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Zinc and copper plants utilise hydrometallurgical stages in their production chains. All these processes are continuously researched in order to optimise process conditions, to reduce costs and to cope with new raw materials.
Leaching and solution purification
Leaching comprises, for example, dissolving the roasted zinc calcine and concentrate. Direct leaching of zinc concentrates is the newest invention developed by Outotec at the Pori Research Center and taken into industrial use. In copper production, heap leaching of copper ore is a new emerging technology.
Bioleaching of low-grade ores is another example of Outotec’s pioneering spirit. In this metal extraction method bacterial action liberates metal from the ore. Bioleaching has been successfully applied to sulfidic ores, gold bearing pyrites and arsenopyrites.
Solution purification is needed to remove impurity elements. Advances in hydrometallurgy bring new knowledge and offer innovative solutions to the challenges of extractive metallurgy in the metals industries. It can be done by precipitation or cementing, as in a zinc plant. Ion exchange techniques, like solvent extraction, are also widely used nowadays.
Reduction of metals
Zinc, nickel and copper can be recovered from purified solutions by electrowinning using insoluble anodes. Impure copper anodes from the smelter are purified by the electrorefining method dissolving anode copper into the electrolyte and depositing pure copper on cathodes.
Equipment development
The Pori Research Center has actively developed process equipment such as leaching reactors, agitators and mixer-settlers for solvent extraction utilising the knowledge of chemical thermodynamics and kinetics as well as electrochemistry. Scale modelling and computational fluid dynamics are effectively used in this area.
HydroCopper®
Outotec has studied hydrometallurgical process routes for copper recovery from sulphide concentrates, both in sulphate and chloride environments, for many years in the Pori Research Center. The innovative development has given rise to an unconventional and beneficial process concept, known as HydroCopper®. After extensive and probing research work and economic evaluations, Outotec designed and built a demonstration plant for the HydroCopper® process in Pori, Finland.
The demonstration plant is proficient and capable of handling almost all kinds of concentrates and process variations. The production capacity is set at one metric ton of copper rod per day and the plant consists of all essential unit processes needed in a full-scale, commercial HydroCopper® production plant and is capable of processing almost all kinds of copper concentrates or even high grade ores.
Read more about HydroCopper® process
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