(727d) Impact of Flow on the Distribution of Particle Agglomerate Impurities and the Development of an Associated Model

Lithium hexafluorophosphate (LiPF₆) products with high purity standards (greater than 99.5%) are in increasing demand in the lithium battery industry. The high production efficiency of LiPF₆ makes dynamic crystallization a desirable process. However, during dynamic crystallization, the crystals are affected by shear, turbulence, and impurities in the flow field to form dense, solid spherical aggregates. Consequently, it is difficult to remove the impurities incorporated into the aggregates, resulting in a low purity of the final product. Despite this, few studies have been conducted on the internal relationship between impurity incorporation and crystal aggregation and breakage. Furthermore, a mathematical model for aggregation and breakup under solvent inclusion has not yet been developed. This study used the cooling crystallization of potassium chloride as a model system to conduct real-time data collection using high-speed visualization methods, which allows a detailed analysis of the transition process in aggregate size and morphology. Then flow characteristics and impurity incorporation were investigated to determine how they influence the aggregation, breakage, and coarsening of crystals quantitatively. Incorporating the diffusion mechanism of impurities on crystal planes into the process of aggregation, breakage and coarsening as well as building sub-models of PBE aggregation, breakup, and coarsening under solvent inclusion.