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By B. H. Kim

It is hypothesized that the standard approach adopted to characterize the ground and to determine the rock strength properties at depth are flawed and generally tend to underestimate the rock strength and possibly the stiffness, particularly when the rock mass is characterized as massive to moderately jointed or blocky to very blocky. It is therefore necessary to conclusively established that the hypothesis, that the rock strength in highly confined rocks is greater than generally anticipated, is actually valid and generally applicable, and then to develop new procedures to establish rock parameters that can be reliably used for the design of deep excavation.

May 1, 2009

Cobalt mostly occurs as a minor, but valuable, constituent in most nickel and a few copper ores, however it is not generally found alone in commercially viable deposits. Its concentration and extraction are therefore intimately linked to the recovery of the primary metals and the major task for the metallurgist is to extract cobalt of commercial grade from a much larger mass of either nickel or copper and sometimes both. With a particular focus on Vale Inco?s operations, this paper provides a brief overview of the mineralogy of the main deposits being currently exploited that contain cobalt as a co or by-product. The concentration and then extraction to metal are reviewed and some advances released into the public domain are discussed.

May 1, 2009

By L. Lui, A. Cauchon, A. R. Laplante

"The gravity circuit at Les Mines Camchib Inc. consists of two pinched sluices to bleed a feed to one of two 76 cm (30"") Knelson concentrator. The Knelson concentrate is upgraded to smeltable grade with a smaller Knelson (18/30 cm) and a riffleless table. Their tails are column cyanided and washed prior to recycle to the grinding circuit. This paper details size-by-size circuit performance. The Knelsons recover around 90% of free gold (as determined by Mozley Laboratory Separator), even below 37 µm. The sluices are ineffective, with upgrading ratios around 2, but approaching unity in the fine sizes. Much of the effectiveness of the circuit lies in the high gold circulating loads in the grinding circuit, which partly atone for the poor sluice performance, and the ability of the Knelsons to recover free gold. Secondary upgrading recovers slightly above 99% of the primary concentrate gold, 90% of it in a 65% Au concentrate and the balance in a heavily loaded (10 to 20 oz/st) pregnant solution. INTRODUCTIONBackgroundThe operating performance of the mill of Les Mines Camchib Inc. has been described earlier (Laplante et al., 1989). The presence of significant chalcopyrite (1 % and up) makes flotation necessary prior to cyanidation, to limit cyanide consumption and minimize environmental impact. In 1982, the presence of very high gold circulating loads in the grinding circuit lead to the commissioning of a gravity circuit, schematically shown in Figure 1. Gravity recovery of gold has been found beneficial because it increases metallurgical recovery by 1-3% (Laplante et al, 1987), as only part of the flotation tail is cyanided, and economic recovery, because of the lower net smelter return of gold in the flotation concentrate (as compared with the gravity concentrate). The latter increase is estimated, with a net smelter return of 95%, at 1.5% when gold recovery by gravity is equal to 30%. In early 1988, a sampling program was initiated to characterize the behaviour of gold in the grinding/gravity circuit. This paper reports on the results of this study."

Jan 1, 1990

By Richard Burt

"In seeking to supply the ever increasing needs for raw materials, the mining industry has been required to develop lower grade resources in increasingly remote regions of the world. This has resulted in the extension of many frontiers, both technologically and geographically.The accent of mineral processing research over the last few decades has been to “do existing things better”. There have been many breakthroughs in equipment and processes; however in general the accent has been to increase capacity of existing unit processes, often by orders of magnitude, or to refine the process itself by basic research and development. This has lead to added sophistication, enabling the process engineer to maintain optimum performance of his equipment while reducing the cost, and the amount of labour needed to operate the plant.While much of the increased requirement for resources is handled by the development of ever larger, lower grade orebodies, a significant portion still comes from the small miner - even the artisanal miner - operating in remote and often politically sensitive parts of the world. For them, innovation and simplicity are the keys, not sophistication.The tension between sophistication and simplicity - or research and reality - is specially evident in the area of gravity concentration of rare metals, such as tin and tantalum. This paper looks at this tension, primarily from the eyes of an operator and seeks to put into perspective the two paradigms."

