Crystallization Kinetics of Alpha-Lactose Monohydrate in a Continuous Cooling Crystallizer

The crystallization of alpha-lactose monohydrate in a continuous cooling crystallizer was investigated at various temperatures and super-saturations. The population balance model was used to analyze the product crystal size distribution as determined by the Coulter Multi-Sizer for each condition studied. Nucleation and growth values were thereby determined for each temperature and supersaturation. Kinetic models were then developed for both nucleation and growth to demonstrate the effects of the operating parameters. The results showed that the nucleation process had a temperature dependence with an activation energy of 17.0 kcal/mole and that nucleation increased with the 1.9 power of supersaturation and the 1.0 power of the suspension density (mass of crystals). The growth process was found to have a temperature dependence with an activation energy of 22.1 kcal/mole and to be a second order function of the supersaturation.