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By St. E. Deák

There is a large preoccupation concerning the development of expert tools (ET) in the mining industry, in order to minimize the impact from waste dumps and processing residues on the environment. In this paper, the authors present a new approach for the development of an expert tool for each area under study, in order to minimize production and disposal of mining wastes on the environment, by taking into account the DKRControl method as well as the Ecomining principles, regarding among others hazard identification, impacts and monitoring. Due to the complexity of this topic a reliable ET requires input from a number of interested stakeholders. The design and management of a mining waste disposal site over its entire life cycle is also considered very important.

Jan 1, 2008

By Normand Tassé

Reactive barriers, which consume oxygen, are prospective though unconventional alternatives to physical barriers for Acid Mine Drainage prevention. However, a reactive barrier implies a problem of duration. Pore gases were analysed in several wood waste piles in order to understand the factors which control wood degradation and help to determine the effective life span of such a cover. Long term efficiency seems to strongly depend on the degree of water saturation at the bottom of the pile, likely because the development of a microbial biomass in such an environment helps to keep the amounts of nutriments and readily metabolizable organic substrates at a high level, which in turn promotes oxygen consumption.

Jan 1, 2000

By V. K. Gupta

A detailed experimental study of the variations in grinding rate with particle size, particle load, ball diameter, ball load, mill diameter, and mill speed was carried out for a soft cement clinker and a hard cement clinker. The effects of the ball diameter, ball load, and particle load were observed to be material (hardness) independent, and those of the particle size, mill diameter, and mill speed to be material dependent. A sharp change in grinding behavior was observed for both the clinkers at about 150 µm size. Below this critical size: (1) the hardness difference between the two clinkers became insignificant, (2) variation in the grinding rate with particle size became markedly more pronounced, and (3) mill speed had little or no effect on grinding rate. The importance of these results in the context of process optimization and control is discussed.

Jan 1, 1988

By B. H. Richard, P. J. Wolfe, T. G. Holdeman

Guided seismic wave propagation was studied in the Lower Freeport (6A) coal seam in the Oak Park No. 7 mine near Cadiz, OH. Three component geophones were implanted in the coal at distances ranging from 72 m to 183 m from the seismic source. Both Love- and Rayleigh-type modes were observed but the Love-type mode produced the best data. Detailed analysis was performed on the best Love data and a Dziewonski map of group velocity vs. frequency was constructed. This map was in excellent agreement with a theoretical dispersion curve calculated for a model of the coal seam. The Love wave group velocity was found to have a minimum value of 510 m/sec at 275 Hz. Only the fundamental mode contributed significantly to the observed signal and it was observed up to the maximum distance available.

Jan 1, 1987

By Olli Järvinen

The precious metal refinery process is divided into the five process stages: 1 .copper/nickel leaching in autoclave 2. selenium roasting furnace 3. doré metal smelting furnace 4. silver electrolysis 5. gold recovery system. The process has been developed during the years in Outokumpu Harjavalta Metals, which treats about 600000 kg /year copper anode slime. The slime treatment process route in Outokumpu Pori plant has been developed from year 1941. During this period the process has been improved radically. The major changes has been the atmosphere leaching into the autoclave leaching, the sulfuric acid roasting furnace was changed into sulfuric dioxide / oxygen roasting. The old doré smelting furnace has changed into the TROF converter and the gold electrolysis / aqua regia process has changed into the quick hydrochloric acid leaching process. The current production in Pori plant is 30000 kg of silver, 1000 kg gold, 30000 kg of selenium and some hundred kg of platinum- palladium concentrate.

Jan 1, 1995

By S. D. Bearden

The world's barite reserve base is adequate for at least 100 years at the current consumption rate. China, India and the United States are expected to remain the leading producing countries, and the United States will continue to be the largest consumer. None of the known substitutes for barium sulfate are expected to impact existing applications. World production in 1995 was 4.41 Mt (4.86 million st), which is about 50% of capacity. Consumption is directly proportional to hydrocarbon well installation activity. Imports are expected to continue to supply more than half of the US requirements.

Jan 1, 1997

By Catherine T. Aimone

A computerized cost model has been developed to simulate the technical and economic effects of strip mine blasting in the vicinity of structures. Current surface mining regulations restrict the allowable level of production blasting as a function of this distance. Blast design modifications,' therefore must be employed when blasting in the vicinity of homes to ensure compliance with federal and state regulations specifying limits to the seismic effects generated from a blast. The blasting level allowed. is computed by the charge weight of explosives per delay from the following scaled distance formula: [ ] where W is the charge weight per delay, in kilograms (pounds), D is the distance factor corresponding to the regulatory limit of peak particle velocity to which a structure may be subjected to. Current regulations specify 2.54 cm (1.0 in.) per second corresponding to a SD factor of 27 (60) (Federal Register, 1977).

