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By J. P. Jarrell

Environmental considerations are of increasing importance in determining the acceptability, schedule and cost of expansion ofCanada's uranium processing industry. Environmental considerations must be addressed in the early stages of facility planning. This results in a dilemma, as the process data needed to predict physical environmental impacts are not yet available from process design activities. Hence, a business risk is incurred if plant design is carried forward to meet these requirements prior to project (or site) approval. On the other hand, project scheduling normally mitigates against leaving process design engineering until such time as project approval is obtained. This paper examines the experience gained in Eldorado Nuclear's proposed expansion of refining capacity as viewed by an environmental engineering consultant. The history of the project and the relationship to process design functions in the two-year period prior to the Port Granby environmental hearings are reviewed. During the Port Granby public hearing, there was a consensus that normal operation of the proposed refinery could be successfully integrated with the site's natural environmental constraints. Moreover, the radiological impact from plant operations was demonstrated to be inconsequential. However, concerns were raised relating to plant upset and accident situations. These concerns are summarized. Process data requirements identified during the environmental hearings are discussed. Finally, the concerns for on-site burial of radioactive waste are reviewed. These concerns focussed on long-term stability of the waste in the presence ofgroundwater transport, erosion and glaciers. The AECB's position on waste management with regard to this project is reviewed in light ofthe implications for design.

Jan 1, 1979

By R. N. Murarka

"Hydrocyclone modelling and selection procedure is illustrated. Computerized procedure for hydrocyclone cut size determination for grinding and non-grinding applications is described.A standard procedure for evaluating operating hydrocyclones is described in detail. Many case studies are illustrated comparing actual plant performance with the computer simulation output in terms of overflow product size distributions.INTRODUCTION Cyclones are widely used for applications such as: close circuit grinding, backfill, tailings and dewatering. Normally, cyclones are used for very fine separations where screens are not suitable or too expensive. Figure 1 shows the separation size range of various classifying devices. Cyclones are popular because of their low capital and operating cost. Cyclone selection procedure for different applications depends on the amount of information available on the cyclone feed slurry characteristics. Closed circuit grinding applications will be discussed in detail in this paper. The Cut Size:The size of the material in the feed which reports 50% to each product stream (i.e. underflow and overflow), after correcting for the feed solids by-passing with the underflow liquid, is termed the cut size or ""d50c"". This is often used as the criterion and the basis for cyclone design.When the corrected recovery to underflow of each mesh size in the feed is plotted against the geometric mean size in microns on a log scale, the micron size corresponding to 50% recovery is the d50c size."

Jan 1, 1992

By J. Nesset, F. Rosenblum, P. Spira

"Sulphide concentrates may exhibit self-heating to various degrees during storage or shipping, the worst cases presenting a serious hazard from fire and SO2 emission. Based on measurements of heating rates on a wide variety of concentrate samples in a special apparatus, combined with field experience, a methodology has been developed which allows concentrates to be rated for their heating potential. This has proven to be very useful in practice, for example, in deciding on the need to take preventive measures. Oxidation under ambient conditions in the presence of moisture initiates heating locally within a stockpile. In the case of highly active materials, such as those that contain abundant pyrrhotite, heating may progress through three stages to temperatures well above 5000C. However, most concentrates show little or no propensity to selfheat. Heating rates were used to estimate values of the heat output, or self-heating capacity (in joules per gram), which sustains the process at each stage. Thermal data from differential scanning calorimetry are also reported. Variables which affect self-heating are discussed and an actual case of heating control on a stockpile by covering is described. A simple apparatus which can be used to simulate stockpiling conditions has been tested successfully and is proposed as a convenient test system.INTRODUCTIONPrevious publications from this laboratory on the evaluation of self-heating in sulphides dealt with tailings backfill (Rosenblum et al. 1982) and waste rock (Rosenblum and Spira 1995). Sulphide concentrates may likewise exhibit self-heating in storage or during shipping. In a comprehensive but dated review, Kirshenbaum (1 968) pointed out the conflicting nature of information on means of controlling the problem, particularly with regard to the application of water and ventilation. Modelling by Simpson (1 97 1) of autogenous heating in stockpiled zinclead concentrate and associated field measurements by Wright et al. (1972) showed that the supply of oxygen by wind and the shape of the piles were the major factors in the development of hot spots. Simpson did not attempt to explain the complex mechanism of self-heating, simply ascribing its onset to oxidation. Pearse (1 980) investigated a potential method of testing for selfheating which consisted of (i) reaction with hydrogen peroxide and (ii) differential thermal anal sis, to characterize the response of concentrates at both ambient and temperatures above 100 C. He found the method sensitive enough to identify the need for careful handling but not to predict ignition. He recommended compacting concentrates and covering stockpiles with plastic sheeting to prevent ingress of air. All these workers recognized the key role played by oxygen and moisture in triggering self-heating."

