Search Documents

By S. K. Bhatt

This paper reviews major developments in continuous haulage technology for underground coal mines. Haulage systems in use and development are investigated through a comprehensive literature search and visits to mines and manufacturers. The systems include flexible conveyor train, mobile conveyor, multiple- unit continuous haulage, extensible and belt turning systems. Strengths and weaknesses of the systems are assessed in light of their operating under remote control and their application to the computer-assisted continuous mining machine being developed by the US Bureau of Mines. Through mining scenarios, candidate haulage systems are conceptualized to be consistent with the capabilities of the mining machine.

Jan 1, 1991

By R. Herrera-Urbina, D. W. Fuerstenau

A large number and a wide variety of chemical reagents are used in flotation processes for wettability and Eh control, particle agglomeration/dispersion and bubble stability. A historical account of the use of flotation reagents through the years since flotation was introduced as a viable and economic process for the concentration of sulfide minerals is given and a review of old and modern postulates of their interaction with minerals is presented. Although the results of surface and colloid chemistry studies with well characterized mineral/flotation reagent systems have advanced our understanding of the role played by these chemicals in the flotation process, many questions remain unanswered. Moreover, new flotation reagents are needed to solve the challenge posed by the treatment of problematic-type ores and fuel deposits that have increasingly become the source of our raw and energy materials. Because of the depletion of high-grade and relatively easy-to-process ores, flotation scientists and engineers are confronted with finding more specific and selective flotation chemicals to effectively and economically concentrate minerals. The development of new flotation reagents is vital for cleaning fine coal and processing polysulfide, polymetallic ores, and mixed oxide/sulfide ores.

Jan 1, 1989

By Barbara H. Carroll

In order to rapidly evaluate an area for its mineral potential, a reconnaissance exploration program generally includes the following: 1. Outlining an area of interest 2. Identifying known mineral deposits 3. Bibliographic search of the literature 4. Evaluation of geochemical and geophysical surveys 5. Compilation and review of geologic maps The information now available from various government agencies regarding the mineral deposits, geology, and geochemistry may be integrated and used as a tool to rapidly evaluate an area before the field season. The databases most commonly used in the United States are the USBM MAS/HILS system and the USGS MRDS system for their information on mineral deposits; GEOREF and GEOARCHIVE for bibliographic information; and NURE data for the geochemistry and geophysics. In conjunction with the project geologist, this information may be used to plot known deposits and their geochemical signature as well as any other areas of like signature for further examination.

Jan 1, 1985

By H. Colijn

Feeders are used to provide a means of control for the withdrawal of bulk materials from storage units, such as bins, bunkers, silos and hoppers. This control function can only be performed properly as long as the bulk materials flow by gravity to the feeder in a uniform and uninterrupted fashion. A feeder can do many things, but it should never be considered a suction pump: During the past few years various papers have been written and presented on feeders and their application. 1,2,3,4,5,6,7,8,9)* It is not the intent of this paper to cover the same ground, and the readers are therefore ad¬vised to consult the referenced publications for supplementary information. This paper will be confined to some specific design criteria of bin feeders, such as feeder load and power requirements. Special attention is given to the basic design criteria of vibratory feeders.

Jan 1, 1968

By Robin Adams

After nearly five years of economic hardship, the world copper industry is, in our opinion, about to enter a period of considerable strength. This opinion is based on three main propositions, namely: 1) there are a number of reasons, both general-economic and industry-specific why copper demand is likely to perform significantly, more strongly in the 1980's than in the 1970's; 2) the virtual cessation of investment in new facilities, especially at the mine level, over the past years makes it physically impossible for capacity to expand as fast as demand in the mid-1980's; and 3) there is much less "excess" inventory available than most analysts believe. If we are correct in these assumptions, then the implication is that copper prices will climb up to, and possibly beyond, the cost-justified price level. Combined with general inflation, this suggests a price in excess of $2/pound by 1985 or roughly treble the 1978 average.

