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By J. Tuzo Wilson

Abstract A division of part of the Canadian Shield into provinces believed to represent former mountain belts is attempted, special emphasis- being laid upon radioactive age determinations, the relation of Archaean to Proterozoic rocks, and the structure of the Grenville province. Original data on the distribution of radioactivity within several batholiths and their connection with ore deposits are' presented. The possible growth of continents and a theory which explains the shape and distribution of the world's younger mountain and island areas are discussed and applied to the Canadian Shield in an attempt to explain how the growth and present structure came about. The relation of the major mining camps of northeastern Ontario to fault zones is discussed in the light of this theory. Introduction The valuable symposium issued by this Institute to celebrate its jubilees emphasizes the important role of major faults in determining the location of many ore deposits in the Canadian Shield. Many of these faults are known to extend for long distances. It is therefore widely appreciated that it would be of great value if the pattern, ages, and causes of these faults were better understood. This would be particularly useful if the relations of the major fault systems to petrological and metallogenic provinces and to former mountain belts could be established. Each year the volume of available data, and hence the chance of reaching a fuller solution of this problem, increases. This article is a review of the present situation. It is accordingly based almost wholly upon the work and ideas of others, which are gratefully acknowledged. Naturally, responsibility for the selection and marshalling of the data is the writer's.

Jan 1, 1949

By Richard P. Curtin, John M. Goris, Lewis A. Martin

Cable bolt supports are being recognized as an effective ground control system in under-ground coal mines in North America, and their use has increased considerably during the past few years. The U.S. Bureau of Mines personnel are conducting both laboratory and field tests to evaluate the performance of these supports under a variety of conditions and to establish realistic design guidelines. This paper describes efforts to evaluate the capability of cable bolts to resist the high shear forces often present in longwall operations. Shear tests were conducted on pairs of 0.025 m3 (0.88 cu. ft) concrete blocks having joint surfaces ranging from rough to smooth. Tests were conducted on blocks both with and without reinforcement with 15.2 mm (0.6 in.) diameter steel cables. During each shear test, the loads and displacements along the normal and shear axes, as well as loads on the cable, were monitored. Cableloads were determined using strain gauges attached to the outside surfaces of the barrel-and-wedge anchors used for pretensioning the cables. Test results show that a cable bolt placed across a joint more than doubled shear resistance of shear blocks having both smooth and rough joints.

Jan 1, 1996

By A. M. Richmond

Introduction The apparent commonplace, and prosaic, nature of building-stones, lime, cement, gypsum, and clay products, and many other miscellaneous non-metallic minerals, such as abrasives, barite, diatomite, magnesite, mica, slate, salts, etc., and their everyday appearance and necessary in our lives, has removed much of the glamour, romance, and speculative attractiveness so frequently associated with our gold, silver, lead, zinc, and copper mining ventures. However, it will be readily appreciated, with but a brief study of the thirty-five or more non-metallic minerals and products which are mined, prepared, or are known to occur, in British Columbia, that the 'industrial minerals' industry in the Province has an abundance of interesting technical problems, is fraught with speculative possibilities, and, as such, fully deserves much more technical attention than it has hitherro received. The brief notes presented in this paper show, in summary form, the magnitude of the British Columbia industrial and non-metallic mineral industry; outline in synoptically form the principal deposits of non-metallic minerals presently known; and indicate in a general way a few of the possibilities which exist in the Province for the expansion of the industry. For convenience in presentation, the assembled material has been divided into four sections: 1.-Sraristical information 2.-Strucrural non-metallic minerals 3.-Miscellaneous non-metallic minerals 4.-Non-Metallic mineral possibilities in British Columbia 1. -Statistical Information The writer does not propose to dwell at length on the statistical comparisons and deductions which may be drawn from the four tables which have been compiled for this section of the paper, nor is it considered essential, as the figures present a most emphatic story in themselves.

