Three-compartment electrowinning cell and methods

A method for electrowinning a metal, the process comprising the steps of:

• (a) providing a three-compartment electrowinning cell comprising a cathode in contact with an aqueous catholyte in a cathode compartment;
• an aqueous anolyte in contact with an anode in an anode compartment;
• and an aqueous solution of a salt in a middle compartment between the cathode compartment and the anode compartment;
• wherein the catholyte in the cathode compartment is separated from the aqueous solution in the middle compartment by an anion exchange membrane (AEM), and the anolyte in the anode compartment is separated from the aqueous solution in the middle compartment by a cation exchange membrane (CEM);
• the catholyte comprises cations of a first metal in aqueous hydrochloric acid and dimethylsulfoxide;
• and the aqueous anolyte comprises cations that differ from the cations of the catholyte;
• (b) applying an electric potential across the anode and cathode for a period of time sufficient to reduce the cations of the first metal to their metallic state and thereby deposit the first metal onto the cathode;
• and
• (c) recovering the first metal from the cathode;
• wherein the first metal is selected from the group consisting of Zn, Sn, Ni, Co, Bi, Mn, Fe, Cu, Pb, and Cr, and other transition metals, and when an electric potential is applied across the anode and the cathode, chloride ions from the catholyte migrate through the AEM into the aqueous solution in the second compartment;
• cations from the anolyte migrate through the CEM into the aqueous solution in the second compartment, and oxygen is generated at the anode.

A three-compartment electrowinning cell comprising:

• a catholyte compartment containing a cathode;
• an anolyte compartment spaced from the catholyte compartment and containing an anode;
• and
• a middle compartment between the catholyte compartment and the anolyte compartment;
• wherein the catholyte compartment is defined by a first portion of a housing and an anion exchange membrane, the anolyte compartment is defined by a second portion of the housing and a cation exchange membrane, and the anion exchange membrane and the cation exchange membrane are spaced from each other to define the middle compartment in combination with a third portion of the housing;
• and wherein the anode and cathode are adapted for connection to a power source.