Jan 1, 1979

By A. K. Sinha

A great potential market for the high BTU midwestern thermal coal exists if the coal is desulfurized and prepared to meet the environmental restrictions and the utility customer specifications. Because the midwestern coal is very high in pyritic sulfur, it can be adequately desulfurized by removing the pyrite with the help of such coal cleaning techniques as the froth flotation. Froth flotation cells are now commonly employed in modern coal preparation plants for recovering the fines but they are not utilized for desulfurizing the coal probably due to a lack of system operating data for such applications. A research project recently conducted at Southern Illinois University shows that the total sulfur in the midwestern coals can be successfully reduced from as high as 5.3 percent to less than 1.4 percent by single stage froth flotation. The results obtained on ten different samples of high sulfur coal obtained from different areas in the Illinois Basin are presented and discussed.

Jan 1, 1985

By Marcel Michaud

Over the past five years, the two-fold growth in Canada's coal industry "Figure, 1" results primarily from the coking coal market to Japan and, to a lesser degree, by the increasing use of sub-bituminous and lignite coal for power generation in the Prairie Provinces. This expansion will continue, but production of coal for domestic thermal generation of electricity will grow at a faster rate than coking coal exports "Figure, 2". Half of the 20 million tons of thermal coal used for electrical power generation in Canada during 1974 were imported by Ontario Hydro from U.S. coal companies in West Virginia and Pennsylvania. Ontario Hydro's Nanticoke station on Lake Erie which will consume 7.5 million tons of coal in 1977 when fully operative, as well as other future planned projects, could cause Ontario Hydro's coal consumption to rise from 10 million tons today to 20 to 25 million tons by 1985

Jan 1, 1975

By Don Phelps, Christopher Tattersall, David McAllister

Located south of downtown Seattle, the Beacon Hill Station & Tunnels is the key section of the southern segment of Sound Transit’s proposed new LINK light rail system. This paper presents an overview of the design, which includes 4,300 ft of segmentally-lined bore twin tunnels and a deep mined station. With platforms located156 feet below grade, the station itself is only the second large-scale mined station in soil the US. Its complex geometry combined with variable soil conditions—sands, silt sand clays with slickensides—challenged the designer’s to come up with a SEM-based design that addresses the owner’s risk, cost and schedule concerns.

Jan 1, 2003

By L. Adler

In spite of distractions from glam-our areas (ground control, computers, etc.), excavating and bulk handling in mining remains paramount but is now undergoing dramatic advances. The massive intervention of mining and civil engineers as "engineer-users" into the tight, exclusive, and specialized bond between the equipment operator ("operator-users") and the manufacturer (mechanical engineers "and sales "reps") has now occurred. Three developments have accelerated this: 1) larger, more costly, complex, specialized, and innovative equipment; 2) a more profound understanding of the equipment, operations, and working conditions (encumbered space); and 3) a concurrent thrust into "high-tech," (automatic and remote controls, sensors, automation, artificial intelligence, and even robotics) and human factors (workload intensity, work-station design). This has produced a well-defined professional discipline, including construction and even military engineering. The mine plant, and to a lesser extent, the mine face, is now being monitored. Equipment conferences, journals, and centers at universities and agencies have multi-plied. The discipline's impact on future mining now becomes more apparent.

Jan 1, 1988

By Y. A. Attia, M. Elzeky

The effects of bacterial adaptation and partial replacement of leaching solution on the rate and extent of bioleaching reactions of a complex sulfidic gold ore were investigated. The ore was first concentrated by bulk sulfide, flotation, and the sulfide concentrate was treated by bioleaching using Thiobacillus ferrooxidans. The residues from bioleaching were treated by cyanidation to extract the gold and silver. Bacterial adaptation before bioleaching significantly increased the rate and extent of bioleaching reactions. Similarly, the daily partial replacement of leaching liquor enhanced to a great extent the leaching rate, and in some cases, increases of up to ten fold were observed. Both bacterial adaptation and solution replacement increased the gold recovery by about 2-fold and that of silver by about 1.3-fold. In this work, more than 95% of the gold and more than 98% of the silver could be recovered from the sulfidic gold ore when bioleaching was used ahead of cyanidation, compared with 18.3% and 52.3% by direct cyanidation.

