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By P. Barrios

The copper refinery of Atlantic Copper was modernised and converted to the Isa permanent cathode system in 1995. The technology installed has proved to be an excellent platform for the development of operational improvements. During the years it has been working, the progressive assimilation of the new technology has been achieved and the level of operator knowledge has allowed design production to be reached and surpassed by more than 10%. At the same time, modifications to the work programmes, using existing equipment, have permitted the incorporation of new cells and the achievement of annual production levels of 250,000 tonnes and a productivity of 0.43 t/man-hour.

Jan 1, 1999

By Mineo Hayashi

Gresik plant, PT Smelting, is the first and the only copper smelter and refinery in Indonesia. It had the original design capacity of 200,000 tpy of LME grade A cathode production and treats copper concentrates mainly coming from Grasberg mine in Papua, Indonesia. The smelter that employs the Mitsubishi process was put into operation at the end of 1998. In April 2004 the refining capacity was expanded up to 259,000 tpy in order to meet with soaring demand of copper cathode in South East Asian market. In addition, the construction work for the second refinery expansion project has started and it is scheduled to be completed in July 2006. At the completion of the project an additional 12,000 tpy capacity will be assured and in total it will make 271,000 tpy,. This paper describes the chronology of the expansion and future operational strategy of Gresik plant.

Jan 1, 2006

By E. Gervais

Modern life in inconceivable without zinc. Zinc provides the most cost-effective and environmentally efficient method of protecting steel from corrosion. Zinc is also used to power electric vehicles and computers, to make brass, automotive equipment, household appliances, fittings, tools and toys, and to support the building and construction industries. It is also used in pharmaceuticals and cosmetics, in rubber, in fertilisers and in animal feeds. The links between properties, applications and performance, as well as zinc demand and market dynamics, will be reviewed along with market development opportunities and successes. The presentation will also include a progress report on the five-year plan of the International Zinc Association to increase the global market for zinc, over and above the natural growth, by 500,000 tonnes/year by 2002.

Jan 1, 2000

Iron(II), sulphur dioxide and sugars such as lactose are potential reducing agents for manganese dioxide to produce manganese(II) for subsequent hydrometallurgical treatment. The leaching of limonitic laterite and manganiferrous ores with sulphur dioxide produces iron(II) which in turn can catalyse the leaching of manganese dioxide in acid media. This paper presents a critical analysis of the kinetics of reductive dissolution of synthetic manganese dioxide and manganese ore to compare and contrast the effect of sulphur dioxide and iron(II) in acid media containing sulphate or perchlorate anions. Both one-electron and two-electron mechanisms are considered in the case of sulphur dioxide. The current knowledge on chemical speciation is used to construct an Eh-pH diagram to show the effect of complexation of Mn(II), Fe(II) and Fe(III) with sulphate. Heterogeneous and electrochemical reaction kinetic models are combined to propose reaction mechanisms which rationalize the dissolution kinetics.

Jan 1, 2003

By V. Gel

An analysis of the operation of rotary tilting furnaces has indicated that they ensure better recoveries of metal when smelting lump scrap from aluminum slags, brass and bronze. On the other hand, processing of slags (concentrates obtained by mechanical upgrading) in pear-shaped furnaces results in much lower performance values as might be expected. At the Novgorod metallurgical plant a process for blister copper production in a rotary TROF converter (Outokumpu, Finland) has been introduced on a commercial basis. Smelting of brass and bronze scrap to produce blister copper is carried out using the technology developed in Russia and differing from the Outokumpu technology by the types of flux used and the blowing conditions in fuel burners and for melt oxidation, as well as by the design of gas removal system, the design of nozzles for melt blowing and the use of carbonaceous reductant (coal) for magnetite reduction in slags. Industrial-scale testing has demonstrated that by means of special techniques the 30-tonne converter productivity can be increased by 30% to 40% as compared with its rated productivity.

Jan 1, 2006

By M. A. Gerdel

In carboxylate collector flotation of bastnasite from other semisoluble salt type minerals such as barite various modifiers must be added in order to achieve selective flotation. One such modifier is a lignin sulfonate. It may function in part by acting as a sequestrant for metal ions present, preventing autoactivation in the system by metal ions derived from the minerals themselves. It also functions as a depressant for both bastnasite and barite, chemisorbing on both. However, it is shown that the lignin sulfonate functions as a much stronger depressant for barite than for bastnasite. It is suggested that the; strong depressing action on barite is related to a good fit of the sulfonate into the barite structure.

