RECOVERY OF COBALT AND PGM METALS FROM COBALT ALLOYS CONTAINING PRECIOUS METALS BY SELECTIVE DISSOLUTION

摘要

This disclosure concerns a process for the recovery of PGM from the cobalt-based, PGM-bearing alloys that are typically obtained after smelting spent GTL catalysts. The process comprises the steps of: - powdering the alloy to a mean particle size of less than 250 µm; - providing a mixed tank reactor equipped with means for feeding H2SO4 and a CuSO4 solution; - leaching in a mixed tank reactor the powdered alloy in a first acidic aqueous solution comprising H2SO4 and CuSO4, thereby obtaining a CoSO4 solution and a PGM-bearing metallic Cu residue; - isolating the PGM-bearing metallic Cu residue from the first CoSO4 solution, by solid/liquid separation; - leaching in a mixed tank reactor the PGM-bearing metallic Cu residue in a second acidic aqueous solution comprising H2SO4 and an oxidizing agent, thereby obtaining a CuSO4 solution and a PGM concentrate; - isolating the PGM concentrate from the CuSO4 solution, by solid/liquid separation; - returning the CuSO4 solution to the step of leaching the powdered alloy. The main advantage of this process is that no H2 is formed at any time, thus considerably enhancing the safety of the process compared to the classical acidic lixiviation of metallic compounds.