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By Michael S. Moats, Daniel Kim, Shijie Wang

"The behavior and deportment of lead, arsenic, antimony and bismuth are critical in producing high quality cathode by copper electrorefining. A critical review of research related to these elements is presented along with a comparison to industrial data, where appropriate. These elements exist predominantly in the anode as complex oxides along die grain boundaries. Upon dissolution, Group 15 elements report both to the electrolyte and slimes while lead essentially enters the slimes. The deportment of the Group 15 elements appears to be influenced by several chemical interactions which are discussed. The effect of these elements on floating slimes and anode passivation is reviewed. Under normal electrorefining conditions, lead, antimony and bismuth are thought to enter the cathode through the encapsulation of slime particles. The literature indicates that arsenic enters the cathode predominately by electrolyte entrainment. Finally, areas for future research regarding these elements are presented.IntroductionControlling lead, arsenic, antimony and bismuth is critically important for the production of high quality cathode in copper electrorefining. The reasons for this are twofold. First, ASTM Grade 1 Cathode specifications [1] for these elements are low, as listed in Table 1. Second, they can affect the efficiency of the electrorefining process (e.g., through passivation, current efficiency, slime processing)."

Jan 1, 2012

By Brian G. Thomas, Quan Yuan, Rajneesh Chaudhary, Rui Liu, Sana Mahmood

"A particle-entrapment model based on local force balances has been developed, implemented into computational models of turbulent fluid flow, and applied to simulate the entrapment of slag inclusions and bubbles during the continuous casting of steel slabs. Turbulent flow of molten steel is computed in the nozzle and mold using transient CFD models. Next, the transport and capture of over 30,000 particles are simulated using a Lagrangian approach. Particles touching the dendritic interface may be pushed away, dragged away by the transverse flow, or captured into the solidifying shell according to the results of a local balance of ten different forces. This criterion was validated by reproducing experimental results in two different systems. Finally, the model is applied to predict the entrapment distributions of different sized particles in a typical slab caster. Although more large particles are safely removed than small ones, the capture rate as defects is still high.IntroductionSurface defects such as slivers and blisters are often caused by captured inclusion clusters, slag, bubbles, and other particles. During continuous casting, jets of molten steel from the submerged entry nozzle (SEN) ports carry bubbles and inclusion particles into the mold cavity from upstream processing, as shown in Figure 1 [1]. In addition, droplets of liquid mold slag may become entrained into the flowing steel due to fluid flow problems, via several different mechanisms [2]. Figure 2 shows some typical inclusion particles [3] that can be entrapped from the flowing liquid into the solidifying steel shell to form defects in continuous-cast product.Liquid steel flow in the continuous casting mold has been modeled extensively. Reynolds Average Navier-Stokes (RANS and URANS) approaches are based on accurate computation of the ensemble-averaged velocity field. Particle transport can be tracked using a Lagrangian approach, introducing an extra model, such as ""random walk"" to generate realistic motion of every particle. Large Eddy Simulation (LES) models can accurately calculate both the transient evolving flow field and Lagrangian particle motion [4, 5] of this turbulent process."

Jan 1, 2012

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from theUniversity of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

By Arthur G. Hunt

Smelting using the direct-to-blister process commenced at Olympic Dam on 31 July 1988. The unique nature of the Olympic Dam ore body led to the selection of the direct to blister smelting process. Significant improvement in the design of the furnace and the understanding of the fundamentals of the process and its operation has occurred in the 10 years of operation. The paper will discuss the operation of the #1 Smelter and the design, preparation for start up and early operating experience of the #2 Smelter.

