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By Serge Perreault

Le cuivre est un métal fascinant qui joue un rôle essentiel dans le développement des différentes civilisations depuis 7000 ans. Le cuivre est aussi un métal polyvalent et essentiel qui est très présent dans notre vie quotidienne. L’un des premiers métaux utilisés par les humains, il est un élément chimique qui se trouve à l’état natif, ce qui est rare pour les métaux. Il apparaît principalement dans des minéraux, notamment sous forme de sulfures, en raison de son caractère chalcophile (c’est-à-dire son attraction pour l’élément soufre). Le cuivre se trouve dans la croûte terrestre sous forme de minéraux de cuivre, tels que dans les sulfures dont la chalcopyrite, la bornite, la covellite et la chalcocite. Il est également présent sous sa forme native ou dans des minéraux oxydés comme la cuprite et dans des carbonates hydratés, comme la malachite et l’azurite. La formation de gisements de minerai de cuivre implique des processus géologiques complexes, notamment l’activité hydrothermale, les intrusions magmatiques et l’altération des roches. Les gisements de minerai de cuivre se trouvent dans divers types d’environnements géologiques, dont les gisements porphyriques, les gisements de cuivre encaissés dans des roches sédimentaires, les gisements de type skarn, les gisements de sulfures massifs volcanogènes, les gisements magmatiques de type nickel-cuivre, les gisements de cuivre oxydé, et d’autres [1].

May 2, 2024

By A. Varma

Successful technology commercialization occurs when a company is focused on creating shareholder value by providing a reliable product at a price point attractive to the market, while at the same time maintaining strict control of its internal cash burn rates. Developing a technology platform and a market platform are equally important in the commercialization of new technologies such as fuel cells. This paper will discuss some of the key barriers that may prevent successful market entry for emerging and disruptive technologies, such as: R&D priorities, supply chain / manufacturing issues, materials, cost reduction strategies, customer needs, developing a market pull strategy, institutional barriers such as existing regulatory/approvals processes and/or current design/purchasing practices, product reliability and resilience, and finding the right path to market. SDTC is an arms length foundation that aims to financially support the successful market entry of emerging and disruptive technologies that can provide significant environmental benefits to Canada. The fuel cell industry, which represents one such technology, is at a critical point in its evolution where market receptivity and the technology platform are converging to potentially create significant customer advantages for fuel cell products being developed today. Since its inception in 2001, SDTC has received over 850 business cases from which it has identified successful strategies to overcome the noted barriers to commercialization. While maintaining commercial confidentiality, the SDTC database will be mined to: Identify specific success stories that have overcome various barriers and discuss their strategy; Identify specific fuel cell related industry experiences that hinder successful market uptake. The general attributes and trends of successful technology developments identified in this paper will hopefully provide guidance to technology developers and prepare them to successfully tackle the next set of hurdles on the path to commercializing their technology, once they have proven their technology works in the laboratory.

Jan 1, 2005

By Michael P. Davies

Mine waste facilities, and in particular tailings impoundments, are one of the highest risk aspects of any mining venture. There are far too many recent examples of how real and/or perceived physical or environmental impact from one of these facilities has had enormous economic impact on both the specific project and the overall parent mining company. In many cases, such dramatic impacts have followed a period where a due diligence of the mine had been carried out (e.g. in an acquisition, merger or similar) or an internal or otherwise audit had taken place. Consequently, it is suggested that there is a need for an audit/due diligence framework to assist those processes in terms of assessing mine waste facilities. This paper presents a recommended framework for completing either an audit or due diligence assessment of mine waste facilities under a number of typical scenarios. The framework will be of relevance to reviews carried out prior to mine construction, during operations and for mines that have been in a care and maintenance position and are to be re-opened. Concepts of risk management are introduced as an essential part of the recommended framework. The paper should be of value to current and prospective mine owners involved in stewarding an area of significant risk to viability of their mining venture. The paper should also interest prospective lenders to these ventures.

