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By E. O. Stensholt

The Hybinette electrorefining process for production of cathode nickel was in use at Falconbridge Nikkelverk A/S, Norway, until 1975 when conversion to the new chlorine leach process was started. In 1978 the conversion to electrowinning had been completed, but further major improvements to the process have been made up to 1987. After a major expansion program in 1985 - 87 the refinery has a nickel capacity of 54 000 mt Ni/year. The main feed materials to the process are converter matte from the Falconbridge smelter in Sudbury, Ontario, Canada, and from the BCL smelter in Selebi-Phikwe, Botswana. A typical composition of the mixed feed to the refinery is: 40 - 45% Ni, 25 - 30% Cu, 20 - 22% S, 2 - 3% Fe and 1.0 - 1.5% Co. The matte is chlorine-leached in the first process step, nickel being dissolved selectively in a train of leach-cementation tanks. Essentially all copper and sulphur that was present in matte appears in the leach residue as CuS. In 1986 an autoclave treatment stage was added to the process to improve nickel extraction from the leach residue. The resulting strong nickel chloride solution is purified by the process steps (1) precipitation of iron and arsenic, (2) solvent extraction of cobalt and other minor elements and (3) precipitation of lead and the remaining impurities. The nickel solution is then fed to the tankhouse, where various nickel products are produced by electrowinning. The chlorine gas that is produced during the electrolysis is returned directly to the chlorine leaching tanks to dissolve more matte. After stripping from the loaded organic phase and solution purification cobalt is also produced by electrowinning. The copper sulphide leach residue, which contains some nickel, is dead- roasted in fluidized-bed roasters. The sulphur is recovered and sold as sulphuric acid. The calcine is leached in spent copper electrolyte, from which cathode copper is produced by electrowinning. Precious metals and the remaining base metals are recovered from the copper leach residue. The Falconbridge chlorine process is very versatile. It can accept a wide range of impurities in the feed and still produce metals of exceptional purity.

Jan 1, 1988

By S. S. Ibrahim

The left behind material after the combusion of fossel fuel in some power stations in Cairo; weighing tens of tons every years, was investigated. The material called "Fly Ashes" containing 7.5% Ni, 10.0% V and 9.50% Cr; could be considered as a promising source of such valiable elements. As well as the small grain size (050 70 "m) of the material, and besides the complexity of their formation history, hydrometallurgical methods appeared to be the effective technique to deal with. Yet, preconcentration is possible by means of magnetic and gravity separation methods. The end product is assaying 16.60% Ni and 20.2S!; V with weight recovery of about 60.15%.

Jan 1, 1995

By Aichun Zhao, Rui Wang, Yihong Li, Yanping Bao, Yafeng Ji, Jiansheng Liu, Xiao Hu, Qingxue Huang

The slag entrapment under different conditions of 80t blowing argon ladle furnace was investigated by physical simulation. The water was used to simulate liquid steel and liquid paraffin was for slag. The processing of slag entrapment under different blowing structures was analyzed and the critical velocity and critical droplets diameter of describing it was obtained. Based on the experiments, the relationship between the interface flow velocity and the critical blowing rate CBR was deduced. In the real process, it is suggested that the bottom blowing rate is from 40 L/min to 180L/min when the interface tension is 0.12~1.2 N/m during the soft argon blowing.

Jan 1, 2016

By H. K. Lin

Pyrite oxidation in chloride solutions was investigated with cyclic voltammetry, ac impedance and potential step techniques. The pyrite oxidation in quiescent electrolytes is irreversible and controlled by diffusion. Depression of the semi-circle in the complex plane plot has been explained mathematically based on the concept of the equivalent circuit. When the semi-circle is depressed, the mathematical formula indicates that the reaction resistance should be obtained from the intersection of the semi-circle with Z-axis instead of the semi- circle diameter. The peak charging current densities at 1.10 and 0.90 V vs. SHE obtained from the equivalent circuit coupled with the ac impedance measurements match the peak current densities obtained with the potential step measurements.

