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By D. Letzig

Wrought magnesium alloys are of special interest as lightweight structural components as a result of their more homogeneous microstructures and improved mechanical properties compared to cast components. Extrusion as a shaping technology offers the possibility to produce a wide variety of magnesium alloy profiles. In this contribution we describe the role of extrusion parameters such as extrusion speed, ratio and temperature as well as the type of extrusion process on the microstructural development of AZ-series magnesium alloys and the resulting mechanical properties. The effect of microstructure on the tensile/compression deformation behavior of the alloys has also been investigated. Aspects of process optimization designed to overcome technical and economic limitations and thus establish magnesium alloy profiles for industrial applications will also be discussed.

Jan 1, 2006

By J. A. Finch, R. R. Cunningham

The amount of foam volume generated in relation to the gas flowrate has long been used to define the foaminess of a solution and to characterize surfactants. The vessel geometry and gas flowrate range can affect the foam volume results. A fixed area column was tested alongside a variable area conical vessel with two surfactants. It was found that the fixed area vessel will cause foam volume to expand or contract which masks the effect of the surfactant. The conical vessel showed two regimes of foam volume production dependant on gas flowrate. The low gas flowrate regime revealed the physiochemical nature of the surfactant while a high gas flowrate revealed kinematic properties. Foaming properties of a surfactant is best determined with a variable area vessel at low gas flowrate.

Jan 1, 2009

By C. Phan

This paper outlines opportunities provided for enhanced management and process control by ISA PROCESSTM technology. ISA PROCESSTM technology has the core advantage of offering the potential for vastly improved electrode handling systems. This fundamental characteristic has enabled ISA PROCESSTM technology to develop management and process control systems that are modular, minimalist in their complexity and tailored to a tankhouse operating environment. A review will be presented on the current status of management and process control in ISA PROCESSTM tankhouses covering the central issue of electrode handling as well as electrolyte circulation systems, voltage monitoring, cathode plate tracking, and product tracking. Particular reference will be made of the recent development by Xstrata Technology (XT) and their technology partners, VRT Systems, of an Radio Frequency Identification (RFID) based solution for tracking ISA PROCESSTM cathode plates. The system encompasses fixed readers which identify plates passing through the stripping machines and the use of sophisticated tracking and database software enabling the development of cathode asset management and operational strategies. The performance of individual plates and batches of plates can be tracked through a full service history.

Jan 1, 2007

By S. Orr

In situ leaching is a complex, multidisciplinary process, which requires both mastering and integration of the different disciplines involved. Particularly, in-situ leaching is the intersection between geology (geochemistry, mineralogy, structural geology), hydrology (hydrogeology, well hydraulics), metallurgy (hydrometallurgy, electrochemistry, aqueous chemistry), and economics (mineable ore, cost of operations, market). The management of such a complex system requires all relevant knowledge base, integration, and continual optimization. Our presentation starts with a description of the "expert system" ? from data acquisition to information and knowledge, including determination of essential in-situ parameters, analyses, and modeling, which ultimately leads to an integrated, real-time, hierarchical management/control system.

Jan 1, 2007

By W. A. MacWilliams, R. G. Reynolds

"This paper describes, for the first time, a patented method of extracting sodium sulphate from a natural deposit in Western Canada. The method resembles, but is not, strictly speaking, solution mining. The fact that a plant based on this method has been in successful operation since late 1969 will be of added interest. The deposit in question is located near Metiskow, Alberta, and conventional surface recovery methods could not be applied because of heavy concentrations of mud. Considerable pilot work went into the separation and recovery process on which the plant operation is based. The history of the industry is covered briefly as background to this development. Today it is clear that the method has broader application within the industry and, in concept, may generate interest in many other applications."

