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By G. R. Haiden, E. Henderson

"An LHD teleoperation and guidance system, developed at the Ontario Division of Inco Limited, has been demonstrated in operation at Copper Cliff North Mine (CCNM) since late September, 1993. The tests performed to date have evaluated the feasibility and production viability of multiple LHD operation, from surface by one operator.The systems technology required to accomplish this consists of an electronic monitoring and control package mounted on the LHD; a high bandwidth mining computer network capable of providing radio frequency coverage; and an operator control console which provides an operator workstation for multiple LHD operation.This paper discusses the systems required to accomplish the task of LHD teleoperation and guidance, the benefits of multiple machine operation and future research and development directions. IntroductionSince underground mining began, persolU1el have entered the mine workings to mine ore. Today, however, the rapid advancement of modem telecommunications, computer hardware and software technology has opened the door to remote mining technology that was considered unfeasible a few years ago. This paper discusses the ingredients of remote mining technology that have been developed at Inco Limited.Figure I represents an historical view of the application of electronics to LHD operation at Inco Limited. In 1980, the first radio remote controls for the operation of LI-IDs in large open stopes were tested. The successful application of this technology at Inco went hand-in-hand with the development and application of the Vertical Crater Retreat mining method. The combination of these two advances had a very positive effect on the productivity in the mid-eighties at Inco. In 1991, the Mines Research Department of the Ontario Division advanced remote control technology by developing a high capacity underground mining telecommunications system. This system is capable of moving voice, data and video information throughout the mine workings. The system is based on broadband communication technology found in most automated factories, with the added benefit of providing the information to and from mobile equipment through radio interfaces. The first test of the system consisted of an operator teleoperating a single LHD (on the 3000 ft level) from the surface. The next test on September 13, 1993, demonstrated the first production application of multiple LHDs being run from surface with a single operator."

Jan 1, 1994

By M. Fairman

The effect of welding speed on the microstructure of friction stir processed (FSPed) AZ31B-H24 magnesium alloy was studied using light microscopy, image analysis, and microhardness tests. The grain size of the magnesium alloy was observed to increase after FSP from about 3.5 µm in the base alloy to about 8 µm in the stir zone. The aspect ratio decreased from 1.60 to 1.55 towards the center of the stir zone. The changes in the grain size and shape caused the microhardness of the samples to drop significantly across the FSPed region from 75 HV in the base alloy to below 55 HV in the stir zone. Decreasing the welding speed increased the grain size due to a greater input of heat energy. The faster heating rate due to the lower welding speed caused a deeper penetration of the annealing effects of FSP. It was also observed that the annealing effects caused by FSP were less pronounced with increasing distance from the interface between the sample and pin tool shoulder. The Hall-Petch type relationship of the micro-indentation hardness as a function of the grain size was observed to hold true after FSP.

Jan 1, 2007

By Franc R. Joubin, Donald H. James

"The Algoma (or Blind River) uranium district is centred in an area of some 600 square miles on the north shore of Lake Huron, about half way between Sudbury and Sault Ste. Marie, Ontario (Figure 1). Its favourable location, adjoining the main provincial highway and Canadian Pacific Railway line which follow the lake shore, has contributed greatly to its rapid development.By Canadian standards, the district has long attracted geological attention, beginning with the discovery of the Bruce mine in 1846. It has been repeatedly prospected at intervals since then, chiefly for copper and nickel but also for lead, zinc, cobalt, silver, iron, and gold. Numerous discoveries have prompted the suggestion by Yates (13) and others that one metal-logenic province embraces the entire mineralized area from Michigan through Sudbury and Cobalt.Geological mapping was initiated by Murray in 1847, and the area attracted much interest as the type locality of the Huronian, the correlation and stratigraphic position of which are still not entirely agreed on. Subsequent contributors to the geological literature of the area have been very numerous, and the bibliography at the end of this paper includes only some of the more modern reports.The history of uranium in this part of Ontario also dates from 1847, when J. L. LeConte identified as uranium-bearing a pitchblende-like mineral which he named ""coracite"". The specimens came from Theano Point, north of Sault Ste. Marie. In 1948 a search for the source of these specimens led to the discovery of the Camray uranium field. Occurrences in this field consist of numerous small and locally rich pitchblende-bearing fractures, within or along the contacts of diabase dykes cutting Archaean granite and gneiss.None of the showings explored proved large enough to justify production, but they stimulated prospecting of adjoining areas and thus led to the Algoma discoveries.The first find of radioactive conglomerate in place was made in 1949 in Long township, and it was partially staked as the Fisher-Audette-Breton property. Rusty, overgrown rock-cuts indicated that the pyrite-bearing conglomerate had been investigated years before, probably during searches for base metals and gold. Examinations were made at this time by a number of geologists, including the senior author. In spite of high radioactivity, sampling returned only negligible uranium. The claims were allowed to lapse and the showings reverted to obscurity."