Jan 1, 1999

By Peter Cunningham

General Description of Projects The objective is to streamline data transfer within our Process Control and Business Systems for the purposes of tracking actual production, reducing manual record keeping, improving process control and improving vehicle maintenance. This presentation focuses on two implementations of mobile equipment data acquisition systems which make use of industry standard data models and data transport protocols. Pilots are part of the Mines Technology Roadmap to improve our mining operations ?Enabling technologies and pilot of key systems

May 1, 2013

By Gilles Landry, Mohamed Ourriban, Pierre Pelletier, Ahmed Bouajila, Claude Gagnon

"This paper summarizes the work carried out to develop and implement the gold cyanidation by size class (CSC) process, a novel concept aiming to reduce cyanide consumption.First, the authors will present the methodology and results of laboratory tests conducted to evaluate the response and the expected gains for the selected ore when submitted to the CSC processing. In the second part, focus will be on the methodology behind the CSC scheme development prior to its implementation at Sleeping Giant Mine concentrator. Finally, the evaluation of the modified circuit performance (operating since July 2007) will be addressed as a reduction of cyanide consumption by more than 30% and of free NaCN in the tailings by more than 50% is confirmed.INTRODUCTIONCyanidation is the most widely used technique to extract gold from hard rock ore. Its use of oxygen as an oxidant still makes it the cheapest process available after more than a hundred years. Unfortunately, gold cyanidation is known to be a slow process that requires high consumption of cyanide. In fact, cyanidation plants are designed with very long residence times (Habashi, F., 1967). Drawbacks of long cyanidation times are, among others, loss of gold in tailings, high reagent consumption and high capital investment and maintenance costs.Responding to their members expectations for the improvement of cyanidation process, COREM undertook a challenging R&D program covering the development of alternative concepts (processes) and the understanding and solving of mass transfer, gold passivation and process water chemistry problems. One of the interesting findings of the R&D program is a patent pending process technology based on the cyanidation by size class (CSC) concept (Côté and Ourriban, 2004; Gagnon and Ourriban, 2007; Gagnon and Ourriban, 2004).The new technology was tested at the Sleeping Giant concentrator, a plant member of COREM. The existing flowsheet was modified in order to implement the CSC process in the full-scale plant. The plant has been operated using the modified CSC based process since August 2007. Laboratory testwork was conducted prior to the industrial application in order to properly design the new process scheme. The modifications included:1) Reclassification of the grinding circuit product through an hydrocyclone2) Leaching of the coarse size fraction3) Addition of the fine fraction to the coarse leaching circuit tails."

Jan 1, 2009

By W. J. González

"With the increasing demand for minerals, technologies to maximize mineral recovery are paramount to a mine’s economic success. Many mining process waters have the potential to form calcium-based inorganic scales, which inhibit effective mineral recovery. Often, the solution to inhibit these deposits is the implementation of a chemical antiscalant program. This paper examines the application of a fouling analyzer to continuously monitor the formation of inorganic scale in mining process streams. The fouling data can be used to compare antiscalant programs and to optimize antiscalant feedrates. Case studies validate the ability of this technology to help optimize mineral recovery processes.INTRODUCTION The mining industry uses significant quantities of water. From quarrying, to crushing, to flotation, leaching, and refining, water is often the integral motive force to move slurries, separate or agglomerate fines, and extract and purify minerals. As well, water is used in a number of ancillary applications at mines, including dust suppression, gas scrubbing, and utility processes such as boiler, cooling, and waste water operations. For many processes, the quality of water being used is inconsequential. However, for certain processes, such as flotation, leaching, and desorption / stripping, water quality plays a key role in the ability of the operation to economically recover the target minerals. Dissolved solids such as calcium and magnesium salts can concentrate in process waters, exceed their solubility limits, and precipitate as scale on metal surfaces such as feed and transfer pumps, piping, and equipment. Some of the more common scales that form in mining operations include calcium carbonate (CaCO3, or calcite) and calcium sulfate (CaSO4, or gypsum), and to a lesser extent, calcium and magnesium silicate compounds. Any scale that deposits in a process stream will negatively impact mineral recovery, and increase the operational costs of the mine site. Whether it is acid washing a scaled heat exchanger in a carbon strip at a gold operation, replacing plugged emitter tubes in a leaching operation, or hydroblasting process lines in a scrubber unit, there are costs associated with labor, cleaning chemicals, repairs, and replacement parts. These costs pale in comparison to the potential costs of downtime and lost production, should the scale deposits occur in a process that is critical to the recovery of the target mineral."