May 1, 2007

By A. R. Byers

"Porcupine Peninsular mine is at the extreme southwestern end of North peninsula in Night Hawk lake, Cody township, Ontario. It lies approximately 10 miles east of the gold-producing district of Porcupine.Gold in quartz veins was discovered on Gold -island in Night Hawk lake in 1906, the same year in which the now famous Porcupine gold camp was discovered farther west. Most of the claims now held by the Company were originally staked by Charles Auer in 1907, In 1910 when the level of the lake was exceptionally low, gold was discovered in a quartz vein near the shore and close to the present mine shaft.The mine is developed by a main shaft to a depth of 440 feet, with levels at 80, 180, 300, and 425 feet vertical depth and by a winze to 630 feet. A mill of 200 tons daily capacity was built during 1923, Production commenced on January 4, 1924, and continued without interruption to May 31; 1926, when operations were suspended due to a decrease in the grade of ore. Total production amounted to 27,416 ounces of gold from 99,708 tons of ore, an average grade of 0.275 oz. a ton. Diamond drilling and re-sampling of the mine during 1934 and 1935 indicated approximately 1,480,000 tons, having an average grade of 0.123 oz. gold a ton, above the 625-foot level."

Jan 1, 1954

By C. O. Aksoy, H. Kose, K. Ozfirat, T. Malli, A. Gonen, S. Gurgen

In selecting mobile mining equipment, factors including availability, useful economic life, maintenance and operating costs, and spare parts availability are considered. Given these factors, trucks and shovels with different capacities are selected. Optimizing equipment for pit and hillside quarry cases, where 8% and 10% ramps are commonly in use, were examined; the effect of other mining activities such as drilling and blasting on unit cost were considered. In principle, 20 m to 25 m high benches should be economical for downhill haulage, and 7 m to 10 m low benches economical for uphill haulage. However, practice of both mining styles favours 10 m to 15 m bench heights. Hence, the analysis here was carried out with the field experience bench height range. In the study, a truck-shovel optimization was based on the movement of 5 to 20 million cubic metres (in 2.5 million cubic metre increments) of overburden stripping at the Eynez open pit mine in the Soma region of Turkey. The outcome showed that low-capacity shovels were unfavourable due to high production expectations. High-capacity shovels were also unfavourable due to health and safety issues causing high instances of impact vibration on trucks during the loading cycle and a decrease in foreseeable unit lifetimes. The number of shovel passes required to load a truck ranged from three to six. Trucks with high-capacity bodies were deemed uneconomical due to high investment and operating costs.

Jan 1, 2005

"THE PACIFIC CONTINENTAL MARGIN OF CANADA is de-fined, for the purposes of this paper, as the area sea-ward from the present mainland coast of British Columbia to the foot of the continental slope. It thus coincides with A. Sutherland Brown's Insular Tectonic Belt. The region is limited to the north and south by the political boundary with the U.S.A., the location of which is still in dispute.The region can be subdivided into: (1) an interior trough comprising the Queen Char-lotte, Comox and Nanaimo basins; (2) a medial uplift comprising Vancouver Island and the Queen Charlotte Islands; and (3) a marginal shelf which is extremely narrow (Jess than 5 km) west of the Queen Charlotte Islands, widens to 160 km in Queen Charlotte Sound and is about 35 km wide west of Vancouver Island, where it is underlain by the Tofino sedimentary basin, with its• extension, the Juan de Fuca Basin, at the southern end.The medial uplift consists of a highly disturbed anticlinorium of mainly Mesozoic rocks, with a core of Palaeozoic. The rocks include thick sequences of eugeosynclinal volcanics and sediments. There is strati-graphical evidence of repeated interruption in sedi-mentation. By late Jurassic, the main eugeosynclinal phase was over and a successor basin was initiated in the interior' trough. This became filled, during Cre-taceous and Tertiary time, with sediments ranging in environment from bathyal turbidites to terrestrial conglomerates and coals. West of the medial uplift, another successor basin developed in early Tertiary times and became filled with mainly deep-water marine sediments. A third effusive sequence marks the base of the Tertiary on Graham Island and over most of the Hecate Strait region and Tofino Basin."

