During pyro-reduction smelting of manganese deep sea nodules from the Clairon Clipperton zone in the Pacific Ocean the copper, nickel and cobalt are concentrated in intermediate product - polymetallic alloy. Characteristic property of the alloy is its high content of iron (65.90%) in compared to copper (12.07 %), nickel (12.81%), cobalt (1.33%) and manganese (5.33 %).
In this paper, a hydrometallurgical scheme for recovery of copper, nickel and cobalt from such an alloy is proposed. The developed scheme includes the following processes:
selective dissolution of alloy in sulfuric acid in the presence of sulfur dioxide to producecopper-rich (54.9%) sulphide residue and a solution containing iron, nickel, cobalt and manganese;
sulphide precipitation of nickel and cobalt from the solution;
hydrolysis purification of the solution from iron and manganese;
autoclave dissolution of copper and nickel-cobalt sulphide precipitates;
separation of cobalt from nickel by solvent extraction with Cyanex 272. The obtained electrolytes have a composition suitable for the extraction of copper, nickel and cobalt by electrowinning.
The main advantage of the proposed scheme is the possibility for achievement of a high non-ferrous metals extraction from the alloy and obtaining of copper, nickel and cobalt cathode deposits with standard purity.