Jan 1, 2001

By A. F. Banks

"Potash processing in Canada commenced on a commercial scale in 1962. Over the last 25 years it has grown into a world-class industry with many advances in processing technology. As it is a relatively young industry, many more advances can be expected. Unlike much of the mineral production in Canada, potash is sold as a range of finished products. The processing involves potash recovery and finishing in about equal amounts in terms of the effort of processing. Environmental concerns are not insignificant and are being treated uniquely in some areas. Research and development efforts, while not carried out on a large scale, are attacking industry problems on a wide front.THE INDUSTRYThe Canadian potash industry has 12 producing mines, 10 in Saskatchewan and 2 in New Brunswick. The total productive capacity of the industry is 18,300,000 tonnes of products per year. At capacity, the industry 1•ill process the equivalent of about 53,000,000 tonnes of ore per year. Plants range in size from 8,000 tonnes to 24,000 tonnes of feed per operating day. In product terms this is from 2,500 to 3,500 tonnes of products per day.Of the 12 mines, 11 are conventional underground mining operations with potash recovery principally by flotation supplemented by crystallization and one is a solution mine where mining is achieved by dissolving the potash and salt in underground caverns and then treating the solution in an evaporator/ crystallizer circuit. In all plants there is commonality of unit operation in the product screening and compaction sections. There are three principal ores being treated in the conventional plants. These may be characterized in general terms as follows:"

Jan 1, 1987

By P. Marcotte, G. LeBlanc, S. Ouellette, J. Boutin

"To characterize noise and vibration sources of different types of mining equipment used in underground mining, the authors performed a study in eight Quebec mines on 28 pieces of equipment. This paper presents the procedure followed to select the equipment to be evaluated, and the low-cost acquisition system developed to perform multichannel time-domain data acquisition in harsh environments. It also presents the results obtained for the noise level produced by the equipment and for handarm and whole-body vibration exposures.RÉSUMÉ Dans le but de caractériser les sources de bruits et de vibrations de divers équipements miniers utilisés sous terre, les auteurs ont étudié 28 équipements dans huit mines du Québec. L’article présente la procédure suivie pour choisir les équipements à évaluer ainsi qu’un système multicanal à faible coût développé pour acquérir des données dans des environnements difficiles. Il présente aussi les résultats obtenus pour les niveaux de bruit produit par les équipements et pour les expositions main-bras et du corps entier aux vibrations."

Jan 1, 2015

"Geoscan is used for multi-elemental analysis of conveyed bulk materials in the minerals industry with proven performance and demonstrated paybacks of weeks or months in iron ore, manganese, copper, zinc-lead and phosphate industries. Geoscan-M measures continuously through the full bed depth and is unaffected by belt speed, particle size, layering, mineralogy and dust levels. Increments of typically two minutes are accurately measured and provide the plant operators with tonnage weighted results of contained elements. Measurement of the composition in real time enables prompt feedback to the mining operators and also feed forward to the process operators. Crushed ore increments can be diverted based on composition, such as diverting waste for disposal or marginal material to a stockpile for separate processing. Bulk sorting allows material to be placed into relevant stockpiles for subsequent blending to achieve consistency for process feed. Parameters used for decisions may be primary metal content, deleterious component content, other process parameter, or a combination of these. Process parameter may be the elemental ratio between critical components, e.g. Cu:S ratio, basicity, or the content of an “indicator” element (such as Si indicating material hardness). Benefits will be discussed based on case studies in copper and iron ore.IntroductionAs operators of process plants strive to remain competitive as capital and operating costs increase and commodity prices fluctuate, more focus has been directed at incremental performance improvements at incremental cost rather than major expansions to increase output. The philosophy of working smarter allows plants to adopt technologies proven in other industry sectors to minimise risk. This paper discusses one such technology that the minerals sector is adopting and has found to be safe, reliable and accurate with paybacks of weeks in most applications. New applications continue to be found and major benefits realised at various stages in the processing and handling of ores and products."