Jan 1, 1992

By L. A. Taylor, R. O. Colson, D. S. McKay

The production of oxygen on the Moon utilizing indigenous materials will be essential for successful lunar colonization. Several processes have been put forth to accomplish Lunar Liquid Oxygen (LLOX) generation. The schemes that have received the most study to date involve: 1) Reduction of ilmenite (FeTi03) by H2, CO, CH4, CO-Cl2 and Cl2, plasma. 2) Molten silicate electrolysis, both unadulterated and fluoride fluxed. 3) Several others, including H, reduction of glass, carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reduction of ilmenite and molten silicate electrolysis processes have received the most study to date. They are both feasible schemes and have various pros and cons, including their feedstock requirements. However, all processes should be addressed at the onset of LLOX research. This paper reviews several of the most studied and feasible processes for winning oxygen front lunar materials. There is an obvious need for more experimentation and study.

Jan 1, 1994

By N. S. Dalal, Xianglin Shi

Metal ions, such as chromium (Cr) and vanadium (V) are found as trace impurities in mineral dust. Since metal ion mediated free radical generation has been implicated in many disease processes, we carried out a detailed investigation of the metabolism of these metal ions by biological redox systems and the possible oxygenated radical generation therefrom. We found that highly reactive Cr(5+) species are generated in the reduction of Cr(6+) by NADPH-dependent glutathione reductase, lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase. The reduced metal ion species react with hydrogen peroxide, to generate hydroxyl (•OH) radicals in a continuous cycle. The enzymatic catalysis processes also involves the reduction of molecular oxygen to the superoxide [(0-1 2)] radical. Thus only a trace amount of metal ions chemisorbed on mineral dusts, such as quartz, can catalyze the generation of the highly toxic oxygenated radical species from cellular hydrogen peroxide, suggesting a new biochemical mechanism for mineral dust induced chronic lung injury.

Jan 1, 1991

By M. Elzeky, A. Attia

The effects of bacterial adaptation and partial replacement of leaching solution on the rate and extent of bioleaching reactions of a complex sulfidic gold ore were investigated. The ore was first concentrated by bulk sulfide flotation and the sulfide concentrate was treated by bioleaching using T. Ferrooxidans bacteria. The residues from bioleaching were treated by cyanidation to extract the gold and silver. Bacterial adaptation before bioleaching significantly increased the rate and extent of bioleaching reactions. Similarly, the daily partial replacement of leaching liquor enhanced to a great extent the leaching rate and in some cases up to ten fold increase was observed. Both bacterial adaptation and solution replacement increased the gold recovery by about 2-fold and that of silver by about 1.3-fold. In this work more than 95% of the gold and more than 98% of the silver could be recovered from the sulfidic gold ore, when bioleaching was used ahead of cyanidation compared with 18.3% and 52.3% by direct cyanidation.

Jan 1, 1989

Surface characterization techniques, i.e. contact angle measurement, atomic force microscopy (AFM) surface force and surface imaging measurement, were applied to investigate the molybdenite surface in aqueous solution. It was shown that the cleaved basal surface of molybdenite was very hydrophobic with a 92 degree water contact angle. The non-polar component of the solid surface free energy is 50.52 mJ/m2 while the polar components are almost zero. The solid surface was not reactive and was only weakly charged at the pH 6. When the aqueous media changes from water to 1×10-4 M KEX solution, the measured contact angle, adhesion force and surface roughness all increase slightly. However, ethanol rinsing made the surface change back to the bare substrate. It was suggested that the hydrophobic chemical, i.e. dixanthogen, which was shown in the morphology of patches by the AFM image, physically adsorbed on the hydrophobic molybdenite surface through the hydrophobic interaction.

Jan 1, 2009

By Scott G. Britton

Many times during the construction of a project, whether large or small, the engineer will become involved with management of the work and workforce. In some cases, mine management will turn over the direction and responsibility of doing the work to the engineer. Because of this, it is important to know some of the basic principles of human resource applications- among other management concerns. This chapter, therefore, looks at the fundamental principles of human resource management. Three broad discussions are presented to the reader. These are: (1) organization, communications, and responsibilities of management; (2) analysis of worker motivation; and (3) supervisory leadership. Each topic encompasses the current thinking for coal mining and mining management. Much of the information in this chapter comes from Practical Coal Mine Management, by this author and published by John Wiley & Sons, Inc., which discusses in depth many of the ideas presented here. Interested persons are directed to this text for more information on management skills.

