MANUFACTURE OF HIGH PURITY ELECTROLYTIC COPPER

摘要

PURPOSE:To manufacture extremely high purity copper by electrolyzing electrolytic copper again in an electrolytic bath acidified with nitric acid and contg. a chlorine source. CONSTITUTION:A chlorine source such as HCl, gaseous Cl or copper chloride is added to a bath of <3pH acidified with nitric acid so that the bath contains 20-130mg/l Cl. Electrolytic copper as the anode and a pure copper plate or a Ti plate as the cathode are placed in the resulting electrolytic bath at 20-65 deg.C at 20-60mm interval between the electrodes and the electrolytic copper is electrolyzed at 30-70A/m<2> current density. The electrolytic copper as the anode contains 8-14ppm Ag, 5-15ppm S, 0.2-1ppm As, 0.1-0.6ppm Sb, 0.1-0.5ppm Bi and 0.3-1.0ppm Pb. Copper deposited on the cathode by the electrolysis is high purity copper of >=99.999% purity contg. <1ppm Ag, <=0.1ppm each of As, Sb, Bi Pb and Fe.