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By William G. Doepken

The extensive use of rubber-tired support vehicles as a complement to a fleet of load-haul-dump and drill jumbo units has proved invaluable in maintaining scheduled multilevel/multiheading development drifting advances at the Henderson Mine. Support equipment, whether self-powered or towed, releases primary drill-blast-muck equipment from the supportive functions of ground control, utilities installation, steel and concrete construction and supply handling, thus providing both balance and increased flexibility to an underground, rubber-tired mining system. Experience has indicated that increases in man productivity and improved safety and working conditions coupled with decreases in overall costs and mining cycle times are realized with the inclusion of support vehicles in the mining fleet.

Jan 1, 1976

Overland conveyor belts that exhibit tracking problems under loaded and unloaded conditions can be tested to' determine the root cause of the mistracking. Moveable conveyors are more prone to mistracking due to structure alignment requirements. In addition, belting quality, splice straightness and carcass condition has a dramatic effect on the performance of a belt in relation to tracking. Methods are discussed that are proven to reduce belt mistracking and improve the operational reliability of the conveyor system.

Jan 1, 1995

By Ihsan Berk Tulu, Haochen Zhao, Deniz Tuncay

The process of designing pillars and selecting support measures in underground coal mines relies highly on the accurate assessment of mining-induced loads and the load-bearing capacities of the supports. This study proposes a new method to estimate the percentage of load carried by the gob in underground coal mines using a new parameter that introduces the site-specific overburden geology.

Jun 1, 2023

By Welland L. Ott, Hans J. Rumland

The Falconbridge Dominicana laboratory receives samples from all parts of the operation. Ore, metal and oil samples are taken by operating departments, gas and water samples by the laboratory staff. Physical sample preparation is essentially standard and produces comminuted samples for wet-chemical analysis and X-ray fluorescence analysis (XRF). T he main operating sections of the laboratory are described indicating in each case the type of instrumentation and method used, sample types analysed and comments on problems experienced. Emphasis is given to the sample preparation and X-ray sections especially with regard to the difficulties caused by our heterogenous ore material, calibration of the instrument and operational malfunctions. General problems related to our remote location and the tropical climate are discussed. Limited statistics on instrument availability, and stability, accuracy, precision, etc., are given.

Jan 1, 1979

By J. E. Golsan

Barrick Gold Corporation installed an expert style control system on the grinding circuit at its Mercur mine. Barrick's main objective was to increase mill throughput by a minimum of 3%. The expert system team collected operating data and then created a knowledge base using Comdale/X expert system development software. The expert system moved from on-line "advisory" mode, testing of expert rules, to full process control in four weeks. Expert system control benefits include a 9-15% increase in mill throughput, consistent mill loading leading to less wear on SAG mill parts, and improved downstream process control.

Jan 1, 1998

Laboratory testing by the Federal Bureau of Mines has shown that the removal of insoluble slimes using selective flocculation and flotation is a viable method for treating low-grade potash ores which have a high content of water-insoluble impurities. Results indicated that up to 85 percent of the insoluble slimes could be removed from sylvinite ore containing 5 percent water insolubles and 13 percent K20 using nonionic or cationic polyacrylamide flocculants and cationic, anionic, and/or nonionic collectors. Subsequent potash flotation recovered up to 88 percent of the potash in rougher concentrates containing 47 to 57 percent K20. Sizing and cleaner flotation of the rougher concentrates upgraded the products to 60 percent K20. Filtration of the insoluble slimes flotation concentrates recovered 87 to 0 percent of the brine. Flotation concentrate filtration rates were 7 times faster than the filtration rates of mechanically deslimed products.

Jan 1, 1977

By C. E. Jordan

The fundamental characteristics of ultrafine chalcopyrite flotation were investigated by the Bureau of Mines to establish techniques to improve recovery of ultrafine chalcopyrite. Intense agitation during conditioning was found to improve flotation recovery of the ultrafine chalcopyrite. A split-circuit flotation design, treating the plus 38-µm-size ore by the conventional method and treating the minus 38-µm-size ore with intense agitation conditioning followed by flotation, recovered 95.6 pct of the copper in a 28.3-pct-copper concentrate, This was a 5-pct increase in copper recovery over the conventional chalcopyrite flotation method.

Jan 1, 1986

By Per-Martin Sandgren

LKAB's ores have specific mineralogical properties that make them especially suitable for the production of super-grade concentrates. Conditions are particularly good for this purpose at Malmberget, where a concentrate for high-purity sponge iron production has been produced for many years. Until 1978 the approximate assay was 71.2 % Fe and 0.45 % SiO2. Since then the assays have been improved by process modifications to approximately 71.5 % Fe and 0.20 % SiO2. Scope exists for still further improvement. In recent years the production of fractioned concentrates has been started. The material lies within the size range 74-125 µm and the approximate chemical analysis is 71.6 % Fe and 0.30 % SiO2. Other special products are under discussion. The Malmberget ores are also suitable for the production of high-purity direct reduction pellets with a SiO2 content below 1 %.