Jan 1, 2016

By Caroline B. Chapleau, Mélanie Proulx, Claude Bazin, Gaétan Lavoie

"Quebec Cartier Mining operates a pelletizing plant in Port-Cartier, QC. Grinding, agglomeration and pellets induration are the three main steps in the preparation of iron oxide pellets. In 1998, following different recommendations, the company increased the speed of one of its ball mill in order to increase the grinding efficiency of the machine. As expected, the increased speed lead to an increase of the power draught, which did not produce the expected increase of fineness of grind, neither its allows to increase the mill throughput. The change of behaviour of the mill could hardly be understood by comparison of discharge size distribution at initial and modified mill rotation speed. On the other hand, the use of the selection function from a population balance model provides an insight of the changes that occurred in the mill. This paper reviews the various steps required for the estimation of a grinding mill selection function. Results of the calibration to Quebec Cartier grinding mills show that the increase in the mill speed leads to higher rate of breakage of coarse particles, at the expenses of less efficient breakage of medium and fine size particles. In the case of the studied mill, breakage of coarse particles was probably not the critical step of the mill operation. INTRODUCTIONOre size reduction is the major energy consumption step in any mineral processing operations (Austin et al., 1984). Size reduction is required to either liberate valuable minerals from the gangue minerals in which they are imbedded, or to increase the specific surface of the ground material. Plant engineers continuously face the challenge to find grinding machines, operating conditions or grinding circuit flowsheet configurations that could improve the size reduction process at lower energy or m6dia consumption."

Jan 1, 2000

By Charles Taschereau

The statements made in this presentation contain certain forward-looking statements concerning potential developments affecting the business, prospects, financial condition and other aspects of Canada Lithium Corp. The actual results of the specific items described in this presentation, and the company?s operations generally, may differ materially from what is projected in such forward-looking statements. Although such statements are based upon the best judgments of Canada Lithium Corp. management as of the date of this presentation, significant deviations in magnitude, timing and other factors may result from business risks and uncertainties including, without limitation, the Company?s dependence on third parties, general market and economic conditions, technical factors, the availability of outside capital, receipt of revenues and other factors, many of which are beyond the control of the Company. Canada Lithium Corp. disclaims any obligation to update information contained in any forward-looking statement. Toronto Stock Exchange: CLQToronto CLQOTCQX: CLQMFOTCQX: CLQMF

May 1, 2011

By J. E. Sepulveda, R. Morrow

"The Linear Wear Theory provides a reliable framework for the assessment of grinding media performance at full scale. This theory can be applied for analyzing grinding media consumption rates in any given grinding operation as well as the evaluation of alternative grinding media products, based on actual operational data, correcting for conditions like ore hardness, feed and product sizes, mill power and circuit throughput; all of them unrelated to the grinding media intrinsic quality attributes. A series of Moly-Cop Tools 3.0 applications have been developed to facilitate the calculations involved. Moly-Cop Tools 3.0 is available, free of charge, to all interested parties through the corresponding author.INTRODUCTION Mineral grinding circuit operators recognize the significance of grinding media (balls) consumption on the cost structure of any full scale grinding facility. The effective cost associated with this essential consumable depends on two factors: delivered price and durability (quality) of the grinding media. When evaluating alternative grinding media varieties, there is a well accepted evaluation criterion by which a given media type is considered to be “cost-effective” when its unit application cost – normally expressed in $/ton of ore ground – is shown to be lower than that of a nominal reference condition: Grinding Media Cost = Ball Price x Ball Consumption (1) ($ /ton ground) ($/ton balls) (ton balls/ton ground) Under this criterion, an alternative, higher-price grinding media product could be “cost-effective” if its associated consumption rate is sufficiently lower than the reference media, enough to yield a lower grinding cost, as dictated by Equation 1. For the proper application of the above criterion, evaluators must rely on representative indicators of grinding media quality, ideally independent of most mill operating conditions. In each particular case, ball price is always a known component; however, it is not so evident how media performance (quality) differences amongst alternative product types could be assessed with a reasonable degree of accuracy and precision."

