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By Richard V. Wyman

The genesis of ore deposits has been tied to plate tectonics through differential petrogenesis in subduction zones. However, many mineral districts, especially in the Basin and Range province of United States and Mexico, appear unrelated to any possible subduction zones or to plate boundaries. It is proposed that the pattern of mineral belts is related to mantle plumes which have been overridden by an advancing continental margin.

Jan 1, 1976

By H. O. Seigel, John C. Robbins

Luminex is a new method of prospecting for mineral deposits based on time-resolved mineral luminescence created by an ultra-violet light source. Developed by Scintrex Ltd., Luminex detects and resolves a group of key minerals - either ore minerals themselves or, more often, accessory or pathfinder minerals for certain types of economic ore deposits. These minerals are commonly found on the earth's surface, even in areas of considerable weathering. The method extends the range of mineral deposits that are remotely detectable from the air. Tungsten, tin, molybdenum, gold, and bedded lead-zinc deposits are included. Therefore, Luminex is a natural supplement to the three classical methods of airborne geophysics. The luminescence of minerals has been known and used qualitatively in mineral exploration for many years. But there are more than 500 minerals known to be at least sometimes luminescent. Luminescence of most is unpredictable and the colors they emit may vary from locale to locale. It is, perhaps, this apparent complexity of the field that has discouraged its proper scientific scale until now. There are two basic types of luminescent minerals - intrinsic and impurity activated. In the first type, luminescence is an inherent property of the mineral in its purest form. In the latter, luminescence is due to the introduction of foreign trace elements, often in very modest amounts (ppm), into the crystal lattice. These trace elements are known as activators. There are very few intrinsic luminescent minerals commonly found in nature. Chief among these are the calcium tungstatemolybdate family, more commonly known as the scheelite-powellite family, and the uranyl minerals such as autunite and saleeite. The vast majority of other known fluorescent minerals such as fluorite, hydrozincite, and many calcites, are impurity activated - that is, they will not fluoresce in purest form. In addition to the many minerals likely to luminesce at the earth's surface under ultraviolet excitation, any prospector who has ventured out at night with a mercury lamp will know that much organic matter luminesces - for example lichens and even scorpions. Just as the eye finds difficulty in resolving the luminescence of minerals from that of organic materials, it also has its limitations at sorting out minerals from one another by their luminescent colors. Figure 1 shows, in part, the photoluminescent emission spectra of scheelite, hydrozincite, and autunite. It is clear that there is a considerable similarity in spectrum between scheelite and hydrozincite and a great deal of overlap. In fact, a small amount of molybdenum in the scheelite lattice can almost bring these two spectra into coincidence. On the other hand, the autunite emission spectrum is clearly resolved from the other two. Basis of the Method The right-hand side of Fig. 1 shows the time waveforms of decay of the photoluminescence of the same three minerals. It is apparent that the lifetimes of photoluminescence of scheelite and hydrozincite are radically different and that these two minerals, therefore, may be readily resolved through their emission lifetime characteristics. It is in the realm of time-resolved measurements (lifetime characteristics) that Scintrex has made its major advance in the Luminex method. With the exception of some work by Exxon confined to uranyl minerals, to the best of our knowledge, no systematic scientific investigation has been carried out in the field of time-resolved mineral luminescence studies other than the work of Scintrex. Scintrex's findings are that all organic materials and most commonly activated luminescent minerals have lifetimes shorter than one microsecond. In addition, only a relatively small number of minerals - among them those called key minerals, or certain ore and pathfinder minerals - have lifetimes greater than one micro-second. Scintrex is able to characterize these minerals primarily by their emission lifetimes and secondarily by their emission spectral characteristics. By a combination of these factors a mineral index is arrived at. From that, photoluminescent minerals can be resolved from one another with a high degree of probability. At least two spectral channels and two time channels - of which one can be common - are required to apply this mineral index. Ground System A portable hand-held Luminex analyzer based on a modulated mercury lamp has been used to date in Canada, the US, and Australia. The current production model of this device is the LG-2. It has two spectral channels and two time channels for each spectral channel. Figure 2 shows a ground Luminex traverse over the Texas-Arizona zinc prospect in Arizona. The instrument was set so the channel read was hydrozincite-specific insofar as possible. The mineralization in this prospect is known to be hydrozincite and other zinc secondary minerals in limestone. Figure 3 shows a ground Luminex traverse over the AAA uranium prospect in Nevada. The instrument was set to optimize the uranyl response. For comparative purposes, broadband scintillation counter readings were made on the same stations (also shown in Fig. 3). It is apparent that both the Luminex and the scintillation counter results reflect a near-surface distribution of uranyl minerals. It is interesting that no visible uranyl secondary minerals

