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By H. Utsunomiya

Most magnesium alloy sheets show low deformability in rolling. Edge cracks and transverse fractures are common difficulties. In addition, rolled sheets show well-developed basal texture <0001>//ND. The texture causes high anisotropy in mechanical properties and low formability in subsequent metal forming. Differential-speed rolling, where the upper and the lower rolls rotate at different speeds, introduces shear deformation through the thickness. Not rolling texture but shear texture evolves in the sheet so that the asymmetric rolling can be a method of texture control. However the primary slip system of the hcp alloy, is basal, the shear texture should be also basal. Differences between the two basal textures, i.e., the rolling texture and the shear texture, have not been understood completely. In this study, conventional (same-speed) rolling and differential-speed rolling have been applied to commercial AZ31B sheets at 623K. Microstructures, textures and mechanical properties of the rolled sheets before/after annealing are compared. It is found that the basal texture is more pronounced by the asymmetric rolling. On the other hand, the asymmetric rolling is effective to decrease the grain size and the planar anisotropy.

Jan 1, 2006

By D. P. Fenton

The Phelps Dodge El Paso Rod Mill produces approximately 2.4 million pounds per day of copper rod from a casting and rolling operation. The newly formed rod is treated to remove mill scale and oxides using a sulfuric acid and hydrogen peroxide solution which is bled periodically when the copper concentration reaches 30-35 g/L. The bleed solution is heated to 75° C to destroy the residual peroxide. Copper is then recovered in a 270 cell EMEW electrowinning plant. Clean acid is also regenerated in the EMEW plant and is returned to the rod cleaning circuit. The EMEW plant commissioned in January 2006, has two operators and replaces a copper sulfate plant with fourteen operators. The EMEW plant has a capacity of 1700 kg/day of cathode copper at 2.1 kWh/kg copper deposited. The electrowinning plant operates in closed circuit with the rod mill returning up to 2600 kg/day of sulfuric acid resulting in zero discharge. Use of dimensionally stable anodes (DSA®) ensures that the acid quality is maintained in the closed loop operation. The operating conditions, performance and plant experience of the EMEW copper and acid recovery plant are discussed.

Jan 1, 2007

By Anna Szostak-Chrzanowski, Adam Chrzanowski

"New techniques in monitoring surveys and new methods in the analysis and prediction of ground subsidence are being developed in the Department of Surveying Engineering at the University of New Brunswick (UNB). The new surveying techniques include a telemetry monitoring system developed at UNB in cooperation with CANMET, and use of the satellite Global Positioning System. A generalized approach to the analysis of deformation surveys has been developed which permits an integrated analysis of geodetic and geotechnical measurements in geometrical modelling of ground subsidence. A computer program, FEMMA, has been developed for the elastic and non-linear elastic analysis and the deterministic prediction of deformations using the finite element method.IntroductionResearch and development of new monitoring techniques and new methods in the analysis and prediction of ground subsidence in mining areas is an integral part of a broad research program on deformation surveys which is being carried out in the Department of Surveying Engineering at the University of New Brunswick.The research concentrates on:developmentof a general method for predicting deformations with an emphasis on the use of the non-linear elastic finite element analysis; development of a generalized approach to the geometrical analysis of deformation surveys with an integration of geodetic and geotechnical measurements; and development of new monitoring techniques with an emphasis on continuous data acquisition and application of new space techniques such as the satellite Global Positioning System (GPS).This paper gives a brief report on the progress and recent developments within the above program."