Jan 1, 1997

By Vânia L. L. Andrade

Igarapé Bahia Mine is located in Carajás area, northern Brazil. Currently Companhia Vale do Rio Doce operates there a CIP / heap leaching plant treating an oxide gold ore containing about 4 g Au /t and 0,2% Cu, which produces 11 t of gold per year. Recent geological survey has identified a signifcant copper-gold reserve underneath the oxide gold ore. The processing aspects of this copper-gold sulphide ore are described in this paper. It includes ore characterization studies, grinding and flotation tests, orebody variability assessment, flowsheet selection and preliminary economical evaluation Emphasis is given to studies aimed at depressing fluorine bearing minerals to achieve a clean and marketable flotation concentrate.

Jan 1, 1999

By B. Ozturk, K. Ito, R. J. Fruehan

"A simulation model for bath smelting processes for the production of iron was developed which predicts the coal, flux, ore, and oxygen consumptions and the off gas volume, temperature and composition. The model is comprehensive in that it takes into account all of the important variables including coal composition, metal composition, ore composition, slag basicity, post combustion ratio, (PCR), prereduction degree (PRO), heat transfer coefficient (HTC) , flux, scrap charge, and heat losses. Four basic cases were considered: I. 30% PRO-50% PCR; II. 90% PRO-O% PCR; III. 60% PRO-30% PCR; and IV. 0% PRO-50% PCR. Several different coals were considered and a sensitivity analysis of the critical variables was performed. The model also estimates the sulfur content of the metal. The major conclusions included:1. Post combustion significantly reduces coal consumption but above 20% PCR little reduction of FeO to Fe can be performed with the off gas.2. Prereducing to FeO (Case I) and having as much post combustion as consistent with good heat transfer is an attractive process. This process only requires a simple pre reducer, uses less coal, and is relatively insensitive to the type of coal used.3. High off gas temperatures may pose a potential problem. The off gas temperature can be reduced by using an 02-Air mixture for post combustion, limiting post combustion or adding water to the gas.4. The use of CaC03 in place of CaO or of supplemental electricity does not appear attractive.5. The melting unit is theoretically an energy efficient scrap melter. For Case I using 200 kg of scrap as part of the charge the coal consumption decreases by about 80 kg.6. With PCR > 30% the FeO content of the slag is expected to be 2-5%, and the metal will not be saturated with carbon. These factors and the increased sulfur load since coal is the fuel indicate the sulfur content of the metal may exceed 0.25%"

Jan 1, 1988

By Batric Pesic

A hydrometallurgical process for recovery of Zn and Mn from Bunker Hill Water Treatment Plant sludge was developed. The process is unique because it treats an unusual combination of metals, Zn and Mn. Another non-standard feature of the process is that leaching takes place with ~S04 in the presence of a reductant (SO2). Zn and Mn are recovered simultaneously by electrowinning, Zn on a cathode and Mn on an anode, as MnO2 The major purpose of the process is to detoxify the sludge by removing toxic heavy metals. The recovered metal values could be marketed to offset the overall costs of water and sludge processing. This work is presented in two separate parts, 1. Leaching and Solution Purification, and II. Electrowinning. This paper covers only the first part of the hydrometallurgical process: Leaching and Solution Purification. Initially, the paper briefly discusses the history of the pollution problem at the Bunker Hill Superfund Site, the origin of heavy metals in the mine waters, and the development and use of the water treatment plant. The leaching of sludge was examined as a function of the following parameters: constant vs. initial pH, initial vs. delayed addition of SO2, temperature, and pulp density. It was found that leaching with H2SO4 at pH 2.0 for 15 minutes (at 60°C), followed by S02 addition for another 15 minutes, could completely dissolve Zn and Mn. Solution purifIcation was done in three stages. In the first stage iron was removed by adjustment of pH (to pH 5.0) and oxidation offerrous to ferric iron (with H2O2). In the second stage, Cu and Cd were removed by Zn dust cementation. Finally, Co and Ni were precipitated with the organic reagents 1-2 nitroso-naphthol and nitroso, respectively. Electrowinning of Zn and Mn is discussed separately in Part II of this paper.

