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By J. Ipinza

The slime formation with several metallic impurities from acidic electrolytes of copper has been studied. On fresh Pb-Ca-Sn anode surface firstly the formation of PbSO4 takes place, then, it is transformed in the conducting PbO2, which covers the anode surface. It has been experimentally established the formation of a manganese dioxide double layer at the anode; this double layer was always composed of a thick external layer of non-adhering and easily removable scales, and of a thin internal layer, which adheres relatively well to the surface of the electrode. It was found that manganese dioxides present in the slime were of different nature: a non-adhering layer produced by electrolysis (-MnO2) on the PbO2 surface and a pure chemical precipitation in the solution (-MnO2). When iron is present in the electrolyte on this last layer of manganese, lead sulfate was found. In the case of arsenic and antimony in the electrolyte the slime generated was found to be lead sulfate and amorphous compounds of those ions. The lower slime generation in Chilean EW plants could be due to the lower contents of iron and manganese in the electrolytes. It was found that this slime formation rate not only is due to the electrolyte composition but also to the poor control of operational parameters at EW plants.

Jan 1, 2003

By Yijun Cao, Shengpeng Su, Guihong Han, Xiangyu Song, Yanfang Huang

Binder is indispensable in the production of iron ore pellets and the quality of pellets seems to be related to the interactions between binders and iron minerals. Humic acid is proved a suitable binder for iron ore pelletizing. In this paper, the interactions between humic acid and iron minerals were investigated by adsorption experiments and molecular dynamic simulations. Adsorption experi- mentalresultsshowthattheadsorptionofhumicacidonhematiteiseasierthanthat on magnetite, and the maximum adsorption capacities of humic acid on hematite and magnetite reach 17.1, 7.39 mg/g, respectively. The results of adsorption iso- therms indicate that the Langmuir model provides the best correlation of the experimental data, while the thermodynamics results demonstrate that the adsorp- tion process is a spontaneous exothermic process. Molecular dynamic simulations reveal that the interaction between hematite and humic acid is stronger than that between humic acid and magnetite. (cid:1) (cid:1) (cid:1)

Mar 1, 2018

By Huang Rui

The coal asphalt is combusted at different temperature in a heating cabinet with the temperature limit by 1200°C. By comparing the mass of the remainder of each experiment, the completely combusting temperature of asphalt smoke can be determined. Based on the experimental process of asphalt smoke, a discrete mathematical model of the asphalt smoke combustion is set by theoretic analysis. Through computer programming, the dynamic combustion process of asphalt smoke is calculated to simulate the experimental model. The result of experiment shows that coal asphalt can mostly react upon 500°C and the mass of remainder is 49.41% to initial mass of sample in the condition. The computing result shows that the temperature and the concentration of asphalt smoke influence its burning temperature approximating linearity. The consumed quantity of fuel to ignite the asphalt smoke needs be considered with the two factors.

Jan 1, 2006

By P. M. Prasad

The last two decades have witnessed the emergence of numerous hydrometallurgical and direct processing techniques for the extraction of some metals from pocketed/lean/complex sulfide ore deposits. A new approach with some inherent technological merits, investigated in recent years, is the lime-enhanced reduction of metal sulfides. Thermodynamic aspects relevant to the lime-enhanced reduction of metal sulfides by H2,C0 and C are discussed. A survey of the researches on the basic features of and factors influencing the lime-scavenged reduction of selected sulfides and sulfide concentrates reveals that lime tremendously enhances the sulfide reduction rates (up to 100 times) and drastically reduces the sulfur emission into off-gas to negligible levels. Further successful practice of lime-enhanced reduction requires only a moderate temperature of reduction (characteristic of each sul¬fide) and, in the case of gaseous reduction, relatively low gas flow rates. Relevant kinetic aspects of the concerned reactions that have a bearing on process development and its understanding are also briefly discussed. A conceptual scheme of general applicability for the processing of sulfide concentrates by the lime-enhanced reduction technique consists of three main steps: (0 lime-enhanced reduction by a suitable reagent (e,g., H,2, CO, gasified coal, water gas), (ii) separation of the product metal from the dry slag (CaS + unused CO) by mechanical separation, magnetic/gravity concentration or flotation and (iii) melting and refining by standard procedures. This novel approach, which is patently less complex, is expected to employ basically simpler flow sheets at comparatively lower operational temperatures and aid in pollution abatement. Potential for developing such a route for the small scale extraction of metals like copper, molybdenum and antimony is indicated. Possibility of utilizing this technique for the production of fibers/ filaments of some metals is also outlined.