Jan 1, 1949

By Q. Ricoux, F. Goettmann, A. Maihatchi

"Electrodeposition processes are widely used in the metallurgical industry to produce, extract and refine metals from various feed materials. However, raw materials used to provide non-ferrous metals often contain high amounts of iron. In the presence of iron, while metals are plated at the cathode, electrowinning processes produce corrosive and highly oxidative ferric ions at the anode that are harmful for the process sustainability. In fact, these ferric ions cause dramatic current efficiency loss, induce high maintenance expenditures to limit the corrosion of devices and it results in the formation of impure and dendritic deposits on the cathode. Consequently, the management of iron in electrodeposition process became a major issue in non-ferrous metals production. Actually, numerous methods have been developed to limit the ferric ion concentration in the electrolyte or, at least, to limit its harmful effect. Many methods aim to limit the iron(III) concentration in the electrolyte, generally by coupling electrowinning to extraction process such as solvent extraction (SX) (Bender & Emmerich, 2015), ion exchange (IX) (Gula, Dreisinger, & Horwitz, 1996) or cementation (Kust, 1979) processes to remove ferric ions. Other routes consist of (i) using the ferric ions oxidant properties to leach raw materials, either directly in the electrolytic cell (Fanta & Tributsch, 1975) or through a secondary circuit (Cain, 1950), or (ii) reducing ferric ions through periodic reversal of direct current to enhance the formation of Fe2+ (Loutfy & Bharucha, 1980). On the other side of the spectrum, papers discuss methods to valorize the iron from by-products of the non-ferrous metal industry, that generates vast quantities of iron containing wastes (A. Agrawal, Sahu, & Pandey, 2004). Many studies on iron electroplating and electrolytic iron production from ores have been carried out (Cain, 1950; Mostad, Rolseth, & Thonstad, 2008), but very few have been conducted on waste or by-products. Therefore, we propose to build on the previous literature review to develop a process for the production of electrolytic iron from by-products.INTRODUCTIONNon-ferrous metals and their alloys are used in a large variety of applications. Aluminum and titanium are used for their strength, light weight and corrosion resistant properties in structural applications. Copper has been used in various applications requiring high thermal and electrical conductivity, as kitchen products and electrical wires. Nickel and zinc are commonly used as plating materials; nickel offers a wide range of working temperature and zinc is used for steel plating. Gold, silver, and platinum group metals are used in electrical/electronic applications, jewelry and chemistry as catalysts."