Jan 1, 2014

By Claude Bazin

"The On-Stream Analyzer has proven and is still proving to be an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the provided assays using a real-time material balance program to calculate the distribution of solids within the streams of a circuit. Mass balance results can be used for process control, process analysis and detection of sensors malfunction. Examples from 3 Canadian and one American concentrators are presented to illustrate the potential of the method.IntroductionThe On-Stream Analyzer (OSA) has gained, over the last two decades, the status of key instrument for the control of flotation plants. The OSA is currently used in almost every sulphide flotation plant and its application in oxide mineral flotation plants is increasing. On-Stream Analyzers provide X-rays pulse counts that are converted into assays using multilinear regression programs. The estimated assays are passed to the flotation operators, via an operator console, or to control loops of various degrees of complexity (McKee, 1991) implemented in a Distributed Control System (DCS). Operators and/or controllers take control actions based on these assays to ensure an adequate operation of the plant. Although this application pays off very rapidly for the purchase of the OSA, one should ask: Could we get more from the OSA?Some plants reported the use of OSA measurements to process optimization (McKee, 1991). The optimization strategy is based upon economic indices calculated from metal recovery using the 2 product formulae (Wills, 1992, page 124). The 2 product formulae is however sensitive to measurement errors in the assays and can lead to considerable scatter in the calculated indices (Hodouin et al., 1993). Least squares algorithms provide an interesting alternative to filter out measurement errors (Spring, 1992). This paper presents a recursive least squares algorithm that estimates in a real time fashion the mass flow rates in a flotation plant using OSA and mass flow measurements. The algorithm is robust and its recursive structure is not demanding in terms of computation time and memory. The method was tested with data from four concentrators. Results of the material balance algorithm prove to be useful to detect sensors malfunction and may potentially be used for the control and optimization of flotation plants.The paper is divided into two sections. The first section gives a description of the proposed method. The mathematics of the method are kept to a minimum, since the detail is presented elsewhere (Bazin and Franklin, 1994). The second section shows the application of the method to different flotation plants."

Jan 1, 1995

By Cardm Jeffrey W.

The decay of 222 Rn yields a series of short-lived decay products which become attached to the surface of a plate or wire exposed in a 222Rn-bearing atmosphere. The alpha-activity of two of the decay products, 218Po and 214Po, can be measured by simple counting techniques. This phenomenon may have direct application to uranium exploration. Laboratory studies have shown that: (a) radon decay products can be collected on a wide variety of materials (including various kinds of metals and plastics); (b) activity increases as a function of the surface area of the 'collector; and (c) the collection of the decay products is enhanced by applying a negative charge. The new technique was used in situ to delineate the anomaly above the South March uranium-copper occurrence. A related technique was developed to measure radium in soil samples. The results of both studies compared favourably with those obtained from conventional methods.

Jan 1, 1979

By L. Boyd, A. Charland, G. Potts, D. Fragomeni, N. O. Lotter

"The Raglan orebody and concentrator has been the subject of study in Process Mineralogy at Falconbridge since 1998. (Lotter and Tuzun, 1998) The orebody is classified into three distinct textural groups, or end members. These are referred to as disseminated, net-textured, and Massive Sulphides, and differ in terms of mineral grain size, nickel grade, hardness, and mineral association. In this paper, it will be shown that the sampling and characterisation of each end member on an individual basis develops a higher-level understanding of the processing requirements and behaviour of the mixture of ore as presented to the mill.The end members have been used in robust prediction of recovery at various grind size p80 from laboratory scale High Confidence Flotation Tests. Weighted mean mixtures of the end members have been mathematically combined to determine impact of textural distribution on metallurgical performance as a function of grind size.The ore end members also vary in hardness and breakage mechanism and have been used to model throughput capability for existing, optimized and retrofit grinding circuits. This modeling has provided a range of expected throughputs as the relative proportions of each end member varies.Finally, the differing grinding requirement per end member has led to the development of grinding and flotation strategy that increases rougher flotation recovery and provides flowsheet options for a concentrator expansion. This leads to further understanding of the plant performance as a function of ore mixture."

