Zinc sulphate purification - by adding zinc dust cycloning and recycling zinc underflow

摘要

Impure neutral ZnSO4 soln. used in Zn recovery processes, is purified by (a) adding Zn dust to flowing soln. and agitating to cause reaction between the Zn dust and impurity cations (b) passing soln. through a cylone to reactivate unused Zn (C) recycling underflow to the ZnSO4, stream and (d) separating the pptd. impurities from the overflow of purified ZnSO4, soln. reactivation of the recycled Zn dust reduces the need for fresh make-up Zn dust. To prevent oxidation and redissolving of pptd. metals the process takes place in non-oxidising conditions.