Jan 1, 2016

By P. C. Holloway, M. J. Collins, K. R. Buban

Historically, there has been little incentive to process copper-arsenic concentrates by leaching, rather than via established smelting operations. However, with ever tightening environmental emission standards and more arseniferous concentrates being produced, increasingly sophisticated and upgraded off- gas handling facilities are required in smelting operations, generating greater quantities of challenging metallurgical dust. In this context, oxidative pressure leaching offers distinct advantages. The current state of pressure leach technology delivers high extractions from copper concentrates, while producing an environmentally stable process residue, without atmospheric emissions of sulphur dioxide or arsenic. However, as was shown in an earlier study, copper extractions and environmental leach residue stability are impacted negatively by arsenic levels above 2.5 to 3.0 wt%. In further studies on pressure leaching of copper concentrates, Sherritt has developed process conditions that allow even highly arseniferous (> 7 wt% As) feed materials to be converted into environmentally stable residues, with excellent copper extractions. At the same time, pressure leach residues can be generated that are amenable to silver recovery via direct cyanidation, without pre-treatment by lime boiling or hot curing. The results of pilot plant test work are discussed. INTRODUCTION As the production of copper has expanded over the years, resource exploitation has extended beyond relatively clean, high grade and easily accessible ores, and copper sulphide concentrates increasingly come with higher levels of contaminants, such as As, Hg, Sb and Bi, and lower copper and sulphide sulphur concentrations. However, as concerns on the impact of the emission of such contaminants into the natural environment have mounted, import/export restrictions have made the trading of copper concentrate more difficult, and, in particular, the export of concentrates with greater than 0.5 wt% As; under ever tightening environmental emission standards, these lower quality concentrates can be a significant strain on the off-gas handling facilities in smelting operations. The processing of arsenic bearing copper concentrates is, therefore, an increasing challenge as copper producers seek to exploit more complex mineralization and to extend the life of their operations. In this environment, processing arsenical copper concentrates with high temperature pressure leaching (>200°C) must be considered as an alternative to pyrometallurgical processing. Leaching kinetics for copper minerals at these temperatures are rapid and acid is generated for potential use in heap leach operations. Pressure leaching of copper concentrates eliminates gaseous emissions of arsenic and sulphur, while generating environmentally stable residues, as measured by the Toxicity Characteristic Leach Procedure (TCLP) (Kalanchey et al., 2007). Both medium and high temperature pressure leaching of copper concentrates have also proven themselves technically on an industrial scale (Marsden et al., 2004) with high copper recoveries.

Jan 1, 2019

By Sarah Belair, Gauthier Deblonde, Valerie Weigel, Alexandre Chagnes, Gerard Cote

"Niobium and tantalum are strategic metals for electronic and alloys industries. They are produced by pyrometallurgy and hydrometallurgy but most of the niobium and tantalum production processes are not environmentally friendly. For instance, in the hydrometallurgical route, niobium and tantalum separation can only be achieved by liquid-liquid extraction in the presence of hydrofluoric acid by taking advantage of the difference in niobium(V) and tantalum(V) speciation in fluoride-based media. Therefore, the environmental footprint of hydrometallurgical processes for the production of niobium and tantalum could be clearly lowered by replacing HF or NH4F by greener media such as alkaline solutions in which high solubility of niobium(V) and tantalum(V) can be achieved.The development of such new efficient and environmentally friendly hydrometallurgical processes requires a fine description of the physicochemistry of niobium(V) and tantalum(V) in alkaline solutions. Unfortunately, literature data show a huge discrepancy on niobium(V) and tantalum(V) speciation in such media. This paper gives a brief overview of the niobium(V)-tantalum(V) production processes and paves the way to the development of alternative processes in alkaline media by presenting and discussing recent advances in the physicochemistry of niobium(V) and tantalum(V) in these media.INTRODUCTIONNiobium and tantalum are strategic metals since they are used for the production of alloys and super alloys, capacitors and magnets in strategic industries such as electronic, aeronautics and automobile. The main sources of niobium and tantalum are given in Table 1."

Jan 1, 2016

By M. A. Upham

"Prairie Evaporites of the Province of Saskatchewan in a deep oil-well hole. Exploitation started in 1950 under a shroud of doubt that this huge reserve could be mined. It was fraught with almost insurmountable physical problems in penetrating the Prairie Evaporites. After 12 years of experimentation and development of new shaft-sinking methods, mining equipment and processes to treat the high-grade potash ore (sylvanite), a new era of high-risk resource development dawned in Saskatchewan.The development of 10 new mines opened up the largest known mineable potash reserves in the world and Canada became the second largest. producer of potash to supply domestic (U.S.A. and Canada) and overseas markets. A monumental program in marketing-devising new transportation systems and strategically locating warehouses-was developed in order to expeditiously service domestic and overseas customers. The year 1969/70 started a period of overcapacity and the problem of prorationing. As the market strengthened in 1974, the Saskatchewan Government applied the reserve tax to the industry. Then, they announced the setting up of a Crown corporation to acquire ownership by purchase of up to fifty per cent of the industry. During this time, potash was discovered in New Brunswick within 50 to 60 miles of a seaport, where two deposits have been explored by the same pioneers who started the potash development in Saskatchewan.With this background, the paper will examine various elements of the economics and marketing of Canadian potash."

