銅電解精製における陽極中の不純物の挙動

陽極中のAs, Oの影響

抄録

In this study the behaviour of arsenic and oxygen in anode during copper electrorefining has been investigated. The form of anode slime and the dissolution state of anode surface after electrolysis as well as the effect of dissolved oxygen in electrolyte have been revealed.
In case of the arsenic concentration in anode was lower than 3%, the major part of it was homogeneously distributed inthe copper matrix, and then that was dissolved as As³⁺ ions into the electrolyte during electrolysis. These ions produced concurrently anode slime on the anode surface. These slime delayed the diffusion of the As³⁺ ions from the vicinity of anode to the short distance area from anode, and the anode was passivated after the drastic increasing of the As³⁺ ions in the vicinity of anode. The anode passivation was greatly accelerated with increasing concentration of the arsenic in anode and the As³⁺ ions in electrolyte. The form of anode slime showed mostly Cu₃As compound and a slight amount of copper powder, irrespective of the concentration of arsenic and oxygen in anode or dissolved oxygen in electrolyte.
It was clarified that the anode slime was produced by the secondary reaction of the dissolved Cu²⁺ and As³⁺ ions on the anode surface, and the anode passivation was caused by the development of the structure of anode slime from the granule to the lamella.