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By C. P. Broadbent

The process metallurgy of many nickel laterite smelting operations is controlled largely by the physical chemistry of the slag system. Consequently, accurate phase diagram information and physicochemical property data are essential to interpret and predict the behaviour and optimisation of the overall process. The system (SiO2 - MgO - FeO) first described by Bowen et al. between 1914 and 1935 and the system (SiO2 - MgO - FeO - Fe2O3) determined by Muan and Osborne in 1956 are of particular relevance to the study of nickel laterite smelting slags as these systems form a reasonable approximation of many industrial slags. This paper will review the literature for these (and other relevant) phase systems. In addition data available from the ternary and (quasi)ternary phase diagrams will be compared with data obtained from industrial slags. The physico-chemical properties under consideration will include; melting and crystallisation behaviour (solidus and liquidus temperatures), viscosity - temperature relationships, heat flux considerations, electrical conductivity, surface and interfacial tension.

Jan 1, 1993

By Leiting Shen

The thermodynamics of tungsten ore decomposition in mineral acid and alkaline solutions were studied. The published thermodynamic data of tungsten minerals were collected and assessed. The Gibbs energies of CaWO4 (−1538.43 kJ/mol), FeWO4 (−1053.91 kJ/mol), MnWO4 (−1206.08 kJ/mol), H2WO4 (−1003.92 kJ/ mol), and Na2WO4 (−1455.58 kJ/mol, aq) at 25 °C were adopted in the calculation using HSC software. The results show that CaWO4 is decomposed more readily in Na2CO3 solution than in NaOH,while FeWO4 andMnWO4 aremore reactive inNaOH solutions. Froma thermodynamic point of view, tungsten ore decomposes easily in acid solutions despite most ΔGo T increasing slightly with temperature. Oxidizing Fe2+ to Fe3+ in acidic solutions facilitates decomposition of FeWO4, and the reaction of CaWO4 in H2SO4 solution occurs more easily than in other mineral acids, due to the formation of sparsely soluble CaSO4. The results fit well with the experimental data and industrial experience previously reported in the literature.

By James Vaughan

Australia is a major miner of ore that requires hydrometallurgical processing. According to the 2016 US Geological Survey Minerals Commodities Summaries, the country is 1st for aluminium (bauxite) and lithium, 2nd for gold, zinc and cobalt, 4th for nickel and silver, and 6th for copper mining, not to mention its wealth in coal and iron ore. In this paper, examples of recent Australian hydrometallurgical activities are summarised. Then, selected research projects from the University of Queensland hydrometallurgy research group are profiled. The projects profiled are related to fundamental aspects of processing bauxite with organics and reactive silica as well as the development of a synergistic hydro- and pyrometallurgical process for copper. The process context and motivation for the research is introduced, key results are highlighted with the associated relevant references.

By Jilai Xue, Jun Zhu, Yongqiang Liu

"Up-grading silicon feedstock by removing B and metal impurities can improve process efficiency and lower production cost in metallurgical processing for solar cells production. Hydrometallurgical study has been carried out in laboratory through alternative treatments of the metallurgical grade (MG) silicon (-200 mesh) by using hydrogen peroxide, hydrofluoric acid (4 mol/L) and NH4Cl-NH4 F (30:5) solution. The experiments were usually performed under mechanical agitation at 70 ? for 5 h. ICP-AES analysis showed that B content in MG silicon after the hydrometallurgical treatment has reduced by 92.4 %, and Fe, Al, and Ca contents by 98.8 %, 98.0 % and 81 %, respectively. Kinetics of these processes was also studied for better understanding of the effects of silicon powder size, acid concentration, leaching and oxidizing time on the processing chemistry.IntroductionAs one of the most clean and promising new energy, solar energy is used more and more in many countries all over the world, especially in United States, Japan and European Union. Most of industrialized states have made their national photovoltaic plans, which have stimulated further increase in use of solar energy. Photovoltaic Industry is at a high growth rate about 30 % [1-2]. For silicon solar cells to remain the mainstay for the photovoltaic industry it is necessary to develop a low-cost solar grade silicon feedstock [3]. At the same time, the availability of the currently M-G silicon from the semiconductor industries becomes limited [4]. With the advantages of low cost and low energy consumption, metallurgical routes to product solar–grade silicon get more attention [5]. These routes mainly include pickling, slagging, vacuum processing and directional solidification, etc [6]. Among them the most important processing step is the directional solidification, but it still can not satisfy the industrial demand for removing B. Removing B from Si remains as one of the most difficult and important processes in making M-G silicon [7]."

