Purification of Zinc Leaching Solution-Mechanism of Removal of Cobalt by Zinc Dust with Arsenious Oxide and Copper Ion-

摘要

Cobalt precipitation by zinc dust with co-addition of arsenious oxide and copper ion in a practical operation was simulated by the experiments using a galvanic cell with a diaphragm and this mechanism for removal of cobalt was explained as follows; a galvanic cell was formed between zinc dust and copper particles, which were precipitated first by zinc dust and cobalt is deposited on copper particles by this galvanic cell and arsenious oxide in a solution accelerated the rate of predication of cobalt by co-depositor of AS-CQ. The anode side reaction of this galvanic cell is Zn = Zn~(2+) + 2e and a main cathode reaction is 2H~+ + 2e = H2(g). Cobalt is difficult to be precipitated on copper without arsenious oxide. The galvanic current between zinc and copper becomes higher by addition of arsenious oxide. The over potential of the cathode reaction sifts the cathode potential to be lower potential than the deposition potential of Co-As, and this Co-As easily deposits on copper cathode with hydrogen.