Jan 1, 1970

THIS article describes the origin and details of a hydraulically operated switch to control the operation of an automatic underground pumping system. This system was installed in December, 1939, on the 2,350-foot level at No. 5 shaft of the Buffalo Ankerite mine. The pumping unit consists of an 8-stage centrifugal pump direct-connected to a 150 h .p., 2,200 volt motor. Pumping capacity is 200 gallons per minute under a 1,315-foot head and with a flooded suction. The control consists of a 200 amp., 2,200 volt oil-immersed starter with thermal overload protection, thermal protection on the pump, and a flow switch that is bypassed for 30 seconds after the pump starts. The 30-second time lag is operated by a relay mounted on the panel. There is a swing check valve in the discharge line of the pump which originally operated the flow switch by means of a connected outside lever which closed the switch as the check valve opened.

Jan 1, 1945

By C. H. Madsen

THE Hard Rock gold mine is in the Little Long Lac mining area, Thunder Bay district, northwestern Ontario. It is four miles by road from the town of Geraldton, which is on the Canadian National railway, 180 miles northeast of Port Arthur. The original discovery of gold-bearing quartz veins on the property was made in 1931. Shaft sinking began in the fall of 1934 and approximately 7,400 feet of lateral development on four levels was completed. In 1935, further discoveries were made half a mile west of the early workings, and the No. 2 shaft was sunk in this area in a porphyry zone. In January, 1938, a 20C-ton cyanide plant was completed and began drilling ore from the gold-bearing porphyry orebody. The daily feed was increased gradually to 300 tons in the next six months and a recovery of 97.5 per cent was effected. During the summer of the same year, a new and larger orebody was discovered to the north of the porphyry zone. It occurs in a band of iron formation and contains a high percentage of pyrite and arsenopyrite. Extensive tests were rr.ace on this sulphide ore in the Mines Branch ore dressing laboratory at Ottawa, in the laboratory of Canadian Industries, limited, at Toronto, and later at the mine, to find a suitable method of treatrr.ent. As a result of this research, a Potation plant was added to the original cyanide mill and on November 7th, 1938, differential flotation was used to separate the pyrite from the arsenopyrite fraction of the ore. The pyrite concentrate was re-ground and cyanide:l, and the arsenopyrire concentrate was stored for subsequent treatment. Differential flotation was discontinued in April, 1939, in favour of bulk formation of all the sulphides, and the whole cyanide residue was stored. On March 15th, 1939, a 10-ton pilot roaster was completed and rests were conducted on the arsenopyrite concentrate and the bulk concentrate. The results obtained led to the building of two roasters of the same type, large enough to roast all the concentrates. These roasters were put in operation on September 24th, 1939, and the calcines were cyanided in the original circuit.

Jan 1, 1941

By J. Kolacz

"A new sensor based sorting system has been developed, providing a possibility for laboratory scale testing and further scale-up of the separation results to the industrial operation. The new system contains different sensors as: X-ray detectors, visible light cameras, NIR cameras, ultraviolet cameras and magnetic sensors, in the same sorting unit. The sorting unit allows advanced calibration options and fine-tuning of the installed sensors to achieve the best separation effect under controlled conditions. Finally, the processed material can be analysed and separated by the rejection mechanism, similarly to the industrial scale operation. At the same time, the process is carried out with limited amount of material allowing detailed statistical calculations for processed particles and all sensor types. The optimal settings and sensor types are specified for the industrial application.The paper describes the scale up of the results achieved for iron ore and coal, where the test work was first carried out using the new laboratory sorting system and where the industrial scale sorting system has been built, in the final stage. The industrial scale sorting results showed a very good correlation between the laboratory and full scale operation. Thanks to the detailed study carried out in the laboratory equipment, the settings of the sensors in the full scale operation provided much better separation efficiency. It was especially important to provide proper setting for the X-ray sensor data calculations, which can be very critical for achieving the best results. During the industrial scale sorting of coal, the input material had 40-55% rock particles as the direct source of ash in the coal stream. The optimal laboratory unit settings and transferring these settings to the industrial sorter, provided 98.8% efficiency for removing rock particles with only few % losses of coal."

