A micro-mechanical model for the rate of aggregation during precipitation from solution

This paper collates approximately 10 years of research by our group on the subject of aggregation during precipitation of inorganic salts From aqueous solutions. We show that by considering the aggregation rate constant to be the product of a collision rate constant and an efficiency we may describe all our results (for one vessel) as a dependence of the efficiency on a di mensionless number, M.. The formulation of M arises from our previously pub lished hypothesis that new aggregates must cement themselves together fast enough to withstand the (periodic) hydrodynamic force acting to disrupt the m. The new analysis presented here shows that our previous deduction of an internal mass transfer limit in the cementing process is incorrect. We are, by means of this analysis, now able to propose simple, physically based, a nd apparently general, kinetic equations For aggregation. (C) 2001 Elsevier Science Ltd. Ail rights reserved.