Jan 1, 1989

By M. D. Crites

As part of a multi-year program for assessing the viability of chrome-free refractories in copper smelting, converting and refining furnaces, dynamic corrosion tests have been conducted on a series of refractories from the magnesia-alumina system, using a ferrous silicate slag. The corrosion rates of the test refractories are compared with those of a reference mag-chrome brick, and recommendations are made for more in-depth evaluations of the more corrosion-resistant materials.

Jan 1, 1999

By H. Aminian

Copper electrowinning (EW) is an important process in connection with the solvent extraction to produce pure and marketable copper cathodes. A phenomenological model was developed to simulate the copper electrowinning process. The simulator is used to predict the operation of the Mines Gaspe pilot plant electrowinning cells put in operation in 1996. Results confirm the potential of the simulator that would subsequently be used for student training, process optimization and assessing the performances of control strategies.

Jan 1, 1999

By A. Robles

The main goal of the present work is to propose a viable alternative for selective arsenic elimination from copper smelter flue dust without the need of a global leaching scheme for all the individual components of the flue dust. Using this alternative, the inherent copper recovery problems are avoided. Arsenic precipitation is also considered for regenerating the solution and completing the process cycle. The experimental results for arsenic extraction and precipitation are satisfactory. Concentration of NaOH used was relatively low. The main reason for succeeding in high arsenic extraction and low NaOH consumption is due to the previous water washing of the flue dust. Water washing dissolves much of the iron and copper that are present in certain percentage as sulphate.

Jan 1, 1999

By K. Osseo-Asare

Rate laws for the hydrogen reduction of metal ions are typically of the form: [r = -d[M(II)]/dt = k[M(II)]xPy2H] where k is an apparent rate constant, [M(II)] and PH2 represent dissolved metal concentration and hydrogen pressure respectively, while x = 0 - 1 and y = 0.5 - 2. Half-order dependences have been reported for some M(II)/H2 systems; however, no satisfactory explanations have been offered. In an effort to bridge this gap in our understanding, the published precipitation rate data (for M(II) = Cu(II), Ni(II), and Co(II)) are reviewed (with emphasis on the reported reaction orders) and compared with the corresponding but limited electrochemical polarization data. Based on the available literature on the electrochemical kinetics of the M/M(II) and H2/H+ systems it is demonstrated theoretically that, under certain conditions (e.g., in the presence of electron-conducting solids), the rate of the M(II)/H2 reaction can be expressed as: [-d[M2+]/dt = k[M2+]2/1P2/12H] It is concluded that electrochemical processes probably play an important role in the hydrogen reduction of metal ions, especially for systems that involve heterogeneous catalysis.

Jan 1, 2003

By Shunichi Ajima

PT. Smelting Co. was established in February, 1996 to construct and operate the Gresik Smelter and Refinery. The construction work of first Copper Smelter and Refinery in Indonesia was completed in the end of August, 1998 and it was put into the integrated test operation in December, 1998. Gresik Smelter and Refinery is designed to produce 200,000 tpy of copper cathode from copper concentrate supplied from Grasberg Mine of PT. Freeport Indonesia Company in Irian Jaya, Indonesia. As by product 592,000 tpy of sulfuric acid, 382,000 tpy of slag, 31,000 tpy of gypsum and 480 tpy of slime will be produced in the full operation. Major processes applied at Gresik Smelter and Refinery are: Smelter: Mitsubishi Continuous Copper Smelting and Converting Process ( Mitsubishi Process ) Anode Casting: Continuous Casting of Copper Anodes with the Hazelett Twin Belt Caster Refinery: ISA Process Acid Plant: Lurgi Mitsubishi Double Contact Process

Jan 1, 1999

By R. Y. Wan

Thiocyanate was evaluated for gold recovery from low-grade refractory gold ores following biooxidation for an acidic heap leaching approach. One of the important features in using thiocyanate is that the leaching can be performed in acidic media, thus avoiding problems related to neutralization and material handling as leaching with alkaline cyanide. Also, the acidic leaching enables the use of ferric ion or bioleach solution as oxidants. In this study, Newmont-Nevada low-grade refractory sulfidic ore was biooxidized in columns at a particle size of 100% passing 102 mm. Thiocyanate leach on the biooxidized ore sample was performed on both ground samples in pulps and coarse material in columns using ferric ion as an oxidant. The variables of thiocyanate and ferric ion concentrations were compared for effect on leaching. Thiocyanate leach results are encouraging and indicate potential for development of a practical process. Gold extractions by thiocyanate are comparable to cyanide leach. Thiocyanate consumption was higher than cyanide, but was in an acceptable level.

