Patent ID: 9657368
Date: 2017-05-23
CPC Classifications: B01D,C22B,Y02P

Claim:
1. A metal leach and recovery process comprising: (a) subjecting a metal bearing material to a reactive process by combining said metal bearing material with a leaching agent to liberate at least one metal value from said metal bearing material and obtain a first aqueous leach pulp comprising a mixture of leached solids and an aqueous leach solution comprising at least one metal value, a leaching agent and water; (b) subjecting the first aqueous leach pulp to a solid liquid separation step to provide a first clarified aqueous leach solution and a second aqueous leach pulp, wherein the second aqueous leach pulp comprises a greater solids content than the first aqueous leach pulp; (c) subjecting the first clarified aqueous leach solution to solvent extraction thereby obtaining a first aqueous raffinate; (d) subjecting the second aqueous leach pulp to at least two further solid liquid separation steps of which some or all of the further solid liquid separation steps are in a counter current decantation (CCD) arrangement in which each solid liquid separation step of the CCD arrangement results in an aqueous liquor and an aqueous suspension of solids, wherein each aqueous suspension of solids resulting from each solid liquid separation step of the CCD arrangement is passed to the subsequent solid liquid separation step of the CCD arrangement and the aqueous suspension of solids resulting from the final solid liquid separation step of the CCD arrangement is removed from the process and wherein each aqueous liquor resulting from each solid liquid separation step of the CCD arrangement is passed to the previous solid liquid separation step, in which at least one further clarified aqueous leach solution results from at least one of the further solid liquid separation steps; (e) subjecting the at least one further clarified aqueous leach solution to solvent extraction thereby obtaining at least one further aqueous raffinate; (f) feeding at least a portion of the one or more of the at least one further aqueous raffinates into the final solid liquid separation step of the CCD arrangement; wherein at least one of the solid liquid separation steps is subjected to a flocculation system in which the flocculation system comprises either: (i) addition of an organic polymeric flocculant to or prior to at least one solid liquid separation step, which polymeric flocculant is formed from 2-acrylamido-2-methylpropane sulphonic acid (ATBS) or salts thereof as a homopolymer or copolymer with at least one water-soluble ethylenically unsaturated monomer; or (ii) addition of an organic polymeric flocculant and at least one support agent to or prior to at least one solid liquid separation step, which at least one support agent is selected from at least one of the group consisting of oxidising agents, reducing agents, irradiation and free radical producing agents.