Jan 1, 1999

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from theUniversity of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from the University of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from theUniversity of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

By Shivendra Sinha

Total pressure oxidation (TPOX) is widely outreached leaching practice for base metals from sulfide minerals, wherein high temperature (T ∼ 200 °C) and oxygen pressure (pO2 ∼ 25 bar) are required. These aggressive conditions intensify the oxygen mass transfer, and therefore facilitate metal dissolution. However, challenging-cum-negative aspects of such practice are energy and material intensive requirements and high oxygen demand. Thus, the present study explores the novel emulsified medium for enhancement of oxygen mass transfer, which assists faster metal dissolution at significantly lower temperature and pressure condition. It is possible to achieve quantitative dissolution (>95%) of Cu, Ni and Co from mixed sulfide minerals at T ∼ 95 °C and pO2 ∼ 2 bar using an emulsion of 2.5% (v/v) n-Hexadecane in dilute sulfuric acid. In addition, n-Hexadecane was found to be inert, stable and immiscible in a pressurized leaching system, thus can be easily separated and recycled in subsequent leaching stages. Thus, this study offers an energy efficient route for low temperature-pressure leaching of sulfides.

By Xueming Lv

The rotary kiln-electric furnace (RKEF) process is the main method for producing ferronickel from nickel laterite ore. However, this process is energy intensive as it involves several high temperature steps. Therefore, a novel process is proposed to directly produce ferronickel from nickel laterite ore by semi-molten reduction, which is expected to be realized in a rotary hearth furnace (RHF). The RHF process is able to shorten the flow sheet, decrease the reaction temperature as well as reduce energy consumption. In this study, the influence of basicity on reduction of nickel laterite ore was investigated. The results showed that it is possible to produce the ferronickel nugget directly at 1400 °C when the quaternary basicity [(mCaO + mMgO)/(mSiO2 + mAl2O3)] was fixed at 0.60. Under this experimental condition, the grade and the recovery ratio of nickel reached 11.53% and 98.59%, and the grade and recovery ratio of Fe were 84.16% and 68.72%, respectively.

By Alistair Burrows

Situated in the oblast of East Kazakhstan, the Ust-Kamenogorsk Metallurgical Complex has spent the past twenty years renovating and remodelling itself as a modern polymetallic sulphide smelting facility, and a regional centre of excellence for custom smelting. Along the way there have been changes to the company structure, introduction of new technologies, investments in expanded capacity, environmental improvements, and addition of new metal products and by-products to the site’s repertoire. These changes have been gradual and incremental, but taken together they represent a significant contribution to placing Kazakhstan’s sulphide smelting industry on a strong foundation for enduring success in the international custom smelting market. In achieving these changes, a workforce that was historically isolated from much of the world now has recognised expertise, internationally competitive skills, and confidence to embrace the future. Further improvements in energy efficiency, environmental compliance and polymetallic processing capabilities are challenges that UKMC stands ready to face.

By Marcel Sturzenegger

Though the extraction of copper is well established, generation of sulfur dioxide (S02) is still a troublesome issue. Conventional processes are further challenged by the increasing amount of impurities in the concentrates. Direct decomposition of the metal sulfides into the metal(s) and elemental sulfur under concentrated solar radiation offers a promising path to solve both problems. Thermogravimetric measurements under inert atmospheres have shown that synthetic chalcocite or chalcopyrite yield copper at temperatures as low as 1773 K. Even though optimum reaction temperatures might be somewhat higher, such temperatures are straightforwardly accessible in solar chemical reactors. The absence of oxygen will reduce the extent of slag forming reactions and thereby alter the evaporation characteristics of volatile impurities such as arsenic or antimony. Chemical equilibrium calculations for a chalcopyrite-enargite feed, e.g., have shown that under inert atmospheres arsenic compounds are completely evaporated at temperatures above 1000 K and an effective separation of arsenic from the matte is expected. An important step towards a solar production of copper is the design and testing of prototype solar chemical reactors for this reaction. Numerical modeling is a key tool supporting a rational design but it requires data of the high-temperature properties that prevail in these processes. Development of techniques for determining the essential quantities such as decomposition rates or radiative properties at temperatures up to 2000 K is therefore a main activity in our laboratory in order to control and optimize the process. Though developed in the frame of high-temperature solar technology, the experimental techniques are also suited to advance the understanding of conventional high-temperature processes. Keywords: Solar technology, Sulfur dioxide, Solar Radiation, Thermogravimetry, Chalcocite, Chalcopyrite, Numerical modeling.