Jan 7, 1983

By Edward D. Elkins

CalMat Co. is one of the largest producers of construction aggregates in the United States. The CalMat Reliance plant is located in Irwindale, California, and is situated on an alluvial fan formed by the San Gabriel River. The fan deposits are of Quaternary age and were derived from granitic and metamorphic bedrock exposed in the San Gabriel Mountains to the north. The sediments are poorly sorted and range in size from large boulders to clay size particles. The coarse material is hard and durable and consists of quartz diorite, granodiorite, granitic gneiss, schist and minor amounts of volcanic rock. The matrix is comprised of silty sand with varying amounts of clay. Thin silt and clay lenses occur sporadically throughout the deposit. The clay content of the matrix and the degree of weathering of the coarse material increases with depth. Based on seismic data, the alluvial fan varies from 200 to 400 feet thick and overlies crystalline bedrock. The Reliance plant was constructed in 1971 and 1972. It has a nominal capacity of 1200 to 1400 tons per hour, and typically produces more than three million tons of aggregate products per year. Alluvial fan sediments are mined from a gravel pit situated adjacent to the plant. The material is fed through a mobile, 48- by 60-inch, in-pit jaw crusher, then transported by conveyor to the main plant to be processed. The plant is modern and highly efficient. It has a typical wet and dry circuit and is capable of producing a wide range of aggregate products. To extend the life of the plant, a 9,000 foot conveyor system is being constructed to connect it to a granite quarry operated by Azusa Rock Inc. The quarry is located north of Irwindale, and is 50 percent owned by CalMat Co. The conveyor will be used to export crushed rock from the quarry to Reliance. The existing plant will be modified to process the crushed rock.

Jan 1, 1995

By B. J. S. Sceresini

The Filblast Cyanidation Process incorporates the advantages of intense high shear mixing, high dissolved oxygen concentra­tion and high pressure to achieve extremely rapid gold dissolu­tion rates. This is made possible without suffering from high energy or wear rates by the unique design of the Filblast gas shear reactor. The reactor is a rugged and compact in-line device which can be constructed from a variety of wear and chemical resistant materials. High temperature tolerance is also possible so that the device can be incorporated into a pressure leach circuit with significant capital cost savings because of the high capacity to volume ratio that is an inherent feature of the device. For cyanidation applications the outer casing is protected by a polyurethane coating and the internal parts are of wear resistant polymer. The largest unit built to date has overall dimensions of 1200 mm length by 300 mm diameter and has a capacity of about 150 dry tonnes per hour at 40-45 % solids. Service life at this throughput is at least three months. Six mines are currently employing the Filblast Process and another six are conducting plant trials. The ore types range from highly reactive, almost impossible to treat, pyrrhotite/ arsenopy­rite to deeply weathered clay ore which forms a highly viscous pulp. It has been found that the effect of shear thinning has resulted in improved leaching and adsorption kinetics resulting in higher carbon loading and reduced soluble gold loss. Total tonnage treated is approximately eight million tonnes per annum. This paper presents the operating benefits and cost savings which have been achieved in four plants, two treating oxide/ sulphide ore blends and two treating highly reactive sulphide ore and concentrate. Filblast leasing and maintenance charges and pump operating costs are about ten percent of the benefits. A conceptual cyanidation circuit based on the Filblast Cyanidation Process is also discussed. The Filblast System is an in-line pressure leach aerator/ reactor which generates very high shear and greatly enhances mass transfer rate by generating extremely small gas particles where oxygen gas is required for oxidation reactions and/or utilising the high shear characteristics to minimise the diffusion boundary layer. Both of these rate limiting factors effect the rate mechanism for gold cyanidation. Initially two multi-stage Filblast aerator cartridges formed a leach train but now the trend is to install a single submersible cartridge of equivalent perfor­mance. This design simplifies installation and minimises change-out times. However the in-line concept can be employed where high pressure leaching or pressure oxidation is required. The reactor is submerged in the leach tank so that the mass of gas micro-bubbles contained in the discharging slurry is entrained in the agitator vortex and is thoroughly dispersed throughout the tank. A diagrammatic representation of a leaching circuit incorpo­rating the Filblast Reactor is shown in Figure 1. The recirculation pump takes new feed directly from the cyclone overflow trash screen either under gravity or pump fed and recirculates the balance to maintain 250 - 270 m3/h total slurry flow. All of the leach feed slurry gets at least one pass through the Filblast thereby eliminating short-circuiting. Typically a 6/4 EAH Warman pump drawing 60-70 kW is required to circulate 250 m3/h through the system. The back pressure generated by the Filblast is in the range of 400-500 kPa depending upon pumping rate, pulp density and slurry rheology. The high shearing rate effectively negates the viscous effect of slurries and the addition of a gas further reduces the pulp density by virtue of the intensely aerated, homogeneous medium. The gold leaching Filblast cartridge elements are made of polyurethane but stainless steel, ni-hard, rubber or ceramics can be used depending on the operating temperature and design duty. The efficiency of the Filblast Leach Reactor in gold cyani­dation is due to the extremely efficient mixing, oxygen dissolu­tion and surface polishing action of the Filblast design. Either air or oxygen may be used but Atomaer recommend the use of oxygen because of the rate benefits gained from cyaniding at [02] significantly > 20 ppm D O in the reactor. Very high DO concentrations have been measured; in excess of 50 ppm. There is some debate as to whether the value is a true measure of the DO or the oxygen meter sensor is measuring the effect of a mass of very fine bubbles of free oxygen. Regardless of the fact the reactor has registered some amazing gold dissolution rates commonly in excess of 80 % during transit of the pulp through the reactor. The elapsed time is less than half a second!

