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By Douglas M. Dwosh

INLAND STEEL COAL COMPANY'S experience with a gypsum cement, with and without fiber glass filler, indicates that the concept of utilizing standard rock dust equipment to dry handle and apply gypsum cement as a mine sealant is feasible, simple and economical. Prior to 1975, Inland had casually experimented with a few sealants and had discussed the advantages and shortcomings of other sealants with various users. Hower in mid-1975, Inland foresaw the need to seriously acquire a practical sealant system. There were nearly a dozen sealant materials on the market at that time: silicate-based materials, Portland cements, vermiculite cements, gypsum cements, and magnesium-oxysulfate cements, each with their own fillers and additives. The applicating equipment ranged from simple to complex: wet mix or slurry machines operating on either a batch or continuous basis, high viscosity pumps, and pneumatic, dry conveying machines with water nozzles. Compounding the selection process, two or more products could often be used with the same machine, or a given material could be successfully applied with more than one type of machine.

Jan 1, 1976

By R. Singhal

Canada's coal production is approximately 65.4 million tonnes of which 95 % is produced by surface mining methods mostly from the three Western provinces (British Columbia, Alberta and Saskatchewan). The mines are highly mechanized; productivity gains during the past few years have ranged from 60 -80%. Truck/Shovel methods are common although Saskatchewan lignite is almost exclusively mined by draglines. This paper provides an overview of Canadian Coal mining industry vis a vis surface mining. Emphasis is on application and utilization of mining equipment and associated mining methods.

Jan 1, 1994

By Alireza Kamrani, Yashar Pourrahimian, Hooman Askari-Nasab

In-pit crushing and conveying (IPCC) is an option to decrease the enormous operating costs that a truck shovel can introduce in an open-pit mine. Finding the best locations for the IPCC over the mine life will impose a new set of requirements for the mine planning. Through a two-step mathematical programming model alongside the road network, this method finds the optimal in-pit crusher locations and relocation times first and then optimizes the long-term mine schedule. The model is verified by a real mine. The results show that the truck travel time could be reduced by 500% and the discounted cash flow increased by 8% with an optimized schedule considering the crusher placement.

Jun 25, 2023

By C. Jack Powell

TVA's involvement in air quality programs is perhaps a bit unique. The Tennessee Valley Authority was established in 1933 as a regional resource development agency and therefore must view clean air and clean water as essential resources for the overall development of the Tennessee Valley region. TVA operates certain resource development and production facilities, including power-generating facilities, which are potential air pollution sources. The remarks in this paper will be restricted to air pollution control technology at power-generating stations. Perspectives of Air Pollution Control The art of pollution control must be viewed from several perspectives: 1. It must be viewed in a time perspective--what is available now for air pollution control, what might be available in the near future, what are the likely technologies for the more distant future, and what the future trends in availability of resources might be. 2. Each air pollution abatement scheme must be viewed in the perspective of its total environmental consequences--not just its ability to clean up the air. The generation of electricity from coal produces waste gases, waste particulates, and waste heat. These wastes must be disposed of either in water, in air, or on land. If the polluting wastes are removed from the gas streams going into the air, then they must be disposed of either on land or in water or, hopefully, converted into a product which has some beneficial use. As an example, removal of S02 from stack gases could be more readily accomplished if one could dump waste sulfur products in water. He would solve an air pollution problem by creating a water pollution problem. 3. Techniques for air pollution control must be viewed in the perspective of regional, national, and world resources with their national security and economic implications. The power industry might reduce air pollution by switching generating plants to burning desulfurized fuel oil or natural gas.

Jan 1, 1972

By F. F. Peng

A unique collector dispersion techniques was developed and used to improve the flotation rate and recovery of coarser and ultrafine coal-rich particles in the froth flotation processes. In this novel collector dispersion method, the collector such as hydrocarbon-oil is gasified and transported by gas phase (air stream) into the pulp. In addition to the excellent mode of collector dispersion, the collector-encapsulated air bubbles are generated in the pulp. This approach alters the surface properties of air bubbles and provides the fast rate of flotation compared to that of direct liquid collector addition froth flotation. Using gasified kerosene as the collector, the effect of altering surface properties of bubbles on the recovery of larger and finer coal-rich particles of -1.7 mm (-12 mesh) and -600 µ m (-30 mesh) raw coal samples were studied. The Redstone seam coal obtained from Northern Central region of West Virginia was used in this work. The effect of particle size on oil-coated bubble flotation rate and recovery were also evaluated. The conventional froth flotation test with a liquid form of kerosene addition was also conducted for comparison purpose.