Jan 1, 2003

By Ian M. Ritchie

Cementation or metal displacement reactions such as Cu2+ + Fe Cu + Fe2+ are among the oldest known hydrometallurgical reactions. They are still used in the recovery of some metals and in the purification of process liquors and waste water streams. However, they are often more complex than the stoichiometric reaction would suggest because they involve the simultaneous deposition of one metal onto a second which is dissolving. For example, sometimes a cementation will not take place, even though it is thermodynamically favoured. On other occasions, a cementation reaction will start but come to a halt as the depositing metal blankets the reacting surface. On yet other occasions, side reactions, catalyzed by the deposit, can be important. In this paper, the electrochemical basis of cementation reactions is described. The conditions for each of the complications encountered in these reactions are described and illustrated by examples drawn from a number of hydrometallurgical processes. The cementation reaction between activated carbon and gold thiosulfate is also briefly described, this reaction being unusual in that no dissolution of the carbon occurs.

Jan 1, 2003

By John Wallace

"Monitoring compound semiconductor crystal growth using multifrequency eddy currents for sensing illustrates some of the extreme problems of measurement and interpretation that are not often seen in metallic systems. Using sensor arrays and scanning sensors have produced a qualitative and quantitative understanding of some of the high temperature electrical conductivity mechanisms in several compound systems. A detailed review of the CdTe/CdZnTe data is presented showing some of the complexity in the data as opposed to what is found in elemental semiconductors.HistoryThe most common goal in the use of eddy current measurement in crystal growth is to deter-mine the curvature of the liquid solid interface during growth to test if the heat transfer estimates of the thermal design were adequate for single crystal growth[l]. This aim could be met but represented only a small fraction of the data that was produced observing a growth cycle. A secondary consideration was what could be discovered in the recorded data about the growth and subsequent heat treatment as the boule cooled. This is usually a more difficult task because a crystal growth process is not a controlled experiment so much as a process that continually sees modification. Using a sensor arrays or a scanning loop has produced a qualitative and quantitative basis for understanding some of the high temperature electrical conductivity mechanisms. The implication of the these measurements of electrical conductivity variations are important in that they reflect the complex defect states that will occur on cooling and heat treatment following crystal growth. In contrast to the complex behavior of the conductivity of these compound semiconductors in the solid and liquid state we have the very well characterized system silicon to compare. Initially the interest on using eddy currents to monitor compound semiconductors came from G. Westphal at the Texas; Instruments Company in 1987 to monitor aspects of growth and compounding of GaAs. This was followed by work on solution growth of HgCdTe with D. Witter. The initial interest in the use of eddy cur-rents for monitoring CdTe crystal growth came from Prof. Wilcox at Clarkson University in the practical interest to determine and control the crystal interface curvature during vertical brigdeman growth. The first actual work was done by one of his former students. G. Neuge-bauer at the II-VI Corporation which was carried on by G. Rosen at Clarkson and R. Shetty at II-VI Corporation and with A. Socha at Johnson-Matthey Electronics. The work on CdTe extends over four years and yielded sufficient data to allow one to evaluate the utility of the information produced as compared to what could be obtained from monitoring an elemental semiconductor such as silicon."

Jan 1, 1997

By Feng Gao

A general unsteady- state model, based on a cracked substrate, has been developed to account for reaction and diffusion within porous substrate during oxidation of Carbon Fiber Reinforced Carbon matrix (CIC) composites. The effects of several parameters, such as diffusion and reaction rate ratio, oxygen concentration, and composite density, on oxidation process are explored. Also, theoretical results for a set of parameter values of the CIC composites are compared with experimental data. It shows that the model predicted values agreed well with the experimental data in weight loss. Based on this model, quantitative predictions of oxidation of a composite with cracked substrate can be made.