Jan 1, 1983

By Alex Mezei

Experimental rheology data are needed to produce design criteria for mass and energy transfer processes. Large throughput plants operate under continuous flow mode. The capital cost is determined by the accuracy of the rheology data used for design. The operating cost is dictated by the energy required to sustain the flowing conditions of various process slurries. Typically, rheology investigations are carried out during the final stages of metallurgical testwork, which is too late to set the design criteria for the pilot plant. This leads to increased testwork cost, and sometimes lowers confidence in the quality of the data produced. In addition, the engineering and feasibility studies are often delayed because of the lack of pertinent rheology data. One of the objectives of this paper is to emphasize the importance of timely planning and execution of the rheology study, which is shown to be a critical component of the overall testwork program. Various applications are discussed, including elaboration of process and equipment design criteria. In this paper, the emphasis is placed on gold and nickel laterite hydrometallurgy applications.

Jan 1, 2003

By Philip Thompson

"Carefully planned laboratory test programs provide valuable data regarding the amenability of low grade gold ores to heap leaching. The most common laboratory test is the column leach test. The overwhelming problem associated with this type of test is the limit on the test column height. Most laboratories use a three (3) meter (10 foot) high column as a standard test due to building ceiling limitations, sample size limitations, etc. This paper presents a case study in which an ore sample was tested in a 1.5 meter, a three meter, and a six meter high column to determine the effect of column height on the test results. Other important factors such as sample preparation protocol, preliminary bottle roll testing to determine appropriate crush size, column diameter requirements, and leach solution analyses, are also discussed.IntroductionColumn leach testing has been used for years by many laboratories to determine the amenability of low grade precious metals bearing ores to heap leaching. However, the test work can be compromised by poor planning, misinterpretation of results, and extrapolation of data beyond the reasonable boundaries of the experiment. Preliminary test work should be performed prior to column testing. This preliminary work provides valuable information regarding the response of the ore to cyanidation and aids in the design of the column tests.The sample should be screened into various size fractions prior to testing. The fractions are assayed to determine the gold content of each size fraction and of the overall sample. The most valuable preliminary test is the bottle roll cyanidation test which is usually performed on five kilograms of coarse sample in a large rolling bottle which can accept material up to 50 millimeters top size. The residue from this test is screened at different sizes to determine the distribution of unleached gold in the residue. Comparison of the gold distribution in the leach residue with the distribution of gold in the feed at the same size intervals provides an indication of the appropriate crush size for the sample. The overall gold extraction from the sample at the crush size tested is also determined from these data. Lime and cyanide requirements can also be estimated from this test. The viscosity of the bottle roll pulp and the size distribution of the feed and leach residue can also suggest whether agglomeration of the ore will be required prior to column testing. Ores which contain significant amounts of clays (greater than 5 percent) will generally require agglomeration to prevent plugging of the test column."

Jan 1, 1997

By Zhongliang Tian, Yun Cheng, Yexiang Liu, Ming Jia, Yanqing Lai

"A fundamental electrochemical study of Si ions in Na3AlF6-LiF melts and electrolysis using liquid cathodes was conducted. Cyclic voltammograms (CVs) clearly showed the depolarization of silicon deposition on liquid cathode by forming chemical complexes with the liquid solvent metals. Besides, co-deposition of Al and Si is possible when Si ions are insufficient in the molten salt. Based on the electrochemical results, silicon diffusion into liquid cathode is modelled and evolution of Si activity with concentration is deduced by a mathematic approach. Electrochemical study using liquid metals as working electrodes, can be used as an alternative approach for the acquisition of basic data on alloy behavior. Galvanostatic electrolysis showed that liquid cathodes are appropriate to collect the deposited solid silicon and the highest collection efficiency is almost 85%.IntroductionRecent years have witnessed an increasing demand for solar-grade silicon (Si) by the photovoltaic industry [1-4]. The preparation of high-purity metals through electrolysis and electrorefining offer many advantages such as low cost, low-energy consumption, and environment-friendly process, and thus has been widely used worldwide. From the perspective of electrochemistry [5-7], by utilizing the electronegativity difference between the impurities and Si and controlling the relevant process parameters, it is possible in principle to electrodeposit monatomic Si from a Si4+-containing compound melt. Moreover, because the carbon content of the high-purity Si obtained through electrolysis can be effectively controlled and used as a very ideal raw material in the preparation of electronic-grade and solar-grade Si, the preparation of high-purity Si through electrolysis has received widespread attention [8,9]. Monnier et al. [9] used a graphite electrode to obtain high-purity Si (99.9 %-99.99 %) from Si02/Na3AlF6 system through electrolysis; however, because the Si was precipitated in a solid form and showed poor conductivity, the deposition rate was too slow. Olsen et al. [10] obtained high-purity Si films via electrodeposition in K2SiF6/KF-LiF system by selecting electrode materials with high surface quality (such as Ag and graphite). However, in order to ensure the film quality, the deposition current density must be relatively low (10-50 mA/cm2), resulting in a low current efficiency and low deposition rate, which are not conducive to reducing energy consumption and applying to practical use"