Jan 1, 1987

By T. P. Johnson, A. Vathavooran

"Conventional mining operations can produce a wide range of wastes containing gold and other precious metals but which are less suitable for processing by traditional methods. There are also types of ore that do not fit easily into a traditional processing flowsheet, e.g. because the refractory nature of their minerology or the combination of valuable metals is less suitable for traditional processes. Nevertheless, these potential sources of valuable metals remain unexploited resources that have attracted growing interest in the metals and mining industries over recent years. The challenge is therefore to develop and use alternative processing methods that have the flexibility of operation to cope with a wide variety of material types and tonnages, whilst providing high recoveries for valuable metals. Tetronics’ DC plasma smelting technology achieves industry-leading recovery rates for precious metals from a wide range of input materials and initial precious metal concentrations, whilst generating an inert slag-based material as a by-product (even when starting from a hazardous waste input material), approved within the EU for use in construction applications. This paper describes how this technology can be used as a key part of an overall process for the recovery of precious metals from these interesting materials.INTRODUCTION The extraction of gold from its ores by various forms of cyanide leaching has been practised by the mining industry for over a century (Minerals Council of Australia, 2005) and it remains the primary extraction method in a wide range of mining operations. The ability of cyanide to extract gold efficiently and quickly from lower grade ores without extensive additional processing, coupled with well-known methods to recycle the cyanide for re-use within the process mean it is often both the most economically preferable and environmentally acceptable method for recovering gold. As a result, 88% of all gold produced from mines in the USA in 2014 was recovered via leaching of open heaps or dumps (UGGS, 2016). Nevertheless, there are occasions where certain combinations of mineralogy and other circumstances reduce the effectiveness of cyanidation techniques, so that ever more elaborate additional processing steps are required, with inevitable increases in operating costs (Swash, 1988). In these circumstances, which are likely to be more common in future as ore qualities diminish, other methods of extraction may offer better alternatives. Whilst much less commonly used for Au extraction at present, pyrometallurgical methods are amongst the longest-established of these alternative approaches and merit serious consideration in such cases."

Jan 1, 2017

By E. L. Bruce

EUROPEAN Russia is mainly a great plain, the average elevation of which is only 600 feet above sea level and the maximum elevation less than 1,200 feet (Figure 1). The main divide between the Arctic ocean and the Black sea and Caspian sea is an indistinguishable topographic feature from which the Dneiper and Don rivers flow southward to the Black sea and the Volga river to the Caspian. The valleys of these rivers are but little below the general level (Figure 2). To the south, this great, rolling plain is broken by a low ridge of Precambrian gneisses and intrusive rocks. The Crimea is an upland from which the descent to the Black Sea coast is precipitous (Figure 3). The Ukrainian Soviet Socialist Republic occupies the southern part of the plain. It is the southwestern unit of the Union, bordered by Rumania and Poland on the west and by the Crimean Soviet Socialist Republic on the south.

Jan 1, 1938

By D. J. Farmer

Mining hoists are major components of any underground mine, however, the detailed design work required to get the actual power required for a particular hoist is outside the scope of preliminary feasibility studies. Nonetheless, a hoist is costly. Therefore, an accurate estimate is needed for the design parameters and the power required. There are two methods available, namely, the O’Hara method and the Society of Mining Engineers’ method. Tests were done for both methods employing nine friction hoists and 19 drum hoists currently in use at Canadian mines. The O’Hara method provided unacceptable results for both friction and drum hoists. While, the SME method was designed for American regulations and factors of safety which often differ significantly from Canadian ones, good results were obtained. The two relationships deter-mined were simply to add 5% to friction hoist design and to add 4% to drum hoist design. Modifying the SME method by these two factors will allow the hoisting system determined by the SME method to be within the error for a prefeasibility study.

Jan 1, 1997

By Charles Camsell

If it were necessary to preface a discussion of the mineral position of the Empire by justifying one&apos;s interest in that subject, there are two points that at once suggest themselves by way of vindication. Tremendous Growth of MINERAL Consumption The first of these points has to do with the general question of the world&apos;s mineral consumption. Most thinking persons appreciate in a more or less vague way the vital rôle that has been, and is being, played by mineral products in building up the material side of our modern civilization. But, apart from that casual and almost subconscious appreciation, very few have any precise knowledge of the extent to which the growth and the operation of our vast present-day industrial structure has been made possible by, and only by, a tremendous increase in the consumption of mineral products of all kinds. The increasing use of minerals confronts us today at almost every turn. It does not matter in what direction we look-at the expansion and the change in transportation facilities, in the air as well as on land and on sea; at the increasing mechanization, not only in factory and mill but even in our domestic life; or at the constantly widening use of machinery for all phases of farm production-everywhere we meet the same phenomena of rapidly growing uses of equipment produced mainly from minerals. Without resorting to any tiresome statistics, a few figures may suffice to indicate with what enormous strides the world&apos;s mineral consumption has been advancing. The figures for recent years may be open to objection on the plea that, ever since the outbreak of the world war, conditions have hardly been sufficiently normal to give us trustworthy data-we have been living under extremes either of depression or of abnormal stimulation. During the last decade before the war, however, from 1903 to 1913, the world was moving along in a quietly prosperous manner; and we have figures, or at least reasonably reliable estimates, as to the growth in mineral consumption during that decade.