Jan 1, 1995

By S. Chander

The fundamentals of flotation are reviewed with an objective to understand the limitations in predicting the performance of a sulfide mineral flotation system and in its scale-up from laboratory studies to plant practice. The difficulties can often be traced back to complex interactions between chemical and physical parameters and nonequilibrium effects. The physical and chemical changes that occur during the long sojourn of sulfide minerals that begins with mining, continues through crushing and grinding, and ends when they emerge from the flotation cell as a concentrate, are reviewed. The benefits of new techniques that have become available in recent years to identify and estimate the amount of surface species are discussed.

Jan 1, 1999

By J. Kalnejais

Discovered in 1896, the Sons of Gwalia orebody was initially mined by unground methods. Euring the mine's uderground operations workings reached a vertical depth of 1080 metres. The same orebody is now being mined by open cut methods. The present operation mines a broad envelope of mineralisation surrounding old stopes, whereas the original underground operation concentrated on mining high grade parts of the Gwalia Lode System. Underground mining continued up to 1963 when operations ceased due to high operating costs and the low grade of ore mined. In 1984 a new company, Sons of Gwalia NL, commenced open cut operations.

Jan 1, 1989

By Mark W. Johns

The design or optimization of a carbon-in-pulp (CIP) plant requires the determination and setting of a number of parameters to ensure optimum economic performance. A number of these parameters are either fixed, a function of the pulp, interdepen­dent, affect other parameters or outputs, so only a limited number of degrees of freedom exist from a metallurgical point of view. The traditional CIP contactor employs a low carbon concen­tration, a low agitation intensity and a reasonably long pulp residence time. The pump cell contactor employs a high carbon concentration, a high agitation intensity and a reasonably short pulp residence time. The two philosophies are dipolar in nature and the question arises as to which configuration is the optimum configuration for a CIP plant. The carbon particle size is shown to have a small effect on the capital cost of a CIP plant. A decrease in the pulp residence time, an increase in the pulp density, an increase in the carbon residence time, an increase in the agitation intensity and an increase in the number of stages are shown to have a positive effect on the capital cost of a CIP plant. The pulp residence time, the pulp density and carbon particle size are shown to have a small effect on the operating cost of a CIP plant. An increase in the carbon residence time, a decrease in the agitation intensity and an increase in the number of stages are shown to have a positive effect on the operating cost of a CIP plant. The optimum CIP plant, therefore, employs a short pulp residence time, the traditional pulp density, a long carbon residence time, the traditional carbon particle size, the traditional agitation intensity, and the traditional number of stages. Neither the pump cell configuration nor the traditional CIP configurations match the optimum configuration.