Jan 1, 2012

By A. Andreas Hejja

Flow of slag and settling of matte in slag resistance electric furnaces are discussed in conjunction with furnace geometries, stirring action of the electrodes, buoyancy and electromagnetic effects. The rectangular electric furnace was regarded as a channel reactor and the mode of slag flow as a channel flow. The flow is affected both by buoyancy and electromagnetic forces, however the effect of electromagnetic forces is minimal. The flow velocity is made up of two components; (i) that developed by the action of the electrodes, and (ii) the bulk flow velocity determined by the smelting rate and the volume of the reactor. Slag samples were taken from various depths of the molten bath and were analyzed microscopically to determine the size and distribution of matte particles, The action of the electrodes was described by a simple mathematical formula indicating a balanced settling rate in the area of electrode action.

Jan 1, 1996

By Marco Olper

The Italian company Engitec Impianti has developed a new electrochemical technology for the treatment of Electric Arc Furnace (EAF) flue dust generated in steel mini-mills. This process is based on a new and completely different concept from the Waeltz technology applied at present and allows, due to its modular nature, for an erection on the steel producer's site. Engitec Impianti spent US $700.000 constructing a 500 t/y throughput pilot plant at Pittini Group's Ferriere Nord mini-mill in Osoppo, Italy in order to demonstrate the process capabilities and obtain the data for a commercial plant design. The paper describes the pilot plant performances and the engineering criteria for a commercial unit of 10.000 t/y throughput. The feasibility study demonstrates a pay-back period of 3 - 4 years for the commercial plant.

Jan 1, 1995

By Jim A. King

The total pressure oxidation of copper concentrates is a potentially viable option for treating copper concentrates that are either low grade or contain significant impurities. Both concentrate types are heavily penalized in smelter contracts. The total pressure oxidation process involves autoclaving the copper concentrate at temperatures of 200-220 C under oxygen pressure. The autoclave discharge can be separated into a solid (oxidation residue) and a liquid (oxidation solution) product. The oxidation solution can be treated for copper recovery by solvent extraction - electrowinning or by direct electrowinning. The direct electrowinning recovery of copper requires prior removal of selenium and tellurium by cementation on finely divided scrap copper. The oxidation residue is washed thoroughly to remove acid and dissolved copper prior to precious metals recovery by conventional cyanidation in the presence of lime. The results of a benchscale investigation involving a number of copper concentrates are reported. Copper recoveries in autoclave oxidation and gold recoveries by cyanidation of the oxidation residue exceeded 99%. The results of benchscale experiments to demonstrate copper recovery are described. Various flowsheet options are presented.

Jan 1, 1993

By F. Elgersma

Hydrometallurgical zinc winning processes ?are frequently based on iron containing concentrates which yield a goethite, jarosite or hematite residue. Jarosite or goethite are mostly stored in waste ponds which ,are lined with foil. Water percolating through the pond is withdrawn from the deposit ,and decontaminated before discharge. Despite these measures, more and more pressure is put upon zinc companies to treat their (historical) residues and to produce environmentally acceptable residues. The criterion which determines this acceptability is the potentiality of leaching out hazardous elements by natural processes. This paper provides the comparison of five different process designs for integrated jarosite treatment in a hydrometallurgical zinc winning plant leading to environmentally acceptable residues. The processes are esigned for producing 200 ktons/yr zinc and for treating 80 ktonslyr historical jarosite. Mass and energy balances are used to determme parameters such as: the energy use per ton waste treated and the amount and composition of final residues. The conclusion of the work is that. pyrometallurgical jarosite treatment integrated in hydrometallurgical zinc winning is preferable to hydrometallurgical jarosite treatment. Integrated pyrometallurgical processes lead to a ?smaller quantity of remaining hazardous residues and require less energy.