Jan 1, 1932

By R. L. Bruening, R. M. Izatt, N. E. Izatt, S. R. Izatt

"Molecular Recognition Technology (MRT) is a simplified, green chemistry process with applications in selective separations of Ni(II), Co(II), and platinum group metals in primary ore beneficiation processes and secondary recovery operations from spent products, scrap, and environmental waste solutions. Simplification in MRT processes is achieved by non-use of solvents, reduced space requirements, and a simple separation system involving columns packed with metal-selective SuperLig® resins. Minimal waste is generated and metal recovery is achieved at 99% levels from g L-1 to <mg L-1 concentrations. MRT systems are attractive technologically and economically compared with solvent extraction, ion exchange, and precipitation separation processes. Commercial examples of MRT use include removal of impurity metals Cd, Cu, Ni. Fe, and Pb to mg L-1 or lower concentration levels from Co streams to produce battery-grade Co. Highly purified Co is required for optimal function of lithium ion rechargeable batteries and superalloys associated with aerospace and gas turbine operations. Impurity metals are recovered for reuse or proper disposal rather than being discarded to landfill. Green chemistry processes, such as MRT, are needed in metal separations going forward into the 21st century to achieve global metal sustainability in processing of native ore and treatment of secondary sources.INTRODUCTION Maximizing efficiencies of metal separations and optimizing metal recovery rates during separation processes are important goals on the road to achieving metal sustainability. Achievement of these goals is consistent with stated principles of green engineering (O'Connor, Zimmerman, Anastas, & Plata, 2016) and green chemistry (Anastas & Eghbali, 2010). Molecular Recognition Technology (MRT) separation processes using SuperLig® resins have a 25-year record of performing competitive, commercial metal separations with metal recovery rates approaching 100% (Izatt, Izatt, Izatt, Krakowiak, & Bruening, 2017). SuperLig® resins are characterized by high selectivities for specific metals over concentration ranges from g L-1 to mg L-1 or lower. MRT systems use no solvents and are simple in design and operation resulting in reduced capital and operating expenses."

Jan 1, 2017

"The successful commissioning and ramp up of the Albion Process™ at the GPM Gold Project relied on the successful scaling up of the process from batch and continuous pilot plant campaigns (Voigt et al., 2015). Critical information about reaction kinetics and residence time, grind size and pulp density were determined at the laboratory scale and successfully applied to the commercial scale. A limitation of small scale testwork, is that some parameters cannot be measured reliably and scaling up is a function of the physical size of the equipment which isn’t possible to test with laboratory scale equipment. Oxygen mass transfer rate is one such parameter since this is a complex interaction of many factors including slurry temperature, solution and slurry chemistry, slurry viscosity, agitator type, dimensions and power, oxygen bubble residence time, oxygen purity, tank geometry and oxygen injection technique. Oxygen generation represents an important operating cost for the Albion Process™. Pivotal to the Albion Process™ operating economically at atmospheric pressure is the capability to efficiently transfer oxygen while utilising as much oxygen injected to the process as possible. To respond to this Glencore Technology developed the HyperSpargeTM supersonic gas injector. This paper compares the HyperSparge™ against other sparging techniques to quantify the benefits of oxygen injection via a supersonic gas jet on scale up of the oxygen mass transfer system. The paper then examines plant survey data from the GPM Gold Project to demonstrate the very high oxygen utilisation that can be achieved with a correctly designed oxygen mass transfer system.INTRODUCTION One of the main challenges in chemical reactor design is the scale-up of processes from the laboratory to industrial scale. Processes which cannot be faithfully simulated with an experiment at the laboratory scale face challenges due to the physical dimensions and complexity of full scale operation. One example of this is the design of oxygen mass transfer systems in atmospheric oxidative leaching circuits such as the Albion Process™. A number of constraints associated with the use of laboratory scale equipment to design full scale circuits are involved in gas mass transfer processes in agitated slurries such as the Albion Process. Chiefly, typical laboratory and pilot size equipment lacks the required volume to provide useful design data without relying on empirical correlations: the specific agitator power input is artificially high, the bubble residence time in the vessel is artificially low, the oxygen partial pressure at the base of the vessel is artificially low and the oxygen delivery method may differ significantly to the industrial process. Further, the dynamic nature of the process introduces additional impacts on gas mass transfer, including the presence of solids, recycle streams and minor elements, plus the variances within the reality of a process plant such as disruptions or variance of feed quality."

