Crystallization of K-alum under Agitation by Aeration

Abstract

With K-alum, secondary nucleation at a constant supercooling temperature and batch crystallization at a constant cooling rate were carried out under agitation by aeration. An increase in aeration rate and in supercooling accelerated the secondary nucleation and decreased the size of crystals produced by the batch crystallization. With an increase in number of seed crystals the secondary nucleation at a constant temperature was depressed at a low degree of supercooling, but the secondary nucleation at a constant cooling rate was promoted, resulting in a decrease in size of crystals produced by the batch crystallization. The aeration is applicable to agitation in a crystallizer, because the crystal size is controlled to some extent by changes in the operating conditions.