Jan 1, 1973

By Martin Encinas, Jesús L. Valenzuela, Jose R. Parga, Salvador Aguayo, Roy G. Lewis

Continuous laboratory solvent extraction of gold from cyanide solutions using LIX?79 guanidine based extractant has been investigated. Different variables that affected the selectivity and extraction include aqueous pH, extractant concentration, and modifier concentration. The extraction isotherms of the aurocyanide complex with respect to the other cyano anions were compared, and the following order of selectivity Au > Ag > Zn > Cu > Fe was observed. According to the pH isotherms, aurocyanide can be extracted in an alkaline media, and a better separation with respect to the other cyanoanions was obtained in the pH range 10.5-11.2. From the McCabe Thiele diagrams, better recovery was predicted when using LIX?79 extractant and tridecanol modifier at 10 vol.%. Stripping of the gold from the loaded organic was carried out at pH > 12 using NaOH and NaCN solution. The continuous tests indicate that a two-stage extraction followed by a single stage strip is adequate to obtain an overall process efficiency of >90%. Better results were obtained using a copper wash stage before gold stripping.

Jan 1, 2014

By Gary Walters, Thomas Gonzales, David George, William Davenport, Andreas Siegmund, Suping Yao, Shijie Wang

The previous survey of world copper smelters was in 2016 (Copper, 2016). The copper smelting industry has grown and improved considerably since then, including continuing growth in China and modernization in Japan (Extraction, 2018). Outotec flash smelting and Outotec flash smelting/Kennecott - Outotec flash converting continue to be adopted while newer processes continue to be adopted in China. In addition, some of the world's original flash furnaces have been completely rebuilt (Extraction, 2018). This paper provides recent industrial production data and discusses these new developments. INTRODUCTION A world copper survey was redone in 2016 after a thirteen year lag since 2003. Some of the notable changes were the significant increases in production particularly from China. Since then, several smelters have gone through modernization processes and decommissioning of older technologies. This paper will review the notable changes since the last publication at Cu2016. In the last paper, Copper Smelting: 2016 World Copper Smelter Data, the author gave an audible sigh after observing that copper smelter sites as well as new and notable smelters have been spreading like wildfire in China since 2003. Indeed, seeing is believing. Figure 1 shows the Ningde Copper Smelter (double flashing, 400,000 MT Cu/Year capacity) that started up producing copper in 2018; Figure 2 shows the Nanguo Copper Smelter that is under construction with 300,000 MT Cu/Year capacity (first phase, side blown smelting and continuous top blown converting). We should not only admire the Chinese copper industry’s significant technological developments, but also the copper price support that it has provided throughout this century.

Jan 1, 2019

By L. E. Gutiérrez

A new filtration model based on porous media transport theory is presented. It predicts capacity and final moisture content in the filtered cake as a function of design and operational variables at the plant. FilterSim® is the computer code where this new model is programmed. Application of FilterSim® to ten-month operation of an industrial copper concentrate filtration plant is shown on a daily basis and using a single set of internal parameters for the whole period. Average error is less than 5%, both in capacity and moisture estimation. FilterSim® abilities to optimize industrial filtration plants as well as to estimate future budgets are illustrated with several real examples.

Jan 1, 2007

By Stephen B. Hearn

The SLon Vertical Ring and Pulsating High Gradient Magnetic Separator was developed to overcome multiple disadvantages associated with traditional horizontal type Wet High Intensity Magnetic Separators (WHIMS) which have been in service for many decades for recovering iron ore and other minerals. Proven successful, with hundreds of units now upgrading low-grade iron ores and maximizing recovery of fines throughout China, the technology is now being tested in the Western world. This paper will discuss the drawbacks of traditional WHIMS, explain the operation of the SLon, and illustrate its practical use in processing hematite ores.

May 1, 2007

By H. Somekawa

The fracture toughness and deformation structures an AZ31 magnesium alloy processed by equal-channel-angular extrusion (ECAE) were investigated. The average grain sizes of as-ECAE and annealed-ECAE alloys were 4.0 and 16.3 µm, respectively. The plane-strain fracture toughness, Kip, in as-ECAE and annealed-ECAE were estimated to be 27.3 and 23.5 MPam1/2, respectively, by stretched zone analysis. The fracture toughness indicated higher value with grain refinement. From optical microstructural observations in samples after fracture toughness tests, although deformation twins were observed in annealed-ECAE, no deformation twins were observed in as-ECAE. From TEM observations, the dislocations on basal and non-basal planes were activated in as-ECAE. With grain refinement, the activations of dislocations on both basal and non-basal planes were possibly related to the reduction in formation of deformation twins in as-ECAE. In addition, in comparison with direct extruded process, ECAE process was more effective method to improve the fracture toughness in magnesium alloys.