Jan 1, 2017

By Sandeep Singh Sandhu, Karanvir Singh Ghuman, Manjit Singh

"Cobalt based super alloy stellite 6 was weld cladded on AISI 304 L stainless steel using SMAW process in order to improve the wear resistance for tyre crusher blades. Microstructure characterization and micro hardness testing was performed on stellite 6 cladding. The suitable parameters viz. 80 Amp current with arc weaving technique was selected by performing bead on plate experiment were further used for depositing multipass multilayer cladding to achieve full filler chemistry at the top surface. Further GTAW process was used for re-melting the top surface of the cladding. Comparative evaluation of the claddings showed that TIG re-melting resulted in increased microhardness and wear resistance in comparison to as cladded specimens even with lesser deposition of material. It was observed that TIG re-melting improved the hardness from 603 HV0.5 kg to 712 HV0.5 kg. Micro structures of stellite 6 contained cobalt solid solution matrix along with inter dendrite chromium carbides which resulted in the increased micro hardness values. Pin on disc abrasion tests were carried out at room temperature and the worn out surfaces were characterized using SEM and EDS.INTRODUCTIONThe crusher blades are used in many industries for crushing various types of material and its wider applications in tyre rubber crushing mills, metal-powder crushers industries etc. Most of the crusher blades are damaged by the wear and impact loading conditions. It is because of metal to metal abrasion and the temperature also plays a vital role in blunting the cutting edges of these blades. The wear is the major cause which leads to loss of material and thus the productivity that can never be recovered (Kotechi et al., 1992). The wear can be reduced by coating of various super alloys which could reduce the behavior of metal degradation even in aggressive environments. Cladding of cheaper low alloyed material with expensive superalloys to enhance the performance of components at low cost has been investigated by many scholars (Deng et al., 2010, Kennametal, 2007, Lolla et al., 2014, Singhet al., 2014, J.N et al., 2003, Ramkumar et al., 2012). Many researchers have reported that cladding is an application of build-up deposits of specialized alloys to resist abrasion, high temperature corrosion and impact loadings. Cladding is used for providing required mechanical strength properties as well as inhibition of oxidation and other corrosive degradation. Coatings are used to protect the heat affected areas like tubes of fluidized bed combustor etc. (Kirchbner et al., 2008, Wang et al., 1994, Hocking et al., 1993, Ananthapadmanabhan et al., 1991, Staia et al., 2001). Coating techniques are widely used for the protection of turbine engine and boiler tubes against high temperature corrosion attack, power generation equipment, chemical process equipment, aircraft engines, pulp and paper processing equipment, bridges, rollers and concrete reinforcements, orthopedics and dental, land-based and marine turbines, ships. Coatings of stellite 6 are widely used in steam turbine blades and boiler tubes for power generation because of an excellent combination of impact, wear and other properties. It can maintain its properties even at high temperature and in harsh environments (Kobayashiet al., 1999, Alam et al., 2009, Munehru et al., 2009). The loading and unloading conditions experienced by the material may induce the surface cracks which lead to its breakage and leaving large pits in the surface (Meng et al., 1995). Many researchers have reported that the properties of cladded layers can be increased by various techniques such as controlling the current variations, dilution, heat input, laser and other re-melting processes, addition of special alloying elements, speed of weldingetc(C.M Anaet al., 2002, Kumaret al., 1999, Luo et al., 2012, et al., Madadi et al., 2011, Shin et al., 2003, Kuzucu et al., 1997, Sudha et al., 2008, Sawant et al., 2017, Houdkova et al., 2016, Ciubo"