Jan 1, 1996

By Soumendra Basu, Uday Pal, Yang Yu, Srikanth Gopalan, Karl Ludwig, Deniz Cetin, Jacob Davis

"A limiting factor for Solid Oxide Fuel Cell (SOFC) performance is the oxygen reduction reaction (ORR) at the cathode surface. Changes in the surface composition and structure on annealing at 800°C has been studied, since these can influence the ORR. Idealized single crystals of cathode materials La0.8Sr0.2MnO3 (LSM) and La1-xSrxCoyFe1-yO3 (LSCF) were grown as heteroepitaxial thin films on lattice matched single crystal substrates. Changes upon heating the films to operating temperature and pressures were characterized using various synchrotron x-ray techniques. Total Reflection X-ray Fluorescence (TXRF) measurements, which probe compositional changes, were made at high temperature in real time. The LSM surfaces were found to develop manganese enrichment when heated. Highly strontium doped LSCF were found to develop strontium-rich surfaces. HArd X-ray PhotoElectron Spectroscopy (HAXPES) was used to investigate the electronic structure of the materials. Highly strontium doped LSCF precipitates a surface strontium phase that contains both oxide and carbonate contributions.IntroductionSolid oxide fuel cells (SOFCs) are chemical to electrical energy conversion devices that could potentially reshape how energy demands are fulfilled. SOFCs have a potential efficiency over 70%, fuel flexibility, low emissions, and low degradation over long time scales. Commonly, SOFCs are operated at high temperatures (above 800°C). At these temperatures expensive housing is needed to contain an operating stack as well as coatings to contain the oxidation of the metallic interconnects. Lowering the temperature of an operating device would allow for more conventional materials to be used, thus lowering overall cost. Understanding the reaction kinetics of the oxygen reduction reaction at the surface of the cathode is vital to designing a system that will perform well at lower temperatures. A commercialization goal is to reduce operating temperatures without sacrificing performance.In order to exploit the advantages of SOFCs, an understanding is needed of the surface chemical states of cations on the surface of the cathode and how this relates to the oxygen reduction reaction (ORR):"

Jan 1, 2014

By Alejandro R. Alonso, Lizet Alvarado, Gretchen T. Lapidus

"Cobalt and lithium recovery from spent Li-ion secondary batteries has been increasingly studied in recent years due to the high value of both metals and the low proven reserves for lithium. The standard method employed until now has been the deactivation and crushing of the batteries, followed by leaching of the L1C0O2 spinel from the battery cathode using acid solutions, such as 1.5 to 2.0 M HC1 or H2SO4, in a temperature range from 120°C to 250°C. Once leached, the cobalt is separated by electrodeposition and the lithium by precipitation, using large amounts of carbonate to bring the solution to alkaline pH values. In the present work, citric-thiosulfate solutions are used for the spinel leach at room temperature, favoring a reductive environment at room temperature, which stabilizes the cobalt(II) as cobalt citrate and lithium(I) at pH 5, and recovers approximately 99% of both metals.IntroductionThe Li-ion batteries industry has become an important economic sector in recent years. This type of battery is the most promising system for energy storage, because of its high efficiency in charge-discharge cycles, and its adaptability to many configurations. The demand will probably increase because of the need for mobile energy sources in many types of devices ranging from cell phones, tablets, and laptops to medical, navigation and sophisticated communication equipment and even in automobiles.One major problem related to the use of these batteries is the method employed for recycling the components, mostly cobalt and lithium. Currently, there are two processes employed on an industrial scale: the Sony/Sumimoto process, used since 1990 [1] and the Toxco Process [2]. In the first case, incineration is used to open the batteries and at same time volatilize the organic solvents. After that, the metals (copper, iron and aluminum) are physically separated. The cobalt and lithium are recovered as oxides and then thermally treated in order to recycle them for new batteries manufacture."

