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By F. F. Aplan, D. D. Xu

A novel system for the depression of pyrite and the ash-forming minerals has been developed. A metal ion, including but not restricted to Fe+2, is added to form a hydroxide coating on the pyrite or ash-forming minerals. A polymeric depressant is then added to attach to these re- surfaced minerals. Nearly 200flotation tests with I1 different coals indicate the effectiveness of this system. Many of the important process variables such as the coal source, frother- collector system. grind size and procedure, pH, metal ion, and depressant type and concentration have been studied.

Jan 1, 1995

By Prasannarao Dontula, Kal V. S. Sastry

Advances are made in the field of mineral processing on a continuing basis both in the industry and the academia. These advances do not always get used fully because of the inherent difficulties in the transfer of knowledge and reduction to practice. In recent years, knowledge engineering is being increasingly employed in other fields to overcome some of these difficulties. This paper presents a vision of how knowledge engineering can be applied to the benefit of the mineral processing industry and includes a discussion of associated principles, techniques, and advantages.

Jan 1, 1993

By W. F. Hahnert, P. A. S. Ralston

In off-line training of a rule-based controller, the significant measure of successful training is the quality of control provided by the generated rule set. In an adaptive or on-line control environment, performance is also measured by the ability to accurately maintain a satisfactory rule set, but within constraints on speed and/or resource availability. Very small population genetic algorithms, or microGAs, have been proposed as a means of capitalizing on the hill climbing characteristics of faster local optimization techniques while requiring less memory and retaining much of the robustness of traditional, larger population genetic search. A traditional genetic algorithm and a similar microGA are developed and applied to two control problems. The performance of these algorithms is analyzed with respect to (1) the quality of the rules learned, (2) the rate at which learning occurs, and (3) the memory resources required during learning.

Jan 1, 1993

By Allen V. Reicks, Thomas J. Rudolphi

Computerization has allowed practical design of complicated and optimized belt conveyors for bulk materials from prediction of belt tensions around the belt circuit for a wide range of belt loadings and conveyance paths. These design methods are based on a knowledge of component operating characteristics and sources of tension change. As compared to generalized 'f' methods, CEMA's historical Kx and Ky has provided nonlinear and more specific predictions of belt tension as affected by various components and operating conditions. These empirical values were developed in a different age and generalizations made in their development are now a constraint to additional conveyor improvements. This paper discusses the potential from improved and standardized ‘friction’ predictions and presents the results of sensitivity evaluations as affected by calculation method

Jan 1, 2004

By Donald S. Clarke

The Umuna epithermal precious metal deposit has provided the target for a simulated rock geochemistry exploration program, directed at bedrock exposed in the drainage system of eastern Misima Island. A geochemical halo to the deposit is readily recognised in the mafic meta-volcanic country rock. This halo is defined by anomalous results for both major (K, Na, Ca, Mg) and minor (Au, As, Sb, Cu, Pb, Zn, Ba, Rb, Sr, Cs, Bi, Ga, S) element geochemistry, extending further than 1km from the deposit. Such halos are sufficiently extensive to provide adequate exploration targets in the search for epithermal mineralisation, complementing mineralogic and secondary media geochemical investigations.

Jan 1, 1989

By J. P. Barbosa, R. V. V. Araújo, R. B. E. Trindade

Bromide stabilizes the auric or aurous ion by forming a stable complex in acidic aqueous solution. The oxidizing agent normally used for the process is bromine, which is a corrosive liquid with high vapour pressure. This is, in fact, the main reason why it has not found acceptance yet as an industrial oxidant for gold. Ferric ion with hydrogen peroxide and/or sodium hypochlorite have already proved to be effective oxidants for the dissolution of gold from a rotating disc in a bromide-containing aqueous solution. In the present work, preliminary tests with four selected ore samples were tested to evaluate the dissolution of gold with the same system already tested with the rotating disc (Br-/Fe3+/H2o2/NaCIO). Compared to the conventional cyanidation, results were superior in one instance only. The major obstacle seems to be the maintenance of a suitable potential to allow the complex formation. However, the studied system may be interesting, is in some situations it may yield better results than conventional cyanidation; therefore, further investigation seems to be worth doing.