Jan 1, 1982

By Steven W. Hunt, J. Patrick Powers, Roger C. Ilsley

Artificial groundwater recharge has been used successfully to mitigate water level drawdown in upper alluvial deposits during construction of the Milwaukee deep rock tunnels. Recharge wells in rock as well as soil were used. The effort reduced settlements from consolidation of compressible estuarine deposits, and has minimized damage to existing structures. The paper describes the geology that presented the consolidation problem, and the hydrogeologic conditions that caused the drawdowns. Also presented are the details of recharge well design, construction, operation and performance in an urban environment. The project design calls for grouting and lining of the tunnels to control groundwater in the long term.

Jan 1, 1991

By D. W. Tedder

Several bauxite feeds and residue sands and muds, produced by Bayer plants in the US and over-seas, were fractionated using dry and wet magnetic separators. The magnetic sand fractions typically contained about 50 to 60 wt % Fe2O3 and the bulk of the radioactivity in the sands. The muds are more difficult to process, but some fractionation is possible using a combination of classification and magnetic separation techniques. Among the mud samples, higher radiation levels are often associated with the less magnetic fractions. Bauxite is more easily fractionated using dry magnetic separation. Much of the radioactivity in bauxite appears to concentrate in the sand and mud residuals.

Jan 1, 1987

By Zhen-lu Zhao

The manipulators possibly used in underground mining must deal with unpredictable obstacle while keeping certain positions and orientations of end effector, and in some cases, are required to possess redundant joints in order to be more flexible. This kind of manipulators might be fitted with jumbo drill or platform as auxiliary to potentially deal with some utility works in versatile way, such as installing rock bolts, guniting, blasting, charging, surveys and measuring work, etc.. This paper describes numerical procedures of performing inverse kinematic problems for redundant manipulators .The procedures, based on the generalized pseudoinverse of Jacobian matrix, are developed to lead to kinematic solution at both singularity and ill conditioning, and to guarantee continuous sequence of positions of the end effect or. Furthermore, the solution to optimization and obstacle avoidance is investigated. A numerical example is shown to illustrate the approach.

Jan 1, 1989

By Thomas W. Camm

The U.S. Bureau of Mines has extensive experience estimating the cost of mining and mineral processing operations as an ongoing part of its information and analysis studies. With the increased interest in remediation of mine wastes, the USBM is developing a methodology to expand its cost estimating expertise to include costs of various remediation techniques applicable to mineral processing and mining wastes. By integrating waste remediation costs with existing USBM cost estimating systems for mine and mill operations, a comprehensive system for cost engineering studies will be developed.

Jan 1, 1995

By A. G. Sciulli, G. P. Ballock, K. K. Wu

This paper discusses common environmental problems associated with coal refuse disposal. It suggests design concepts to minimize potential hazards. Discussion focuses on site selection, embankment design and construction, site preparation, facility operation, abandonment, and reclamation. It emphasizes measures that should be adopted in the design phases and during construction of the facility. Recommendations are also made concerning special problems, including seepage, ground water contamination, and mine sealing.

Jan 1, 1987

By K. L. Branham, D. W. Steeples

Surface collapse over abandoned sub- surface coal mines continues to be a problem in many parts of the world. High-resolution P-wave reflection seismology was successfully used to locate water-filled cavities in a 1-m (3-ft) thick coal seam at depths of 9 m (29 ft) in southeastern Kansas. A dominant frequency of 275 Hz was attained enabling us to delineate the top of the coal seam. To our knowledge, this study is one of the first to locate water-filled coal mine cavities at depths of less than 30 m (100 ft) wing high-resolution P-wave seismic reflection techniques.

Jan 1, 1987

By Anis Farah, Khosrow Aref

Pull-out tests were conducted on cable bolts grouted with concrete, and cement paste. The influence of several parameters on the performance of these cables were studied under loading rates varying from very slow to relatively fast. These parameters include water-cement ratio, cable surface conditions, curing time and embedded length. In addition to being more economical, the results indicate that cables grouted with concrete have higher ductility and ultimate bond strength as compared to those with cement paste only.

Jan 1, 1986

By Frank F. Aplan, Robert S. Thomson

A placer ore jig, typically used to recover fine gold, tin and diamonds from alluvial ores, has been modified to remove fine pyrite from minus 6.4 mm (-114 inch) coal. In parallel tests, it proved to be far superior to two conventional coal jigs, the Baum and the Baum-feldspar, in removing fine pyrite from coal. The Pan-Am placer jig was found to remove essentially all of the +28 mesh pyrite and from 99% to 90%, decreasingly, in the 28 to 200 mesh range. This jig also showed a superior performance to the Baum-Type jigs in removing fine coal from its associated refuse. The superiority of the Pan-Am placer jig is related to the strong emphasis given on the suction stroke and, hence, on consolidation trickling, whereas the Baum jigs principally emphasize the pulsion stroke during jigging.

