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By J. B. Gwiazda

Introduction Thick seams constitute a considerable portion of Polish coal reserves. In producing mines and those under construction, the reserves where the height is more than 4.5 m (15 ft) total about 24v0 of all the hard coal reserves. The reserves that are under urban and industrial areas can be extracted using stowing methods for surface protection. About 50v0 of thick seam reserves can be extracted by caving methods. Thick seam mining methods Thick seams are usually extracted by multilift methods. There are some methods of thick seam mining that generally can be divided into caving and stowing methods. The stowing method is more expensive, but must be used when mining to protect surface features. The more known methods of thick seam mining include: • extraction of thick seam in ascending order with stowing; • thick seam mining in descending order with consolidated stowing; • thick seam mining with gob consolidation; • thick seam mining in descending order with roof caving; • sublevel caving thick seam mining system; and • thick seam mining system using an artificial roof. • Thick seam mining with introduction of an artificial roof The most advantageous method of thick seam mining is the method using an artificial roof. The artificial roof usually consists of wire mesh. Such wire mesh must be durable and must prevent small rock fragments from passing through. The mesh is usually made of steel properly protected against corrosion. The artificial roof is placed on the coal floor of the top slice (Fig. 1). Caving rock falls on the artificial roof and is thus separated from the coal. The next slice is extracted under the artificial roof. The producing face of the next slice must progress within 10 m (33 ft) behind the front of the first slice. As the second producing face progresses, the wire mesh moves down on the coal floor and may be used as an artificial roof for the next slice. Thus, one artificial roof allows the extraction of several consecutive slices. Application of the artificial roof allows for clean extraction and reduces coal losses. It also eliminates the hazard of spontaneous combustion. Introduction of the artificial roof has been limited due to a lack of artificial roof laying equipment. Manual laying of wire mesh is a labor-intensive operation, and it delays face progress, resulting in poor productivity. To eliminate these problems, artificial roof laying equipment was designed at the Polish Central Mining Institute. The support and the method of laying operation is covered by a patent. Artificial roof laying powered support To extract thick seams using an artificial roof; four-leg shield supports with lemniscate linkage were developed (Fig. 2). This shield is used in the first top

Jan 1, 1988

By R. Bernard

This paper will discuss innovative strategies that combine the capabilities of an Enterprise Asset Management (EAM) solution, sometimes referred to as a Computerized Maintenance Management System (CMMS) and E-Commerce solutions. Strategies discussed include solutions that minimizes the costs of operations through maximized equipment productivity and availability. Thusly, achieving the ultimate goal of keeping the cost per production unit as low as possible.

Jan 1, 2001

By R. J. Pruett, J. Yuan

Kaolin clays from five different commercial deposits in Georgia were studied to understand the variations of zeta potential and related fundamental properties. The results suggest that higher negative zeta potential is related to exchangeable or soluble calcium ions in the clays.

Jan 1, 1999

By V. Nemec

The paper deals with further progress of the space and time models achieved since some of the previous APCOM symposia (1970, 1975, 1980) where original methodology was presented. Various transformations, de- and retectonization of space models, transfer of patterns, interactive time models are among the most important improvements. Enlarged possibilities of practical applications of the developed system are shown.

Jan 1, 1986

By D. L. Passmore, J. D. Bennett

The reliability of mine operators' reports to the Health and Safety Analysis Center of the US Department of Labor of days lost from work by injured miners is 0.267.

Jan 1, 1987

By Muammer Kaya, Derya Oz

The main objective of this study was to remove printing ink from waste newspaper and improve the de-inked paper brightness as close as the unprinted paper by bleaching agents. This paper summarizes results of laboratory investigation into the de-inkability of newsprint printed with offset printing. Different chemicals and process parameters were varied to assess the effect on the brightness and cleanliness. The operations involved in de-inking process are briefly described and some of the problems being encountered are discussed.

Jan 1, 1995

By Charles D. Litton

This paper presents a description of the hazards of smoke from fires, the detectability of smoke using smoke sensors, and the operational characteristics of such detectors. It places in perspective the advantage that smoke detectors have over other forms of fire detection and also provides a discussion of smoke as a significant fire hazard.

Jan 1, 1992

By S. K. Kawatra, S. Bagley, T. C. Eisele

To meet federal air pollution guidelines, it is necessary to remove a considerable quantity of sulfur from many North American coals. This may be accomplished by oxidizing the sulfur to water soluble forms, followed by washing the coal. Selective oxidation of the various sulfur forms can be accomplished through the use of a variety of types of bacteria. In this paper, the various bacteria and their requirements are described, and processes using bacteria to remove coal sulfur are discussed.

Jan 1, 1988

By F. L. Wilke

Truck haulage costs form a major part of the total mining costs in hard rock open pit, mining operations. In order to minimize these costs one has to - determine the optimal truck fleet (type, size and number of trucks), and. simultaneously - determine the optimal organization of running the haulage system, i.e. especially select the optimal dispatching strategy in order to ensure maximal utilization of the trucks, and simultaneously - establish a reliable maintenance and servicing system to guarantee maximal availability.

Jan 1, 1982

By Bob Clayton, David Readett

Jameson Cell technology has found applications in the cleaning of entrained material in copper Solvent Extraction - Electrowin plants. The materials involved are largely organic substances that have not been totally removed prior to treatment of the rich electrolyte in the tank house. This paper discusses the recovery of the entrained organics in the rich electrolyte streams at Phelps Dodge Morenci in Arizona. Mount Isa Mines in Queensland. Australia and the Olympic Dam Operations in South Australia. The paper details the design, performance, the feed and product characteristics, capacity and operation. In one operation the entrained material has been observed to include crud that has been formed in the SX train. The mechanism of recovery is also discussed.