Jan 1, 2017

By Stephen Esposito

Outline ? Brief Overview of Solid Energy New Zealand ? Need for Integrated Risk Management at Solid Energy New Zealand ? Overview of Solid Energy?s IRM program ? What are the results and key learnings? Overview Of Solid Energy New Zealand ? 100% NZ Government Owned ? Produces 95% of New Zealand?s Coal ? Sales turnover USD150 million per year ? Sold 4 million tonnes of high quality coal in 2003 ? Coking and Thermal coals ? Exported 2 million tonnes of coal ? Significant international and domestic growth expected going forward

May 1, 2004

By D. W. Ginsberg, D. Cieplinski

"The lifetime cost of a material handling system, or any mine system, can be reduced through the application of quality engineering. Dynamic simulation is a powerful tool that can be used to enhance the experience and ingenuity of the design team. It cannot only de-bottleneck the system to improve system productivity, but also define critical design criteria to eliminate over-design and reduce capital cost. Eliminating over-design also reduces operating costs by lowering component replacement costs and by ensuring all parts of the system operate at a higher utilization and efficiency. IntroductionA mine owner’s profitability is improved when a mine is developed at the lowest lifetime cost. This cost relates not only to capital and operating costs, but also, to a great extent, on the efficiency and reliability of the operation. These factors are tied directly to the quality of the engineering which depends on the experience of the engineers involved, and their ability to apply known system information in a rational and constructive manner.It is becoming apparent that it is increasingly more difficult to deliver the quality of engineering expected and needed to provide attractive lifetime costs using traditional design methods. Historically, system information has been evaluated based on a limited amount of information to which global rules-of-thumb and the engineer’s personal experience were applied to develop design criteria. However, market forces are dictating that more system parameters be defined and that they be defined more accurately so that the most economical system can be developed. This increase in the volume of information and the need for more accurate predictions is straining, if not already exceeding, the ability of engineers to apply simple global rules of- thumb and to combine all the information in a rational, comprehensive and representative set of design criteria. Furthermore, as proposed system production rates increase beyond established industry practice, the extrapolation of the engineer’s experience becomes more difficult and increases the risk in the proposed design."

Jan 1, 1998

By Ahmad Ghahreman, Lin Li

"In this study, the Fe(II)/Fe(III) redox reaction kinetics on the surface of pyrite, have been investigated in a 0.5 mol L-1 sulfuric acid solution for a temperature range of 22 to 65°C. Based on mixed potential theory, chronoamperometry is introduced to study the Fe(II)/Fe(III) kinetics by subtracting the current density of pyrite oxidation in an iron-free acidic solution from that in an iron-containing solution at the same applied polarized potential. Tafel behavior was established by this method to analyze the kinetics of the Fe(II)/Fe(III) redox reactions. The results showed that exchange current densities increased slightly with temperature, however remained on the order of 10-5 A cm-2. The activation energy for Fe(II) oxidation and Fe(III) reduction on the pyrite surfaces was calculated to be 102.0 and 32.7 kJ mol-1, respectively. Anodic transfer coefficients also increased, from 0.24 to 0.39, with increasing temperature, which indicates a weakened n-type semiconductor property at higher temperatures. Electrochemical impedance spectroscopy measurements have indicated that at lower anodic over potentials the charge transfer is the rate determining step of pyrite oxidative dissolution in sulfuric acid solution. In the presence of Fe ions, the major contribution of the total current density comes from the Fe(II)/Fe(III) redox reaction. INTRODUCTION Pyrite, an abundant sulfides mineral in the nature, is commonly considered a valueless gangue mineral frequently associated with other valuable sulfide minerals such as chalcopyrite, or metals such as gold, or coal (Lin & Say, 1999). Pyrite oxidation has been the subject of extensive research in view of gold metallurgy, as oxidation of pyrite is the initial step to break down the pyrite lattice and expose the encapsulated fine gold particles (Gasparrini, 1983). Fe(III) ion and dissolved oxygen (DO) have generally been considered as the two most important oxidants with respect to pyrite oxidation, having been studied extensively in previous research (Zheng, Allen, & Bautista, 1986; King Jr & Lewis, 1980). The process of pyrite oxidation can be viewed as a series of reactions amongst pyrite, ferrous, ferric and oxygen in which pyrite is initially oxidized by the dissolved oxygen in water forming ferrous (Eq. 1), and then the ferrous also is oxidized by he dissolved oxygen to form ferric (Eq. 2). The ferric, produced by reaction 2, then could potentially oxidize pyrite (Eq. 3) and convert to ferrous."