Jan 1, 2014

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Solange Kazue Utimura, Amilton Barbosa Botelho, Carlos Gonzalo Alvarez Rosario

In this study, the recycling of waste materials is interesting in the environmental aspect to reduce the amount of waste in land fill and attenuate the pollution of groundwater, air and soil due to the liberation of dangerous elements. Recycling materials is an important issue once it represents a potential source of valuable metals. Waste printed wired boards (PWBs) as a principal part of Waste Electrical and Electronic Equipment (WEEE) and it is a fast growing stream with complex composition. The composite materials from PWBs are ceramic, polymers and metals. Biohydrometallurgical route may offer possibilities to recycle PWBs from discarded computers with the order to recover copper. The extraction of copper from PWBs by bioleaching processeswas studied using a mixed culture of acidophilic bacteria fromacid mine drainage (AMD) and the bacteria Acidithiobacillus ferrooxidans (A. ferrooxidans). The bioleaching experiments were performed in shaker flasks at temperature 30 °C and 170 rpmwith 10% (v/v) inoculum and pulp density of 35 g/L. Themetals concentration was determined by energy dispersiveX-ray Fluorescence (XRF). The results showed that the maximum copper recovery from PWBs using A. ferrooxidans was approximately 89% and with a mixed culture of bacteria from AMD the copper recovery was 92%.

Mar 1, 2017

By Xiang Ma, Halvor Dalaker, Kai Tang, Stefan Andersson

Silicon carbide (SiC) is one of the most important non-oxide ceramic materials for many industrial applications and is mainly synthesized by carbothermic reduction of silicon oxide by coke above 2200°C. Replacing natural gas (mostly methane, CH4) for coke in SiC synthesis could considerably reduce energy consumption and CO2-emissions owing to higher carbon activity of CH4 at lower temperature. The generally accepted reaction mechanism is that SiC is synthesized through gaseous intermediate silicon monoxide, SiO. In the present study, the reaction mechanism for the SiO and CH4 gaseous mixture has been examined using atomic scale modelling. Molecular dynamics (MD) using a reactive force field (ReaxFF) has been utilized to examine the initial stages of reactions involving a gas mixture of SiO and CH4 and surfaces of SiC. The MD results revealed some interesting SiC formation mechanisms. The reaction energies of the critical intermediate species were also estimated by density functional theory (DFT) calculations and the implications for the force field parameters used in ReaxFF was discussed.

Jan 1, 2015

By O. I. Platonov

The experience that has been gained by MMC ?Norilsk Nickel? at its Trans-Polar Division (PD) operations since 1981 in the field of recovery of elemental sulfur from off-gas generated by the Vanyukov and flash smelting through its reduction by natural gas is briefly outlined in the present paper. The key challenge the operators treating off-gas originated from autogenous smelting are usually faced with is the presence of sulphur trioxide in it. Furthermore, air inflows along the entire gas flue increase oxygen concentration in off-gas, thus leading to over-consumption of the reducer (natural gas). Another issue attached to the methane technology is a low yield of hydrogen sulphide largely preventing efficient downstream Claus conversion of the gas. The new flowsheet for treatment of autogenous smelting off-gases including dry dust-cleaning followed by the gas reduction in homogenous reactor developed by OAO Gipronickel Institute on the basis of industrial-scale production of elemental sulfur in Norilsk is presented.

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

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

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

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

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 C. Wieckert

Concentrated solar energy can be used as heat source for the production of metals. One of the most promising respective processes, the solar carbothermic production of Zn from ZnO, is investigated within the European research project SOLZINC, a cooperation of institutes and industries from France, Germany, Israel, Sweden and Switzerland. The solar produced Zn can be used as commodity or as an energy carrier for further processing on demand to electricity in Zn-air fuel cells/batteries or to generate hydrogen by reaction with steam. In both cases the Zn is oxidized to form ZnO, which can be recycled back to the solar plant. In these cyclic processes Zn acts as a means to store and eventually transport solar energy. Second product of the solar process step is a CO-rich offgas, which may e.g. drive a gas engine or may be shifted to hydrogen in a conventional reaction with steam. A pilot plant using 300kW concentrated solar power input has been constructed and operated successfully. 86mass-% of ZnO mixed with 14mass-% of charcoal are reacted to produce Zn and CO at a temperature of about 1200°C, yielding about 50 kg gaseous Zn per hour. Zn-dust with 95% purity is recovered from the offgas system that was designed to produce Zn for Zn-air fuel cells. Based on the results and findings from the pilot plant, a two tons Zn/h solar demonstration plant has been designed conceptually. Cost studies have been performed and scenarios for producing electricity or H2 via these ZnO/Zn-cyclic processes are evaluated.

Jan 1, 2006