Jan 1, 2005

By A. Taylor, M. Blanchette, J. Doucet

"A Z1600 Jameson Cell Test Rig was rented for test work at Vale’s Clarabelle Mill operation. This paper discusses the evolution of renting the unit for test purposes to owning the unit and operating it as a revenue generating process component. The paper focuses on three aspects of the Z1600 project; the initial rental and installation, the test work performed in the cleaning circuit, and the business factors which led to the unit being permanently incorporated into the copper circuit.INTRODUCTION Clarabelle Mill is located in Sudbury Ontario (approximately 350 km north of Toronto) on the southwest rim of the Sudbury basin a meteoric impact crater that is 62 km long and 30 km wide. The result of the meteoric impact was concentrated nickel (Ni), copper (Cu) and platinum group metal (PGM) ore bodies in the outer perimeter of the basin; described in more detail by Hanley (1957). Vale currently has seven operating mines in the Sudbury basin, from which nine distinct ore types are mined. Ores are also received from two QuadraFNX mines. Clarabelle Mill processes all of these ores for the Ontario Operations of Vale. The mill, commissioned in 1971, was originally built as one of four mills operated by then Inco Limited. Between the late 70’s and the early 90’s process changes were made to consolidate the Sudbury Operations milling processes into a single operating mill, Clarabelle Mill. In 1990, the SAG mill was installed resulting in peak mill throughput of 11.9 million short tons per annum (Mstpa), with typical throughputs of ~10 Mstpa. Mill average feed grades were 1.4% Cu and 1.2% Ni. During the resources boom, plans were developed to increase the mill capacity at Clarabelle Mill in stages to a final capacity of 13.5 Mstpa. The project known as the Clarabelle Mill Expansion and Recovery Project (CMERP) included expansion and reconfiguration of the grinding and flotation circuits. The first stage was a planned increase in grinding capacity with the reallocation of existing mills, the existing flotation capacity would be required to treat higher throughput until the new flotation circuit was constructed."

Jan 1, 2012

By M. N. Brodie

"The ability to adjust the speed of a SAG mill offers benefits to the process and to equipment maintenance. It can be provided with some slight effect on availability ranging from somewhat enhanced to somewhat reduced, depending on the particular equipment that is used. Several techniques have been developed for monitoring the magnitude of the contained charge, and several algorithms have been used to control mill feed rate and mill speed. The various benefits and the means by which they can be realized are examined and compared. Reasons for Variable SpeedProcess RequirementsThe recovery of minerals from ore is dependent on particle size and residence time in process. Separation in a given plant is most efficient at a particular rate and a particular size (e.g., 80% minus 200 mesh). If the particle size increases, less mineral will be liberated. If the particle size is significantly reduced, the process of choice may not be able to effect separation, and power, media, and maintenance costs would be increased.If a SAG mill-ball mill combination delivers the desired throughput at the correct size for efficient separation when processing ore of the design hardness, some adjustment must be made to maintain this condition when the ore changes. The processing of ore softer than design will result in overgrinding, unless:• the throughput is increased inversely to the change in hardness which lowers recovery by overloading the separation facilities;• or the SAG mill feed rate remains constant, but the speed is reduced to feed coarser material to the ball mill for finish grinding to the desired size.There is also the effect of changing milldiameter to consider. A nominal 36 ft diameter SAG mill will have an effective diameter of 35 ft with new liners and 35 ft 6 in. with worn liners. A mill designed to operate at 0.76 p.u. (per unit) of critical speed with new liners (9.84 rpm) will be changed to 0.765 p.u. with worn liners. If 0.76 p.u. is the desired value, the mill speed should be reduced to 9.77 rpm."