Jan 1, 1991

By J. L. Parks

Designs, installation procedures, and performance characteristics of martensitic cast steel concaves are reviewed. Longer wear life, fewer pieces to install, and eliminating the need to scarf joints are the principal benefits of using martensitic steel to replace austenitic 12% Mn (Hadfield's) steel, the traditional concave material for large gyratory crushers. Installation procedures that reduce the risk of breakage are described. Operating practices that affect concave performance are also discussed.

Jan 1, 1992

By Lauren W. Choate

Wollastonite, a calcium metasilicate, derives its name from the man who discovered the mineral, Doctor William H. Wollaston, an English scientist. OCCURENCE Occurences of the mineral have been noted in Finland, Switzerland, Russia, Japan, Mexico and in the United States in Texas, California, Arizona, and New York. The only commercial deposit now being exploited is at Willsboro, New York. It is mined and processed by the Cabot Corporation whose home offices are in Boston, Massachusetts.

Jan 1, 1964

By E. M. Frizzell

An ongoing research program at the Spokane Research Center of the U.S. Bureau of Mines is directed toward investigating drilling parameters (thrust, torque, penetration rate, and drill revolutions) during the drilling of roof bolt holes. A system that measures these drilling parameters calculates the specific energy of drilling, and determines drill bit position has been developed by the Bureau and mounted on a roof bolting/drilling machine, through the use of a microcomputer, critical drilling parameters can be immediately interpreted and analyzed. This makes it possible to inform the operator of hazardous roof conditions. Initial results of this program are presented here.

Jan 1, 1990

By M. Z. Emad, M. U. Khan, A. ur Rehman

Stemming plugs are used as an accessory in drilling and blasting industry. They supplement conventional stemming material (i.e. drill cutting) with retention of gases in the drill hole that result in better fragmentation of rock and improved explosive utilization. Better fragmentation and explosive utilization along with economic benefits enhance efficacy of the project. Incorporation of stemming plugs in drilling and blasting industry is in exercise for about thirty years. The efficiency of stemming plugs is a key factor in their rising induction in mining industry. Different studies have been conducted on the economic viability of these plugs. The focus of this paper is the selection of stemming plugs for a bench blasting operation and the examination of blasting operation efficiency based on ergonomics and human factors. Three types of stemming plugs were evaluated during multiple blasts at a limestone quarry. Their performance was evaluated using split desktop software. Based on the human factors plastic molded stemming plug (stemming plug-1) was found to be the best among all selected plugs. INTRODUCTION Surface mines and quarrying operations heavily depend on bench blasting to achieve high volumetric targets and production demands. Use of explosives is the most economic method adopted for rock breakage and movement. Extensive research had been performed to enhance explosives energy utilization. This include changing the drilling pattern, application of air decks, stemming plugs, and use of other supportive devices. Optimization of explosive energy has been a major concern in those mines that rely on drilling and blasting operation to carry out main production. Due to continually increasing cost, efficient mining demands, and associated hazards of using explosives, it is necessary to utilize explosives at their best. Efficiency of a blasting operation is generally evaluated by the fragmentation size. From post blast conditions at blasting site to efficiency of processing plant, anything can be affected due to improper blast resulting in bad fragmentation. Better fragmentation is necessity for better operation of the system along with consideration of the safety of operation, environmental issues and related costs. For developing a blast design, an engineer should always attempt to minimize the cost of operation without compromising with acceptable technical and safety necessities [1]. Blast performance is dependent on many different factors associated with the process. These factors have been gauged as blast geometry, explosive specification, and rock mass properties [2]. Similarly, in 2013 Mohammad et al. concluded that fragmentation dynamics depends on blast hole diameter, primer, spacing, stemming, burden, and delay timing for blasting operation [1]. At the work site where this study was performed, blast holes were filled by drill cuttings and muds to help in confining gases. In a blast hole, gas confinement helps in better rock fragmentation along with reduced flyrocks. This practice is most common in many countries including Pakistan. Due to lack of homogenized particle size, the effectiveness of confinement is variable and majorly based on the size of stemming. Extremely small sized drill cuttings often result in hole blow out along with flyrocks from the collar. This improper blast energy will result in poor blast, bad impacts on environment, and reduced operational efficiency. In addition to the stemming material, the length of stemming is also a prime consideration. The decrease in stemming length will increase the quantity of explosive in the blast hole and an increase in stemming material generally improves stemming performance.