Jan 1, 2012

By Akram Alfantzai, Farzad Mohammadi, Maysam Mohammadi

"Degradation of lead anodes has always been a major concern among the electrowinning industries. In this study, the effect of agitation of the zinc electrowinning solution on the integrity of lead anodes was investigated. Galvanostatic experiments were performed at 37±0.5°C using 0,600 and l000rpm magnetic stirring rates for 24 hours. The Pb02 layer formed on the anode surface was reduced to PbS04 (discharged). The discharge information was used to calculate the amount of Pb02 present on the surface. Weight loss measurements along with the discharge calculations revealed that the degradation rate of the lead anode increased as the solution was stirred more vigorously. Furthermore, the amount of remaining Pb02 on the surfaces was decreased as a function of solution velocity. Therefore, it may be concluded that, degradation rate oflead anodes is controlled by detachment of the corrosion products from the surface rather than by electrochemical reactions. IntroductionElectrowinning is one of the extraction stages of zinc, in which pure zinc is deposited from acidic solution after froth flotation, roasting and leaching processes. The anode electrode materials play important roles in the electrowinning process. Their electrocatalytical capacities determine the oxygen evolution overpotential, and consequently the cell potential and energy efficiency of the zinc electrodeposition [l]. Purity of the zinc deposited on the cathode is affected by the solubility and corrosion resistance of the anode materials. Using insoluble materials as anode in the electrowinning leads to the higher purity of the deposited metal on the cathode[2]. Lead (Pb) and its alloys have been used as the anode in the zinc electrowinning because of its special properties such as relatively low cost, low melting point, insolubility in solutions containing sulphuric acid and high conductivity in both states of metallic and oxidized [3, 4]. In zinc electrowinnig, zinc reduction occurs on the cathode (reaction 1) and the oxygen evolution reaction (OER) (reaction 2) is the main anodic reaction [5, 6]."

Jan 1, 2013

By G. Richards

The Trail smelter of Teck Metals Ltd. produces about 90,000 tonnes of lead per year through two stages of refining following KIVCETTM smelting. Bullion from the KIVCET furnace is first treated in a pyro-refining plant in preparation for Betts electrorefining which makes 99.99% pure lead. Pyro-refining consists of number of integrated unit operations to remove primarily copper, arsenic, antimony and tin. The operation of this plant to meet the specifications for electrorefining requires attention to bullion management and selective use of reagents. The processes used for pyro-refining are reviewed in terms of chemistry and control.

By N. J. Tannyan

Laboratory bath smelting tests were conducted to determine the feasibility of smelting nickel- copper concentrate directly to a low iron matte in one step. Concentrate, air/oxygen and a silica flux were fed to a matte-slag bath kept in MgO crucibles at I 300°C. Various oxygen enrichments and smelting rates were used to maintain 0.5 to 2 wt% iron in the product matte. The slag losses are comparable to those obtained under similar industrial conditions. Due to the highly oxidizing conditions required to produce mattes with low iron contents, it is not recommended to target iron contents below about 2% in the matte. The specific bath smelting rates were equal to or higher than those in various industrial bath smelting processes.

Jan 1, 2003

By Sung Jin Han

Magnesia-based refractory is generally used in an electric arc furnace (EAF) due to its relatively high corrosion resistance and strength at high temperatures. However, the magnesia refractory is attacked by EAF slag and thus the lining life continuously decreases. Thus, it is significant to identify the interfacial reaction between magnesia refractory and FeO-rich EAF slags. In the present study, the influence of FeO-rich slag on the corrosion behavior of MgO refractory was evaluated. The (Fe,Mg)Oss layer was observed at the slag-refractory interface and its thickness increased with increasing content of FeO in the slag. The specific reaction phenomena and formation behavior of (Fe,Mg)Oss layer were evaluated by thermochemical computing program, FactsageTM7.0.

By N. J. Tannyan

Laboratory bath smelting tests were conducted to determine the feasibility of smelting nickel- copper concentrate directly to a low iron matte in one step. Concentrate, air/oxygen and a silica flux were fed to a matte-slag bath kept in MgO crucibles at 1300°C. Various oxygen enrichments and smelting rates were used to maintain 0.5 to 2 wt"10 iron in the product matte. The slag losses are comparable to those obtained under similar industrial conditions. Due to the highly oxidizing conditions required to produce mattes with low iron contents, it is not recommended to target iron contents below about 2% in the matte. The specific bath smelting rates were equal to or higher than those in various industrial bath smelting processes.