Jan 1, 1995

By C. R. Copeland

Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration, and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. Suppressant effectiveness was also improved using hygroscopic reagents which retained moisture, improving longevity. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

Jan 1, 2008

By Raymond F. Mikesell

This paper evaluates the contributions of "third parties" to surplus capacity in the world metals industries in the 1980s. Special attention is given to the role of international development agencies, such as the World Bank, that have made project loans to state mining enterprises. The paper also reviews the contributions to surplus capacity of the International Monetary Fund and evaluates the large volume of credits from commercial banks to developing countries. Although the credits to Third World countries during the 1970s facilitated the expansion of mining capacity in those countries, no one source of financing can be held responsible for a significant portion of the expansion.

Jan 1, 1989

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 Sam H. Patterson

Australia has led the world in bauxite production since 1976, and only the Republic of Guinea has larger bauxite resources. India has a small integrated aluminum industry, and deposits containing more than 1 Gt (billion metric tons) of bauxite were discovered in the 1970's. The Peoples Republic of China has large bauxite resources scattered in several regions, but it is a monohydrate type that is difficult to process for aluminum. Indonesia and Malaysia both have long histories of bauxite mining, and both have limited resources of high-grade bauxite. Districts containing bauxite resources in the 10 Mt to 150 Mt (million metric tons) range are scattered in countries along the eastern rim of the Pacific Ocean, on islands in this ocean, and on the western and northern rims of the Indian Ocean.

Jan 1, 1982

By E. M. Frizzell

In an effort to economically and efficiently enhance the erosion control aspects of present surface coal mine reclamation practices, the US Bureau of Mines has recently completed a two-phase research program wherein irrigation strategies and equipment developed under the first phase were field tested on three surface coal mine sites. The fundamental basis for the use of irrigation as a reclamation tool is to provide the plant moisture requirements as a supplement to prevailing natural precipitation, and thereby support the natural growth of drought-hardy native vegetation. Portable solid-set irrigation equipment and several irrigation strategies were tested on large 6-ha (15-acre) sites in Montana, Wyoming, and New Mexico. Results of these tests will be presented which include daily irrigations, precipitation levels, soil moistures, climatic data, and density cover and biomass of the native plants.

Jan 1, 1987

By H. Sis, D. Dahlin, S. Chander, C. Summers

Bench-scale selective-flocculation tests were conducted on samples of Florida phosphate and Western phosphate process tailings to recover upgraded phosphate concentrates. After physical and mineralogical characterization, the slurry samples were treated with a broad suite of flocculants with a range of molecular weights and anionic functional groups. Parameters investigated included pH, dispersant and flocculant types, and dose; conditioning parameters and settling times were, for the most part, held constant. Where selectivity was achieved, phosphate minerals remained dispersed, whereas silicate minerals flocculated and settled. Single-stage tests using reagents with low to medium anionic characteristics produced upgraded phosphate concentrates at moderately elevated pH. Two- stage site-blocking tests, in which low-molecular-weight flocculants were used as site-blocking agents, gave improved results.

Jan 1, 2002

By Peter McKenna

A mineral rights holding can ultimately only be turned to account by the profitable mining of ore on that property. The evaluation of South African gold mineral rights properties must therefore be carried out by assuming that they have potential to form part or all of a future gold mine. Such analysis involves the simulation of many of the estimation procedures that are normally carried out in a full feasibility study of a new mining venture but using far less data. This paper describes in detail the evaluation procedures that may be applied to an individual property and then indicates how these techniques can be applied to a whole mineral rights portfolio.