Jan 1, 2019

By N. S. Tanious

The accuracy of vibrating wire stress meters has been questioned by various users in the mining industry. During an in situ coal pillar study, a laboratory evaluation program was developed to determine whether stress meters could produce reliable measurements in coal. More than $0 stress meters were tested for accuracy, repeatability, effects of setting pressure, and the concept of using a single curve for interpreting the stress-meter data. The testing medium was lucite, a material with a modulus of elasticity very similar to coal. The evaluation demonstrated that the stress meters did provide repeatable measurements, but that accuracy was lacking when the recommended interpretation technique was used. Therefore, a new technique was developed that required all stress meters to be calibrated in the laboratory before use in the field. This new technique reduced the average error to typically less than 10% and, in the worst case, to below 15%.

Jan 1, 1988

By T. F. Torries

The primary merit criteria used by the mining industry is internal rate of return (IRR) rather than net present value (NPV) although NPV is favored by academicians. This paper discusses the problems with IRR and NPV and compares the multi-goal nature of decision makers and their need for information with the characteristics of NPV and IRR. Conclusions are that both NPV and IRR are needed for investment ranking, that NPV suffers the same multiple root problem as does IR.R, and the determination of incremental IRR to reach NPV consistent project ranking is misguided in practice.

Jan 1, 1997

By L. G. Austin

A simple finite difference algorithm has been used to compute a simulation model for unsteady-state ball milling. The model considers the mill to act as if it were three fully-mixed reactors in series (one-large/two- small), it incorporates the-Rogers-Austin mass transfer law relating mill hold-up to flow rate through the mill, and it allows for the reduction in breakage rates caused by over-filling of the mill at high flow rates. The computation is rapid and requires only small storage space. Examples are given of use of the model.

Jan 1, 1984

By V. Price

Abstract: Action of certain strains of bacteria has been implicated as a significant factor in the oxidation of ore deposits. Other bacteria are thought to be significant in the formation of syngenetic sedimentary ores and in supergene enrichment processes. A normal soil/ground-water regime provides all of the necessary pH and Eh conditions for several groups of bacteria which influence the sulfur cycle in nature. Limiting concentrations of nutrients such as sulfate ions can determine whether a particular microbial species is active at a given place. In the present study, ground water was analyzed from a mineralized area and from a presumed barren area. Trace metal content of the ground water gave no well defined clue as to the presence of a sulfide ore deposit. Sulfide producing bacteria (presumably sulfate users) were found in water from about 50% of wells sampled in the mineralized area and in about 30% of samples from the barren area. These bacteria are readily detected and may provide a useful tool for regional geochemical recon-naissance. Bacterially produced sulfide ions can remove metals such as copper and zinc from solution thus complicating the interpretation of hydrogeochemical prospecting.

Jan 1, 1972

By M. Niec

Poland lies at the junction of three geologic provinces: the East European Precambrian platform, the Middle European Paleozoic platform, and the Alpine orogenic belt comprising the Carpathian Mountains. However most of the rocks that contain mineral deposits and many of the recently explored and mined deposits are commonly hidden under thick overburden, sometimes up to over 500 m thick. The discovery of these mineral deposits was due to the combination of geologists talents for inference and the keen interpretation of geophysical data ultimately tested by drilling. Examples of such use of the state-of-the-art geology include the following: 1. Sedimentologic and paleogeographic reconstructions led to the discovery of 8.8 Gt of bituminous coal under 500 m of Jurassic and Cretaceous cover in the Lublin basin, 2. Tectonic and paleogeografic data suggested a potential for discovery of burried Upper Permian copper de-posits on the Foresudetic monocline; subsequent exploration discovered 75 Mt of copper and 0,17 Mt of silver, 3. Geological interpretation of gravity and magnetic da-ta combined with sedimentologic data and regional subsur-face geology resulted in the location of 1.3 Gt of Fe-Ti-V ore in the Precambrian basement of northeastern Poland under -500 m of cover 4. A combination of metallogenic theory and geological interpretation of regional geophysical mapping led to the discovery of Caledonian-Hercynian granites and grano-diorites with accompanying porphyry-type Mo-W-Cu ores below 300 m cover on the northeastern border of the Upper Silesian coal basin 5. Tectonic reconstructions based on gravity and seismic data combined with theory on the origin of native sulfur led to the discovery of 1.0 Gt of native sulfur under cover up to 300 m thick. Five deposits were found at the northern margin of the Carpathian Foredeep. The other deposits found include lignite, polyhalite, lead-zinc ores.

Jan 1, 1996

By N. Edmonson

A review of the evolution of the North American sulfur market's structure serves to dramatize the kinds of changes that the market is undergoing at the present time. In 1970, the U.S. accounted for 23 percent of world sulfur production. This share has not declined dramatically--to 21 percent in 1993--but the U.S. developed into a substantial net importer of sulfur in the past 25 years. U.S. output was based on large deposits of native sulfur in the western part of the Gulf Coast region with production by the Frasch mining process. Producers of Frasch, or on-purpose sulfur, have historically absorbed cyclical fluctuations in sulfur demand. Two major changes in the North American market from that time to now have been the introduction of increasingly large quantities of by-product sulfur from petroleum refining and natural gas processing operations in the U.S. and Canada, and that Canadian producers have become the marginal supply source for U.S. sulfur consumers.