Jan 1, 1981

By R. R. Young

Good afternoon gentlemen. It is always a pleasure to talk about a subject dear to our hearts--the high speed transfer of bull; materials. Specifically, today we will be reviewing the engineering approach to an age old problem of ship loading and unloading. You may be puzzled by the title of this paper and we will attempt to explain this for you--particularly the use of the words "New Era", since high speed automated facilities are nothing new to the material handling engineer. The new era in material handling designs refers to an all out concerted effort to provide custom engineering tailored to specific operations and economic requirements of the client. It shuns hardware type of engineering wherein existing machines and devices are dusted off and reapplied. It provides automation when automation can be justified and it exemplifies the application of systems engineering to solve specific problems.

Jan 1, 1967

By H. Colijn

The design of bulk materials handling facilities is greatly influenced by the handling characteristics of the bulk solids. For instance, free flowing materials need only small discharge openings in hoppers, while cohesive materials require large discharge openings. Chute and hopper slope angles are affected by the sliding friction coefficients. During the past ten years, large lignite deposits in Texas are being opened up for energy production, both in generating plants as well as in synfuel projects. The early plants have encountered many problems in handling and storing this lignite. This paper will provide some information about the handling characteristics of Texas lignite.

Jan 1, 1982

By Harry Perry

The decline in coal production has been slowed somewhat in recent years, mostly because of the industry's own remarkable success in holding the line on costs, and partly as a result of advances achieved through industry and government research. Nevertheless, the decline has continued. This downward trend combined with the increased productivity of labor through mechanization that has been necessary for coal to retain even its present competitive position, has resulted in a serious reduction in the number of miners required and large scale economic dislocations in mining communities. For coal to regain a more favorable position it must either expand existing markets by reducing the cost of the delivered product and thereby compete more effectively with other fuels or develop new uses that will require large tonnages of coal. New markets involving several million tons, which would look extremely attractive to most other United States industries--including the organic chemical industry--would do little to alleviate the coal industry?s depressed economic conditions, While such small new markets would be welcome, an industry producing over 400 million tons per year must look to large tonnage outlets for solutions to its long range economic problems.

Jan 1, 1964

By Xiangze Shu, Yuzhong Xing

All programs used to optimize main fan nowdays have to be run on the large and medium- sized computers. With a lot of array elements, complex processes, low convergence speed and large storage, these programs are both time consuming and difficult to be used in the micro computer. This program uses two languages (dBASEIII and BASICA) to calculate the network and to choose the fan respectively. It allows user to compare and choose the parameters of various kinds of fan and to transfer the selected fan parameters to the master program by a data communication system. Then the user can get the air quantity, the air pressure, the power and the efficiency of the main fan. The advantages of this program arc as follows: 1. It can be run on IBM-PC or compatible micro computer. 2. It can select a fan more quickly and less time consumingly. 3. It can choose desired one or a set of fans according to user's requirements. 4. It is suitable for the research institutions and coal mines.

Jan 1, 1991

By C. Flores, L. G. Twidwell, T. S. Jordan

It is well known that manguniferous silver ores containing manganese intimate) associated with silver are not amenable to conventional extraction methods. The segregation process has been applied primarily to the recovery of copper from oxidized and oxide-sulfide ores. A new alternative process, consisting of segregation roasting followed by flotation to recover the silver from refractory manganiferous silver ores, was studied using a 23-factorial experimental design. Laboratory investigations were conducted on a manganiferous silver ore analyzing 0.02% copper, 0.09% lead, 0.33% zinc, 12.55% manganese and 187 g/t silver. The investigation was designed to study the effects of the addition of salts, coke and copper (11) oxide on silver recovery. The results indicated that 79.3% of the silver can be recovered in the absence of copper oxide and 88.4% of the silver can be recovered with a copper oxide content of 1.5% at 750°C, 2% salt (NaCI). 1 % coke and 30 min of roasting. It was concluded that the addition of copper oxide improves silver recovery.