Jan 1, 1992

By Albert Wraith, Thomas Price, Wayne Boyd, Skip (I. E. ) Hills, Cameron Harris

Most Peirce-Smith converters inject air through tuyeres, with nitrogen representing the majority of gas passing through the process. The nitrogen controls the temperature of the vessel by carrying away heat from the reactions, both globally and locally at the tuyere tip. However, nitrogen adds energy to the bath and contributes to splashing and limits the blowing rate. High oxygen smelting has made streams of gas containing high concentrations of sulphur dioxide commonplace, which can be used to substitute SO2 for nitrogen and drastically changes Peirce- Smith converting (and all other smelting/converting processes as well). Less SO2 is required to carry away the same quantity of heat, which allows higher concentrations of oxygen and leads to the possibility of increased production. The paper investigates this substitution, its impact on converter productivity, and on the remainder of the plant. 181

Jan 1, 2009

By V. Jiricny

There is a growing need to process galvanized steel scrap from automobiles, etc., in order to remove the zinc coating that otherwise causes problems in remelting of the scrap in electric arc furnaces. One approach that has moved to the pilot plant stage is that of Metal Recovery Technologies, Inc., of East Chicago (MRI). That company leaches the zinc fiom the scrap with a sodium hydroxide solution. The leached and washed scrap can then be returned to the steel industry. What is left is a sodium hydroxidelzincate solution which must be processed to recover the zinc and the NaOH. Presently, this is done by MRI using electrodeposition on planar electrodes at moderate current density and the resulting zinc is in the form of fine powder which is hard to process into, say, zinc for galvanizing. MRI has supported an investigation of a novel electrode, the spouted bed electrode (SBE), for zinc electrodeposition. In laboratory cells, zinc particles with low porosity have been grown up to 3mm in size. Microanalysis of the deposited zinc showed low level of impurities. DC energy consumption values were usually in the range of 2-2.5 kWg which is well below the energy consumption of the existing cells (and of present-day cells for electrowinning from acid sulfate electrolytes). These results were achieved at current densities (few thousand A/m2) that are much higher than possible with conventional electrodes. Discussion is provided of the scale-up of the cell to a commercial scale.

Jan 1, 1998

By T. Shi, Q. Yuan, S. P. Vanka, B. G. Thomas

"The quality of continuous cast steel is greatly affected by fluid flow in the mold region, especially involving transient phenomena. Mathematical models are being applied to investigate many different aspects of these phenomena, but their accuracy must be validated before they can be applied with confidence. As part of a long-term effort to develop and apply comprehensive models of the continuous casting process, this work evaluates the relative accuracy of models of three different fluid flow phenomena in continuous casting through comparison with measurements.Firstly, transient flow simulations of velocities in the mold region are compared with digital particle image velocimetry (PIV) measurements in a single phase water model. Large-eddy simulations (LES) are found to reasonably match the flow measurements, including transient flow variations, except at long time scales, which could not be modeled owing to the excessive computation costs. The standard K-e model produced very good agreement with time-averaged velocities for relatively little computation time, although it is inaccurate at predicting the transient variations. Secondly, particle trajectory calculations are compared with water model measurements to study the distribution and flotation removal of inclusion particles. The LES model was able to match the measurements both qualitatively and quantitatively. Thirdly, steady, multi phase flow computations are compared with flow patterns observed in both a water model and an operating steel caster with argon gas injection. For the same conditions, the water model and steel caster produced very different flow behavior. The computational model was able to match the measured flow patterns in both cases.This work suggests that computational flow modeling has the potential to match real processes as well or better than water models, especially when complex related phenomena such as particle motion and multiphase flow are involved. Much work is still needed to further improve the models and to apply them in parametric studies."

Jan 1, 2001

By Dengfu Chen, Mujun Long, Youguang Ma, Xin Xie, Xing Zhang, Leilei Zhang

"Processing parameters of a submerged entry nozzle (SEN) affect significantly on the patterns of fluid flow and temperature distribution in beam blank continuous casting mold with double SEN s. Effect of the geometry structure and immersion depth of double SEN s on the fluid flow in beam blank continuous casting mold was studied by water modeling. Results showed that, the optimal nozzle inner diameter was 40mm, and immersion depth was 70-90mm. The mold surface fluctuation, slag distribution, impact depth and removing rate of inclusion particles were discussed under different processing parameters of double SENs. As the results indicated, slag distribution was more non-homogeneous with a higher casting speed. The results provided basic data for the design and optimization of SENs used in beam blank continuous casting mold.IntroductionNear-net-shape casting has the distinct advantages of less rolling procedures, higher metal recovery and lower energy cost. Therefore, in the recent decades, one of the recent trends in the steel making process is moving toward near net shape casting. in which beam blank casting is a typical technology. The schematic section of beam blank is shown in Fig 1."