Jan 1, 1980

By R. C. Lo, M. D. Scott

"This paper reviews tailings management at Highland Valley Copper, and outlines main features of its tailings storage facility enclosed between the H-H and L-L dams. Key management focusses are: energy efficiency, cost effectiveness, safety and integrity of the tailings impoundment, environmental protection, and reclamation after decommissioning. Main features of the tailings facility include: high international standards for seismic and flood design criteria, water management and water quality monitoring, operations and construction optimization, reclamation and decommissioning plan, and geotechnical challenges associated with the complex geology of the L-L tailings dam foundation.IntroductionHighland Valley Copper stores its tailings mainly in the Highland Valley tailings facility (ultimate capacity: 1.8 billion tonnes). Smaller tailings storage facilities were operated by predecessor companies: the Number One Pond, the Trojan Pond at Bethlehem and the Highmont Pond at the Highmont operation as well as backfilling the Heustis and Jersey lona Pits at Bethlehem. These areas are currently not in use, and are in the reclamation phase prior to decommissioning. This paper focusses on tailings management in the main facility. As indicated in Figure I, the facility includes three tailings dams: these are, going from east to west, the H-H, J-J and L-L Dam, named after the alignment alternatives in the initial feasibility studies. From 1970 to 1977 Canadian Bechtel Ltd. advised Highland Valley Copper's predecessor company Lornex, on tailings storage at the H-H and J-J Dams and on the L-L Dam. Since the completion of the L-L Starter Dam in 1977, Klohn Leonoff Ltd. has provided ongoing consultation and construction monitoring of the raising of the L-L and the H-H Dams. The J-J Dams is currently buried by deposited tailings. This paper reviews key tailings management focusses and main features of the tailings facility."

Jan 1, 1992

By J. P. Bennett, K. S. Kwong

Slagging gasifiers are used to produce chemicals and/or electricity from feedstocks such as coal and/or petroleum coke. A gasifier environment includes pressures from 400 to 1000 psi, temperatures from 1250-1550°C, are cyclic, reducing gases of CO and 112, and molten ash that interacts with the refractory liner materials. The high Cr2O3 refractory liners of gasifiers fail within 3 to 24 months. Gasifier users seek materials with increased reliability and service life. This paper discusses causes of refractory failure and efforts to increase refractory service life.

Jan 1, 2004

By H. W. Hughes

"The Wasamac Gold Mines mill, situated 10 miles from Rouyn-Noranda on highway 59, commenced milling April 1st 1965 at a rate of 700 tons per day. This has gradually increased to over 1200 tons per day in December. The mill has done up to 1400 tons on occasion.The ore was formed in the Wasa shear zone by means of replacement. The minerals which replaced the original rocks were carbonates, quartz, pyrite, chlorite, gold and silver. Work index varies from 9. 6 on the chlorite to 11. 6 on the quartz. The gold is very finely disseminated throughout the gangue and while associated with the pyrite is not included in the pyrite. Very seldom is gold found or seen in the free state.Test work showed a medium fine grind of 85 to 90 per cent was necessary to achieve a 95.00 per cent extraction. Straight cyanidation time of 30 to 36 hours was indicated. This has been borne out by subsequent mill performance with a grind around 87 per cent minus 200 mesh and extraction ranging from 95 to 96 per cent.When it was decided to bring the Wasamac property into production, the Bicroft Uranium Mines Ltd. crushing and grinding units together with one pebble mill and the pachuca tanks from Dyno Uranium Mines Ltd. were purchased.Wasamac crusher house and mill buildings are of laminated wood construction, covered with 5/ 8th inch plywood and corrugated iron sheeting."