Jan 1, 2006

By M. Ghamgosar, Erarslan N.

Rock cutting includes many unknown parameters which result in different consequences of the different cutting conditions. However, based on the current suggested models for rock cutting, there are some critical parameters that control the fracture initiation and propagation in the rock domain. In general, there are two major cutting tools are used in rock cutting: drag bits and indenters. Different mechanical attacks of cutters result in different fracture models. For example drag bits break the rock parallel to the rock surface, which is called ‘undercutting’ while indenters cut rocks by pressing normal to the rock surface. Both tools cause rock failure by inducing tensile cracks in the rock. However, drag bits induce more tensile cracks compared with the indenters. The full benefits of improvement in rock cutting efficiency will arise from a clear understanding of rock fracture mechanics principles. Therefore, fracture mechanics principles will be applied to the rock cutting as the rock fragmentation process is based on the rock fracturing. The Oscillating Disc Cutting (ODC) has more advantages than drag bits and disc cutters. The forces transmitted back through the cutting head are much lower with ODC. Although ODC attacks rock in much the same way as drag bits, a combination of the oscillating action of the cutter and the undercutting mode produces the lower cutting forces and causes rock fatigue. Fatigue phenomenon in rock has advantages for the rock breaking by applying less effort and energy due to the cyclic loading. The aim of this study is using the Extended Finite Elements Analyses (XEFM) numerical modelling for simulating the ODC cutting with different cyclic loading conditions. An accurate prediction of numerical investigation requires detail laboratory experiments. A series of laboratory tests were performed to obtain the fracture toughness values of our Monsonite rock samples under various cyclic amplitude and frequency values. The numerical results showed different types fatigue damage mechanisms due to the various cyclic loading conditions. Thus, modelling and understanding the crack propagation behaviour depending on different amplitude and frequencies are believed very important for the dynamic rock cutting researches and rock cutting machine manufacturers.

Jan 1, 2015

By G. T. Lapidus, J. Trejo-Gallardo

A phenomenological model is presented for leaching silver from silver sulfide contained in mineral particles with ammoniacal thiosulfate solutions of copper in stirred reactors. Experimental results were used to adjust the kinetic parameters of the model, such as the reaction order and velocity. The incorporation of the cuprous sulfide-silver sulfide equilibrium at the reaction interface allowed the prediction of the conversion limits for different reagent concentrations. The information obtained from the reactor model was later integrated into a heap leaching simulation, whose results adequately describe tendencies observed in column tests, with respect to variations in copper and thiosulfate concentrations. Comp

Jan 1, 2005

By Carmen M. Neculita

Optimizing the long-term efficiency of passive systems for the treatment of highly contaminated acid mine drainage (AMD) is still a challenging issue. The optimization lies, among others, on improving the understanding and quantification of metal removal mechanisms in order to predict and enhance the stability of neo-formed minerals in secondary phases. Sorption, and precipitation as oxides-hydroxides, carbonates and bio-sulfides are likely the most important metal removal mechanisms involved in passive biotreatment of both slightly and highly contaminated AMD. In the same time, the preferred mechanism is precipitation of metal sulfides that are more stable and less pH dependent than carbonates and oxides-hydroxides. However, results of relatively recent research studies performed at laboratory scale showed that sulfides accounted only for up to 15% of total metals removed in passive bioreactors treating highly contaminated AMD dominated by iron (around 500 mg/L). Several approaches were used in the aforementioned studies to understand and quantify metal removal mechanisms in spent reactive mixtures collected from long-term (12-15 months) operating column bioreactors. These included: thermodynamic equilibrium modeling and various chemical extractions and mineralogical analyses (such as single and sequential extractions, acid volatile sulfides-simultaneously extracted metals determination, scanning electron microscopy, X-ray diffraction, and thermo-gravimetric analysis). The large proportion of metals (85%) removed by sorption and precipitation as oxides-hydroxides and carbonates suggests a relatively high mobility of the neoformed minerals, especially in low pH conditions. However, no data is available on the long-term stability of spent reactive mixtures and, on the implications for the sustainable management of this type of solid waste. Lately there is almost a consensus that the efficiency of highly contaminated AMD treatment is warranted by the use of multi-step passive systems, including both chemical and biological units, installed sequentially. However, very few well-documented studies are available on the design, construction, operation and long-term efficiency of these multi-step systems. A leading example is the tri-unit passive system installed on the abandoned Lorraine mine site (Québec) to treat a highly contaminated AMD dominated by iron (about 2,500 mg/L). This tri-step system (160 m3), consisting in two bioreactors separated by a unit filled with wood ashes, achieves to date a satisfactory removal of iron (up to 99%). Moreover, based on the data collected during laboratory testing, iron was mainly removed in the wood ashes unit (from around 3,200 mg/L to 10 mg/L) by precipitation of oxides-hydroxides as predominant mechanism and only partially by sorption. However, no data is available on the actual metal removal mechanisms in the field. Overall, theses multi-step systems are more complex and their long-term performance is even less predictable than the single unit systems. This paper presents the current knowledge and the research needs on metal removal mechanisms in passive bioreactors and multi-step systems for the long-term treatment of highly contaminated AMD. KEYWORDS