Jan 1, 2016

By Xiang-dong and Zhu, Xia-jie Hao, Yi-lin Fan, Quan Jiang, Lian-xing Hu, Xia-Ting Feng, Shao-jun Li

"Columnar jointed basalt (CJB), which typically originates from lava flows, is characterized by a special geological structure. The joint network inside the CJB is self-organized into a rough hexagonal arrangement. The field test and measurement during the unloading excavation showed that the columnar joint sets and other internal joint sets not only are important for determining the mechanical properties of the CJB, but also induced its asymmetric unloading deformation and failure. A constitutive model, which considered mechanical deterioration of both the joint sets and rock blocks, was also developed to simulate the unloading behaviour of the CJB. The crack-confinement supporting method for surrounding CJB was developed to overcome the failure of columnar jointed rock mass in the diversion tunnel. Application to the CJB segments of the diversion tunnels in the Baihetan project indicated that this supporting method was reasonable and efficient. INTRODUCTIONColumnar jointed basalt (CJB) rock mass, which typically originates from lava flow, is characterized by a special joint structure. The joint network of the CJB is self-organized into a roughly hexagonal arrangement and leaves behind an ordered colonnade. The widely accepted current view regarding the formation of columnar jointing involves a thermally induced contraction–cooling mechanism (Peck and Minakami, 1968; Degraff and Aydin, 1987; Budkewitsch and Robin, 1994; Lore et al., 2000; Goehring et al., 2006). Although the columnar basalt formation mechanism is fairly understood, the geotechnical characteristics of such rock mass are not well established. In practice, joint sets always induce the multi- failure modes of surrounding rock in the tunneling space (Ibarra et al., 1996; Waltham and Swift, 2004; Mahendra and Bhawani, 2008).According to conventional wisdom in rock mechanics, structural joints affect the mechanical response of rock mass by introducing strong anisotropic effects (Barton and Bandis, 1980; Hudson and Priest, 1983; Brady and Brown, 1985). The columnar jointed rock mass should be considered an anisotropic material given that the joint sets are distributed with some principal directions and characteristic spacing distributions (Cundall and Fairhurst, 1987; Hoek et al., 1998; Wu and Wang, 2001; Budetta and Nappi, 2011; Fortsakis et al.,2012). Columnar jointed rock mass would result in structurally controlled failure patterns, even serious disasters during underground excavation because of the low shear and tensile strengths of intensely joints (Gencer,1985 ;Ishida and Uchita, 2000; Jia and Tang, 2008). The CJB rock mass in the Baihetan hydropower station has exhibited serious stability issues, including sliding, fracturing and even collapse (Shi et al.,2008). Therefore, the geotechnical and geomechanical characteristics of such rock mass should be assessed through in situ investigation and numerical analysis to minimize future accidents during underground unloading excavation."

Jan 1, 2015

By W M. Cameron

Geophysical studies have extended seaward in recent years, and the important discoveries which have been made have led to a better understanding of geological processes. A present source of certain minerals, the sea will eventually serve as an important source of desalinated water. The continental helves, in particular, represent a potential mineral resource. The expansion of Canadian oceanographic effort that is now underway will eventually lead to the exploitation of the wealth beneath the sea. THE subject of this symposium, which emphasizes the word "geophysics," the specialties of the speakers who are contributing and the nature of the audience at first made me believe that I, a a physical oceanographer, would be out of place. However, I shall undertake to classify myself as a geophysicist, and shall arrange my remarks on my specialty o that they might be of interest to those of you who are predominantly geologists, metallurgists or mining engineers.

Jan 1, 1963

By J. A. MacLellan

"CONSTRUCI'ION OF SHERRITT'S CONCENTRATORSSherritt Gordon is operating two mills north of the 56th parallel, and is presently engaged in building a third. The author was closely involved in the design and construction of all three of these concentrators.The Lynn mill is the oldest of these three concentrators-it is a 4,000 ton per day nickel-copper plant built in 1953. The Fox mill is a 3,000 ton per day copper-zinc concentrator built in 1970. The Ruttan mill will be a 10,000 ton per day copper-zinc plant scheduled to go on line in July 1973.LYNN MILL The Lynn mill including the crushing, concentrating, drying and load out plant is about 69,700 square feet or 17.4 square feet per ton per day. '!his plant was originally built in 1927 at Sherridon, 150 miles south of Lynn Lake, as a 2,000 ton per day copper-zinc plant. In 1952 the plant was moved by tractor train to Lynn Lake. The whole plant was re-oriented within the original perimeter walls as a 2,000 ton per day nickel-copper plant. This plant was expanded to 4,000 tons per day by the addition of t1-Jo rod mills and a 5-1/2 short head crusher in 1959.The Sherridon mill processed its last ore in Sherridon in September 1951 and the first load of nickel concentrate was loaded at Lynn Lake on November 9, 1953 when the railroad arrived at Lynn Lake.The site for the Lynn Lake mill was cleared of overburden in the summer of 1952 and foundations for structural steel and SO!l8 equipment foundations were poured the late summer and fall of 1952 • Steel was erected from January to June 1953. Most of the equipment came in from January to March of 1953 by tractor sleighs. Sane sleighs upset but no equipment was lest through the ice."