Jan 1, 2003

By G. S. Nus

Technology for treating man-made metal-containing raw materials in DC electric furnaces with polarization of the bottom phase (PDF furnaces) has been developed and proven on a semi-commercial scale. PDF furnaces permit processing of man-made raw materials, i.e. current and accumulated intermediate products with rather high contents of valuable metals (i.e. slags, sludge, residues, Waelz slag, etc.), as well as secondary raw materials and virtually any type of waste using an environmentally safe technique based on sublimation of volatile metals and transfer of non-volatile metals and sulfur into the bottom phase in the furnace. Processes developed on the basis of the use of PDF furnaces make it possible to take advantage on a full commercial scale of electrolysis of molten materials, including electrochemical reduction of metals, intensification of their settling into the bottom phase and sublimation of volatile components, as well as to significantly improve recoveries of nonferrous metals, resolve the problem of excessive accretion formation in slagging processes and substantially improve the environmental situation. The low-grade discard slag obtained can be utilized in the construction industry; in particular, slag can be added to the limestone feed for cement manufacture.

Jan 1, 2006

By V. A. Bryukvin

A characteristic feature of the macrokinetics of the interaction process is the presence of two specifically defined areas of oxidation which had a linear time dependence. The effect of variables, such as residual sulphur content of the melt, temperature and the oxidation potential of the gas phase, on the macrokinetics of oxidation are investigated. Phase composition and structure of products of solidification of partially oxidised melts and thermodynamic properties pentaining to Cu-S-O melts are used to analyze the macrokinetic behaviour and mechanisms of the interaction. The process of interaction of sulfide copper melts with oxygen may be considered as a disproportional absorption process and its mechanism is based on localized interaction on the surface and inside the melt volume. Superficial processes include also the process of primary chemisorption of oxygen by melts at place of metal-metal donor bonds proceeding with formation of oxysulfide liquid solutions and volumetric decomposition of the latter accompanied by evolution of sulfur dioxide and metallization of sulfide melts. It is the degree of dynamic balance of such interaction processes that determines specific individual features of the macro-kinetics and mechanism of oxidation of sulfide copper solutions with oxygen in the gas phase.

Jan 1, 2006

By M. Boussuge, M. -D. Dupuits, A. Piant

This paper summarises a part of the work that has been essentially carried out at the Ecole des Mines de Paris in the framework of an Eureka European programme funded by the French Ministry of Industry, in partnership with Metaleurop and Carborundum (subsidiary of Saint Gobain). It deals with the measurement of different properties (density, thermal linear expansion, elastic modulus, strength) of a SiC-based refractory constituting the trays that are used in the refining columns in the New Jersey zinc distillation process, especially in the boiling section. These parameters have been investigated to check the homogeneity of the asreceived trays as well as to estimate the influence of ageing of the material under operating conditions. With this aim, specimens have been sampled in used trays having more than two years of operation. The as-received trays exhibited a good homogeneity, the strength being slightly lower in the direction in which they are compacted. Despite microstructural changes, most of the properties measured at room temperature are not significantly affected by ageing. High temperature tests involved thermal treated under vacuum to remove metallic zinc before testing at high temperature. An increase in temperature, as well as ageing, induces a decrease in the elastic modulus and strength.

Jan 1, 2000

By Maria de Campos

The pre-reduction behaviour of chromite particles in methane-argon and methane-hydrogen gas mixtures was investigated between 1050°C and 1250°C. Loose bed of chromite particles were reacted in a vertical tube furnace under a pre-set gas mixture predetermined time intervals. Metallization results were obtained for the Cr and Fe components by chemically analyzing the reaction products. SEM-EDAX techniques and X-ray diffraction were employed to elucidate the reduction mechanism. It was found that higher reduction kinetics and higher Cr:Fe ratios in the metal phase would be achieved when hydrocarbon gas was used in comparison to classical carbothermic reduction at a given temperature. The reduction rate was generally bulk gas mass transfer controlled to the reaction site for initial stages which then was followed by ionic diffusion rate control. It is proposed that methane did not partake directly in the reduction but cracked, presenting the reaction site with hydrogen gas and atomic carbon, which was able to immediately react at the immediate area of reduction regeneration CO and H2 and thus maintaining a low partial pressure of oxygen at the reaction site.