Jan 1, 1935

By Francis Dakubo, Courtney Young, Avimanyu Das

"Hydrometallurgy of copper ores typically involve acid leaching followed by solvent extraction and electrowinning (SX/EW). EW is the final purification stage in which a voltage is applied across two electrodes causing the copper ions to reduce and deposit on the cathode. Applied voltages are near 2 volts with current densities around 300 amps/m2. In this study, research was undertaken to decrease the energy consumed in the EW process. To do this, various cell designs were constructed and tested in which a membrane was used to separate the cathode and anode compartments with concentrated solution from SX serving as catholyte and raffinate from SX serving as anolyte. Therefore, copper in the concentrated solution would be deposited on the cathode while ferrous in the raffinate would be oxidized to ferric at the anode. Because it is assumed that ferric acid leaching is used, resulting ferric would be recycled to the leaching process. A positive side effect of the envisioned process would be the elimination of oxygen evolution at the anode and thus the prevention of acid-misting. After a cell design was selected, it was used to test a number of variables: flowrate, concentration, temperature, ion-exchange membrane, and applied voltage. Following experiments in which variable ranges were determined, statistical modeling was conducted using STATEASE software. Optimal results indicate the voltage can be decreased to 1.5-1.7 volts with current densities of 300-400 amps/m2. Significant reduction in the energy consumption was accomplished by reducing the applied voltage. Furthermore, current efficiencies and copper production rates was increased by application of the membrane.INTRODUCTIONLeaching of copper ores is achieved using mostly sulfuric acid. The copper pregnant solution is contacted with an organic solvent or resin adsorbent which picks up copper ions as in Equation 1:"

Jan 1, 2016

By J. Cayouette, C. Bolduc, P. Blatter

"The LaRonde mill was commissioned in 1988 and began treating ore from the Penna shaft in 2000. The mill has been expanded to accommodate 7,500 t/day, but ramped down to 6,000 t/day since the deep extension began. The process recovers gold, silver, and base metals. In 2008, the Goldex plant began trucking gold-pyrite concentrate to a treatment plant feeding pulp to the LaRonde mill, increasing gold output by 40,000 oz. In 2009, the high-grade Lapa ore processing facilities were annexed to the LaRonde plant, increasing gold output by 120,000 oz. This paper outlines the metallurgical considerations related to the treatment of different ore types.RÉSUMÉ Le concentrateur de la mine LaRonde a été mis en service en 1988 et a commencé à traiter le minerai du puits Penna en 2000. La capacité du concentrateur a augmenté afin de permettre le traitement de 7 500 tonnes de minerai par jour, capacité qui est retombée à 6 000 tonnes par jour (tpj) depuis le début de l’extension en profondeur de la mine. Ce procédé permet de récupérer de l’or, de l’argent et des métaux communs. En 2008, l’usine de traitement Goldex a commencé à transporter par camion du concentré de pyrite et d’or vers une usine de traitement alimentant en pulpe le concentrateur de LaRonde, augmentant ainsi la production d’or de 40 000 onces. En 2009, les installations de traitement du minerai à haute teneur de Lapa ont été annexées à l’usine de traitement de LaRonde, augmentant la production d’or de 120 000 onces. Cet article passe en revue les considérations métallurgiques liées au traitement de différents types de minerai.INTRODUCTIONThe LaRonde metallurgical plant in the Abitibi region of Quebec, Canada, evolved into a mature milling site following expansions in 2000–2003, thanks to improved processes, manpower, and water treatment capabilities that better accommodate the complex constituents of the LaRonde ore. The ore requires a sequence of grinding, copper- lead and zinc flotation, and precious metals leaching, ending with a carbon-in-pulp (CIP) gold recovery. A portion (35%) of the tailings is sent back underground as paste backfill after being treated with the SO2-air cyanide destruction process. The tailings area has a dedicated cyanide destruction and metal precipitation area through which the used water passes before returning as recycled water. A biological water treatment plant was built in 2004 to address water toxicity in the final effluent. The water toxicity was the result of the high sulfide content of the LaRonde ore (from thiocyanate or stable cyanide species buildup) and the use of 90% recirculated water in the mill. The water treatment plant uses bacteria to transform thiocyanate into nitrates and precipitate phosphorus from the water before it is discharged into the environment."

