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By G. G. O. O. Uwadiale, E. G. Okafor

A study was performed to characterize the Ishiagu lead-zinc deposit prior to beneficiation. The study included the use of XRD, SEM and both reflected- and transmitted-light microscopy. The results showed that the ore consists mainly of galena (PbS), sphalerite (ZnS) and quartz (chert), with pyrite, siderite and chalcopyrite occurring as trace minerals. The textural relationships among the minerals, their grain sizes and their locking characteristics, coupled with the chemical analysis of the ore, indicated that the galena and sphalerite can be separated by conventional beneficiation methods.

Jan 1, 1998

By Paul Gribbon, Greg Colzani, Jim McDonald

The $300 million West Side Combined Sewer Over?ow Project consists of over5.5 kilometers of soft ground tunnel, an 833-million liter per day (220-MGD) deep shaft pump station, 3 kilometers of micro tunneling, and other miscellaneous shafts and pipelines. The construction contract, underway since September 2002, is a reimbursable cost plus fixed fee contract that included a quali?cations-based contractor procurement process and has undergone some modi?cation since execution. This paper will describe the contractual issues addressed to date, dispute resolution, where improvements can be made, and how an Owner can evaluate whether this type of contract is the best approach for an underground project.

Jan 1, 2005

By B. Bringhurst, J. J. McClelland

A filter consisting of a synthetic fibrous material has been determined to be a viable alternative to the wire mesh panels currently used in irrigated filter dust collection systems. An extensive laboratory investigation of the material showed that it removed a higher percentage of both respirable coal and quartz dust from the air entering a collector than did the flat and pleated wire mesh panel designs. This improvement in dust collection efficiency reduced the amount of coal and quartz dust discharged from the collector exhaust by approximately 44%. Since continued exposure to excessive levels (>5%) of respirable quartz dust presents a severe health hazard, this alternative filter medium could be of use to those mines required to comply with more stringent dust standards due to quartz.

Jan 1, 1992

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

To reduce their sulfur emissions, many coal-fired electric power plants use wet flue-gas scrubbers. These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of. This sludge is a result of reacting limestone with sulfur dioxide to precipitate calcium sulfite and calcium sulfate. The majority of the sludge is simply landfilled, but with increasing landfillimg costs this can cost the plant millions of dollars per year. As a result, this option is rapidly becoming less attractive. Producing marketable materials from the sludge is a far more promising avenue, provided that the products can meet the necessary specifications at a reasonable cost. In this paper, a method is described for using froth flotation and water-only cyclones to remove unreacted limestone from scrubber sludge. The water-only cyclone was found to be very effective for removing the coarser unreacted limestone, grinding ball chips, gravel, and similar coarse impurities. Froth flotation was found to remove fine unreacted limestone, with a minimum of reagent addition.

Jan 1, 1995

By A. Unal

Coal resource characterization usually calls for estimating more than one variable over a block or node simultaneously. Within the realm of geostatistics, each variable has been evaluated independently from the others assuming a lack of significant correlation. Research conducted with coal seams, however, has shown that the variables of immediate interest, such as seam thickness, ash, sulfur content, and density depict some correlation schemes in distinct zones, if not throughout the entire area. The above findings have two immediate consequences : (1) correlation analyses provide guidelines to determine the geologically distinct zones, and (2) where possible, cokriging should be used instead of kriging. This will maximize data utilization decreasing the frequently criticized high estimation errors. The cokriging formulation will also provide more accurate estimates for under sampled variables using better-sampled ones. This is a common case with coal with regard to the non-cored reconnaissance drill holes for which only very few variables were recorded. A case study illustrates the improvements that may be obtained by taking advantage of the intervariable correlations.

Jan 1, 1986

By J. J. Kellar, W. M. Cross, H. Du, C. D. Struckman, D. A. Boyles

Silane coupling agents have been used in the filler industry for years. One particularly unique feature is the ability of the coupling agents to enhance the adhesion between filler and polymer matrices. This paper will review the use of coupling agents for polymer matrix composite applications and discuss a new approach to coupling agent chemistry, namely, direct formation of a silicon-carbon non-hydrolyzable linkage between glass and coupling agent. The grafted silane monolayers were evaluated by infrared spectroscopy to ascertain their surface coverage and relative stability. Finally, composite specimens were fabricated and their mechanical properties were compared with traditional silane coupling agent treatment.

Jan 1, 2003

By Thomas Fenner

Surface and underground mining operations are often hindered by unknown tunnels and slopes and the precise locations of adjacent workings. Mine safety and planning are adversely affected especially in previously undermined areas where historical records are incomplete or nonexistent. The results of several ground penetrating radar (GPR) studies for the detection of known mine tunnels in underground coal, salt and gold mines are presented. A case study to locate unknown, abandoned mine workings at a surface gold mine successfully located all workings to a depth of 11 m (36 ft).