Aug 1, 2013

By Gaston Gingras

"IntroductionL'entretien de l'equipement minier dans les mines à ciel ouvert est une activité qui est aussi vieille que I'existence des mines et qui a progressé au cours des années pour suivre l'évolution des techniques d'exploitation. Lors de la mise en usage de s premières pelles à la va peur, celles-ci étaient généralement entretenues par I ‘équipe de quatre hommes qui était responsable de son opération. Pour les travaux plus compliqués ils utilisaient les services de machinistes qui eux savaient comment réparer Ie moteur à vapeur et couler des coussinets de ""babbit"". Les premières pelles diesel étaient entretenues de la même façon mais pour les réparations au moteur, on devait recourir au représentant du manufacturier qui était Ie seul à avoir les compétences nécessaires.Ce n'est vraiment qu ‘après la deuxième guerre mondiale que I ‘usage de l'équipement mobile s'est répandu dans les mines à ciel ouvert pour débuter les extractions selon les méthodes que I'on connaît aujourd'hui.L'entretien de l'équipement minier de façon organisée à débute avec I ‘usage de ces machines dans nos mines. Ces machines étaient un peu primitives, petites et pas très dispendieuses a I'achat. Même si la disponibilité était basse, elles fournissaient quand même un rendement qui en ces temps était acceptable. L’organisation de I ‘entretien de cet équipèrent était assez primitif et n'occupait qu'une place secondaire aux yeux de la direction de la mine."

Jan 1, 1988

By M. Sokoto, H. Hata, K. Nishina, K. Haiki

Fluoride ions in zinc electrolyte cause corrosion to aluminum cathode plates at zinc electrowinning process, so we have developed an iron compound as a fluoride ion adsorbent used in zinc sulfate solution. The iron compound is synthesized from FeC13 solution with a small amount of sulfate ion by neutralizing reaction with Na2CO3 solution. The fluoride ions adsorbed on the surface of the iron compound are desorbed in alkaline solution and the iron compound can be reuse as a fluoride ion adsorbent. Moreover, if adsorption capacity of the iron compound decreases, it can be dissolved in HCl solution and re-synthesized.

Jan 1, 2008

By Sergio Romo, Gerardo Fuentes, Adriana Garcés

Refractory ores with gold entrapped in a sulfide matrix, must be processed in a first stage with chemical or physical treatment in order to liberate the gold for a subsequent step with cyanide. The goal of this research was to compare the refractory behavior of a gold concentrate treated using two pretreatment methods: pressure oxidation and fine grinding. Gold concentrate from Viacha Mining in Bolivia, assaying 50.11 gpt, with a P80 of 131 ?m was used. The concentrate contains arsenopyrite and pyrite as main sulphides in the matrix. A preliminary test with cyanide resulted only 13.5% of gold extraction with 4 hours of stirred leaching. Using an autoclave oxidation with sulphuric acid and 12 bar oxygen pressure at 220°C pretreatment, the cyanide gold extraction increased to 69.0% in 4 hours. When material was ground in a pulverizer, producing a P80 of 20 ?m and the product directly cyanided, stirred leaching gave a gold extraction of 65% in 4 hours. For both techniques, the effect of temperature, sulfur produced in autoclave oxidation, optimization of the cyanide and the nature of residues were also studied.