Jan 1, 1972

By R. Noorani, M. Cai

"Excavation of deep underground openings in highly stressed grounds can generate new fractures near the openings. As a result, rock mass bulking may occur, leading to large wall deformation. A better understanding of brittle rock failure and the associated fracturing process at the laboratory scale is an essential step towards evaluating dilation behavior of rocks. A grain-based model that can capture dilation behavior of rocks under various loading conditions at the laboratory scale can be a useful approach to study rock mass bulking at the field scale. The aim of the paper is to study the dilation behavior of rocks at the laboratory scale employing numerical simulation. A modified grain-based model is used to simulate the macroscopic response of crystalline rocks by considering micro-fractures at the grain scale. Grains generated with the Voronoi tessellation are allowed to fail in tension or in shear using a strain-softening model. Damage is represented by either grain boundary fracture or grain failure, or the combination of the two. As stress increases, the process of damage, fracture initiation and coalescence in rocks can be captured.The grain-based model was calibrated using test data of the Lac du Bonnet granite and a parametric study was conducted. Numerical simulation results showed that the proposed modeling approach is able to capture most of the mechanical properties, fracture pattern, and dilation behavior in both unconfined and confined loading conditions. In an unconfined compression test, interactions of microscopic fractures may lead to macroscopic shear or axial splitting failure depending on the chosen micromechanical parameters. Numerical experimental results show that the dilation behavior of the model is strongly related to the failure mechanism of rocks. Tensile-failure-dominated failure mode generates large dilation due to the formation of new cracks that are sub-parallel to the loading direction. On the other hand, shear-failure-dominated failure mode produces small volume increase. One significant finding from this study is that in order to capture large dilation using grain-based UDEC models, intragranular grain failure should be considered."

Jan 1, 2015

By Clemens Kuhnert

"Nickelhütte Aue GmbH is specialized in the recycling of waste materials containing non-ferrous metals. We treat nickel, copper, cobalt, vanadium, molybdenum and precious metal containing materials like spent catalysts, ashes, dusts, grindings, liquids, slurries and sludge's as long as they contain one or a combination of the above mentioned metals. In our pyrometallurgical works we produce non-ferrous metal concentrates suitable for further treatment in our hydrometallurgical plant where we refine Ni-, Cu-, Co- and V-chemicals. Our production is based on synergy effects due to the combination of pyro- and hydro-metallurgy. As an example we can mention our heat recovery system and internal recycling of by-products. Furthermore, the use of alternative fuels instead of fossil fuels contributes to the economic and environ-mentally friendly treatment system.INTRODUCTION Nickelhütte Aue GmbH (NHA) can look back on nearly 400 years of tradition as a pyrometallurgical works and recycling company. The existence since its foundation in 1635 as a blue dye works shows responsible and successful action in the past. Therefore, we see highest customer service, minimization of interferences with nature by closing material cycles and maximized health and occupational safety protection by avoiding injuries and diseases, still as our future duties. These duties are evaluated and monitored by an integrated management system that meets the standards of DIN EN ISO 9001, 14001, 50001 and BS OHSAS 18001. We commit ourselves to the observance of all juridical and customized demands. The management and the department managers perceive their model function. We require responsible action from all employees. To protect the continuity of our enterprise, we will also perform in future continuous improvement of products and their quality, as well as steady progress in the areas of environment protection, health protection and industrial safety. Equally the effectiveness and propriety of the management system is checked and developed regularly. In order to obtain the objectives resulting from this policy, our company determines activities and measures by involving all employees."