Jan 1, 2017

By J. G. Kelly, C. P. Brown

"In June 1983 a new borehole hoisting system was commissioned at Sherritt Gordon's Fox Mine. Twelve hundred tons-per-day of ore from the 2600 and 2800 levels are being hoisted to the 2000 level through an 8-jt diameter bored winze. This new method replaces the diesel truck haulage system which had been in operation at the mine since 1975.A study was initiated in 1980to determine the most effective method of achieving the required production. The study examined several hoisting alternatives including: expanding the existing trucking system; converting to electrically -powered truck haulage; and deepening the skip compartments of the existing main shaft. The alternative selected as the hoisting method most suited to the requirements was borehole hoisting.Development of the new system commenced in April 1982. Underground excavations included 700 feet of 8-ft diameter borehole, a hoistroom and headframe, storage bins, and a grizzly and rockbreaker station. Equipment installations included: a 5-ft diameter double-drum Nordberg hoist; a counterweighted Kimberley-type skip; two rockbreakers; and the steel sets in the winze. These installations were completed in June 1983. Some problems were encountered after the initial commissioning but these were solved, and since August 1983, the system has proven that the designed capacity is achievable within expected costs."

Jan 1, 1985

By S. Esfahani, M. Barati, Y. Kauwachi

"Heat recovery from slag has gained attention due to its high potential in lowering energy intensity of metal extraction processes. A direct method to recover the thermal energy of slag is to use countercurrent air flow that extracts the heat from falling droplets. Often, the solidified slag is aimed to be used as a substitute for Portland cement, thus high cooling rates are required to form an amorphous slag with sufficiently strong hydaulicity. Rapid cooling however involves using large gas flow rates that in turn lower the thermal efficiency of the process. This article presents a mathematical model that was developed to determine the optimum conditions in the heat recovery process and to investigate the effect of the air flow and granule diameter on the cooling rate of the droplets as well as the thermal efficiency of the heat recovery system. INTRODUCTIONMetallurgical slags are the largest by-product of high temperature materials refining and extraction processes. The total amount of metallurgical slag produced in the year 2008 has been estimated at up to 422 million tonnes containing up to 222 TWh/y (Barati and Esfahani, 2011) of thermal energy. Over the past four decades attempts have been made to recover this substantial amount of energy as heat, electricity, or fuel, while none of the proposed method has been commercialized yet.During slow cooling the slag tends to crystallize the constituents (CaO, SiO2, Al2O3, etc.) into a hard, heavy solid. In the past, over 90% (Bengt, 1983) of the molten waste was discharged onto heaps and allowed to cool slowly, then crushed and used in road construction or land filling or as coarse aggregate for concrete. However, later it was found if cooled rapidly, the slag can be used as a substitute for Portland cement. As a result, processes such as wet granulation were created in which molten slag is fragmented with water, forming amorphous (glassy) phases. Despite its effectiveness in producing a suitable material, heat would not be recovered through this process. Thus, dry granulation was introduced in 1930’s and was developed further in 1970 – 1980’s."

Jan 1, 2012

By G. Reuben Yourt

IN 1935, Wright-Hargreaves Mines, Limited, initiated an enlarged programme of ventilation. In the mine, surveys were made from time to time by the geological staff, and improvements in ventilation were effected to accord with progress in mining as greater depth was attained. In the summer of 1938 an engineer was trained in the technique of dust sampling. Instruments and equipment for this purpose, such as konimeter, microscope, furnace, etc., were purchased, and a suitable office, equipped with laboratory facilities, was provided. The full time of the engineer is devoted to ventilation and dust control. On surface, in the mill crushing-plant and in the assay office and sample crushing room, an elaborate arrangement of hoods and exhaust systems has been installed to eliminate the dust. These installations, however, are not described in the present paper, which deals only with an extensive programme of underground ventilation as a method of coping with high dust concentrations, increasing temperatures and high humilities.

Jan 1, 1940

By W. E. Roscoe

"Mineral exploration properties are those on which an economically viable mineral deposit has not yet been discovered. Such properties are bought, sold, optioned and joint ventured on the basis of their perceived potential for the existence and discovery of a viable mineral deposit. The intrinsic value of an exploration property is therefore based on the exploration potential. One measure of the exploration potential is the amount that can be justified to spend on exploration for a viable deposit.The appraised value method uses a cost approach to value exploration properties. It is based on the premise that an exploration property is worth the meaningful past exploration expenditures plus warranted future costs to test remaining exploration potential. Results of past exploration work are analyzed in order to retain only those past expenditures that are productive in terms of identifying remaining potential. Warranted future costs comprise a reasonable exploration budget to test that potential."

