REMOVAL OF COBALT FROM ZINC ELECTROLYTE USING ZINC DUST AND COPPER ARSENATE

摘要

Hydrometallurgical process for the recovery of copper arsenate from zinc plant cement copper cake residues and the use thereof in the purification of zinc electrolyte, with the attendant upgrading of the copper value in the treated cement copper residues. The cake residues are first subjected to an acid leach followed by an alkali addition to adjust the pH of the slurry to about 3.5 to 4.0 and to extract zinc, cadmium and cobalt in solution and provide a copperenriched residue. Cobalt is then precipitated and separated from the extraction solution. The copper-enriched residue is subjected to caustic leach to extract arsenic in solution therefrom and provide a copper-enriched cement copper cake product. The arsenic containing extraction solution is then reacted with a copper salt to form copper arsenate residue and leave purified zinc electrolyte. This divisional case deals with the process of purifying zinc electrolyte containing cobalt contaminant prior to electrolysis thereof in the electrowinning of metallic zinc comprising maintaining said electrolyte at a temperature of about 80 to 90.degree.C, adding zinc dust and copper arsenate then raising the temperature to and maintaining it in the range of about 90 to 95.degree.C until the cobalt level of said electrolyte is less than 0.1 ppm, and adjusting the pH to about 4.0 and then removing the solids from said electrolyte.