Jan 1, 1995

By R. D. Hansen, R. R. Klimpel

This paper discusses the influence of frother type and dosage on recovery/selectivity in coal/sulfide mineral flotation as a function of particle size. It is shown that different frother structures exhibit quite different but consistent performance characteristics depending on the underlying particle size ranges involved as well as the dosage levels of both the frother and collector. The data presented on existing commercial frothers and some new special purpose experimental frothers is used to illustrate some general operator guidelines on proper frother selection and use.

Jan 1, 1987

By Vicki Seppala

Phelps Dodge Mining Company operates some of the world’s largest open pit mines. Safely mining in these deep pits requires the commitment to a proactive integrated slope management process. The slope management process also includes the continued look for improved slope design, construction, and maintenance of slope faces. This paper discusses integration of such technology as electronic programmable detonators, 3D imaging using ground-based LiDAR scans, and reflectorless slope monitoring systems in a slope management program.

Jan 1, 2005

The design of solvent extraction plants has been generally based on the assumption of steady operating conditions in both the settler and the mixer units. However, recent experience in both large and small plants has shown this not to be the case. Mixer transients include start up aqueous locking and partial phase separation in secondary mixers, which both lead to reduced plant capacity or overflow of upstream mixers. Analysis of the hydraulic pressure profiles has generated new design methods to eliminate the effects of the partial or complete phase separation. Changes to the method of specification and selection of primary and secondary mixers have been made to eliminate the onset of partial separation during operation. The observation of settler operation has shown that it is also a dynamic process, even under "steady-state" conditions. Four transient phenomena have been identified that lead to internal circulating flows, poor disengagement of fine secondary haze and erratic and high entrainment levels in the discharges. A, first approximation analysis has shown that there are significant pressure differentials within settlers, and these change along the length and with the phase separation rates. A technique to control the effects of these transients was developed that allows plant performance to be improved beyond "standard" expectations. The design and selection of the settler internals is described. Key words: Solvent extraction, Mixer-settlers, Phase separation, Entrainment, Mixer transients

Jan 1, 2003

By P. R. Taylor

The ability to process complex precious metal sulfide concentrates containing antimony and arsenic in an economic and environmentally safe manner is an important problem facing the mining industry in the United States. Preliminary experiments have been performed to evaluate the possibility of treating a complex sulfide concentrate to recover antimony and precious metals while fixing the arsenic and sulfur as calcium arsenate and calcium sulfate. The process involves: • the oxidation of the antimony and arsenic minerals in the presence of soda ash (to collect the sulfur dioxide and to keep the antimony and arsenic from forming volatile compounds), •the selective leaching of the arsenic from the roast calcine with a heated caustic solution, •the precipitation of the arsenic and sulfate with calcium hydroxide and/or calcium chloride, •the reduction of the residual antimony (collecting the precious metals), •fuming of the metal to form a marketable antimony oxide, and •crucible reduction of the residue to obtain a gold and silver dore. Batch experiments, using synthetic concentrates of stibnite and arsenopyrite, were performed to evaluate the first stage of this process. Variables studied included mixture weight fractions, temperature, gas flow rate, oxygen partial pressure, and time. All of the off gas dust and sulfur containing gases were collected and analyzed. The roast solid residues were subjected to arsenic leach tests, and the leach solutions were subjected to arsenic and sulfate precipitation tests. Introduction The ability to treat a precious metal ore containing appreciable amounts of antimony and arsenic is dependent upon the characteristics of the ore. For some ores, selective flotation can be used to separate the antimony and arsenic minerals, which are then treated separately. Unfortunately, many ores are not treatable in this way, and the concentrates obtained may contain appreciable contamination (which limits the ability to make acceptable grade antimony products). If we consider the added value of the precious metals in the concentrate, then it is worthwhile to evaluate the potential for new methods to treat these types of concentrates. In addition, the environmental difficulties associated with arsenic disposal must be taken into account in any proposed process. If there is appreciable arsenic present, then it must be either recovered as a marketable product or placed in an insoluble form. The problem addressed in this research program has become increasingly important as the precious metals mining industry is encountering more ores of this type. A large deposit of this type exists in Idaho where the antimony occurs primarily as stibnite, with minor amounts of kermesite and tetrahedrite (Cooper, 1951). The gold appears in association with arsenopyrite with minor amounts of other arsenic minerals. Flotation has been used to obtain an antimony concentrate. The concentrate, however, is contaminated with appreciable amounts of arsenic and also contains precious metals. If the ore or concentrate contains appreciable amounts of base metals, then the recovery process becomes much more difficult. There are a number of other known deposits of this type in Alaska, Canada, Montana and elsewhere. The objective of this research program was to develop a fundamental understanding of the oxidation and leaching chemistry of the arsenic and antimony minerals so that technology may be developed to treat these ores in an economic and environmentally safe manner. Wendt (1949) and Koster and Royer (1940) discussed the possibilities of oxidative roasting of stibnite concentrates containing arsenic. Wendt describes a process used at a smelter in Czechoslovakia (in the 1930s) where roasting was carried out in rotary furnaces at 723° K (500° C). Most of the arsenic was removed as fume, as well as 25% of the antimony. No sulfur dioxide containment was described. The oxide fume from the furnace went to a heated caustic water leach, where the arsenic was preferentially dissolved and then precipitated with calcium chloride as calcium arsenate following solid-liquid separation. The antimony oxide was sold, and the solid oxide discharge from the rotary furnace was sent to a blast furnace where the antimony metal, containing the precious metals, was recovered. The metal was fumed to obtain antimony oxide, and the precious metals were left in the residue and collected with copper. The copper