Jan 1, 1996

By P. J. Macbeth, R. F. Overmyer, K. K. Nielson

INTRODUCTION Over the past several years, Ford, Bacon & Davis Utah Inc. (FB&DU) has been involved in research, development, and engineering activities concerning uranium mill tailings; specifically of interest in this paper are efforts in radon gas exhalation and surface flux attenuation measurements, environmental influences on radon fluxes, and basic research into radon gas behavior. Our projects have included measurements of effectiveness of specific cover material in attenuating radon surface fluxes from mill tailings, characterization of the parameters in cover materials and tailings that influence radon exhalation, long-term tailings stabilization planning, determination of the effects of moisture on radon emanation and diffusion from ores, and determinations of baseline radon fluxes. Our efforts have been sponsored by U.S. Department of Energy, the U.S. Nuclear Regulatory Commission, Tennessee Valley Authority, the commercial uranium industry, and we are presently engaged in efforts for the U.S. Bureau of Mines. Much of the material presented in this paper is taken from our published reports on radon flux attenuation and tailings stabilization (Macbeth et al., 1978; Nielson et al., 1980; Rogers et_ al., 1980; Thamer et al al., 1980). CHARACTERIZATION OF RADON GAS EXHALATION One dimensional diffusion theory based on Fick's laws is the basis for the modeling of radon gas migration through large quantities of porous tailings and cover materials applied over the large areas of tailings piles. Fick's first law relates the gaseous concentration gradients to the flux over the entire surface and defines the effective diffusion coefficient De as: [ ]

Jan 1, 1980

By Luigi P. Gonano, John C. Sharp

The Drakensberg Pumped Storage Scheme in South Africa with an operating head of 500m is located in sedimentary rocks containing relatively weak argillaceous strata. The paper describes design and construction aspects of the high pressure concrete-lined tunnels, and the associated investigation techniques and construction controls.

Jan 1, 1983

This chapter contains the edited transcript of the "Gold Heap Leach Information Exchange" session that was held at the 1990 SME/AIME Annual Meeting in Salt Lake City, Utah. The exchange occurred on the afternoon of February 27, 1990. The session was intended to act as a forum for discussing some of the more prominent operating problems associated with heap leaching precious metals. The information exchange was very successful. The exchange consisted of several panelists introducing and discussing different topics, follow by a comment and question period. This transcript contains the panelists' presentations as well as comments and questions from the floor and the panel. Extraneous comments and remarks have been edited out. Some wording has been changed for clarity, but the transcript is basically an accurate account of what was said. At the end of the transcript are two papers submitted as part of the panel discussion

Jan 1, 1990

By B. K. Slone

The depth at which it becomes more economical to use slope access as opposed to box-cut access for near-surface coal reserves, termed "transition depth," can be established for a given coal property by considering cost estimates for those parameters that determine respective access method. Fourteen parameters that influence access cost were identified and ranges determined. A Transition Depth Formula was developed to permit determination of the better method of accessing a reserve, given such information as highwall slope, road width, total bench width, pit dimensions, road grade, belt component costs, pumping costs, and cost of overburden removal and reclamation. In most cases, in Appalachia, studies indicate that the transition depth ranges between 20 and 30 m.

Jan 1, 1998

By Madeline Mello, Michael Low, Nick Karlin, Bryce Scofield

The LA Effluent Outfall Tunnel is the first tunnel in the United States to incorporate post- tensioning into the precast segmental lining. Several unique components were integrated to ensure that the post tensioning could be carried out successfully in the tunnel, even concurrently with the TBM excavation. This also required the development of new processes both in the casting facility and in the TBM to ensure that the almost 3,700 rings could be successfully manufactured, threaded, stressed, and grouted. This paper will discuss the material selection, fabrication, and installation of, as well as lessons learned from, this first in country tunnel lining.

Jun 23, 2024

The effect of the chemical composition of pulverized bituminous coal particles on their physical transformation during the initial stages of combustion has been investigated. The results suggested that cenosphere formation does not require extensive thermal decomposition of the coal particles. The vitrinites in the bituminous coal softened earlier and developed larger cenospheres than the othe macerals. The coal particles swell to a higher extent during combustion than in pyrolysis; however, the cenospheres formed in the former process experienced a higher extent of fragmentation. The development of microporosity occurred predominantly after the resolidification of the swelled char particles. The type of macerals originally in the coal did not significantly affect the microporosity of the chars. Conversely, the morphology and anisotropy of the chars were strongly dependent on the maceral composition of the coal.

Jan 1, 1986

By Frederico J. Price

This paper describes the production of a specific iron oxide pellet that has given very good and consistent results as feedstock for HYL-Process Direct Reduction Plants. The sponge iron originated from these pellets has been used for the economic making of almost 15 million tons of low carbon steel via electric arc furnace meltshops. An overview of mining, benefication, pelletizing direct reduction and steelmaking for this case is given with emphasis on the characteristics of the self-fluxing oxide pellets. HYL Operator and management training is described.

Jan 1, 1979