Jan 1, 2014

By K. Ghyselbrecht, R. Swennen, Y. W. Chiang, V. Cappuyns, R. M. Santos, T. Van Gerven, B. Meesschaert

Heavy metal contamination from mining and metallurgical activities of aquatic systems poses significant risk to the environment and human populations. The investigation of the distribution and immobilization mechanisms of heavy metals in sediments and soils has recently attained high priority. Different remediation methods can be employed to suppress or eliminate these contaminants. A tailored approach using both commercially available and in-house made adsorbents to rem ediate a heavy metal contamination site due to historical metallurgical activities in north Belgium is studied in this paper.

Jan 1, 2011

By T. H. Etsell, P. C. Holloway

Vanadium is concentrated in the fly ash which is produced as a solid waste from oil sands operations in northern Alberta. Although a process flowsheet using sodium chloride as a roasting reagent has been developed at the University of Alberta, recent studies examine the p otential o f p otassium o r c alcium s alts a s alternative reagents for roasting Suncor fly ash to recover vanadium. Suncor fly ash was roasted with CaO, Ca(OH)2, CaCO3, CaSO4.2H2O and KC1 at 750, 850 and 950°C. Water leach extractions for the calcium compounds were low (<45%); leaching with 100 g/L Na2CO3 gave maximum extractions of 56 to 69% at 950°C. Ash roasted with KCI behaved similarly to ash roasted with NaCl. These tests indicate that similar roasting conditions (25 to 30% KCI, 850°C, and 2 to 4h) could be used to achieve similar water leach extractions (75 to 85%). However, the lower solubility of KVO3 in solution, compared to NaVO3, would make the use of KCI instead of NaCl less attractive from a process and economic standpoint. Mineralogically, leucite (KAlSi3O8) was the predominant phase in ash roasted with KCl while, in crystalline samples of ash roasted with calcium compounds, anorthite (CaAl2Si2O8) and pseudobrookite (Fe2TiO5) were identified. Ash roasted below 950°C with the calcium compounds remained poorly crystalline.

Jan 1, 2004

By T. Gerritsen, C. Martinez, F. Stober, T Ma, J. R. Frias, M. Sedighy, J. Janzen

Electrode control systems regulate power by physically positioning electrodes. Due to the weight and inertia of the electrodes and hoist equipment, this is a relatively slow process where power fluctuations of less than a few seconds are not fully corrected. Nickel laterite AC furnaces operating in high voltage, shielded arc mode typically incur frequent power variations of approximately +/- 20% or more around the power set point. To provide enhanced power control, Hatch has recently supplied, at commercial scale, a thyristor-switched reactance system called an SPLC. The SPLC incorporates predictive control software to operate furnaces at the maximum transformer rating by reducing the large power swings experienced without the SPLC. The resulting higher average power enables higher production, without increasing transformer or power plant capacity. A 60 MW production version of the SPLC has been commissioned on Falconbridge Dominicana&apos;s laterite nickel furnace, yielding excellent results with a 3 to 1 reduction in power fluctuations.

Jan 1, 2005

By A. Welty, T. Garn, K. Lyon, B. Jakovljevic, R. S. Herbst, M. Greenhalgh, Cytec Solvay Group

"Industrial rare earth separation processes utilize PC88A, a phosphonic acid ligand, for solvent extraction separations. The separation factors of the individual rare earths, the equipment requirements, and chemical usage for these flowsheets are well characterized. Alternative ligands such as Cyanex® 572 and the associated flowsheets are being investigated at the pilot scale level to determine if significant enhancements to the current separation processes can be realized. These enhancements could be defined as higher separation factors, reduced stage requirements, or reduced chemical consumption. Any of these enhancements can significantly affect the costs associated with these challenging separation proccesses.A mid/heavy rare earth element (REE) separations flowsheet was developed and tested for each ligand in a 30 stage mixer-settler circuit to compare the separation performance of PC88A and Cyanex® 572. The ligand-metal complex strength of Cyanex® 572 provides efficient extraction of REE while significantly reducing the strip acid requirements. Reductions in chemical consumption have a significant impact on process economics for REE separations. Partitioning results summarized Table 1 indicate that Cyanex® 572 offers the same separation performance as PC88A while reducing acid consumption by 30% in the strip section for the mid/heavy REE separation."

Jan 1, 2016