Jan 1, 2017

By A-A. Bogno, M. Rappaz, J. Valloton, H. Henein

"Rapid solidification of Al-Cu droplets of eutectic composition was carried out using Impulse Atomization in an argon atmosphere, to study the microstructures forming at different cooling rates and undercoolings. Two distinct morphologies were observed within the investigated Al-33wt%Cu droplets microstructures: (i) A regular lamellar morphology and (ii) an undulated morphology. The volume fraction of each type of morphology was measured as a function of the droplet size and the nucleation undercooling was deduced using the hypercooling limit equation. The scale of the microstructures was determined through measurements of inter-lamellar spacing across and along the growth direction. Growth velocity and undercooling were deduced using Jackson and Hunt (1966) eutectic growth theory. Finally, mechanical properties were estimated through micro-hardness analysis using a Vickers hardness tester, revealing exceptional properties for an aluminum-copper alloy. Indeed, the hardness values, increasing with growth rate and undercooling, were 3 times higher than the values obtained in hypo-eutectic Al-Cu alloys.INTRODUCTION Eutectic alloys are very attractive due to their good fluidity allowing ready shaping of parts in casting processes as well as in thermal spray deposition. In addition, they yield microstructures with high mechanical properties, by the virtue of their scale/size which is defined by the solidification parameters and the thermodynamic and thermophysical properties of the given alloy. Therefore, it is important to understand the relationship between the microstructures and the solidification parameters of eutectic alloys in order to control their solidification path and mechanical properties. The latter could be improved by either adding an appropriate strengthening component to a base eutectic material (Böyük, MaraslI, Kaya, ÇadIrlI, & Keslioglu, 2009) or by refining the microstructures for more effective dislocation pinning (Campbell & Campbell, 2003). Tailoring the microstructure can also be beneficial to chemical (Freitas, Osório, Spinelli, & Garcia, 2014; Osório, Freire, Caram, & Garcia, 2012) or electrical (Kaya, 2012) properties of the material. Eutectic-type microstructures, usually formed from liquid (eutectic transformation) or solid (eutectoid transformation), are made up of two or more different phases, generally of lamellar or fibrous (rod like) morphologies (Kurz & Fisher, 1998). In general, a binary eutectic structure can be regular (when both phases are non-faceted) or irregular (one of the two phases is faceted), the two solid phases having roughly the composition of the liquid from which they are formed."

Jan 1, 2017

By D. Yamada, T. Tanaka, N. Inouchi, J. Nakahigashi, H. Yoshimura, T. Nonishi

The use of cereal food materials as lubricants was investigated in an attempt to develop nonpolluting lubricants. Suspensions of wheat flour in water and other types of cereal food lubricants were prepared and their friction coefficients measured. The results indicate that a cereal food lubricant containing 30% lipids, 2% proteins, 60% carbohydrates and 0.6% calcium carbonates has the lowest friction coefficient for a sheet (cpTi-1). As example applications, the lubricant was tested with a forming press and a screw-fastening device. In both applications the cereal food lubricant performed relatively well in comparison to conventional lubricants and thereby has potential for practical applications.

Jan 1, 2006

By K. E. Waters, N. Brodusch, R. Gauvin, A. Jordens, Teng. C., H. Demers

Rare earth elements (REEs) become increasingly significant for renewable energy devices and high-technology electronic products because of their large-scale popularity and applications. In this project, a field-emission scanning electron microscope was used to characterize the composition and distribution of REEs-bearing minerals. X-ray elemental maps were acquired with a large area x-ray detector (60 and 80 mm2 collecting area) and annular detector (60 mm2 collecting area), which allow fast x-ray acquisition at high count rate. These elemental maps were transformed into phase maps, which are used to identify the composition of the mineral phases and the REEs distribution over a large area. The phase maps are an easy way to distinguish the phases with and without REEs and compare the efficiency of different REEs extraction processes. Different methods (manual and automatic) for producing phase map were studied by comparing the distribution of REEs obtained from the same area.