Jan 1, 2003

By H. C. Counsell, R. Webber

"The mill at Denison Mines' Elliot Lake Operations started up in 1957, with a capacity of 6,000 tons per day. Over the years various plant modifications expanded th.is to 7 500 tons per day. In 1976, management decided to carry out a major expansion of the milling capacity, and during 1980 the grinding capacity was increased to 15,000 tons per day.The original comminution system consisted of a conventional crushing plant feeding minus S/s-inch material to rod and pebble mills, in closed circuit with mechanical classifiers. The key decision that had to be made was whether the expansion should include conventional or autogenous grinding flow sheets.During 1977, extensive pilot plant studies at Lakefield Research showed that two-stage semi-autogenous grinding, with some steel media in the primary mill and with pebble media in the second stage, produced stable grinding conditions. This type of circuit was selected by Denison for the expansion, and went into production in 1980. Primary millThe flow sheet of the semi-autogenous grinding circuit is shown in Figure 1. The primary grinding mill is a Koppers 28 foot by 10 foot mill, driven by a 4,000 h.p. synchronous motor. It is fed with a minus 8-inch run-of-mine ore, and 4-inch grinding balls are added as supplementary grinding media. There are two Koppers 15.5 foot by 22 foot secondary pebble mills, driven with 1500 h.p. synchronous motors. Each grinding stage operates in closed circuit with cyclones, and the primary cyclone overflow is the feed to the secondary mills. The circulating load in the primary stage can be controlled by adjusting the cyclone apexes."

Jan 1, 1984

By W. R. Cowan

The availability of mineral aggregates for construction purposes is rapidly declining through inadequate resource planning. restrictive zoning and legislation , and competing land uses. The Geological Branch of the Ontario Ministry of Natural Resources has undertaken to provide aggregate inventory reports for all townships designated under The Pits and Quarries Control Act, 1971, and eventually for all towns hips in heavily populated areas. The reports contain maps and recommendations for extractive zoning by municipalities; of necessity only the largest deposits are given priority recommendations. It is intended that these reports should improve the resource planning in areas underlain by large aggregate deposits. The inventory is only possible because a concentrated effort has been made to map the Quaternary geology of populated areas over the last ten years. Future needs require that we develop methods to determine the extent of poorly defined and buried aggregates and that we look for natural alternatives.

Jan 1, 1978

By L. Flett, S. Woods, C. Deredin

"Following a significant reduction in world Imperial Smelting Furnace (ISF) capacity from 2003 to 2008, a major optimization initiative was successfully carried out on the lead upgrading and bulk (zinclead) flotation circuits in the Brunswick Concentrator.This paper describes the process improvements that have taken place in order to reduce the quantity of bulk concentrate:•,Increase in lead upgrading rougher flotation circuit capacity•,Installation of a closed-circuit bulk regrind utilizing MillPebs and 150 mm Cavex hydrocyclones•,Installation of two additional cleaner flotation stages on the bulk circuit•,Optimization of the manipulated variables in the lead upgrading and bulk circuitsINTRODUCTIONThe Brunswick Mine (Xstrata Zinc Canada) is located near Bathurst, New Brunswick and is one of the world’s largest lead/zinc mines. Milling of ore commenced in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore from the No. 6 open pit mine. The planned closure of the mine will take place at the end of the first quarter in 2013. The ore is a complex massive sulphide, consisting of approximately 20% valuable minerals, 60% pyrite and 20% silicates.A simplified flowsheet for the concentrator is given in Figure 1. The overall flowsheet involves SAG milling, secondary ball milling, selective flotation, and dewatering by thickening, filtering and drying. The complexity of the flowsheet evolves from the requirements for fine grinding and the production of four concentrates: zinc (sphalerite), lead (galena), copper (chalcopyrite) and bulk (sphalerite plus galena).Primary hydrocyclone overflow feeds the copper-lead aerator-roughers for flotation at pH 9.0 with soda ash. Plant xanthate (80-20 sodium isopropyl and potassium amyl) and AP407 are used as collectors in the copper-lead circuit. The rougher concentrate is directed to the copper-lead regrind circuit and the tailings are fed to the secondary grinding circuit. The secondary hydrocyclone overflow from the secondary grinding circuit feeds the copper-lead rougher-scavenger banks. Rougher concentrates are reground to a P80 of 28 µm prior to three stages of copper-lead cleaning. The first stage of cleaning is done in an open circuit with the tail reporting to the cleaner scavenger. The cleaner scavenger concentrate reports to the regrind circuit and the cleaner scavenger tail combines with the rougher/scavenger tail to feed the zinc circuit. The second and third stages of cleaning are performed in closed circuit with the cleaner tail being recycled to the copper-lead regrind circuit. The average final concentrate grades 23% Pb, 3% Cu and 704 g/t Ag, and is fed to the copper separation circuit."