Jan 1, 2014

By P. R. Richardson

"Milling is the weak link in the process chain of many mineral operations. While this activity accounts for only a relatively small proportion of the direct costs of most mineral processing complexes, there are intangible and indirect costs associated with milling which are extremely large. For example, significant opportunity costs are associated with the relatively low yields which characterize this stage of the process.There are changes abroad in the world which I believe are going to cause us to reformulate the whole concept of milling. Increased competition in mineral markets are going to force managers to look anew at the high mineral values reporting to tailings which are a high opportunity cost for many operations. Tailings recovery plants are not the ultimate solution to this problem. Greater environmental concerns are going to increase the costs associated with tailings disposal and force the mining industry to look for other ways to dispose of waste products. Technology changes currently underway in manufacturing and other process industries, such as the automated 'lights-out' plant are going to be brought into this industry, and the changes will be dramatic.These are major long term changes which probably seem rather remote to many managers and professionals in existing operations which are faced with much more mundane challenges arising from day-to-day operations. However, I believe that milling is increasingly a 'lean and keen' operation involving fewer and fewer people, but who are increasingly skilled and professional. Traditional cost management approaches are no longer adequate and the industry has to take a new look at the nature of cost reduction in this core activity. This stage in the mineral process provides opportunities for value creation leading to a significant unit cost advantage for the corporations willing to adopt a total cost approach."

Jan 1, 1988

By M. Kalin

"SUMMARYWaste management in general, and the water treatment of mine and mill effluents, has become an ever increasing burden for mining operations. A reduction in these expenditures would undoubtedly be desirable if this could in fact be achieved within effluent guidelines and monitoring requirements.A brief summary is presented of the research which has as its aim the development of methods which would reduce such costs and lead to solutions for environmentally acceptable close-out conditions for acid generating mine waters. The basic concepts of Ecological Engineering and Biological Polishing are presented, together with an indication of the present state of these research efforts. Details are provided of the progress of various experiments which aim to promote reducing conditions, organic matter production and the establishment of biological filters which remove metals from the water which are then retained within the waste management areas. These conditions should lead to a curtailment of acid drainage and an improvement in effluent quality.A description is provided of the first pilot demonstration using this approach to achieve a walk-away condition for the close-out of a massive sulphide tailings resulting from 10 years of operating a copper/zinc concentrator in Northern Ontario.1.0 INTRODUCTION1.1 Waste management and close-outIt is recognized that the achievement of a cost-effective and competitive mining operation, from the commencement of exploration for ore bodies through to the day-to-day efficient operation of the mine, requires a certain expertise and sophistication. However, the environmental effects of these activities are considered peripheral issues and their importance as an integral part of the planning and development of the mine/mill, is not always appreciated."