Jan 1, 1966

By Al Holmes

"In a recent survey of Canadian work values, 89% of the men surveyed and 97% of the women surveyed described the work in a mine as ""not at all auraetive"", Work in a mine, in fact, was rated by both sexes as the least attractive of all of the types of work surveyed. Confronted with this prevailing attitude, Canada's mining industry starts out with two strikes against it in its bid to attract and hold on to its fair share of available work force.Behavioural scientists have, for decades, been seeking answers to the questions:• ""Why do people work?""• ""Why do people choose a particular occupation?""• ""Why do people choose a particular organization?""• ""Why do people leave one organization for another?""• ""Why do some people stay in an organization?""• ""Why do some people work harder than others?""Their answers to these questions, although tentative and often contradictory, are being used by more and more organizations to solve people problems. Few industries can afford to ignore them, least of all, perhaps, the mining industry.Consider the following developments:I. General Motors and the United Auto Workers turn around the car assembly plant in Tarrytown, New York in seven years from the plant with the poorest labour relations and production record to one of the best under a program referred to as ""improving the quality of work life.""2. Shell Canada and the Oil, Chemical and Atomic Workers have designed a new petro-chemical processing plant in Sarnia using a set of principles that seek to optimize both the social and the technical system."

Jan 1, 1980

By M. K. Abel

"The Strathcona Mine is located in Levack Township on the North Range ofthe Sudbury Basin. The main orebody consists of pyrrhotite-pentlandite-chalcopyrite mineralization associated with an embayment of the footwall of the Sudbury Irruptive. A zone of massive chalcopyrite-cubanite-pentlandite mineralization occurs in a complex vein system in a series of mixed gneisses and breccias in the footwall. Vein widths vary from a few millimetres to 6 metres. In December 1979, this zone was estimated to contain 976,000 metric tonnes, with a grade of 9.31% Cu and 0.46% Ni. The vein system has a general strike of N 68°W at an angle of 60 degrees to the average strike of the footwall contact of the Irruptive. The dip of the vein system is 45 degrees sw. The strike and dip of individual veins in the system coincide with the directions that would result if a compressive stress had acted in a direction normal to the footwall of the Sudbury Irruptive, producing a conjugate set of fractures. The strike of the Irruptive at the Strathcona Mine is parallel to the long axis of the basin.IntroductionThe Strathcona Mine, owned and operated by Falconbridge Nickel Mines Limited, is located in Levack Township on the northwest rim of the Sudbury basin (Fig. I) . It is one of a group of nickel-copper sulphide ore deposits present along an 8.2-km section of the North Range of the Sudbury Irruptive. In the mines of the North Range, subunits of the Irruptive, going from hanging wall to footwall , include felsic norite, dark norite and dark norite breccia. The footwall complex at Strathcona includes the late granite breccia, which hosts a large proportion of the nickel-copper ores, and a compositionally variable group of brecciated and migmatized rocks, herein referred to as the feldspathic gneiss complex. It is within this latter group of rocks that the vein system of the Copper Zone occurs."

Jan 1, 1981

By R. O. Burt, R. W. Bruce

"IntroductionGravity concentration, the separation of two or more minerals due to the difference in their relative specific gravity and usually in a fluid medium, is the oldest recorded form of mineral processing.The principles of gravity concentration were known to, and practiced by, the ancients and Hoover's commentary to De Re Meta/lied'' notes many early references.Over the centuries, as direct smelting ores became more and more uncommon, the mineral processing industry developed and along with it many varied methods of concentration. Gravity concentration declined rapidly in importance in the early twentieth century, and it is only in the last decade that its advantages are being re-evaluated.A significant proportion of ores are processed by gravity; a large proportion being in the iron and coal industries<'>, or in the treatment at very high volume of relatively coarse alluvial deposits. The tin dredges of South East Asia and Beach sand plants of Australia are prime examples.An indication of the broad application of gravity concentration is the variety of minerals presently recovered. A list is given in Table 1; this list is not exhaustive.Principle of Gravity ConcentrationGravity concentration methods separate minerals of different specific gravity by their relative movement in response to gravity and one or more other forces, the latter often being the resistance to motion offered by a viscous fluid, such as water or air.The relative movement of minerals to one another is achieved by a variety of methods. These are: separation in a fluid of intermediate density (heavy media separation); by stratification (such as in jigging); in a flowing fluid (cones, spirals, sluices etc.) and with a horizontal shear (shaking tables etc.)."

Jan 1, 1989

By Linruo Zhao, Qi Yang, Akihiro Sato

TiN coating has a wide range of tribological applications from wear reduction of cutting tools to erosion protection of gas turbine engine compressor components. The performance of TiN coating depends on its microstructure, mechanical properties and adhesion strength which are influenced by the coating deposition process. In this study the effects of cathodic arc deposition conditions on the microstructure, hardness, adhesion and erosion resistance of TiN coating were investigated experimentally. It was found that varying deposition temperature, substrate bias and N2 pressure could derive a processing window in which TiN coating with superior erosion performance can be fabricated.