Jan 1, 1993

By J. S. Lewis

Beneficiation and physical and chemical processing of non-terrestrial materials will borrow strongly from terrestrial experience but will also involve the necessity of handling literally unEarthly feedstocks, reagents and environmental conditions. The present state of scientific and engineering understanding of the processing of non-terrestrial minerals, gases and hydrocarbons is reviewed, with the production of rocket propellants, life-support fluids, structural metals and refractories as the goal.

Jan 1, 1994

By J. Paraszczak

Water-powered jackleg rock drills, introduced recently in South African mines, are reported to be more efficient, faster and more comfortable to operate than conventional pneumatic drills. Comparative testing of these drill types was performed in Quebec. Based on the test results and on time studies performed in the mines, water-powered drilling was reviewed. The review considered the drilling rates achieved, the infrastructure needed, side effects and health and safety considerations. This study shows that the application of water-powered drills may, under specific conditions, help increase the footage drilled and may improve the working environment. Examples of such applications are presented in the conclusions.

Jan 1, 1997

By K. L. Kasperski, M. T. Ityokumbul

The effect of reaction conditions on the desulfurization of oil-sand coke residues was studied. The variables investigated were temperature, reaction time, heat transfer resistance and mode of caustic soda addition. The results show that oil-sand coke desulfurization increases with temperature, reaction time and heat-transfer rate. In an oxidative environment, coke combustion during molten-caustic leaching (MCL) commences at temperatures above 500 °C. The mode of caustic addition has no effect on coke desulfurization.

Jan 1, 1996

By J. D. Raulerson, R. P. Farias, G. A. Gruber

A flotation process has been developed to successfully treat ore from the Santo Domingo phosphate deposit in Baja California Sur. The ore contained less than 4% P2O5 with quartz, silicates, and carbonates as gangue minerals. Flotation of the low- grade feed in seawater required that the conventional Crago process, comprising direct anionic flotation, deoiling, and inverse cationic flotation, be augmented by an anionic cleaner flotation step, phosphate depression, and a calcite flotation step.

Jan 1, 1988

By A. Cavero, M. Diaz

The annual rainfall at Minera Yanacocha's gold mining operations in northern Peru averages 1.2 meters. The influx of water into the operations is higher than losses to evaporation and by ore absorption which results in a positive water balance. To minimize water intake and maintain a balance, some special operating procedures are required, and a system involving diversion ditches, storm ponds, heap skirting and detoxification and treatment of excess water is practiced. An operation background is also reviewed at the beginning of the paper.

Jan 1, 1998

By P. Somasundarrtn, A. Sivakumar

Flotation of minerals is governed by many processes at the solid/liquid/gas interface, such as adsorption and precipitation of surfactants. In this paper, the basic principles governing these processes and hence flotation are discussed. Also, recent techniques such as fluorescence and ESR spectroscopy which have been used to study in situ surfactant adsorption and to obtain information on the structure of adsorbed layer are discussed.

Jan 1, 1987

By J. B. Nanor, J. Lorengo, M. Misra, C. B. Bucknam

The dissolution of mercury during the gold cyanidation process is the cause of many environmental, health and processing problems. The removal of mercury-cyanide complexes from synthetic solutions and process water were investigated using sodium and potassium dimethyl dithiocarhamates and sodium sulfide as precipitating reagents. The results have shown that efficient mercury removal can he achieved by the formation of stable mercury compounds with the addition of potassium dimethyl dithioearhamate. The mercury dimethyl dithioearhamate precipitates are stable under plant operating conditions, and they do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is possible to stabilize mercury in the heap during cyanidation by adding dimethyl dithioearhomate.

Jan 1, 1999

By Michael E. Kelahan, Glenn A. Gruber

A review of recent phosphate beneficiation developments shows that Flotaire cells, ranging from 0.20 m to 2.44 m in diameter, have been examined in pilot scale and commercial plants. Applications of the column cells have included sized feed fractions using anionic and cationic reagent systems. In plants where the Flotaire was installed as a test unit or as an optional circuit, its use has been largely discontinued. On the other hand, when management committed to installing the Flotaire as an integral part of the flowsheet, the performance expectations were met or exceeded.

Jan 1, 1988

By Michael F. Jeglic

Dust control methods are practiced throughout the mining industry in order to protect the health and safety of its workers, the integrity of the environment, and to guard against the loss of valuable product. The use of water is often the best and most economical method of controlling dust. Increasingly, chemical agents are being chosen over more traditional mechanical means of controlling dust. Some chemicals are used alone, and many are used to enhance the dust controlling properties of water. This paper describes the various types of chemicals available and their applicability to specific problems encountered by industry.

Jan 1, 1986

By Guerry H. McCullen, Bruno Despujol

Quartz and phosphate grains from concentrates and ores from Atlantic Coastal Plain sediments often are wholly or partially coated by humates. Coatings were studied in situ using infrared microscopy, by transmission Fourier transform infrared of extracts, and scanning electron microscopy. The 14C age of the coatings is about 20,000 years, much younger than the mineral substrates. Coatings on double flotation concentrates indicate that the conditioning pH may be too low, allowing coated quartz grains to follow phosphate grains through beneficiation. Organic matter from coatings may contribute to processing problems as well as affect final product quality.

Jan 1, 1999