Jan 1, 1983

By John Matthews

During 1982 and 1983, it became increasingly clear that North River No. 1 Mine would have to buy a set of replacement longwall shields. Despite extensive efforts to make improvements, the shields that were in place at that time were incapable of holding the roof. North River Energy had limited experience in specifying and acquiring longwall roof supports, but a great deal of experience with our conditions and needs. We there- fore compiled a shield evaluation method that uniquely responded to our situation. The resulting system emphasized teamwork among operating, maintenance and engineering personnel. The charge from management was threefold: select shields to support maximum expected loads, optimize face operations, and pay attention to detail. Final selection was made objectively, based on all available information. We chose a 5516 KN (620 tons) support with a minimum yield load density of 760 KN/m2 (7.9 tons/ft2). This paper reviews our process of specification, design, prototype testing, and fabrication, and offers some relevant suggestions.

Jan 1, 1986

By Janusz S. Laskowski

The most important type of potash ores, sylvinite, contains sylvite, halite and a small percentage of insoluble gangue [sulfates (anhydrite), carbonates (dolomite), and clay minerals]. Primary normal long-chain amines are exlusively utilized to float sylvite from halite, but since mines are also adsorbed by insoluble slimes, the process requires prior desliming. This is carried out either by mechanical means, or by flotation of slimes and blocking off the adsorption centers on clays with the use of polyelectrolytes. Fractional crystallization is employed to produce fertilizer grade KC1 from disseminated ores with a high content of slimes. An extender oil is needed in addition to mine to float coarse sylvite fractions. The process is carried out in a saturated brine at mine concentrations exceeding the solubility limit and is strongly affected by temperature fluctuations. All these important features, which make this process differ from a conventional flotation, result from a high electrolyte concentration.

Jan 1, 1994

By Thomas A. Wheeler, Robert O. Keys

The choice of the flotation reagent that suits a particular coal has become more complicated with the development of new, more efficient reagents. Frothers and conditioning reagents, in particular, have experienced a dramatic reevaluation of their role in floating various types of coals. This paper offers a better understanding of how each of the following factors contributes to the reagent selection: 1. Natural Flotability 2. Degree of Oxidation 3. Size Distribution 4. Percent Solids in Feed Slurry 5. Fluctuations in Plant Feed 6. Limitations on Froth Handling 7. Clean Coal Specifications 8. Ash Content in Feed a) discrete ashable minerals b) inherent ashable minerals 9. Water Chemistry 10. Petrographic Composition of Coal 11. Free-Swelling Index 12. Convictions of Customer The application of conditioning reagents - both promoters and emulsifiers can substantially improve the coal recovery. Some low-rank, hydrophylic coal, previously considered unfloatable can be economically recovered with the use of the proper reagent.

Jan 1, 1986

By Edward L. Mooney

In the, West, walking draglines often offer the least cost method of uncovering coal for surface mines. However, with each of these machines costing millions of dollars, a good deal of analysis can be justified by the potenial savings or, conversely, costs associated with the choice of a machine. This has resulted in the recent development of a number of computerized models for dragline selection and pit design. One of the earliest reported models for this purpose was developed by Dunlap and Jacobs (1). Later, Rumfeldt described the computer approach to sizing stripping draglines given the required production rate and mine site parameters (2). This basic approach is probably still the most widely used with models for more complicated mining methods reported by Stefanko, Tomica, Finch, as well as others (3,4,5). furthermore, detailed simulation models useful in this regard have been developed by McDonnell Douglas and Fluor, Utah (6,7)

Jan 1, 1982

By Jack W. Murphy, Kent J. McGrew, Rudolph H. Jacobson

Introduction Maximization of profit consistent with environmental protection is the principal goal of new applications development for any conventional or in-situ mining technique. Efficient evaluation of all the parameters that contribute to mining costs and production hinges on proper design and evaluation of testing programs and data. The program discussed herein utilizes several field and laboratory procedures to estimate ore deposit characteristics and optimize lixiviant compositions. The ore characteristics and lixiviant compositions are then used in a long path leaching test (stream tube test). The stream tube test data are analyzed by mathematical models with computer assistance to predict such well-field rate parameters as target metal production, lixiviant consumption, and restoration. When these predicted rates are combined with market values for target metals, capital expenditures, prices of lixiviant chemicals, and other economic variables such as labor costs, power rates, licensing fees, and others, an assessment of the relative feasibility of various proposed mining plans is possible. The flowsheet in Figure 1 illustrates this process.

Jan 1, 1984