Jan 1, 2017

By The Staff

Introduction In this paper it is proposed to discuss briefly some of the problems confronting the management of a gold mine in choosing a method of milling to recover the gold from various classes of ore. In order to simplify the discussion, the more common types of gold ores are classified from a metallurgical point of view as follows: Class 1?A: Free-milling ores which require only relatively coarse crushing. B: Free-milling ores which require finer grinding to release the gold. Class 2?A: Gold ores which contain the gold partly in the flee state and partly associated with a small amount of iron sulphide, and which do not require fine grinding. B: Gold ores similar to 2A, but which require fine grinding. Class 3?A: Gold ores containing copper in quantities insufficient to interfere to a serious extent with cyanidation. Gold ores containing copper in sufficient quantity to interfere with cyanidation but in which a large proportion of the gold is in the free state, the remainder being chiefly associated with the copper mineral, chalcopyrite. Gold ores containing copper and other sulphides, such as pyrite, etc., in which the gold is principally associated with these sulphides.

Jan 1, 1931

By A. Allaire, J. Torrealba-Vargas, R. Welyhorsky

Early testwork was carried out to select the plant process design criteria and flowsheet selection. Additional testwork was carried out during the feasibility study to support the optimization of the plant design criteria. The test results showed that the recovery of gold was not very sensitive to grind size in the range of 75 to 105 microns. An additional result was that the presence of lead nitrate did not improve the kinetics of gold leaching. This conclusion was supported by the low content of sulphides in the ore. It was also found that the presence of lead nitrate increased copper dissolution, producing the potential for an increase of copper reporting to electrowinning, which is detrimental to the overall gold recovery process. The use of oxygen in leaching was investigated to increase leach kinetics. The results of leaching tests to compare using oxygen instead of air indicated that, due to the improved leach time, it was possible to reduce the number of leaching tanks from twenty four (24) to twenty (20).

Jan 1, 2011

By F. Duan, J. Pfarr, J. M. Goris

"The U.S. Bureau of Mines, in cooperation with the Homestake Mining Co. and the University of Utah, is conducting a field demonstration to evaluate the behaviour of rock masses supported with cable bolts. One of two rock masses being studied is supported with both conventional and birdcage cables. This rock mass is located between the 6500 and 6650 levels of the 45-48N stope, 21 ledge. The second rock mass is the hanging wall of the D-limb stope between the 3500 and 3650 levels near the Ross Shaft and is supported with conventional cables. The primary objectives of the project are to monitor the behaviour of the two rock masses during mining using extensometers and cable support strain gauges, after which the rock will be modelled using the finite-element code UTAH III. Field data will be used to verify the modelling. In addition, a comparison between the effectiveness of conventional and birdcage cables will be made.45-48N StopeThe 45-48N stope is located in the 21 ledge between the 6500 and 6650 levels and contains about 233 000 short tons of mineable ore. The orebody lies within the Homestake Formation and is very irregular being approximately 200 ft long and 75 ft wide. Between the 6500 and 6650 levels, it dips from 35 degrees to 60 degrees east with a near-vertical plunge to the south. Mineralization is characterized by arsenopyrite and pyrrhotite with minor gold. The contact between the Homestake and the overlying Ellison Formation creates a plane of weakness along localized graphitic layers. The footwall dips at approximately 60 degrees but between 100 ft and 120 ft above the 6650 level , the hanging wall flattens to almost 20 degrees causing a significant mining problem."

Jan 1, 1991

By F. Mackay, S. A. B. da Fontoura

"The theoretical solution for a viscoelastic well was presented by Gnirk and Johnson in 1964. From this an exercise was executed to validate the numerical simulation of a cemented salt well. The exercise comprised the geomechanical behavior through time of a cemented salt well, this was achieved using a finite element commercial software. This simulation showed the accuracy of the theoretical solution for viscoelastic materials such as salt rock. The theoretical solution presented elastic and viscoelastic analytic equations for the tangential and radial stresses. The equations for the elastic material (casing and cement) and for the viscoelastic material (salt rock) are presented here: Where equations 1a & 1b are the radial and tangential stresses of the elastic material; equations 2a & 2b are the radial and tangential stresses of the viscoelastic material; and a, r and b are the geometrical parameters explained in Figure 1. These equations are function of Pb, a stress time dependent factor that comes from the Burgers model of viscoelasticity. This is well explained in Gnirk and Johnson (1964) and for the sake of simplicity is not disclosed here. Po is the stress at section A-A’ dependent of the depth h."