Jan 1, 2010

By Jorgen Elbrond, Noel Billette

"La connaissance du niveau de variation de I&apos; alimentation d&apos; une usine minéralurgique est essentielle pour estimer le taux de récupération dans un concentrateur. De plus, il est important de connaître la période moyen ne de correlation afin d’améliorer la qualité des contrôles et de l&apos; au tornatisation.Le modèle proposé permet de prédire ces paramètres à partir du minerai en place et des activités d&apos;exploitation dans une opération à ciel ouvert. II est basé sur la combinaison des variogrammes directionnels dans diverses zones d&apos;un gisement, ce qui permet de définir la correlation à la sortie de chaquc zone en fonction des decisions opérationnelles, puis sur une loi binômiale modifiée, afin de séparer minerai et stériles dans Ie but de décrire variance et corrélation dans Ie minerai même, Les statistiques classiques sont alors utilisées pour décrire la combinaison de plusieurs zones et obtenir la variance et la correlation au concentrateur.IntroductionUn concentrateur est habituellement rodé de facon à recevoir une alimentation à teneur fixe en métal ; Ie minerai qui s&apos;y presente a, par contre, tendance à osciller auteur de cette valeur cible, tantôt plus riche , tantôt plus pauvre . Ces variations entraînent des pertes de deux types: tout d&apos;abord, la teneur du concentré oscille de facon similaire à celle de l&apos; alimentation , ce qui peut même impliquer des pénalties a I&apos;usine de smeltage lorsqu&apos;elle est trop riche ou trop pauvre; la récupération peut pour sa part être diminuée de plusieurs points par un engorgement du circuit lorsque la teneur est trop forte."

Jan 1, 1984

By W. G. McBride

The mining industry has already become highly technical in all its branches and this has brought about specialization in mining engineering. Increasing demand for mineral products, exhaustion of high-grade or easily worked deposits, and narrowing of the fields for exploration and development, are forcing mines to greater depth and to working material of lower grade and more complex composition. The Robinson Deep at its Turf shaft has reached a depth of 7,640 feet and expects to go to 8,500 feet; Miami Copper, under normal market conditions, profitably mines ore running only 16 pounds of copper to the ton; Alaska Juneau is making a profit on ore running about $1.15 per ton in gold; and many mines are handling ores of an extremely complex nature. In each case, the success of these operations has depended upon the application of sound scientific principles and good business methods to the problems involved. It may be safely assumed that mining at great depth and the exploitation of low-grade, or complex, ores will become more and more important as time goes on, and this means that greater and greater demands will be made upon the technical skill and business ability of the mining engineer. To meet this condition, the more or less haphazard methods of training the young engineer that have prevailed in the past will have to be replaced by a careful and well-ordered system of engineer-training. Upon the industry and the older mining engineer falls the duty of providing means to assist the deserving student to prepare himself properly to meet the increased demands that are falling upon his profession. Consideration of the training of the mining engineer involves a decision as to what constitutes his field of usefulness. Technical control of methods and processes obviously falls upon the engineer, but there are still many who doubt his usefulness in the executive field, particularly in positions involving close contact with the men and work. Many engineers have failed as shift-boss or foreman, but this has been generally due to fault in the management in using men who were temperamentally unfit to lead others or who lacked the necessary preliminary training.