Jan 1, 1988

By Dave Bulled

"This paper describes the design of an SABC grinding circuit using CEET technology applied to grindability data produced from testing 100 samples and distributed across the blocks of a mine plan using a geostatistical approach. The data distribution required the identification of the location of the sample points and a geological plan of the 130 million ton Ruby Creek orebody together with a mine plan of about 11000 blocks to be mined during the proposed 18 year life of the mine. The mill design was then made with consideration for the estimated hardness of each block in terms of both SAG and Ball milling with allowance for annual periods when the ore is harder to grind. Operating specifications were selected to achieve an optimum of capital and operating costs through use of the CEET program. The geostatistics assigned the statistical error that arises from having a limited amount of sample testing data to the hardness estimate of each block of ore in the mine plan. The final design could then include a quantification of risk and determination of safety factors based on the accuracy of block hardness estimates and CEET model fitting.INTRODUCTIONThe traditional approach to plant design involves the extensive testing of a single large composite sample or a small number of composite samples that are reputed to represent the ore body. It is accepted that the tests used can accurately measure in the laboratory the grindability of the sample by a process representing that to be used in the plant. The size of equipment required to achieve a specified throughput and product size is then calculated from one of a variety of models that have been developed by metallurgists over years of trial and error. Since these tests and models are tried and tested, they are accepted as reasonably precise; however during the operation of the resulting plant the design is sometimes found to be inadequate. It is then suspected that the flaw in the design process lies in the samples not being sufficiently representative of the ore body, since using only a single or small number of composite samples does not recognize the variability of the hardness of the ore, nor does it allow for the lack of precision in the hardness value used in the design.This paper outlines a design procedure suited to an orebody that is described by a geostatistical analysis of a reasonably large number of small samples of drill core. The analysis required the identification of the location of the sample points and a geological plan of the orebody, together with a mine plan of the blocks to be mined during the proposed life of the mine. The mill design was then made using the estimated hardness of each individual block with an allowance for annual fluctuations in the grindability of the ore. The geostatistical analysis assigned a statistical error to the hardness estimates of blocks and of each production year such that the final design included risk estimates and safety factors based on the possible errors that arise from having a limited amount of sample data (Kosick et al. 2002)."

Jan 1, 2007

By Hannu J. Häkkinen

Metal clusters exhibit unique size-dependent physical and chemical properties that differ from those of bulk materials or large particles. Here we discuss recent theoretical investigations of the catalytic properties of free and MgO-supported gold clusters. The catalytic activity of gold clusters depends sensitively on the environment, charge state, and chemical composition of the catalyst. Relativistic bonding effects stabilize large planar structures for gas-phase gold clusters, and non-compact ?quasiplanar? structures are present as important isomers also for surface-supported clusters. The hybridization of the atomic 5d and 6s states is significantly enhanced by the relativistic effects, and large spatial variations in the nature of the local electronic structure make the low-coordinated gold atoms preferable adsorption sites for oxygen molecules. The adsorbed oxygen molecules are activated to superoxo- and peroxo-states via charge-transfer from gold, and Eley-Rideal and Langmuir-Hinshelwood reactions with CO proceed via low-barrier formation of intermediates, which do not require O-O dissociation as precursors. This facilitates the low-temperature (below 300 K) activity of gold nanocatalysts in CO oxidation. Other gold nanostructures, such as mono-atomic gold nanowires, may also become important prototype systems in chemical sensing and nanocatalysis; here we show that they are active promoters of hydrogen dissociation.

Oct 1, 2003

By D. F. Cooper, J. G. Paterson, K. H. Pang

"Effective control of metallurgy by manual adjustment of cell levels is common flotation practice. With an on-stream XRF analyzer interfaced to a process control computer it is possible to program the computer to carry out this function automatically. This paper describes the development and implementation of closed loop control of the concentrate and tailing grades at the Clarabelle Mill of the International Nickel Company of Canada, Limited, The XRF analyzer was used as the sensor, cell level as the control and the computer as the controller.IntroductionThe International Nickel Company of Canada, Limited recently brought on-stream Clarabelle Mill having a rated capacity of 35,000 tons per day. The plant was required to increase milling capacity in the Sudbury area by 9,000 tons per day and to improve milling efficiencies by replacing the obsolete crushing and grinding equipment at the Copper Cliff Mill. This represents the fourth mill built since 1959 and incorporates the latest thinking in a continuing evolution of instrumentation and control concepts. Table 1 illustrates control progress at Inco since 1959.In 1967 Frood-Stobie Mill came on-stream incorporating a central control room, an on-stream analyzer, a data gathering computer, and a significant change in instrumentation from direct-contacted pneumatic to miniature electronic. The computer successfully controls the analyzer but has very limited process control capability. Based on this experience a process control computer system was installed at Clarabelle Mill with the objective of carrying out extensive supervisory control and a limited amount of direct digital control."

