Modeling and estimation of the kinetics of seeded solvent-mediated phase transformation in a batch crystallizer

Modeling the kinetics of the preparing process is necessary to produce a product with the appropriate particle properties and minimum production cost. Owing to the lackness of crystal size distributor (CSD) information, however, solvent-mediated phase transformation encounters difficulty in modeling the kinetics as compared to solution crystallization. Consequently, a model was established by making the product CSD to move along by horizontal translation to obtain the CSDs of the stable phase in the process of transformation. Then the moment method was used to solve the popular balance equation, and the least square nonlinear regression method was applied to estimate the kinetics parameters. The model has been successfully used to simulate the transformation of CaSO4·2H2O to α-CaSO4·1/2H2O in an isothermal seeded batch crystallizer with different stirring speeds, and it is beneficial to producing high performance α-CaSO4·1/2H2O crystals which have the right particle characteristics.