Jan 1, 2002

By Marc Arpin

La Bolivie possède tout pour réussir. Son vaste territoire de plus d'un million de km2 et qui occupe une position stratégique au coeur du continent sud-américain recèle des ressources naturelles (forêts, minéraux, gaz naturel, etc) variées et abondantes. Elle a une frontière avec pas moins de 5 pays dont le géant que constitue le Brésil ainsi qu'avec l'Argentine, l'autre puissance régionale. Pourtant, malgré tous ces atouts, la Bolivie demeure l'un des pays les plus pauvres du continent. Ce paradoxe n'est nulle part mieux reflété que dans le secteur minier. Celui-ci fait face à une situation de crise en dépit d'une tradition minière de plus de quatre siècles et d'un potentiel géologique indiscutable ayant conduit à la découverte et à l'exploitation de fabuleux gisements d'argent et d'étain. Les habitants des districts miniers vivent dans des conditions de pauvreté extrême et les indicateurs de développement humain de ces régions sont parmi les plus bas en Amérique du Sud. La Bolivie réussit difficilement à attirer les compagnies minières alors que, chez les voisins, et particulièrement en Argentine, qui n'a pas de tradition minière, les investissements miniers majeurs affluent. Dans cette conférence, nous chercherons à expliquer les causes de cette situation et proposerons des solutions possibles.

May 1, 2001

By R. Bashir, J. F. Hatley

ABSTRACT Northern Saskatchewan boasts some of the world’s largest known high-grade uranium deposits. The successful mining of these deposits cannot be accomplished without overcoming technical challenges, however, which include high grade of the uranium ore, specialized mining methods to deal with groundwater at high pressures, and poor ground conditions. This paper discusses the various mechanisms of inflows at three of Cameco Corporation’s sites in northern Saskatchewan. The risk of inflows is quantified in terms of unique challenges due to hydrogeological conditions, rock mass integrity, and uncertainty in geological conditions. Strategies in the case of an inflow are also briefly described.

Jan 1, 2013

By L. D. Eccleston

Any man-made structure will eventually decay, but we are basically concerned with the prevention of corrosion within a fairly limited time span. How corrosion can be minimized by design, the removal of oxides and a careful choice of paint systems is discussed, and mention is made of the electrical nature of most anticorrosive systems. Also discussed are the characteristics of certain paint binders and how mechanical properties will differ for various environments. Corrosion of a substrate by acidic breakdown products of some paints is mentioned in conjunction with a discussion on convenience versus ultimate performance. A brief mention is made of the three main components of a paint system, and the principal types of paint are placed in broad categories, with the main strength and weaknesses of each type listed.

Jan 1, 1979

By B. K. Mishra, Avijit Biswal, B. C. Tripathy, Abhijeet Singh, K. Sanjay, T. Subbaiah

We studied theeffect of anode substrates such as pure lead (Pb), lead antimony (Pb-Sb), and lead-silver (Pb-Ag) on the structural and electrochemical properties of electrolytic manganese dioxide (EMD). X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and chemical analyses were used to determine the structural and chemical characteristics of the EMD samples. The charge-discharge profile was studied in 9 M KOH using a galvanostatic charge-discharge unit. In all the substrates the current efficiencies were more than 99% except with Pb-Sb where it was 90%. Results revealed the nature of the substrate strongly affected the morphology of the deposited material which in turn affected the electrochemical properties of the EMD samples. XRD analyses revealed that the nature of the anode did not affect the crystal structure of the deposited EMD and all the samples were predominantly ?-MnO2, which is electrochemically active for energy storage applications. The EMD deposited on lead substrate showed superior discharge capacity of 245 mAhg-1 when compared with other substrates.