Jan 1, 1993

By Tapio Ahokainen

Commercial modeling software and increasingly efficient computers enable today computational fluid dynamics (CFD) to be used as a tool for a more comprehensive understanding of the flash smelting and flash converting processes. CFD modeling can be used for design purposes in many technological areas, but some relevant physical and chemical phenomena are still missing in the commercial CFD solver packages. Therefore, Outokumpu has developed several subroutines for solvers to describe analytically the phenomena in the flash smelting environment. CFD sub-models of the copper concentrate and matte combustion, the particle-particle-wall interactions and for more accurate radiation properties of the gas-particle suspension are needed to ensure reliability of numerical simulations on the flash smelting and converting vessels. Several basic combustion phenomena can be modeled with a number of commercial solver packages, but own models for combustion must be included in the case of sulfides as the feed. Mathematical models for copper concentrate and solid matte combustion have been developed during the last decade. They calculate compositions of the particles and temperature, based on extensive experimental research work in laboratory scale furnaces with validated kinetic parameters and temperature measurements of reacting particles. Inside and near the concentrate burner, the standard particle tracking methods do not include the particle-particle interactions and the particle-wall interaction is too much simplified to describe properly the particle collisions with the distribution cone. Therefore, additional models for the particle-particle as well as particle-wall interactions have been written and implemented. For thermal radiation, models for the emissivity of a gas mixture and for calculating the particle absorption and scattering coefficients have been developed and tested. In addition, the advanced radiation model can be used i.e. in the enhanced simulation of off-gas cooling in the heat recovery boiler area of the flash smelter.

Jan 1, 2006

By Hélio Wiebeck, Fabio J. Esper, Wildor T. Hennies, Guillermo R. Martín-Cortés, Francisco R. Valenzuela-Díaz

"Natural rubber reinforced commonly with carbon black to produce vulcanized material, turns into a new environmentally friendly nanocomposite when carbon black is replaced by organically modified clays of Brazil. Carbon black is substance derived from the oil refining process with consequent pollution to the environment. Its substitution in this industrial process must contribute to diminish the oil derived products dependence. As the added clays are only a third in weight of the traditionally carbon black added, then, to obtain the same final volume it is necessary to add low cost neutral filler that does not damage the technological characteristics of the final material. This paper presents results using as neutral filler of this type rice husk ashes from industrial wastes. Experiences realized with this nanocomposite material show results of quality and technological characteristics similar or superior to those of the rubber made with carbon black.IntroductionTraditionally rubbers are black or a very dark color. But they can have different appearance when filler of distinct composition of the carbon black is used. The carbon black is substance derived from the oil gotten during the final phases of the mineral fuel treatment with consequent pollution of the environment. Carbon black show nanometric grain sized distribution and a depth black color, because these properties it is also used for computer printers inks production. The substitution of this substance, traditionally used as a reinforced load in the rubber production, will have to contribute in such a way to diminish the dependence of these products as to diminish the pollution of the environment. The present work shows the results of the use of another kind of mineral nanoparticulate material substituting carbon black in the production of some rubber products. This nanoparticulate material is the organic modification of smectite clay treated with some types of ammonium quaternary."