Jan 1, 1996

By D. D. Runnells, D. C. Keith, G. A. Doyle, J. Tilk

Until the suspension of conventional operations in 1996, the White Pine Mine was the second-largest active underground copper mine in the United States, underlying an area of approximately 30 km2 (13 sq. miles) in the Upper Peninsula of Michigan. The mine operator intends to initiate in-stope solution copper mining by circulating a solution (lixiviant) of mine water, sulfuric acid and ferric iron through rubblized ore. As planned, the solution would be retired in the mined-out stopes following completion of the solution-mining activities. Investigations into the fate of the retired solution indicated that the solution, through time, would change from an acidic, metal-rich solution to a near-neutral, reducing solution containing much lower concentrations of metals. Investigations included reaction-path modeling (EQ3/6) and laboratory and in-mine tests. The combination of neutralization and reduction will result in precipitation of most metals, primarily as metallic sulfates, chlorides and sulfides.

Jan 1, 1998

By R. K. Mehta, G. T. Adel

A review of the literature reveals that methods for simulating the coupled behavior of size reduction and liberation are limited to binary mineral systems containing one composite particle class. The aim of this paper is to describe the development of a mathematical model to simulate such behavior for binary and ternary systems containing multiple classes of composite particles. A modified Levenberg-Marquardt algorithm and a finite difference Jacobian are used in conjunction with the developed model and a set of constrained equations to estimate all kinetic parameters. This estimation scheme is validated far a binary ore (sphalerite-dolomite) with five composite particle classes using experimental data.

Jan 1, 1991

By T. H. Combs, G. T. Lineberry

Increased productivity in the US underground coal industry has taxed pre-existing conveyor belt haulage systems. The usual remedies are costly and can disrupt production. A reduction in the belt feeder discharge rate on shuttle car sections results in more uniform loading and reduces spillage vulnerability. An investigation was made to determine the effect, if any, on shuttle car discharge time arising from lower feeder discharge rates. A five-section, underground mine is modeled, and belt spillage is introduced. The sectional feeder discharge rate is progressively lowered until spillage is precluded. At each level, the simulated spillage is measured and compared to the loss in face production. Methods for predicting the loss in face production from lower feeder discharge rates were investigated.

Jan 1, 1995

By Dilip K. Sinha

In the paper some interesting cases of applications of Operations Research and Computer Methods as worked out by the author and accepted by the management of some of the newly formed Indian mining organisation for implementation are highlighted. The main emphasis on the application cases was to use simple techniques and methods which yield the result in shorter time period, The case problems mainly deals with the production system optimisation in unit mines, areas/divisions and at the corporate levels. Also the management decisions regarding reorganisation of transport and distribution system of material and mineral are attempted to be optimised. Further, the case of management system development with computer aided decision making worked out for single large Iron Ore Project captive to a steel plant is outlined. Finally, the case of a large mining company having decentralised units and divisions geographically dispersed throughout the country, computerised management decision-information system designed on the basis of inputs and outputs of decision models relevant for different levels of management in the organisation is depicted.

Jan 1, 1986

By Peter A. Burger

The Greenvale Orebody comprises a series of contiguous lateriteprofiles developed terrace-like during the Cainozoic over a serpentinized harzburgite intrusive emplaced within Proterozoic schists. Each terrace displays individual characteristics of metal distribution. Topographically higher (older) profiles have been partially eroded and metal concentrations reworked. Within the laterite profile, metals have been concentrated or depleted according to their relative solubilities. At tropical temperatures, acidic meteoric waters have progressively depleted the ultrabasic parent rock of Si and Mg, leaving A1 and Fe to form a surface duricrust. Ni, Co, Mn and Cr have accumulated in the lower and middle levels of the weathering mantle. Only Ni and Co have accumulated to exploitable grades. Lateritization has evidently proceeded over a considerable portion of the Cainozoic and may be still continuing.

Jan 1, 1979

By J. Drelich, J. Pletka

Lost foam casting is a process in which a polymeric material is formed into the shape of the part to be cast. Parts that are more complex are fabricated by simply gluing several patterns together. The pattern is then coated with a refractory material consisting of a mineral mixture and binders. Finally, hot metal is poured into the pattern, evaporating the expanded polystyrene and taking the shape of the coating shell. Prior to casting, a significant number of the patterns are damaged and inevitably landfilled. In this study, a process was developed for the recovery of expanded polystyrene from the coating and glue contaminants. The process consists of shredding, impact comminution, size classification and pneumatic separation. It is successful in separating up to 97% of the contaminants, while recovering 95% of the polystyrene. Key words: Casting, Lost foam process, Expanded polystyrene recovery

Jan 1, 2003

At periodic intervals-typically at the end of each month, quarter, and year- the accounting department in each division of a company distributes a set of reports to the division's managers. These reports describe the financial performance of the division and its major departments over the time period. They identify the revenues generated from the division's products and the costs incurred in their production. The results from individual departments are combined to determine divisional results, and the results from individual divisions are in turn consolidated to determine the results for the overall corporation. Cost reports for each of these activities show actual amounts, budgeted amounts, and the differences between the two. This reporting is carried out for the individual period and for the year to date.