Jan 1, 2014

By Alan Rice

Abstract-The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultramafic igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on fluid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other fields dealing with suspended loads in fluids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By Alan Rice

The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultrama?c igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on ?uid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other ?elds dealing with suspended loads in ?uids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By Marcondes Lima Costa

Abstract-The Amazon region is characterized by the development of deep chemical weathering represented by widespread lateritic covers and soils. Two distinct periods of laterite formation can be distinguished: mature laterites from the Eocene-Oligocene (and locally from the end of the Cretaceous), and immature laterites from the Pleistocene. The older laterites occur on plateau landscapes, and the younger ones on widespread hilly to flat lowlands. Both types show complete or truncated profiles, generally covered by deep yellow to brown topsoils. The mature laterite profiles contain high concentrations of gibbsite and/or aluminum phosphate, whereas the immature ones are poor in these minerals. The Amazon region is rich in mineral deposits related to lateritic profiles. Some mineral deposits are of primary origin but were concentrated to economic grades by lateritic processes. The most important ore deposits are of iron, aluminum (bauxite), kaolin, manganese, gold, nickel, copper and phosphate. These are mainly related to mature profiles. The wide spectrum of ore deposits and mineralogical and geochemical complexity of the Amazon laterites has been promoted by: (1) the prevalence of ideal conditions for laterite formation throughout much of the Tertiary; (2) the presence of varied basement lithologies due to contrasting geological environments; and (3) a variety of epigenetic alteration types. The lateritic profiles show a well-developed ore zonation which is related to specific lateritic horizons. Iron and gold deposits occur in the ferruginous horizon, which is nearest the surface; the central aluminous horizon hosts bauxites, aluminum phosphate, strontium and gold; and the lower clayey horizon contains deposits of manganese, nickel, copper and kaolin. Resistate phases which residually accumulate throughout entire profiles include titanium (as ilmenite and anatase), chromium (as chromite), tin (as cassiterite), yttrium (as xenotime), and niobium (mainly as ilmenorutile). Epigenetic alteration, caused by swamp environments developed above truncated lateritic profiles, has led to the formation of high-grade kaolin and refractory bauxites. The laterites in the Amazon region contain most of all known kinds of ore mineralization related to laterite processes.

Jan 1, 1997

By Marcondes Lima Costa

The Amazon region is characterized by the development of deep chemical weathering represented by widespread lateritic covers and soils. Two distinct periods of laterite formation can be distinguished: mature laterites from the Eocene-Oligocene (and locally from the end of the Cretaceous), and immature laterites from the Pleistocene. The older laterites occur on plateau landscapes,and the younger ones on widespread hilly to ?at lowlands. Both types show complete or truncated pro?les, generally covered by deep yellow to brown topsoils. The mature laterite pro?les contain high concentrations of gibbsite and/or aluminum phosphate, whereas the immature ones are poor in these minerals. The Amazon region is rich in mineral deposits related to lateritic pro?les. Some mineral deposits are of primary origin but were concentrated to economic grades by lateritic processes. The most important ore deposits are of iron, aluminum (bauxite), kaolin, manganese, gold, nickel, copper and phosphate. These are mainly related to mature pro?les. The wide spectrum of ore deposits and mineralogical and geochemical complexity of the Amazon laterites has been promoted by: (1) the prevalence of ideal conditions for laterite formation throughout much of the Tertiary; (2) the presence of varied basement lithologies due to contrasting geological environments; and (3) a variety of epi-genetic alteration types. The lateritic pro?les show a well-developed ore zonation which is related to speci?c lateritic horizons. Iron and gold deposits occur in the ferruginous horizon, which is nearest the surface; the central aluminous horizon hosts bauxites, aluminum phosphate, strontium and gold;and the lower clayey horizon contains deposits of manganese, nickel, copper and kaolin. Resistate phases which residually accumulate throughout entire pro?les include titanium (as ilmenite andanatase), chromium (as chromite), tin (as cassiterite), yttrium (as xenotime), and niobium (mainly asilmenorutile). Epigenetic alteration, caused by swamp environments developed above truncated lateritic pro?les, has led to the formation of high-grade kaolin and refractory bauxites. The laterites inthe Amazon region contain most of all known kinds of ore mineralization related to laterite processes.

