Process for recovering electrolytic copper of high purity by means of reduction electrolysis

US4030990A · kind A · utility

Assignee

• Duisburger Kupferhutte

Inventors

• Norbert L. Piret · Duisburg, DE
• Hans Joachim Rabben
• Herbert Kudelka · Duisburg, DE
• Siegbert Schmidt

Key dates

• Filing date: Jun 22, 1976
• Grant date: Jun 21, 1977
• Expiry date: Jun 22, 1996

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P10/20
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Copper sulfate solution obtained by the sulfuric acid leaching of cupriferous material and containing impurities such as Fe, As, Sb, Bi, Se, Te, Sn, Pb, Cl, Ag, Hg, and PO.sub.4, are subjected to a two step purification process. In the first step, the pH is adjusted to 2.7-3.3 with, e.g. Ca(OH).sub.2, and the potential in relation to the standard hydrogen electrode is adjusted to at least 575 mv with an oxidizing agent, e.g. air. The temperature is 50.degree.-90.degree. C. Impurities precipitate and are separated. Se, Cl, and possibly Ag and Hg remain in solution and are removed in the second step, wherein the potential is reduced to below 350 mv by addition of a cupriferous reducing agent, e.g. Cu or Cu.sub.2 O. The pH is below 3 and the temperature is below 50.degree. C. Impurities precipitate as copper (I) compounds, and are separated to provide the solution in condition for the electrolysis. The copper produced is of high purity, having a conductivity of at least 58.8 mho .times. m/mm.sup.2 and a maximum semi-hard temperature of 200.degree. C.