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By Lenny Winkel

With the aim to develop a solar-driven process for the extraction of copper from sulfide concentrates research on the decomposition of copper sulfides under inert atmospheres has been initiated. Thermogravimetric measurements on chalcocite (CuzS) revealed that copper is formed already at 1823 K. Chalcopyrite (CuFeS2) also disintegrates at this temperature, although at a lower rate. Copper and iron have been identified in the solid residue. The results confirm the feasibility of copper extraction by direct decomposition of sulfides under atmospheric pressure. The decomposition under inert atmosphere prevents generation of SO2, it also alters the behavior of volatile impurities during decomposition of copper sulfide concentrates. Chemical eqUilibrium calculations for chalcopyrite contaminated with enargite (Cu3AsS4) have shown that the absence of an oxidic slag allows for a complete evaporation of arsenic and subsequent separation from intermediate sulfides. The need to better assess the potential of direct sulfide decomposition has prompted the development of an experimental setup for studying the decomposition reactions. The experiment has been devised such that data on the decomposition kinetics and on impurity removal can be obtained at temperatures up to 2500 K.

Jan 1, 2003

By Kim Fagerlund

Boliden Harjavalta Oy operates a copper smelter in Finland, which is based on flash smelting together with Peirce-Smith converting of copper matte. This paper reviews a case study when a high arsenic feed mixture was successfully eliminated in order to guarantee the anode quality. Based on theoretical and practical knowledge in slag chemistry at Outokumpu Research, the CaO-fluxing practice was introduced. Description of a thermodynamic simulation using MTDATA and implementation of the results into converting practice is given. Results showed that the impurity fluctuations in raw materials could be effectively controlled by efficient utilization of different slag chemistry.

Jan 1, 2005

By A. Deepatana

Bioleaching of nickel laterite ores is based on the use of heterotrophic fungi organisms and their metabolites (organic acids) to dissolve nickel and cobalt from oxide minerals to form metal-organic complexes. Metal recovery from this process using an aminophosphonic acid based chelating resin (Purolite S950) was investigated as a function of metal concentrations, complexing agent including citric, dL-malic and lactic acids. Batch adsorptions were conducted using synthetic leachate solutions of nickel and cobalt with concentrations from 15 to 2000 mg/L prepared in 0.01 and 0.1 M organic acids. Adsorption equilibrium data were interpreted using the Langmuir, Freundlich and Dubinin-Kagner-Radushkevich (DKR) models. The results showed that equilibrium adsorption data for nickel-organic complexes followed the Freundlich model and those for cobalt agreed with the Langmuir model. It was observed that the maximum adsorption capacities of nickel and cobalt were 3.26 and 10.48 mg/g resins respectively. These were achieved in metal complexes prepared from 0.01 M lactic acid. Metal elution was conducted using 2 M nitric acid. High metal recoveries were achieved from low metal concentrations but were found to decrease with increasing metal concentration. The results suggest that effective recovery of nickel and cobalt from low concentration of metals, such as those generated from bioleaching operations, can be achieved suitably using chelating resins.

Jan 1, 2006

By Emma Arakelova

An increase in concentration of a Zn-containing volatile complex for synthesis of ZnO films was investigated when processing their target by ultraviolet radiation emitted by mercury lamp. The experiments were carried out using a flow-type quartz reactor. ZnO tableted target was preliminarily irradiated during 2 to 7 hours. H2O2 (98%) vapor at 25Pa passed through the reactor with ZnO target at 373K. As substrate material, five subsequent quartz cylinders were used at 423K. The experiment lasts 4 hours. H2O2 decomposition on ZnO surface was accompanied by formation of a Zn-containing volatile complex which passed in gas phase and decomposed on the substrates with isolation of final ZnO. The concentration of the Zn-containing volatile complex (N) in gas phase increases with UV pre-irradiation time (t) (without irradiation N = 1.05 1011 particles/cm3; after t=2 hours, N = 5.19 1011 particles/cm3, after t=4 hours, N = 9.95 1011 particles/cm3; after t=7 hours, N = 1.86 1012 particles/cm3.