Jan 1, 1973

By F. Hassani

This Paper describes a sudden spill of rock waste used for backfilling from a waste pass at one of the underground mine in Canada thus causing a major failure/accident. The mine operator immediately launched a detailed investigation to understand the causes of this accident and develop procedures to prevent any recurrence of such events in future. The investigators from McGill University were invited to collaborate with the engineers at the mine to examine this accident. The events leading to the accident were studied and appropriate measurements were taken and samples of the waste material was collected for further test and analysis. The field visit and the interview of the witnesses allowed a detail documentation of the events. The sequences of events related to the incident together with the experimental results obtained in the course of the investigation is detailed. The waste material was characterised in the laboratory with regard to its behaviour in the presence of water. This information is then discussed and the failure mechanism involved in this accident is identified. The full recommendation as well as the immediate operational measures implemented by the mine to prevent future occurrence of such events are discussed and presented.

May 1, 2003

By J. Davis, M. G. Reading

"INTRODUCTIONInternational Minerals and Chemical Corporation (Canada) Limited operates two potash mine/refinery complexes near Esterhazy, Saskatchewan. Annual production of approximately 4.2 million tons is sold in the United States and overseas in five grades according to size and quality.Ore grading 25% K2 0 equivalent is mined from a horizontal bed by continuous boring machines, crushed, and hoisted at 8 inches. The refinery operation consists of the eight basic steps shown in Figure 1. Particle sizes handled are similar to those experienced in other forms of mineral beneficiation: 8 inches to 100 mesh. The ore is crystalline and particles are angular. Fortunately the major mineral constituents, sylvite (KCl) and halite (NaCl), demonstrate relatively low hardness at 2 to 2.5.Therefore, while simple abrasion must be acknowledged, it is not a major problem except, of course, in circuits carrying magnetite.Corrosion, as represented by the classic equations of Figure 2, occurs in all its various forms."

Jan 1, 1983

By E. W. Johnson

"The title of my paper is ""I 'Wonder Where The Yellow Went"". As you can readily guess, it is not related to an old-fashioned ""Pepsodent"" sales pitch! Rather, it concerns a situation which arises all too frequently in some gold milling operations, namely when actual ounces of gold production do not come up to estimated or projected ounces. The boss man scratches his head and wonders where the missing gold has gone and how it has disappeared. The problem, if one exists, is amplified if one forgets that an estimate is just that - an estimate - and not a hard fact - even though the numbers are produced by computers. And yet, from the point of view of engineering; financial and production planning and security; it is most desirable to tie together all data relating to production estimates, losses and actual production.In the course of this paper reference will be made to the term ""variance psychology"", to a few of the physical properties of gold and to the nature of its occurrence in Canadian ores, in relation to the topic under consideration. Activities which have a bearing on production estimates will be reviewed. These include: weighing, sampling, assaying, estimating residual losses and, in cyanide plants, gold precipitate production. Mention will be made of apparent, unaccounted for and unknown losses. In conclusion, I shall draw from personal experience and relate three examples of ""Where the Yellow Went''."

Jan 1, 1986

By M. Lahtinen, P. Latostenmaa, I. Kojo, E. Peuraniemi, M. Lindgren, S. Jyrkönen, M. Jåfs