Jan 1, 1994

By J. W. Craven, M. Katom, K. M. McCaffery

At Ok Tedi, ore type and SAG feed size distribution vary widely and frequently. This makes control of the SAG mills by application of the power/pressure relationship difficult. Power logic has traditionally been conservative due to power spikes associated with rapid size-distribution changes. A new expert system was installed in early 2000. The system incorporates multiple state fuzzy logic to deal with frequent and radical ore type and size variations, along with monitoring of motor temperatures. A short-term power spike no longer warrants immediate radical action. This has resulted in increased mill throughput and improved circuit stability. Key words: SAG mills, Mill control, Fuzzy logic

Jan 1, 2003

By Nellie E. Guernsey, Louis J. Sousa, Alfred Weiss, Nickolas J. Themelis

Over the past decade, numerous factors have led US copper firms to face increasingly severe competition from low cost foreign producers. As a result, greater attention is being devoted to developing and implementing new technology that can reduce costs and maintain the competitive position of domestic firms while simultaneously meeting environmental requirements. To obtain a better understanding of the likelihood of the development, adoption, and use of innovative copper technologies in the future, the Bureau of Mines contracted with Mineral Systems Inc. of Stamford, CT, to undertake a systematic survey of technological experts in industry, government, and the academic community. According to the survey, major developments in exploration over the next 25 years are likely to be in technologies that facilitate analysis and interpretation of deposit data rather than those that enable the collection of additional data. Most new copper mining and beneficiation technologies are likely to represent evolutionary extensions of existing systems with a notable increase expected in the application of information systems technologies and computer control methods. A possible movement towards increased usage of continuous mining systems in copper was also noted. Experts indicated that several copper smelters are under consideration for extensive renovation and, as a result, flash smelting technology is expected to become much more widely used in the US. A gradual movement toward continuous smelting methods was also forecast. In copper refining, the major technological change expected is the gradual automation of various refinery operations. Finally, though increased usage is expected, in situ solution mining and hydrometallurgical processing of sulfide ores are not expected to become widespread over the forecast time horizon. This first article in a two-part series describes the survey method chosen and the technological innovations selected for eval¬uation. Also discussed are the assessment panels, background scenarios, critical events, and diffusion forecasts. Next month, part two will address technology forecasts resulting from the study. Featured are discussions on future copper exploration, mining, beneficiation, smelting, refining, and recycling. A cost/benefit analysis will also be included. Methodology Selection of Assessment Method To develop a consensus forecast of technological change in the copper industry, a technique for systematically polling subjective opinions of experts was required. After conducting a literature survey and some preliminary testing, the direct probability assessment method was selected. With this assessment method experts are asked to express in quantitative terms their judgment of the probability that a specified event will occur, usually over a series of time frames. The method was chosen because the experts were observed to be more comfortable with this approach during the testing period, and the results of this process effectively satisfied the assessment objective. The experts generally could provide more precise estimates of the timing of future events using this technique because it was the least cumbersome of the assessment methods tested. Identification, Selection, and Description of the Technologies The initial list (Table 1) of innovative copper technologies assessed in the study was developed from two principal sources: knowledge and expertise of the study team and a review of relevant technical literature. From this list of 47 potential technologies, 10 were selected for detailed assessment. Table 2 lists 35 technologies that were subsequently identified in the first series of assessments. Twelve technologies from this list were also selected for detailed evaluation in a second assessment round. Criteria used for the final selection of technologies for detailed assessment specified that: • The expected impact of each technology on copper supply (i.e.,