Jan 1, 2013

By Brian A. Ferguson, Raynald O. Vezina, Marielle Gaudet, Raoul R. Boissonneault

"Kiena has been committed to developing a fresh management and employee relations approach since the commencement of production in 1981. The functional organizational structure encourages joint participation and commitment on the part of all employees to common goals in safety and production. The results over the last four years have been extraordinary. Kiena won the John T. Ryan Canada Trophy for 1983 for its safety record and has experienced a steadily increasing productivity through the application of new mining equipment and technology in the hands of a well-trained and motivated team of employees.This paper serves to highlight the fact that productivity, safetyand technical innovation are closely linked to employee participationand involvement which are likely to be the key to theCanadian mining industry's survival in the years ahead.This presentation follows up on an earlier unpublished paper, given at the 84th Annual Meeting of CIM in Quebec City in April, 1982, which discussed the philosophy and the planning which took place before implementation of the management and employee relations system at Kiena. This present paper reviews and expands on material given in the earlier work. IntroductionThe mining industry, which has always been considered as rather conservative in its approach, has experienced with some regularity, cyclical periods related to metal prices. These cycles, previously foreseeable to some extent have become less coherent over recent years during which time the industry has had to face fierce international competition. The issue to productivity is without doubt the major concern of the mining industry in Canada today and it represents the greatest challenge facing us during the present decade. Developments that have been made in mining technology over the precious two decades have failed to completely produce the significant advancements in higher over-all productivity that were expected."

Jan 1, 1987

By R. E. Gilmore

PREAMBLE THIS PAPER comprises material presented in two separate 'Papers at the British Commonwealth Scientific Specialist Conference on Fuel Research held in London, England, in July, 1950. These papers are now available for publication in Canada, since only essential parts of the conference discussions, in addition to the resolutions resulting therefrom, will be published in the official Proceedings of the Conference. Inasmuch as the information presented concerns Canadian organizations and training facilities for fuel research, it should be of general interest to Canadian scientists, and especially to the Coal Division of the Canadian Institute of Mining and Metallurgy. Part I, the alternate title of which is Facilities in Canada for Fuel Research and for Exchange of Information and Staff, does not include research on peat, oil shale, petroleum oils in general, and natural gas, and omits studies of the geology, constitution, and production of coal. Special reference is, however, made to research on the heavy crude oils and bitumen of the Western Prairie Provinces, and particularly to their production and treatment to produce crudes for oil refinery processing.

Jan 1, 1951

By Patrick Pelletier, Pierre-Alexandre Bossé, Julie Fournier, Gianni Bartolacci, Jayson Tessier, Ahmed Bouajila, Carl Duchesne

