Outokumpu hydrocopper process: A novel concept in copper production

In Outokumpu Research various hydrometallurgical process routes have been studied for copper recovery from sulphide concentrates, both in sulphate and chloride environments. The utilisation of chloride solutions is advantageous due to their aggressivenessin leachingand the stability of the cuprousion. However, the electrowinning of copper from choride solutionspromotes dendroid copper deposits, makingoperations some what complicatedin an electrolytic diaphragm cell. To overcome thisdrawback a novel process has been developed, in which cuprous oxide is precipitated with sodium hydroxide from the purified pregnant leach solution. Sodium hydroxide is regenerated in a chlor-alkali cell.The otherproducts of the electrolyser are also recirculated, chlorine gas to concentrate leaching and hydrogen gas to the reduction of cuprous oxide to metalliccopper. In this paper, the experimental work andevaluations of the different process options are discussed. To verify the technology Outokumpu will design and construct a demonstration plant in Pori, Finland. Operations will start in early 2003.