Jan 1, 2006

By Claire A. Chanenchuk

Catalytic Extraction Processing (CEP), a technology commercialized by Molten Metal Technology, Inc., a US.-based company, can convert industrial, household, and government wastes into commercial resources. CEP is an innovative elemental recycling technology that uses a molten metal bath to completely dissociate hazardous or toxic components of a feed and convert them to valuable products. The catalytic action of the molten metal bath converts the feed to its elemental constituents and the reducing atmosphere prevents the formation of any dangerous byproducts (NOx, SOx, dioxins, furans, etc.). Selective reactant addition allows engineering of valuable products from otherwise unexploited resources. Synthesis gas is generated from hydrocarbon feeds, ferro-alloys from metallic wastes, and ceramics from select inorganic species. Commercial-scale processing of multiple wastes and waste surrogates has been carried out at a destruction and removal efficiency exceeding 99.9999 wt.%, validating theoretical predictions. Unlike conventional hazardous waste treatment technologies, CEP offers resource recovery, minimal byproduct generation, and the potential for closed-loop recycling.

Jan 1, 1994

By Osamu Iida

In the Mitsubishi converting furnace (C-furnace), molten matte continuously undergoes intensive conversion into blister, and an excess amount of heat is generated, even after taking into account heat loss from the furnace, off-gas, and latent heat of melt. To absorb excess heat in C-furnace, recycled granulated converting slags (C-slag) were wastefully charged in the C-furnace. In contrast, supplementary coal is necessary to make up a shortage of reaction heat in Smelting furnace (S-furnace). To utilize the excess heat of the C-furnace effectively and accommodate the unbalance of heat utilization between S and C furnaces, three technological innovations had been carried out. ? Spent anode charging facilities in C-furnace was modified, in order to solve some spent anodes hitting and eroding the hearth bricks. ? Cubic pressed copper scrap charging facilities were installed in C-furnace. ? Facilities were newly installed in C-furnace to treat neutralized residue from the wastewater and dust treatment plants, previously treated in the smelting furnace. Above innovations led to the further effective utilization of heat, increase in production, and savings in energy costs.

Jan 1, 1999

By Peter Kettle

This paper describes the performance of the copper industry over a period of some two decades and examines the theme that improvements in operating efficiency have not been matched by improved returns on capital. The financial performance of the copper industry is analysed using CRU's MICA database. Regression analysis indicates a two percentage point increase in operating margins but no increase in returns on capital. The gain in operating efficiency appears to have been mainly achieved in the mid 1980s. The investment boom of recent years has resulted in a rapid increase in the industry's level of debt and gearing ratio (now some 47%). Data on 44 copper mine projects is used to show the linear relationship between scale and capital costs. Typically new capacity costs some US$5,000 /tpy. The relationship between cash costs and capital intensity of projects is also plotted. The greater attention now being focused on efficient use of capital means that capital intensity rankings will become increasingly important in determining which projects go ahead.

Jan 1, 1999

By R. D. Prengaman

Wrought lead-calcium-tin anodes developed by RSR Corporation have improved the performance compared with the other lead alloy anodes. These anodes have been in continuous service at various locations around the world for as long as fourteen years. Calcium provides mechanical strength to the anode to prevent the deformation while tin increases the mechanical strength, reduces the rate of corrosion, prevents the formation of non-conducting layers on the anode surface, and dramatically improves the conductivity of the anode. Tin is also instrumental in developing the unique rolled structure of the anode which leads to the reduced rates of corrosion, longer life, and improved oxygen evolution. Cobalt additions to the electrolyte further enhance the oxygen evolution and improve the anode life. Higher current densities and higher operating temperatures reduce the anode life. The unique patented method of attaching the rolled anode sheet to the bus bar substantially reduces the resistance of this important joint and offers the substantial savings in power over the life of anode.

Jan 1, 1999