銅陽極不働態化に及ぼす液温の影響

銅陽極不働化の研究 (第7報)

抄録

The known effect of increasing electrolyte temperature in preventing anode passivation in copper refining was extensively reviewed.
It has been found that a layer of anode slimes formed at a higher electrolyte temperature tends to become more porous with the simultaneous decrease in slime fall. While this increased permeability allows the diffusing ability of Cu² ions away from the surface of a corroding anode to increase, a gravitational flow of the electrolyte also becomes more pronounced within the slime layer. That is, a more concentrated copper electrolyte at the anode surface streams downwards through the micro pores and cracks, and this type of mass transport removes excessive Cu²⁺ ions far more efficiently.
A thorough investigation of electrolyte properties such as diffusion coefficient of Cu²⁺ ions, viscosity, solubility of copper sulfate and vapor pressure etc. measured using copper electrolyte of a nominal composition over the temperature range 45-65°C, proves the fact that the gravitational flow is a predominant factor contributing to the decreased tendency to passivate at a higher temperature.
That anode passivation occurs more readily at a lower level of anode height is also explainable by this claim.