粗銅の陽極溶解活性に及ぼす含有酸素量の影響

銅陽極不働態化の研究 (第5報)

抄録

A study was done by means of an electrochemical technique to determine how anode oxygen affects the dissolution activity during electrorefining of copper anodes.
One particular anode material was remelted, and spiked with a wide range of oxygen levels. This set of copper anodes was used to investigate the dissolution characteristics by comparing pairameters such as critical anode current density, activation energy and i-t decay curve which were measured both at a fresh and aged surface.
The results obtained have shown that,
1) Increasing oxygen level in the copper anodes initially results in an enhancement in the dissolution activity. This beneficial effect, however, is only so when the surface is fresh, and becomes counteracted soon by a layer of anode slimes which tends to grow thicker and denser with increasing oxygen level.
2) When oxygen content increases in a copper anode which already contains a high nickel level, the tendency of this anode to passivate increases drastically. This is due to the formation of refractory NiO during anode casting making the slime layer denser and more restrictive to the mass transport of Cu²⁺ ions away from the surface of a corroding anode.