MODEL FOR SECONDARY NUCLEATION IN A SUSPENSION CRYSTALLIZER

A model that makes it possible to evaluate the secondary nucleation ra te in a pilot-scale industrial crystallizer is presented. It relates t he secondary nucleation rate directly to the volume rate of attrition of large parent crystals. Two other terms are included in the equality , one that expresses the distribution formed by the attrition fragment s, and the other that expresses a survival efficiency accounting for t he percentage of attrition fragments that grow out after the attrition step. The model is further tested on a 970-L draft-tube-baffled evapo rative crystallizer with ammonium sulfate as the model material used f or crystallization and having an on-line crystal size-distribution mea suring device.