Jan 1, 1997

This paper generalizes open stopes into elliptical cross sections and applies the results of calculations based on the mathematical theory of elasticity to indicate stress distribution on the boundaries of such stopes. These show both compressive and tensile stresses and provide an ex-planation for the development of excessive dilution in shrinkage toping. Introduction T HE stress pattern around shrinkage stopes is identical with that around other stopes under the same physical conditions. However, a shrinkage stope ends as an unsupported open stope, and the method i limited to the stress range within which the rock is generally self-supporting. If it is acceptable to generalize the outline of a shrinkage stope into an elliptical cross section, then the graphs of Geldart & Udd (1) (see also Panek (2) and Denkhaus (3)) provide a good base for approximating the stress distribution as mining progresses. However, with failure conditions in the walls, the axis ratio, as cut

Jan 1, 1964

By M. Sider, D. L. Piron

"The cost of energy is a growing factor in the cost of zinc production. Electrowinning from sulphate solutions with periodical reverse current or from acidic chloride or alkaline solutions could be the way to lower costs. A comparison of the energy consumption for electrolysis shows that the alkaline solution may be considered the most promising alternative. IntroductionZinc electrowinning from sulphate solutions is a very energy intensive process (typical specific energy usage : around 3.1 kWh / kg zinc). This energy consumption represents 35% of the total cost of electrolysis and is the most important cost component.In order to lower costs, the energy efficiency of the sulphate process should be improved or alternative processes should be developed. In this laboratory, that objective has resulted in research on electro winning in sulphate solutions with the use of periodical reverse current (PRC) and in acidic chloride and alkaline solutions.Some of the results obtained in this laboratory and already published and new experimental results reported in this paper make it possible to present a more critical comparison of the energy consumption of the three processes mentioned.ExperimentalThe experiments at constant current were carried out as described previously. Specific conditions are indicated in Table I. Current efficiencies were obtained by weighing deposits.ResultsThe best energy consumptions for electrolysis obtained in this laboratory for the three media are presented in Table I. More detailed results can be found in the papers already mentioned."

Jan 1, 1988

By John Redstone, André R. Laplante

"Le rebroyage des concentrés d'hématite en usine (Sidbec-Normines, Port-Cartier) et en laboratoire a été modélisé selon le modèle de Reid (1965).L'effet du pourcentage solide sur la cinétique de broyage a été étudié en usine. La fonction de sélection corrigée (pour tenir compte de l'effet du pourcentage solide sur le temps de rétention) augmente lorsque le pourcentage solide augmente de 80 à 84 pourcent. Cette amélioration est contrebalancée par une augmentation de la quantité de pulpe court-circuitée, à des pourcentages solides supérieurs a 81%. La densité optimum de broyage se situe à 84 pourcent.Comme alternative au mode d'opération actuel, l'assemblage des broyeurs en série plutôt qu'en parallèle a également été simulée. Le moins 44 µm passe alors de 68.1 à 72.5 pourcent, ce qui correspond à une capacité supplémentaire de 32 tonnes à l'heure par broyeur. Ces résultats doivent toutefois être interprétés avec prudence, car la cinétique de broyage n'est généralement pas linéaire lorsque le taux d'alimentation est plus que doublé.IntroductionL'usine de bouletage de Sidbec-Normines Inc. a été décrite par Morimoto (1977), Lévesque et al. (1979) et Pabst (1979). La section de broyage des concentrés contient six broyeurs à boulets en parallèle et en circuit ouvert, d'un diamètre de 5. 18 mètres et de 10.36 mètres de longueur. Ils contiennent chacun environ 350 tonnes de boulets d'acier forgé de 3.8 cm de diamètre. Le concentré est broyé de 10 pourcent moins 150 µm (100 mailles) à 65-68 pourcent moins 44 µm (325 mailles), à un pourcentage solide de 78 à 80 pourcent. Cette fragmentation poussée exige une consommation d'énergie de 32 kWh/tonne. Cette énergie est surtout libérée sous forme de chaleur, la pulpe étant déchargée a une température de 68-72° C. II en résulte un milieu de broyage corrosif, et une consommation de boulets élevée, de 3.4 à 4.0 kg / tonne broyée."

Jan 1, 1983