Jan 1, 1932

By M. Mahdi Aboutalebi, Roderick I. L. Guthrie, Mihaiela Isac

"A preliminary computational fluid flow model has been developed to simulate the flow field of liquid steel in the mold region of billet mold casting. This study reports the effect of different Submerged Entry Nozzles (SEN) on the fluid flow in round and square billet, curved mold, casters. In this study, ANSYS Fluent 14.5 software was used to model the 3-D turbulent flow of liquid steel. The standard k-0 model was used to simulate turbulence in the mold region. Similarly, the species transport equations were discretized to simulate the dye injection test into the mold cavity. The behavior of flow in the mold region was validated against previous experimental work. Predicted results showed that different nozzle types plus the slight curvatures in the molds can significantly influence the flow patterns generated within the mold region, and thereby affect the finished quality of the billet products.INTRODUCTIONConventional Continuous Casting (C.C) processes are presently used to solidify more than 95% of the 1.5 billion tons of steel now produced in the world annually (World Steel in Figure, 2014). This overwhelming contribution of C.C processes for steel production is the prime motivation for this study, in order to understand and optimize the casting processes and thereby reduce internal defects and minimize energy consumption. The primary objective of all C.C processes is to maintain liquid metal purity during the casting process and to create a uniform flow within the caster so as to avoid internal and external defects. In this regard, studying fluid flows in the mold region of continuous caster has attracted many research groups, in both academia and industry, in recent years. The mold region is one of the most critical parts of the C.C. process, in which the transport phenomena associated with this region can significantly affect the quality of the final products. Thus, proper control of fluid flows within this region can be expected to greatly decrease both internal and surface defects such as Oscillation Marks (OM), inclusion entrapment, and Mold Powder Entrapment (MPE). In the casting process, the fluid flow in the mold region can be affected by a number of variables, such as; the flow control system (stopper rod or slide gate), nozzle geometry, SEN (Submerged Entry Nozzle) depth, casting speed, mold dimensions, gas injection, and the application of electromagnetic fields. One of the most influential and easily-changed fluid flows are the jets of steel issuing from the SEN. Nozzle geometries are variable, consisting of a number of exit ports, different port angles, and/or port sizes, the bottom shape of the nozzle, and the SEN immersion depth (Thomas, 2001). The SEN characteristics can markedly affect meniscus surface velocities, surface level profiles, and turbulence levels that can vary in terms of the frequency and the magnitude of their fluctuations."

Jan 1, 2016

By J. Mirza, E. Nicol, J. Lipkowski

Gold passivation in thiosulfate leaching media is a major barrier to its implementation. Addition of Cu (II) into the leaching solution has shown to aid in gold dissolution, but the mechanism by which it acts, and its role in the passive layer, remains unknown. Surface Enhanced Raman Spectroscopy (SERS), in tandem with linear sweep voltammetry, were employed to determine the dependence of leaching currents on mass transport and for fingerprint identification of sulfur species on the surface of gold. SERS leaching experiments were performed using gold nanorod electrodes that showed increased stability compared to other SERS active surfaces.

Jan 1, 2011

By K. T. Aye

An investigation into the leaching of chalcocite and covellite in cyanide solutions at concentrations typically encountered daring gold cyanidation has been conducted. The results indicate that, for both minerals, the extent of leaching is greater under anoxic conditions, but is still incomplete even in the presence of free cyanide ions, with undissolved copper solids remaining in equilibrium with solution species. The speciation of the sulfur and cyanide reaction products in solution are interpreted in terms of the fast formation of a copper(I)- cyanide complexes in solution and a sulfur-rich copper(I) polysulfide solid phase, which then reacts more slowly to produce thiocyanate ions.

Jan 1, 2011

By O. Alonso-Gonzalez, F. Nava-Alonso, A. Uribe-Salas, R. Pérez-Garibay, C. Jimenez-Velasco

A current problem in gold production is the presence of copper minerals which dissolve during conventional cyanidation practice. The dissolved copper causes several problems in the different stages of the process. This issue is the base for copper elimination/recovery methods such as the Sulphidization, Acidification, Recycling, and Thickening (SART) process, which is currently used in gold production plants around the world. Even though the process is well established, new challenges appear as the composition of the solution varies from ore to ore, in some circumstances affecting the performance of the SART process. This work presents a thermodynamic study and experimental tests performed to understand the role of the initial copper concentration and sulfur addition, on the efficiency of the copper removal. For a constant cyanide concentration, an increase in the initial copper concentration causes a decrease in copper removal; high sulfur/copper molar ratios favor copper removal. We demonstrated that the cuprous sulfide formed from solutions with high ionic strength, presents better sedimentation rates than solutions with less ionic strength. For solutions with low sedimentation rates, the use of some pretreatment is necessary to facilitate the sedimentation such as addition of flocculants, particle recirculation and the used ultrasonic pretreatment.

Jan 1, 2014