Jan 1, 2014

By Y. Y. Liu, H. M. Domanus, W. T. Sha

"Casting is fundamental to manufacturing of many types of equipment and products. Although casting is a very old technology that has been in existence for hundreds of years, it remains a highly empirical technology, and production of new castings requires an expensive and time-consuming trial-and-error approach.In recent years, mathematical modeling of casting has received increasing attention; however, a majority of the modeling work has been in the area of heat transfer and solidification. Very little work has been done in modeling fluid flow of the liquid melt. This paper presents a model of fluid flow coupled with heat transfer of a liquid melt for casting processes. The model to be described in this paper is an extension of the COMMIX code and is capable of handling castings with any shape, size, and material. A feature of this model is the ability to track the liquid/gas interface and liquid/solid interface. The flow of liquid melt through the sprue and runners and into the mold cavity is calculated as well as three-dimensional temperature and velocity distributions of the liquid melt throughout the casting process.IntroductionBower et al. (1), in their 1969 review of the evolution of some of the casting techniques, stated that:""The evolution of technology requires alternatives to be available so that choices can be made that lead to changes. The role of solidification science and other disciplines related to casting technology is to develop a better understanding of process and product, so that a wider range of alternatives is possible.Alternatives, whether from science or from invention, must lead to improvements in casting ""utility."" Utility, or economic advantage, must include consideration of total system costs, and final product value. The cost of materials, melt processing and finishing should be optimized with casting costs, since all are part of the production system. It is the favorable relationship between total processing costs and product value that makes a change in casting technology viable, but the best change is not possible unless technology has provided an understanding."""

Jan 1, 1986

By J. Phillip Mackey

The Peter Hayes Symposium on Pyrometallurgy, held as part of Extraction 2018, is an acknowledgement of his contributions to the basic science and principles underpinning modern pyrometallurgical processing. After completing his PhD at Strathclyde University, Scotland, in 1974, Peter took up a teaching position at The University of Queensland, Brisbane, Queensland, Australia in 1976. Peter Hayes’ research at the University since then has been focussed on: • The mechanisms and kinetics of heterogeneous solid/solid, gas/solid and liquid/ solid reactions, and • Experimental measurement of phase equilibria in complex high temperature metallurgical systems. This paper provides a brief biography of Dr. Peter Hayes and gives a full listing of Peter Hayes’ publications.

By W. L. Dalmijn

The processing of scrap and scrap cars starts with size reduction by a hammermill, or shredder. After the liberation the magnetic fraction is removed. The remaining non¬magnetic fraction mixed with other materials is screened and each fraction is processed separately. The increased use of plastic has a negative effect on the recovery of metals and waste production. At Huron Valley, Belleville Michigen, USA, the non-ferrous fraction from 5 million obsolete cars per year, containing 200,000 tons of non-ferrous metal, is processed. Aluminium Is recovered with a heavy medium separation process and concentrated with eddy current separators. The remaining heavy non-ferrous fraction is concentrated by a new combination of eddy current separation and image processing. After this separation process the zinc fraction is melted and refined and the copper, brass, stainless steel and other high-quality concentrates are sold to the secondary industries. The recycling of car scrap has become an important source of metals and materials for the secondary. materials processing industry.

Jan 1, 1995

By G. K. Ruhlandt, C. W. Kim

"A 3-D Finite Element Method program called ""SOLCAST"" has been developed to simulate the casting solidification process. Using the temperature recovery method to evaluate the latent heat of fusion and applying a new combination of the time integration scheme, SOLCAST reduces the computational time significantly compared to an existing commercial FEM program, and produces accurate results comparable to experimental casting results. Prediction of casting shrinkage porosity for A390 aluminum alloy will also be discussed. To make this FEM program useful for foundry engineers, this program was connected to a commercial pre- and post-processor.IntroductionBecause of recently increased competition, foundrymen must produce high quality castings more economically. Therefore, casting solidification analysis prior to casting production is an attractive way to reduce costs and development time.Although the actual casting solidification process is a very complicated phenomena, foundrymen could predict where shrinkage defects would occur based on a transient conduction heat transfer analysis that includes the liberation of latent heat. A numerical analysis is generally required to solve the heat diffusion equation with the latent heat diffusion term, because casting shapes are very complicated and pure materials are rarely used.Different numerical methods have been applied to the casting solidification analysis 1. Among them, a finite difference method 2 and a finite element method (FEM)3 are most commonly used.Each simulation method has one or more basic difficulties which are different for each method. These difficulties are:(1) Modeling casting shapes on a computer.(2) Time consuming computation.(3) Uncertain material properties."