The year 2019 marks the 70th anniversary of Flash Smelting. The technology was operated on industrial scale for the first time at the Outokumpu Harjavalta copper smelter in Finland in 1949. Since then Flash Smelting technology, now owned and developed by Outotec Oyj and the first plant, now owned by Boliden Harjavalta Oy, have been evolving throughout history by optimizing the process for various feeds and raw-materials, as well as through developing the equipment and operating practices. Even though sustainability was not a popular theme during the first days of Flash Smelting, it has still been the key principle in guiding the development. This is well proven by the wide adoption of Flash Smelting for the processing of copper and nickel concentrates, mostly due to its ability to fulfil the economic and resource efficiency criteria demanded by its operators. This paper describes the history and improvements of the Outotec® Flash Smelting process by looking into the early days of operation and how the development of the process and equipment has taken place over time as a joint effort between the technology provider and the users of the technology. INTRODUCTION In the 1940s, Outokumpu Oy refined the concentrate produced in the Outokumpu mine into metallic copper initially in Imatra, and later from 1945 to 1949 in Harjavalta, based on the most modern electrical melting process of the world at that time. After the war, Finland lost a significant part of its hydropower production, and due to the increasing use of electricity, the availability of electricity weakened, and the price rose. To maintain Outokumpu's profitability, it was forced to look for a melting solution that was not based on electricity.

Jan 1, 2019

By P. Scinto, A. Festa

"Orway Mineral Consultants Ltd (OMC) as a consultancy has specialized in comminution circuit design for over 30 years. The OMC Power Model is OMC’s in-house software for specific grinding energy power-based circuit calculations. The model uses ore hardness parameters from testwork, circuit configuration, equipment geometry and operating conditions as inputs. The model combines proprietary and published power models to predict the total specific energy and the specific energy for each of the components of the comminution circuit. This makes the software a valuable tool for the design and validation of JKSimMet modelling or actual plant performance. Proprietary calculations have been developed and reconciled with over 100 plant benchmark projects encompassing a variety of comminution circuit configurations.This paper describes the OMC approach for determining power requirements for the design of grinding circuits. The accuracy of the OMC Power Model software is confirmed through plant survey benchmark performance and comparisons are made with other power modelling techniques. Practical examples are presented, showing applications for single stage SAG (SS-SAG), SAB and SABC circuit configurations.IntroductionConventional low throughput grinding options, consisting of multi-stage crushing followed by rod and ball mills, have almost become obsolete in the move to higher milling rates required to process lower metal grades. Grinding circuits with fully autogenous (AG) or semi-autogenous (SAG) mills, often combined with ball mills are now the standard to meet the high capacity requirement for processing ores with lower metal grades. Simulation software and power-based equation methodologies have been established for designing AG/SAG based grinding circuits and predicting their energy requirements.Presently, power-based equations remain the principal method for designers to size mills and estimate the power requirement for comminution circuits. The technique is simple and it relies on the design to specify a feed and product size plus a hardness index to produce a specific energy value (kWh/t). The desired throughput of the mill is multiplied by the specific energy to give the mill power requirement, which is used in turn to size a mill for dimensions, internal geometry and loading conditions to match the power draw."

Jan 1, 2015

By Larry A. Lien

"A brief summary of the different membrane separation options currently available to the mining industry will be presented and discussed. The processes described involve operating membrane plants on the following applications: pregnant leach solutions (PLS) in the copper and gold industries, fractionation and concentration of metals and acids in refineries, and wastewater treatments to meet state-of-the-art surface discharge criteria.Included is a specific discussion on cost savings resulting from an operating membrane treatment system of nearly 3,500 m3/hr barren water relative to the prior, conventional precipitation practice at a major heap leach gold mine. This Engineered Membrane Separation® (EMS®) plant has produced water for six years that has met all standards for direct discharge into the environment, and captures and returns to the operation valuable minerals and solvents which were not previously being extracted in the Merrill-Crowe process.INTRODUCTIONMembrane technology has been available for more than 35 years, but has been used sparingly in the mining industry. However, recent developments in polymer chemistry, spiral-wound element design and construction, water clarification pretreatment equipment and techniques, and an expanded understanding of membrane fouling and cleaning techniques have dramatically improved the reliability and robustness of membrane-based systems for potential use by the mining industry.In the past 15 years large operating plants have successfully demonstrated the use of this “new” membrane technology to include the separation of pay-metals from large-volume acid and cyanide heap leach mining solutions containing copper, zinc, gold and silver. Moreover, variations on these same membrane technologies are ideally suited to fractionations that add value to processing fluids from refineries, like separating metals from acids or concentrating acids and producing high-quality process fluids."

Jan 1, 2010