Population balance: The auto-catalytic nature of secondary nucleation in seeded batch crystallizations

Existing models for secondary nucleation kinetics predominantly attribute the generation of nuclei to varying forms of particle breakage or attrition during the crystallization process. However, recent literature has provided new insight into a secondary nucleation mechanism in seeded batch reactions whereby the seed itself serves as a breeding ground for new secondary nuclei to form on its surface (Anwar, et al., 2016; De Souza, et al., 2016). Furthermore, it has been reported that crystal breakage can be neglected almost entirely in typical crystallization processes as a boundary layer effect between crystals and reactor features, such as impeller blades, effectively protects against any potential breakage events (Tyrrell, et al., 2017). Through this deeper understanding of the crystallization process, process modelling tools such as the Population Balance (PB) method have become gradually become more accurate as these tools are only as strong as their underlying kinetic expressions.