Jan 9, 1983

By R. P. King, M. K. McCarter, K. S. Free

Mine plans typically consider the profits and costs associated with extracting and processing minerals into marketable products. Interrelationships between mine and mill costs are often overlooked during the process of mine plan optimization. A simple and quick method for predicting milling costs for a given block would improve the planning process, especially if the procedure could be incorporated as part of routine ore grade analysis of drill core or cuttings. Incorporating milling costs as part of the mine planning process could improve overall optimization of the mine/mill combination. A method developed by the Utah Comminution Center (UCC) at the University of Utah provides a possible answer to the need for quick and reliable grinding cost estimation (King et al., 1996). Using results from single-particle impact tests, a work index, called the Utah Load Cell Work Index (ULCWI), is calculated. The potential for routine use of the new method is explored by comparing ULCWI values with corresponding Bond Work Index (BWI) values for eight mineral materials (Free, 2000).

Jan 1, 2004

By S. G. Malghan, V. K. Pujari

Detailed characterization of all the powder constituents during powder processing is necessary for the reproducible manufacture of ceramic components that will perform reliably in intended applications. In this paper, selected physical and surface chemical techniques for characterization of silicon nitride powder are evaluated. The characterization data are discussed in the context of how these data, through their influence on powder processing unit operations, can affect the final microstructure. In the forming of ceramics, some of the major variables of injection molding are evaluated. Accurate measurement and control of these variables is emphasized for manufacture of Si3N4 ceramics with a high degree of reliability.

Jan 1, 1990

By Robert J. Wise, Mark Alspaugh

Underground longwall coal mines depend on conveyor haulage to transport large volumes of coal from the longwall face conveyor to the mine portal. In the last few years, the need for longer and larger longwall panel conveyors has become very significant. In order to keep conveyor equipment to a minimum and still transport higher tonnages over longer lengths, intermediate drive technology has been developed. The use of DC motors and controls in conjunction with load sharing techniques have a1 so proven effective. A case study of a new longwall panel conveyor at Utah Fuel's Skyline Mine incorporating these design techniques will be presented.

Jan 1, 1993

By F. H. Mertens

The concentrators of Gecamines are fed by a great variety of ores and produce different types of oxide and sulfide concentrates. It is therefore important to translate the performances of each circuit in terns of dollars in order to reach cost optimization in each mine to product line. A new system has been recently implemented for achieving this objective. Technical data and expenses are collected, allocated and analysed on mainframe applications. On the other hand, optimization and simulations are carried out on microcomputers which are linked with the mainframe files. Various kinds of auditing reports can be produced, including those leading to investments and cash-flow pattern which are

Jan 1, 1991

Engineering programs usually do not provide sufficient opportunities for students to develop written communication skills. The responsibility for developing those skills is frequently delegated to the humanities faculty, who in a single technical writing course are supposed to transform engineering students into proficient communicators. A general template which was developed for report writing in our senior level capstone design courses is discussed. Students have improved their writing skills by using the template. The writing assignments have provided the students the opportunity to write and revise more technical reports that communicate their design.

Jan 1, 1995

By Ronald L. Haxby

This report presents a refractive seismic technique for evaluating the strength of rock within an open pit bench. A concept of correlating rock strength and seismic velocity is discussed and a method of predicting the degree of fragmentation of a pit bench is introduced, Figure 1 shows the area of interests [ ] Most of the work was performed while completing graduate studies at the University of Arizona.

Jan 1, 1967

By J. H. Fewings

The rapidly escalating capital costs for new projects, or extension of existing projects, has placed greater emphasis on maximum use of existing resources. Thus, when increased grinding capacity was required to achieve metal production from lead-zinc ores a number of alternate approaches were studied. The most cost effective way of achieving the required 5% increase in grinding circuit capacity was to install upgraded instrumentation and computer control of grinding - Fewings, Wickham and Wiseman (1). Once the computer installation cost had been borne by the financial returns from that project, other projects involving computer control were economically viable on an Incremental cost basis. These Included centralised control of tailings thickening and return circuit water distribution, centralised control of the crushing plant and use of the computer as a data processor for an on-stream analysis system for flotation slurries.

Jan 1, 1979