Jan 1, 1995

By James L. Crowe

Electric-power-generating plants fired by fossil fuels are faced with increasingly stringent requirements for control of sulfur emissions. Several approaches for limiting these emissions, or for operating such facilities in an environmentally acceptable manner, are being pursued. Some of the approaches are based on the use of naturally occurring carbonate rocks or of materials derived from them. This paper discusses primarily the carbonate-rock-based processes being developed for control of sulfur dioxide emissions from fossil-fueled electric-power-generating plants. It includes a discussion of the role of carbonate rock materials in removal of sulfur dioxide from stack gases after combustion, capture of gaseous SO2 during the combustion process, and removal of sulfur from fuel prior to complete combustion. Materials derived from carbon- ate rocks are generally used in processes which convert the sulfur to a throwaway product, but there are also proposed processes in which the sulfur is converted to a useful product and the absorbent is regenerated for reuse.

Jan 1, 1974

By L. Piga, P. Cipriani, F. Pochetti

High-temperature roasting of alunite in the presence of K2CO3 gives rise to a reaction that results in up to an 80% recovery of its potassium content as K2SO4 by leaching of the roasted mixture. K2SO4 is also generated from the reaction between the added K2CO3 and the SO3 driven off during roasting of the alunite. This limits the environmental and corrosive problems involved in the thermal treatment of this mineral. A solid residue containing mainly aluminum oxide is also obtained. This could be used as raw material for the production of aluminum, as the use of K2CO3 does not introduce different cations than are in the ore. A statistical study was performed on the factors assumed to affect the recovery of potassium, namely, roasting temperature, K2CO3- alunite stoichiometric ratio and leaching temperature.

Jan 1, 2000

By Rick Sarkisian, Albert D. Bonneau, David Keech

The Drummond Co. Inc.'s Shoal Creek Coal Mine Slope Belt Conveyor transports 5000 mtph (5500 tph) of material over a length of 1400 m (4600 ft.) and a lift of 3609 m (1180 ft.). Four 1500 kW (2000 hp) motors power the 1830 mm (72 in.) Goodyear Flexsteel 5800 steel cable belt. In May 1993, Dodge Manufacturing was selected to design and build the conveyor pulley assemblies for this conveyor. The conveyor includes five pulley assemblies. The 2135 mm (84 in.) diameter by 2135 mm (84 in.) face primary and secondary drive pulleys were designed for a resultant belt load of 3060 kN (688,000 Ib.) This paper describes the design and manufacture of the two drive pulley assemblies. Design details included are component evaluation, material selection, locking assembly selection, bearing selection and lagging selection. Manufacturing details include material procurement, welding process, lagging installation and component assembly. Quality control procedures are also discussed.

Jan 1, 1996

By Arthur P. Chaves, Lauro S. Norbert Costa, Adão B. Da Luz

A series of bench-scale bleaching tests have been carried out on kaolin samples from the Rio Capim area( northern Brazil) at CETEM/CNPq. The whole sample has been homogenized and submitted to particle size separation, when the + 44 µm fraction has been discarded, prior to being bleached. The main objective of this series of tests has been to evaluate the possible effects of interactions among variables which are believed to play important roles in the bleaching operation on the efficiency of the process itself in terms of the brightness achieved in the final product The tests have been planned according to a classical four-variable, two-level factorial technique. The chosen variables have been the pH, sodium dithionite addition, aluminium sulphate addition and bleaching time. The study has shown that, apart of time, all other three variables are significant. None of the interactions among them have shown to be of significance. Brightness numbers close to 88 have been obtained in the products, which represents an improvement, since brightness for the non-bleached - 44 µm Rio Capim kaolin sample averages 83.

Jan 1, 1995

By Gerald H. Luttrell, Roe-Hoan Yoon

Flotation columns are becoming increasingly popular due to their ability to improve selectivity and to reduce operating costs. Unfortunately, these advantages are not often realized because of poor operating practices and difficulties associated with design and maintenance. This article provides guidelines for the operation and design of columns. The discussion will focus on designing proper wash water systems for improved selectivity, maximizing throughput by increasing the bubble surface area rate, and minimizing operating and maintenance costs. It is suggested that the design of the air sparging system is the most critical element in column flotation.

Jan 1, 1993