Jan 1, 1986

By Aiyuan Ma, Tu Hu, Chenyu Sun, Yonggang Zuo, Hongying Xia, Jinhui Peng, Libo Zhang, Yongguang Luo

"In this study, the adsorption characteristics of tannin acid in aqueous solution were investigated using regenerated activated carbon (AC), with the aim to remove the tannin acid organic matter from the solution after zinc hydrometallurgy and Ge precipitation. Results showed the temperature has little effect on the adsorption ability (q.) of the regenerated activated carbon. The experimental equilibrium data were tested for the Langmuir and Freundlich isotherms. The adsorption equilibrium was better described by the Langmuir isotherm (R2 > 0.99). Pseudo first- and second-order kinetic models were used for describing kinetic data. It was determined that the kinetics of tannin acid removal was well fitted by second-order reaction.IntroductionGermanium recovery is a complex processes [1]. Hydrometallurgical processes are favoured and these are based on the precipitation of germanium as hydroxide or sulphide or alternately with tannic acid [2]. However, in the germanium recovery process, too much tannin is consumed by the germanium-tannins complexation process, and results in a high content of tannic acid remaining in solution, which is harmful to the valuable metal recovery [3]."

Jan 1, 2014

By R. J. Wesely

The paper describes the various methods which are currently being used or considered to refine gold and silver. These methods are then compared on a technical and economic basis. Conclusions are drawn on the factors which might influence the choice of process for different feed stocks and economic constraints

Jan 1, 1990

By S. M. I Kytö, J .. K. Mäkinen, K. Saarhelo

"At the Outokumpu Oy Harjavalta Copper Smelter the control philosophy of the flash smelting process has been changed from the slow feed-back control to feed-forward control. This is important as the fluctuations in the flash smelting furnace matte grade and slag temperature are desired to be minimized.The system is based on a specially designed automatic sampling device and the Outokumpu Courier 20 on-stream X-ray fluorescence analyzer. A microcomputer-based Analyzer Operator Station (AOP) controls the system and calculates the process parameters for the furnace from the analyzed chemical composition and other existing data.A considerable reduction in the deviation of the matte grade and slag temperature has been gained. This has resulted in conservation of energy and refractories, lower copper losses and higher through-put in the flash smelting furnace and converters.1.0 IntroductionThe flash smelting technology for copper concentrates was developed at the Outokumpu Oy Harjavalta Smelter soon after the World War II. The incentive for this development was shortness and high price of any form of energy. The fact that smelting can be carried out autogenously, without external energy by utilizing the latent heat of sulfide combustion was known decades before, but Outokumpu Oy was the first company to take the advantage of this knowledge in practical operation. A further advantage of this technology was that the SO2 containing gases suited well for sulfuric acid production, thus minimizing the detrimental effects on the environment (1).The very heart of the flash smelting process is the reaction shaft of the flash smelting furnace (see Appendix I). Heating up of the dried feed mixture, dissociation of several compounds, ignition and oxidation of the feed take place very intensively in the reaction shaft during 2 - 3 seconds, which the fine grained particles reside in the reaction shaft. A very accurate control of the amounts of the feed materials as well as of oxidizing gases, fuel, etc. is of primary importance."

Jan 1, 1989

In low carbon TRIP steels, the formation of carbide-free bainitic ferrite is crucial for the stabilization of austenite. Based on experimental investigations modeling the bainite reaction is examined adopting diffusional and displacive mechanisms, as well as the semi-empirical JMAK approach. Transformation tests were carried out to study the isothermal austenite decomposition into bainitic ferrite for a model steel containing 0.6wt%C, 1.5wt%Mm and 1.5wt%Si which replicates the composition of remaining austenite at the start of the bainite reaction in a classical C-Mn-Si TRIP steel. In the diffusional approach, classical nucleation theory is employed and subsequent growth of bainite plates is modeled using the Zener-Hillert theory. In the displacive approach, the autocatalytic nucleation of bairtite plates is assumed to be rate controlling. The predictive capability of all models is evaluated for temperature ranges where different morphologies of bainitic ferrite have been detected, The shortcomings and inherent challenges associated with either of these modeling approaches will be delineated.

Jan 1, 2003