Jan 1, 1989

By S. Chander

The advantages and disadvantages of various techniques available for controlling reagents in the mineral flotation systems are discussed. Special interest is placed on potentiometric and voltammetric sensors for monitoring flotation pulps. Different approaches to increase the sensitivity of detection and to facilitate in-stream monitoring of solution species are also discussed. The potentiometric sensors are simple to use but are limited by the availability of an electrode reversible to the species to be monitored. In some cases the response signal could be unreliable due to the presence of interfering species. In comparison, voltammetric sensors require a higher degree of instrumentation which, however, provides an opportunity to decrease interferences and increase levels of detection.

Jan 1, 1993

By Shamsuz Zaman, Barry Hansen

The major development in the evolution of the conventional subaeration flotation machine has been the steady increase in the size of the individual units. In 1950, large machines were of 1.35 m3 (48 ft3) volume capacity. In 1989 the largest volume capacity operating is 85 m3 (3,000 ft3 ) These improvements have enabled the mining industry to operate successfully in the face of declining ore grades and adverse metal prices. This paper describes the design features and performance characteristics of a number of significant flotation machine designs.

Jan 1, 1989

By Chester R. McKee, Amar C. Bumb, Kohei Kawakita

Unlike many other heavy metals, gold can be profitably mined in small operations because of the prices. One mining technique that seems ideally suited for small deposits of gold and for certain large, lowgrade oxidized disseminated deposits is solution mining. Solution mining generally requires lower capital investment and operating costs than conventional mining and milling and is safer and less degrading to the environment. Although gold has long been recovered by cyanide leaching following conventional milling, solution mining as discussed here gained momentum only in the past two decades, during which time alternative lixiviants instead of cyanide have been researched. Chamberlain and Pojar (1981) classified solution mining systems used today as three types, namely heap, dump, and in-situ leaching.

Jan 1, 1990

By J. M. Johnson, J. Vialpando, C. Lee

Since 1951, Molycorp has operated the Mountain Pass Mine in San Bernardino County, California to extract fourteen lanthanide elements, or rare earths, from a carbonate ore body. Wastes generated by the open pit mining operation consist of overburden and 1800 tpd of tailings. The tailings are classified as Group B mining wastes by California regulators. Paste tailings is one of several alternatives being considered during the permitting process for future mine operations. This paper presents the findings of study to assess the feasibility of using paste tailings to develop an unsaturated tailings stack instead of dilute slurry discharge behind a tailings dam.

Jan 1, 2004

By Walter Keune

Object Modeling Technique. This formal descriptive language makes it possible to formulate requirements in the real world in such a way that they can be implemented in the form of entities (cf. Entity Relationship Model[Che83]) and methods (see Figure 1). The object {Roadway} is graphically depicted by means of the Polygon method.

Jan 1, 1996

By Rodger E. Denison

The Middle Ordovician Simpson Group in the Arbuckle Mountains of southern Oklahoma contains sandstones of unusual purity. These have been exploited as glass sands since 1913 (Ham, 1945). Where quarried, the sandstones are uncemented or weakly cemented, greatly facilitating mining and processing. The origin: sedimentary setting, and lack of cementation of these valuable sands has been the source of much discussion. The lowest of the sandstone units in the Simpson is at the base of the Oil Creek Formation. The basal Oil Creek sandstone is exposed in a series of accessible quarries north of the town of Mill Creek in Johnston County. Virtually all conclusions and generalizations concerning origin of the Simpson sandstones are based upon observations made in these quarries. The three Simpson sandstones overlying the Oil Creek share many of the same distinctive qualities, and there is an assumption that they share a common origin.

Jan 1, 1999

By S. Eugene Sankey, Geoffrey L. Payne

Modern metallurgical processing often depends heavily on the use of flocculants to achieve the high levels of efficiency required. Selection of the optimum polymer can be complicated by the effects of process streams on the chemical and physical stability of the chosen polymer. Similarly, the presence of the polymer can have positive or negative side effects on process streams, such as phase disengagement in solvent extraction, foaming at filters and thickeners, crystal growth modification or flotation performance. Guidelines are given to highlight areas where problems may occur and suggestions made as to how these can be overcome. Practical advice on the preparation and application of polymers in process liquors is provided.

Jan 1, 1986