Crystallization Processes☆

Crystallization processes addressed in this discussion are focused on applications involving separation and purification and they are used in the chemical, energy, petrochemical, pharmaceutical, food, metals, agricultural, electronics, and other industries. Moreover, the principles of crystallization are important in all circumstances in which a solid crystalline phase is produced from a fluid, even when the solid is an intermediate in the process. Much has been done in recent years to improve the understanding of crystallization, and a large portion of the research on the topic has dealt with mechanisms of nucleation and growth. Especially important has been elucidation of the effects of process variables on the rates at which these phenomena occur. Additionally, extensive progress has been achieved in modeling both steady-state and dynamic behavior of crystallization systems of industrial importance and in measuring process variables and product characteristics. For example, the U.S. Department of Health and Human Services Food and Drug Administration (FDA) defined a mechanism that takes advantages of such measurements in designing, analyzing and controlling pharmaceutical manufacturing processes at process analytical technology (PAT). The primary elements of the discussion that follows are the principles that influence yield, morphology, and size distribution of crystalline products.