Jan 1, 1996

By Roland W. Merwin

The Bureau of Mines has studied the possibility of using the heap leaching process for treating the gold ores in the sedimentary beds of northeastern Nevada. This paper summarizes all available information on the technical and economic feasibility of heap leaching oxidized ores from these beds, past industry application of vat leaching, results of recent Bureau of Mines and industry tests on heap leaching ores from this region, and requirements for planning the proper application of heap leaching. Preliminary tests on representative samples of ores from the region show that a satisfactory recovery of gold can be obtained by heap leaching the ores with cyanide at a relatively coarse size. Significant deposits of gold ore occur in sedimentary beds of various locations over an extended area 40 miles wide and 200 miles long in northeastern Nevada. The area is centered 40 miles west of and runs parallel to the leading edge of the Roberts Mountain thrust fault system, a prominent geologic feature in the area. The general locations of past and present gold mining operations are shown in figure 1. (slide 1)

Jan 1, 1969

By Raul A. Deju

This paper shows how one can relate the chemical reactions between water and a silicate bed to the equations of flow. First the reaction mechanism is studied both theoretically and experimentally. Once the reaction mechanism is established, the equations of flow are solved and a solution (under physically reasonable side conditions) is obtained. Experiments to substantiate the solution are also presented.

Jan 1, 1969

By Vas Choudhry

The eighties are likely to witness the first commercial-size coal-to-gasoline plant(s) in the U.S., although uncertainty regarding crude prices and cautious involvement of the Federal Government in the synfuels development are evident. The formation of The U.S. Synthetic Fuels Corporation with passage of the Energy Security Act is projected to pave the way for some of the projects on a moderate scale. The corporate objectives (1) are to provide funds for supporting a number of feasibility studies and loan guarantees for the construction of at least some commercial-size plants and the possibility of product price supports or purchase commitments. There are a number of coal conversion processes (2) currently under evaluation for producing either gaseous or liquid plus gaseous fuels, the other processes such as SRC I are for producing desulfurized deashed clean solid fuel for commercial use.

Jan 1, 1982

By M. D. Bishop

Early solvent extraction circuits in the uranium industry utilized bona fide kerosenes as diluents for extractant chemicals. These kerosenes were used successfully in the uranium industry; however, at least one plant was destroyed by fire resulting from the use of a low flash point kerosene. Although the term "kerosene" is used throughout the solvent extraction industry, the authors have been unable to find any use of kerosene in copper solvent extraction circuits. A term that is occasionally used with reference to diluents is "metallurgical kerosene." Such a term is unrecognizable in the petroleum industry. Kerosene [or kerosine] is a flammable hydrocarbon mixture that is less volatile than gasoline. It is produced for combustion purposes and may have variable compositions of organic compounds including alkanes, alkenes, alkines, and aromatics. Diluents are constant composition hydrocarbon mixtures developed specifically for use in solvent extraction processes. These products usually have much lower vapor pressures and higher flash points than kerosene. In solvent extraction systems, they typically comprise 70 to 95 v/o percent of the circuit organic. The primary purpose of the diluent is to adjust the extractant concentration to the working range of the operation. The diluent and extractant must be completely soluble or miscible with each other. Secondary diluent effects are to promote transfer kinetics, optimize phase disengagement, and minimize both organic in aqueous and aqueous in organic entrainment.

Jan 1, 1996

By L. G. Hendrickson

Direct-reduction processes for converting iron ores to metallic iron in the solid state have been available for some time; and whenever scrap becomes expensive, there is a new wave of interest in these processes. It is well established that direct reduction, coupled with electric-furnace steelmaking, is a technically viable method for making steel and in some circumstances is economically competitive with the conventional blast-furnace--basic-oxygen-process (BOP) route to steel. This raises a number of interesting questions, several of which could be of great interest to the coal and ore mining industries. For example, what are the quality requirements of the raw materials for direct-reduction--electric-furnace steelmaking? Would they be different from the present requirements for blast-furnace--BOP steelmaking? Other questions relate to how much steel will be made by the direct-reduction route in the future. The quality questions can be discussed with a fair degree of certainty, but a prediction of the amount of steel that will be produced by the direct-reduction--electric-furnace route is beyond the scope of this paper. However, an attempt will be made to identify some of the factors that will influence whether there is a swing to direct reduction and the rate at which it may occur.

Jan 1, 1978