Jan 1, 2006

By Valery M. Paretsky

The effect of the degree of nickel oxide reduction and the reaction gas composition on the furnace productivity has been estimated by computations and the established relationship is in good agreement with the practical data obtained in the process of electric smelting at the Severonickel smelter. An increase in the reduction degree within a range of =0.65 - 0.9 results in an increase in the furnace productivity by 19% to 37% and in a decrease in the unit electric power requirement by 16% to 27% depending on the reaction gas composition. The agreement between the computed and practical data has confirmed that the decisive factor for the process of treatment of reduced nickel oxide in an electric-arc furnace under the given conditions is the specific heat absorption, which is dependent on the nickel oxide reduction degree and the reaction gas composition.

Jan 1, 2005

By Z. Sun

Magnetic fields have been used for inclusions removal from melt and preparation of materials with gradient compositions. Fundamental in these applications is that the induced magnetic forces on the particles/melt can enhance migration and change the interaction behavior. In the present paper, migration and interaction behavior of electrical-insulating particles in a conductive melt under strong magnetic field are theoretically analyzed. It is found that the migration can be considerably enhanced for micrometer sized particles by applying a strong magnetic field. In addition, two forces are involved in the interaction between two particles: the interparticle magnetic dipole-dipole attractive force due to magnetization and the repulsive force induced by flow of the melt. This theoretical analysis renders a better understanding of recent experimental results. Additionally, a new method by using strong magnetic field can be proposed to control the particle size distribution for the preparation of metal-matrix composites.

Jan 1, 2009

By M. Hochenhofer

Due to economic aspects and environmental regulations recycling of slag and waste from ferroalloy production became a very important issue for the companies during the last years. The treatment of slag depends prior on the composition, especially on their content of valuable metals and impurities. The final aim should be a total re-use of these materials in the industry e.g. cement industry, pig-iron production etc.. Therefore, to reach the required physical and chemical properties for a further use, possibilities of a metallurgical treatment have been investigated. The conditioning of slag with a high V-, Mo- and P-content via reducing metal bath showed to be one alternative. To determine the optimal process parameters, practical investigations with different slag compositions and thermodynamic calculations were carried out.

Jan 1, 2006

By Chen Song

Keywords: Mixed extractant, Copper, Cobalt, Nickel, Synergistic effect During separation process of copper and cobalt from nickel sulphate solution, the effects of constitutions and compositions of mixed extractant D2EHPA and PC88-A or Cyanex 272, has been studied. In one step extraction cycle, the following results are obtained:[Ni]/[Co]>4000 and [Ni]/[Cu]>40000 in nickel sulphate solution, [Co]/[Ni]>1000 and [Co]/[Cu]>30000 in cobalt chlorinate solution, [Cu]/[Ni]>10000 and [Cu]/[Co]>200 in copper sulphate solution. It was elucidated that the above-mentioned synergistic mixtures can effectively separate cobalt and copper from nickel sulphate acid solution and achieve a greater synergistic effect.

Jan 1, 2005

By Jukka Tuominen

The history of making blister copper in an Outokumpu Flash Smelting Furnace dates back to the late 1960?s, when Outokumpu first piloted the Outokumpu Direct Blister (ODB) process. The first commercial scale applications have been in use at Glogow, Poland, since 1978 and at Olympic Dam, Australia, since 1988. These applications utilize special concentrates, which are low in iron, and thus the formation of slag is also low. In 1995 the same principle was applied to smelting copper matte into blister copper in industrial scale at Kennecott Utah Copper. This application, the Kennecott-Outokumpu Flash Converting process, will celebrate its 10th anniversary of commercial scale operation this year. This paper outlines the development in efficiency and flexibility of Blister Flash Smelting processes compared to other smelting and converting options. The focus is on the economical aspects i.e. on the total feasibility of both greenfield investment projects and revamping of existing smelters.

Jan 1, 2005

By Melissa L. Trapani

Keywords: Copper, Taphole, Flow Instability. ?Blister spitting? is a flow irregularity where the molten blister copper stream ? or part thereof ? sprays from the taphole exit rather than following a regular flow profile to the collection box. As well as being a general ?housekeeping? issue, the unpredictable nature of the flow is a threat to operator safety. Also, the aggressive flow pattern may contribute to the mechanical wear of the taphole refractory, compromising the integrity of the taphole. This paper brings together a collection of first-hand observations and reports from process personnel, and suggests some theories as to the causes of blister spitting.