Jan 1, 2015

By D. Sagara, V. G. Makhado

"A model based control strategy was implemented at Loulo Gold Mine in Mali, to stabilise the thickener underflow stream density. This stream acts as the feed to the leaching circuit. pH control of the leaching circuit was integrated with the model-based controller due to slow process dynamics that are not suited to PID control. The controller performance was quantified over a period of 6 months, and was compared to the performance before implementation. The model based controller reduced process variability for both thickener underflow density and pH considerably, and resulted in a reduction in flocculant and lime consumption of 9.32 and 6.55%, respectively. INTRODUCTION Reagent consumption in gold processing plants significantly contributes to the total operational costs. In a typical Carbon-in-pulp (CIP) circuit, the reagent consumption associated with leaching, adsorption, elution and regeneration contribute to approximately 15% of the total operational costs (Stange, 1999). At Loulo Gold Mine, the reagent consumption associated with leaching, adsorption, elution and regeneration contributes to 6% of the total operational costs. As such, a reduction in reagent consumption will present a significant opportunity for savings on operating expenditure. Variability in feed ore characteristics results in continuous changes in steady state operating regions, which presents process control challenges as a result of the long residence times in some of the process units associated with gold processing plants. Overdosing often occurs in the presence of process variability to ensure safe operation and to maintain recovery targets. As a means of reducing reagent consumption and accounting for significant changes in the feed to gold plants, some of the plants have resorted to improving their process control strategies around their circuits. This paper focuses on the implementation of a model predictive based controller at Loulo Gold Mine on their thickener and Carbon-in-leach (CIL) tank to: •,stabilise the thickener underflow density, and •,the CIL tank pH."

Jan 1, 2017

By D. B. Dreisinger, D. G. Dixon, G. Nazari

"The kinetics of chalcopyrite leaching in acidic ferric/ferrous sulfate media under atmospheric conditions in the presence of pyrite has been investigated. It has been found that pyrite samples from different sources affect the rate of chalcopyrite leaching differently. A strong correlation between the amount of silver associated with the pyrite and its effectiveness has been noted. In this study, improvement of the catalytic properties of pyrite such that all pyrite samples accelerate the rate of copper extraction regardless of their sources is demonstrated, and a detailed discussion of the mechanisms involved in the process of chalcopyrite leaching in the presence of silverenhanced pyrite is presented. INTRODUCTIONIt is well known that chalcopyrite resists leaching in sulfate media. It has been proved that pyrite facilitates the leaching of chalcopyrite (Berry et al., 1978; Dixon et al., 2008; Mehta and Murr, 1983; Muñoz et al., 2008; Nowak et al., 1984, Tshilombo, 2004). Considering the catalytic effects of pyrite on accelerating the kinetics of chalcopyrite leaching, Dixon and Tshilombo (2005) have developed a new process, known as Galvanox™, which has several advantages over other hydrometallurgical processes. Galvanox™ runs under atmospheric conditions, so it requires only low-cost leaching tanks. The sulfur yield at this temperature is high (>95%) which leads to low oxygen consumption and low sulfuric acid generation. The operating temperature is below the melting point of sulfur which eliminates the use of surfactants. This process also does not require fine grinding. Reaction 1 shows the overall leaching reaction in the Galvanox™ process.CuFeS2 + O2 + 2 H2SO4 = CuSO4 + FeSO4 + 2 S0 + 2 H2O (1)Complete copper recovery from the Galvanox™ process can be achieved at a considerably higher rate than other atmospheric ferric sulfate leaching processes (Dixon et al., 2008). Recycling pyrite and recovering copper from tailings with the Galvanox™ process have also been evaluated in continuous pilot leaching campaigns (Dixon et al., 2007)."

Jan 1, 2012