Jan 1, 2008

By P. J. Uggowitzer, K. Steinhoff, A. Wolf

"With the increasing acceptance of the Thixoforging process in the last few years, also the technical and commercial requirements for this forming technology and its components increased. So far, a great deal of work has been done in the development of an efficient process and control design. However, less attention has been paid to the development of new specifically tailored aluminum wrought alloys for this specific manufacturing process. · In this paper a new AlMgSi-alloy (A6082), optimized for the Thixoforging process, is presented. In the first part, the technical potential of the new alloy is specified by its microstructural evolution and flow characteristics in the semi-solid state. In the second part, the mechanical properties of thixoforged components of different conventional AlMgSi-alloys a (e illustrated · and compared to the new alloy.IntroductionSemi-solid metalworking, also known as semi-solid forming, is a hybrid manufacturing method that incorporates elements of both casting and forging. The key to the process relies on the peculiar flow behavior of slurries containing non-dendritic solid, which was first studied at the MIT by Flemings et al. [i], in the early 1970s. It was discovered, that if an alloy is uniformly stirred during freezing, discrete rounded particles of solid are formed rather than the normal dendrites, and the slurry is highly fluid (-5 Pas) up at least 50% solid. In addition, these slurries posses thixotropic flow characteristics: the viscosity is dependent on sheare rate and time. The more vigorously they are stirred, the more fluid they become. However, on standing the viscosity recovers and the material stiffens (-106 Pas).The semi-solid forming process exploits this phenomenon. In a first step, the required non-dentritical- microstructure is obtained by mechanical or electromagnetic stirring during primary solidification of the alloy. The stirred slurry is generally fully solidified as a feedstock billet and - in a second process step - reheated above the solidus temperature into the semi-solid state. In this condition, the thixotropic properties permit the material to be handled by robotic devices and transferred to a die (Thixocasting) or subjected to- a forming process by means of forging (Thixoforging). Owing to the shear stress which acts on the semisolid material during forming operation, the viscosity of the material is reduced attaining so the desired fluid-like flow characteristics."

Jan 1, 2000

By M. Hadj Meliani

This paper explores direct use of finite element analysis by CASTEM 2000 in order to determine the evolution of T-stress term for arc of pipe specimens with external surface crack. A simple method, called the stress difference method proposed by Yang (1999), is used to compute the elastic T-stress in mode I at a crack tip. The different crack geometries and length-to-thickness ratio on T-stress and stress-intensity factor (SIF) are examined. The revisited stress difference method is shown to be an accurate and robust scheme for evaluating T-stress in arc of pipe.

Jan 1, 2006

By Lztok Peruš, Goran Kugler, Matevz Fazarinc, Milan Tercel

"Hot deformability of M42 tool steel additionally alloyed with cobalt and molybdenum was investigated. Hot-compression tests were carried out in the temperature range 850 °C -1200 °C, at strain rates range 0.001--6s-l up to strain of0.9. Field-emission scanning electron microscope and optical microscopy were used for characterization of microstructure of deformed samples, which revealed a very complex precipitation of carbides that strongly depends on the soaking temperature, the soaking time, the stress state, the deformation temperature as well as on the strain rate. Gathered data was used to calculate the processing parameters such as process maps, apparent activation energies and strain hardening exponents. For better understanding of thermodynamical properties of the studied steel a simultaneous thermal analysis was conducted. Furthermore the analysis of phase equilibrium was calculated using Thermo-Cale software. On the basis of these studies the optimal soaking temperature and process windows were determined.IntroductionHot workability ofledeburitic tool steels is important economic factor. This means that for each tool steel individuallysafe range of hot working parameters should be revealed. Publications in the literature with regard to the hot workability of tool steels are rare and therefore more information from this research area is desired.The relatively low hot workability of ledeburitic tool steels, i.e. steels in which the solidification is completed by a eutectic transformation of the residual interdendritic liquid to austenite and various alloy carbides (ledeburitic carbides), is usually characterized by the production of surface and internal cracks during the hot deformation."

Jan 1, 2013

By Christoph Pichler

A special desulphurization slag accrues during the processing of iron ore to steel, which is needed to generate high quality steel. Sulphur removing is done by different technologies, but the most common one is the generation of a high sulphur containing slag by sulphur affine elements. Currently, this desulphurization slag is partly recycled, however, huge amounts are still dumped. To utilize this desulphurization slag for future purposes, a recycling process must be established. Therefore, first characterization of this material started some years ago at the Chair of Nonferrous Metallurgy, Montanuniversität Leoben. Subsequent trials in lab scale size were performed, also some investigations for different treatment steps were evaluated, starting with a parameter study in a hot stage microscope at various gas-atmospheres. Finally, the developed recycling process concept was verified in pilot scale trials to confirm the new recycling technology. Due to the successful treatment process, also a patent was applied.