Jan 1, 2005

By Elli Nurminen

Keywords: Thermal conductivity of sulphates, flash smelting, heat recovery boiler, flue dust Accretions and build-ups in metallurgical heat recovery boilers decrease the efficiency of the heat transfer and may cause process shut downs. Transient plane source method (Hot Disk) has been applied to measure the thermal conductivities of the Copper Flash Smelting flue dusts. Thermal conductivities of copper, iron and zinc sulphates, and process flue dusts were measured. The results indicate that all the components are effective thermal insulators, having a thermal conductivity of less than 1 W/mK. Decreasing dust layer porosity has an increasing effect on thermal conductivity. Insulating layers on the boiler walls decrease greatly the heat transfer efficiency of the boiler. The gathered information will be used in CFD-modelling of the process, and in the process control.

Jan 1, 2005

By N. E. Idenyi

The effects of compositions and firing temperatures on the physico-mechanical properties of blended Nsu fireclay and Nkalaha redbrick clay have been investigated. The clay samples were compounded according to the following ratios: 10:90, 20:80, 30:70, 40:60 50:50, 60:40, 70:30, 80:20 and 90:10 in the order Nsu: Nkalaha respectively, and test samples made and fired at 9000C, 10000C 11000C and 12000C. The properties tested for were the modulus of rupture, porosity, shrinkage, apparent density, water absorption and bulk density. From the results obtained, it is inferred that the blends have a maximum service temperature of 11000C, with the 30: 70 blend presenting the best characteristics. A conclusion is drawn to the effect that the blend could be adapted for the production of ceramic earthenware, electrical porcelain pin insulators, cement manufacture and for refractory linings where temperature requirements are less severe.

Jan 1, 2006

By Pengfu Tan

A thermodynamic model of KIVCET lead smelting process has been developed. The model has the capability to predict the distribution behaviors of Pb, Zn, Fe, S, O, As, and heat balance in KIVCET direct lead smelting furnace. The compositions of lead bullion, matte, slag and gaseous phases, and heat balance are calculated. The effect of the ratio between oxygen and feed on the chemistry of the smelt and heat balance of the coke checker has been simulated and discussed. The thermodynamic model also helps to understand the tapping issue of the lead bullion. In this paper, some applications of this model in the industry have been presented.

Jan 1, 2006

By Anat Deepatana

Bioleaching of nickel laterite ores is the extraction technology based on the use of heterotrophic micro-organisms and their organic acid products to dissolve metals from oxide minerals. This study examined the chemical leaching kinetics of limonite and nontronite ores with metabolites including citric, lactic and malic acids. The leaching process was found to follow the chemically controlled model. The leaching kinetics was found to be significantly influenced by the acid strength or dissociation of acids in solution. Although increasing the acid strength increased the rates of leaching, this trend was not indefinite. An optimal acid concentration that defined the fastest leaching rates was identified for each acid. The amenabilities of the minerals hosting the nickel and cobalt in limonite and nontronite to organic acid leaching were also established.

Jan 1, 2006

By Etsuro Shibata

The saturated solubility of chromium oxide and the valence of chromium in the slag are important matters when considering how to effectively utilize chromium-containing slags. The experimental data of various types of slags cited in the literature were arranged according to the optical basicity in order to evaluate the effects of the oxygen potential and the slag composition. The saturated solubility of chromium oxide and the Cr2+/ Cr3+ ratio tend to decrease with the increase of the optical basicity of the slag at an oxygen potential below 10.5 atm. However, at an oxygen potential of 0.21 atm, the saturated solubility and the Cr6+/Cr3+ ratio tend to increase with an increase of the optical basicity. A practical approach was suggested to reduce chromium in the stainless steel slag and simultaneously recover it as a ferroalloy by the direct smelting reduction of chromium oxide in the molten slag using some reductant in a small furnace.

