G. Irish, E. E. Vidal, M. J. Jahraus, P. R. Taylor

An experimental system has been designed to monitor on-line variations of leaching parameters in a closed circuit of cyanide leaching solutions and gold bearing ores. Experiments performed to deter-mine variations in some important leaching parameters of the solution: pH, dissolved oxygen, free cyanide, oxidation/reduction potential, gold content, temperature, pressure and solution chemistry. By comparing results obtained when the leaching solution is allowed to become acid or kept basic, it was possible to infer the chemical reactions that occurred between the solution and the ores.

Jan 1, 2004

By F. C. Wagner, E. P. Klier, D. E. Nulk

The presence or absence of plastic strain at a cleavarage surface is a question of much importance, and upon its answer depends future possible theoretical work. To investigate this question back-reflectinn X ray patterns were obained on the cleavage facets of ferrite grains. The test set-up consisting of FeK colli- mated radiation, single grain material and stationary cassette and specimen will not lead to a diffraction pattern, in general, but is an ideal arrangement for the exami-nation of surface effects. A pattern taken on hydrogen purified

Jan 1, 1949

By Héctor Quispe

El presente trabajo señala la aplicacíón de las estrategias en Sistema de Gestión de la producción en la mina Raura, de forma que mejore su administración de flujo de recursos y actividades para lograr óptimos resultados con mayor productividad. Entre sus principales objetivos están: la determinación de los stándares de producción en tonelaje, leyes, costos y plazos, que hagan rentables los procesos de operación minera, la definición de sistemas standarizados que generen valor económico en cada uno de sus procesos. Asmismo, se realizó un diagnóstico previó que abarcó los procesos de geología, planeamiento, exploración, explotación, beneficio de minerales en planta concentradora, mantenimiento y proceso de comunicación gerencial. Los resultados y datos de este diagnóstico tiene como base la referencia para la evaluación y avance del proyecto.

Sep 13, 2001