Jan 1, 1999

By R. Sivamohan, F. Huang

A mineral processing strategy developed for the finely and complexly interlayered calcite rich wollastonite, microcline, and iron-garnet ore of Jokkmokk, northern Sweden, gives an overall calcite recovery of 89.4% at a grade of 90.7% CaCO3. The wollastonite product assays 53.0% Ca- SiO3 at a recovery of 92.2%. The significant elements of the developed strategy are stepwise grinding, wet high intensity magnetic separation (WHIMS), reverse flotation and starvation flotation. Stepwise grinding avoids the overgrinding of soft calcite. WHIMS removes the colored iron-garnet impurity and thereby increases the whiteness of the product. Reverse flotation enables a simple flotation circuit and starvation `flotation helps to optimize the physicochemical conditions in cleaner flotation by giving rougher products of narrow particle size distributions. Moreover, with the reagent scheme developed in this work only one cleaner stage is necessary for the various rougher flotation products to be upgraded to give the foregoing results. In this paper, the strategy is presented in detail along with appropriate results.

Jan 1, 1990

By Jorma Miettunen

The Plant. The annual production of the Pyhasalmi mine is 900 000 tons of copper- zinc-pyrite ore containing approximately 0.7 % Cu, 2.5 % Zn and 30 % S. During 1976...1981 altered surface ore, 850 000 tons in all, was also treated at the concentrator. The surface ore was crushed and ground in a separate plant and was then fed into the copper or zinc flotation or was flotated in its own circuit, depending on the degree of alteration and the content of copper and zinc in the ore. The surface ore was exhausted in October 1981. Flotation comprises three consecutive flotation circuits; copper, zinc and pyrite circuit. The zinc circuit includes an open circuit roughing and scavenging. The scavenger concentrate and cleaner tailing are pumped to the middlings flotation. Rougher concentrates of the open circuit and the middlings flotation are pumped to cleaning which includes four stages. Figure 1 describes the flowsheet of the zinc circuit.

Jan 1, 1982

By R. C. Ford, J. Kelsey, S. A. Pierce, M. D. Ankeny

Evaluation of acid drainage risk from spent (leached) ore in arid climatic zones consists of two components: (1) whether residual and secondary minerals will release acid and metals when exposed to rainfall, and (2) whether ambient rainfall is likely to infiltrate, and eventually impact surface or ground water resources. The risk of acid drainage from spent ore at the El Abra on-off copper leach pad operation was evaluated using conventional geochemical methods and unsaturated flow models. Although geochemical testing indicated poor quality water would result from any seepage, unsaturated flow modeling demonstrated that infiltration and seepage were unlikely given the arid climatic conditions. Modeling further demonstrated that the residual moisture content of the spent ore when it is removed from the leach pad controls the risk of seepage. To further reduce the risk of seepage, operational controls were developed and implemented at the El Abra site.

Jan 1, 2000

By B. Elevli, M. D. G. Salamon

Production scheduling of an open-pit mine is one of the most important steps in open-pit mining. The mine's production schedule defines the distribution of cash flows and, as a result, directly influences the net present value (NPV) and overall economic feasibility of a project. The need to plan and operate a mine with an optimum production schedule has been obvious for some time, but the methods used to obtain such a schedule have not been so obvious. The current practice is to do a trial and error analysis by hand. In an attempt to improve the way production scheduling is currently done, a new computer based production scheduling algorithm was developed. This paper describes the fundamentals of this newly developed heuristic scheduling algorithm and its application to a gold deposit. The results of this case study show that the schedules, based on the new method, provide improved cash flows compared to production schedules done manually.

Jan 1, 1992

By William A. Faust

La Colorada Mine was begun in 1993 as a small heap leach mine and was the first operation for Eldorado Gold Corporation. 'This paper describes the growth of the mine to annual production levels near 60,000 ounces of gold and highlights recent improvements that were made to maintain a profitable operation by efficiency gains and cost containment programs.

Jan 1, 1998

By Pierre Mousset-Jones, Felipe Calizaya, Malcolm J. McPherson

The algorithm presented in this study determines the combination of fans that provide all working districts of a mine with predefined airflows at the minimum operating cost. It is based on an existing ventilation simulator, VNETPC, and a set of linear equations associating fan pressures and the added resistance of regulators. Two assumptions are undertaken: (1) fan locations are predetermined and (2) the number of working districts is equal to or greater than the number of fans. By means of this algorithm, the optimal solution to an n fan ventilation system may be found after n + 1 simulation runs.

Jan 1, 1987