Chlorine Leaching Mechanism of Nickel Sulfide

Abstract

 MCLE (Matte Chlorine Leach and Electro-winning) process developed by Sumitomo Metal Mining Co., LTD. is well known as a unique commercial nickel refining process with high nickel recovery ratio. Two types of nickel sulfide, nickel matte and mixed sulfide (MS: mixture sulfide of nickel and cobalt), are treated in the MCLE process, and the leaching rate difference for each materials become obvious in this process. Bench scale tests had been carried out and leaching rates and activation energies of chlorine leaching reactions were identified. The nickel leaching rate of MS in chlorine leaching reaction is 60% smaller than that of nickel matte.
 The nickel leaching rate difference between nickel matte and MS in chlorine leaching reaction is derived from their reaction free energy difference. The determinants of the chlorine leaching reaction rate of nickel matte and MS are respectively a chemical reaction rate and elements diffusion ratio on their surface.