"This paper summarizes research into the study of the control of flotation processes based on froth images. The use of numerical image analysis techniques for the extraction of significant patterns (froth structure and colour) from industrial flotation froths is discussed.First, the froth was analysed by the use of the Multivariate Image Analysis (MIA) method to extract the spectral variation contained in a RBG image. The Partial Least Squares (PLS) was applied to develop the empirical model for the prediction of froth grade. The results of this application are illustrated using one industrial case study.Second, the froth was also analysed by Gray Level Co-occurrence Matrix (GLCM) and Wavelet Transform Analysis (WTA) to extract features related more to morphological aspects. Since there is useful information hidden in froth texture, these methods are used as texture descriptor to classify different types of froths.Third, a control strategy based on a froth structure indicator was developed and implemented on an industrial zinc flotation circuit. The feedback controller uses a reagent flow-rate in order to maintain the froth structure at its set point. Process improvements obtained with the implemented control strategy are highlighted.Finally, the feasibility to implement a hybrid control strategy consisting in a froth structure supervision controller based on the froth concentrate grade estimated by MIA and recovery inferred by image analysis is discussed.INTRODUCTIONThe development of control strategies to achieve satisfactory control performance has always been a great challenge for engineers and the need for improved process diagnosis, control and optimization has become more and more evident for the mineral processing industry in the last decades. That is why new process variables need to be measured particularly in highly multivariable processes such as flotation. This industrial process is subject to a wide variety of disturbances mainly generated by frequent and sometimes abrupt changes in physical and/or chemical ore characteristics and also, due to some irregularities in manual process operating procedures. A flotation circuit scheme is always a complex network of more than two dozens slurry streams. Information about those streams (% solid, metal content analysis and flow rates) is important for process diagnosis performance evaluation and control. Also, because of the grade decrease and increasing complexity of the new processed ores, more instrumentation outputs and more powerful and significant pr"

Jan 1, 2005

By Walter S. Bergholz, Michael L. Schreder

"Since Escondida began operations in fiscal 1991, a series of aggressive expansion projects have enabled market share to be increased and ever larger profits to be realized. This was possible due to the very large size of the ore body and its high grade - averaging 2.7% copper from startup through fiscal 1997. The situation has now changed: ore grade is falling rapidly and is projected to be only 1.55% by 2003. Since revenue is directly proportional to ore grade, while costs are proportional to quantity of ore processed, profits will begin to fall dramatically. The Phase IV Expansion Project is intended to forestall this drop in profits by increasing ore processing capacity by over 85%.The Phase IV concentrator is designed for a nominal capacity of 110,000 MTPD and the key to achieving this value is through the proper design of the grinding circuit. This paper presents the general design criteria for the grinding circuit, as well as a description of the facility.INTRODUCTIONThe Phase IV Expansion Project consists of a new copper concentrator located 8.5 km south of the existing operations, a new tailings disposal and water reclaim system, a new concentrate slurry pipeline to the coast, and added concentrate handling capacity at the port of Coloso. The new concentrator has a nominal capacity of 110,000 tonnes per day (MTPD), compared to the existing concentrator’s capacity of 127,500 MTPD. The Laguna Seca concentrator is based on using the largest and most efficient ore grinding mills now available.The concentrator has been designed for a 110,000 MTPD nominal capacity. The process design criteria for the Phase IV project were established from in-house operating information and from test work. Unlike a green field project, Escondida already had an operating plant and it processes ore from the same pit that feeds the Phase IV plant. It is expected that the current mineralization will be similar for the first 6 years of operation of the new project. Therefore, some of the current plant operating conditions were incorporated directly into the design criteria."

Jan 1, 2004

By Jessica Egan, Daniel Hodouin, Claude Bazin

"The recovery of gold by leaching is influenced by the size of the gold carrier particles and the chemical environment. Using the relationships between the leaching rate, infinite recovery and particle size for a given set of chemical conditions, it is possible to simulate gold recovery for various feed size distributions. However the use of these particle size relationships is only valid if the leaching of gold from a given size class is independent of the production history of this size class. For instance, to use these relationships it is necessary to verify that gold recovery from the leaching of the 200-270 mesh size class remains the same if the size fraction is taken from a coarse or finely ground ore sample. Several laboratory tests were carried out to answer that question. Results of the tests show that within the large error margin associated to gold content measurements, the history of the production of a size class does not affect the gold leaching from that size class. Emphasis of the discussion is put on the difficulty associated with the processing of data containing significant measurement errors as it is the case for gold assays of leaching tests.INTRODUCTIONMore than 75% of the gold produced in the world is extracted by cyanide leaching of gold ores. The ore is ground to expose the gold carriers and the ground material is reacted in an oxygenated cyanide solution that dissolves gold, leaving solids gangue minerals that are disposed to tailings ponds or returned in underground mines as paste fill. The gold contained in the solution is recovered by either the carbon in pulp process or by cementation onto zinc powder, before being melted and casted into a brick (Marsden and House, 2006)."

Jan 1, 2009