Jan 1, 2003

By Grigore Matei

The thermodynamic properties of CU2S-FeS system are important not only in the case of copper smelting but also in the case of general pyro-mctallurgy, However there are not many reported activity data In this study, activities of FeS and CU2S in the CU2S-FeS system were calculated using the Darken's method from the activity data of the CU2S-FeS-Sb2SJ systems measured by the transportation method at 10S0°C. The activities of CU2S and FeS in the CU2S-FeS system showed negative deviation from the ideal behaviour and satisfied the relation of the Gibbs-Duhem equation,

Jan 1, 2003

By J. Dille

Metallic cobalt exist in two allotropic forms : the hexagonal compact a which is stable at low temperature ( ( 420') and the cubic form 0 stable at higher temperature. This latest form is the only one which is ductile. During the electrode position of Co, in moderate acidic conditions, we noticed a code position of both a and B forms. The influence of several parameters on the B/a ratio in the deposit was investigated. High acidity and the presence of Fe increased its ratio; on the opposite, high temperature promote the a phase. No significant influence on the material were noticed. The differentiation of a and B forms of Co is rather difficult and the method of J. Scoyer was improved quite successfully.

Jan 1, 1988

By Milan Lj. Stamatovic

The hydrometallurgical recovery of zinc from recycled blast furnace dust from a steel plant (Smederevo Metallurgical Company - Yugoslavia) was investigated. The dust contained 22% Fe, 17% Zn and 0.2% Pb. X-ray diffractometry showed that the main components were hematite and magnetite, in combination with zinc oxide and a very low content of lead oxide. Individual particles were generally spherical and ranged in size from 10 to 150 microns; 63% were less than 33 microns in diameter. An effective hydrometallurgical approach proved to be by caustic leaching followed by electrowinning. Recovery of zinc in the form of zinc powder was over 90%. This powder can be used for the cementation of impurities in the conventional hydrometallurgical process for zinc production.

Jan 1, 1993

By Maurizio Marezio Bertini

Successful treatment of contaminated sediments was achieved by sparging either 0.5 M NaOH solutions or distilled water with an SO2/O2 gas mixture. Metals such as Cu, Pb, Cr and Cd were successfully removed in a relatively short time. The effect of temperature and pH was investigated. Higher temperatures produced faster and higher recoveries with Pb and Cr more affected to temperature increase than Cu and Cd. The removal of copper, up to 50% percent, was achieved in alkaline solutions through the formation of copper sulfite complexes. The complete removal of metals such as Cu, Pb, Cr and Cd required that part of the treatment be carried out in acidic solutions. A preliminary cost analysis was carried out.

Jan 1, 2003

By T. B. Braun

Cathode contamination is the principal factor affecting the quality of electrorefined copper. It is commonly accepted that annealability is unfavorably affected by the following elements, in decreasing order of adverse effect: tellurium, selenium, bismuth, antimony, and arsenic. Silver in cathodes has importance as it represents a nonrecoverable loss of silver to the refinery. Mechanisms for the contamination of cathodes by these elements are examined and the effect of operating variables on contamination, including anode composition, electrolyte composition, electrolyte temperature, addition agent practice, and electrolyte discard rate, are discussed.

Jan 1, 1976

By Wolfgang Steffes-Tun

Pyrite ore concentrate from the Meggen mine (FRG) , which contains about 0 300 400 ppm thallium, is roasted in a fluid bed furnace at 1000 -1100 C to form sulfur dioxide and ash consisting mainly of hematite. Subsequently, the sulfur dioxide is separated from the ash or dust during several steps while cooling to about 250oC. The pyrite ash fractions show decreasing grain size down to 5 pm, a pH-decrease down to 2,4 and a marked enrichment of arsenic and thallium by a factor of 12. In the final fraction, the hot electroprecipitator dust of the dump (EGR), minute crystals of thallium-containing jarosite can be detected by analytical transmission electorn microscopy (TEM). Under oxidizing, acid conditions, jarosite may be a possible "reservoir mineral" for immobilizing thallium.

Jan 1, 1989