Jan 1, 2003

By Sung Wng Kim

The binary antimonide compounds with the skutterudite structure have a potential for thermoelectric applications because of the high carrier mobility, high thermoelectric power, and relatively low thermal conductivity due to the complex crystal structure. However, the room temperature thermal conductivity of these skutterudite materials is as high as about IOW/mK with an estimated 80-90% contribution from the lattice thermal conductivity. Because the lattice thermal conductivity of related ternary skutterudite compounds can be substantially reduced due to the additional phonon scattering, a study of thermoelectric properties of these compounds is of interest. The binary IrSb3, ternary Ir1.xRuxSb3 and Ir(MxSb1.x)3(M=Ge, Sn) compounds were prepared by hot pressing of pre-reacted powders. We have measured the electrical resistivity, thermoelectric power, and thermal conductivity, in a temperature range from room temperature to 973K. The binary IrSb3 compound is found to have P-type electrical properties exhibiting a good Seebeck coefficient (up to 225µV/K around 773K), electrical resistivity(5x10-5Ohm M around 933K), and relatively low thermal conductivity(6W/mK around 950K). The lattice thermal conductivity, K[2] was calculated from the Wiedemann-Franz relationship.

Jan 1, 2002

By Jesús Contreras

Within its programme for continuous improvement and cultural change, Atlantic Copper has installed the Six Sigma methodology as a basic tool for the improvement of management techniques in all its production centres. Following an implementation period, the methodology is widely used for analysis and improvement, not only in the fields of production and maintenance, but also in other areas of the business such as supplies or energy management. The present paper describes, phase-by-phase, the project that was developed to improve the quality of converter slag through the application of Six Sigma techniques, from the initial set up to the final results obtained.

Jan 1, 2005

By Viviane Tavares

The liquid crystal display (LCD) are currently known by its vast application in electro ? electronic devices, amongst them can be detached the devices of TV, laptops, electronic date, calculators and even though the mobile telephones (mobiles). The mobiles are changed more frequent of the TV for example, this happens due to the technology advance. With the constantly mobile exchange, the batteries, printed circuit board and liquid crystal display accumulation its become an environmental problem. To minimize the environmental impacts caused by mobile telephones residues are considered the segregation process of the LCDs main components, to goal to recover the recycle material. This process involves the use of treatment ore techniques with disc, hammers and balls mills. The process with best efficiency (about 98%) of LCD glass release was the hammers mill. The glass recovered can be used in the glass recycling and the sand substitution in the production of concrete blocks.

Jan 1, 2009

By Asmo Vartiainen

Background of Direct-to-Blister Flash Smelting is discussed; especially slag chemistry relating to copper solubility, slag fluidity and impurity behavior. In December, 2000, Mini-pilot Flash Smelting test runs were carried out at Outokumpu Research Oy to produce blister copper from Chilean concentrate and white metal and from a mixture of them. Tested slag types were iron silicate slag, ferrous calcium silicate slag and calcium ferrite slag with different slag compositions and different concentrate/white metal ratios. The test runs were successful. The fluxing effect of copper oxide was clearly demonstrated and ferrous calcium silicate slags remained fluid on a very wide liquidus range. The distribution of arsenic between ferrous calcium silicate slag and blister copper is much higher than between iron silicate slag and blister copper. This successful test run with the new slag type offer new possibilities in Direct- to-Blister process design.

Jan 1, 2003

By Vijaya Thangavelu

Biological leaching of low-grade nickel laterite is based on a non-traditional leaching of oxide minerals using heterotrophic micro-organisms. The organisms solubilise metals by excreting organic acids; these acids then form complexes with heavy metals. High salinity of water supplies and soils in the vicinity of nickel laterite ore bodies is a major abiotic stress to fungi and represents a major challenge in the application of bioleaching process in-situ. Salinity exposes fungi cells to Na+ toxicity and osmotic stress. This study examined the salt tolerance development of Aspergillus foetidus based on gradual acclimatization of organism, its salt threshold and the salinity effect on its metabolism. The biological leaching of weathered saprolite ore with the resulting halotolerant organism under saline conditions was assessed. It was observed that salinity stress affected the organism?s growth and energy utilization

Jan 1, 2006