Jan 1, 2015

By G. P. Holmes

"Bell Copper is situated (Latitude 55°0''N, Longitude 126°14W) on Newman Peninsula on the east side of Babine Lake at an altitude of 2,450 feet above sea level. The mine site is approximately 170 miles north west of Prince George and 40 miles east of Smithers. Access to the property is by way of 30 miles of paved road to the Village of Granisle on the west shore of Babine Lake and then a further 9 miles of unpaved road to Bell Copper's west dock. The two mile lake crossing is made using a tug and barge. A compressed air bubbler system maintains an ice free channel for the barge during the winter months.Temperatures range from summer maximums of around 32 °C to winter minimums in the region of minus 40°C. Long periods in winter may be spent with temperatures in the range of minus 15""C to minus 28°C. Freezing temperatures usually start in October and last for six months. The lake normally freezes over in mid December and the ice breaks up in mid May. Snow accounts for approximately two t11irds of the annual precipitation of twenty-one inches."

Jan 1, 1976

By A. Blackmore, D. Baker, L. Human

"Mechanical mixing equipment is common in a wide variety of mining, metals and process applications, such as hydrometallurgical reactors, solvent extraction, digestors, and tanks for storage of slurry or hydrocarbons. Computational Fluid Dynamics (CFD) has been applied successfully to single-phase mechanical mixing problems for several decades and is established as a reliable design tool. As computational power and CFD codes have improved over the years, there have been significant advances in modelling capabilities including improved models of turbulence, interaction of rotating and stationary components, multiphase flows, and modelling of free surface interfaces, for example. This paper will provide an overview of the application of CFD to mechanical mixing problems. First, it will review the traditional single phase Multiple Reference Frame (MRF) approach and introduce a range of advanced modelling techniques. Three examples of the application of CFD to industrial mixing problems will be given. It will be demonstrated that CFD is an effective tool for reducing technical risk in design, for identifying the root-cause of mixing problems, and testing modifications to existing operations."

Jan 1, 2015

By Mostafa Benzaazoua, Bruno Bussière, Jean Lelièvre

De nombreuses opérations mimères exploitent et traitent des minerais sulfurés pour concentrer des métaux precieux (Au, Ag ... ) OU des métaux de base (Cu, Pb, Zn ... ), laissant en fin de parcours des tonnages considérables de résidus plus ou moins générateurs de drainage minier acide (DMA) selon leur contenu en sulfures. De nos jours, Jes restrictions en matière de protection de l'environnement obligent Jes opérateurs miniers a trouver Jes solutions Jes plus efficaces pour préserver Jes sites environnants de la pollution due a l'oxydation des sulfures. Cette oxydation cause une acidification accrue du milieu et une mise en solution des metaux toxiques. L'utilisation des recouvrements multicouches est l'une des solutions Jes plus efficaces pour limiter la pollution liée au DMA mais entraine des coilts de construction qui sont souvent considérés par l'industrie miniere comme prohibitifs. Une façon de rendre cette technologie applicable, d'un point de vue économique, est de désulfurer Jes résidus à l'usine de traitement et d'utiliser la fraction inerte comme composante d'un recouvrernent multicouche. Cette opération de desulfuration peut etre réalisée par flottation non sélective des résidus dans le but d'obtenir d'une part un faible volume de concentré de sulfures qui devra être géré convenablement et d'autre part un rejet non générateur d'acide.

Jan 1, 1998

By E. R. Dixon

Copper SX/EW plants often bleed part of their electrowinning electrolyte to control impurities and maintain consistent cathode quality. Depending on the specific situation at each site, the bleed is either returned to raffinate, to an SX extraction stage, to an SX wash stage, or to the PLS pond, to avoid losing the copper in the bleed. This practice can have undesirable effects on the overall process. An alternative is to electrowin all or most of the copper in the bleed, thus avoiding the recirculation of the copper in the bleed. In this manner, the bleed is converted to metallic copper without interfering with the SX circuit. This in turn reduces the copper concentration in the raffinate, improving global copper recovery because of improved leaching conditions.

Jan 1, 2007