Transport Processes and Separation Process Principles (Includes Unit Operations) Fourth Edition

12.12. CRYSTALLIZATION THEORY

12.12A. Introduction

When crystallization occurs in a homogeneous mixture, a new solid phase is created. An understanding of the mechanisms by which crystals form and then grow is helpful in designing and operating crystallizers. Much experimental and theoretical work has been done to help understand crystallization.

The overall process of crystallization from a supersaturated solution is considered to consist of the basic steps of nucleus formation or nucleation and of crystal growth. If the solution is free of all solid particles, whether foreign or of the crystallizing substance, then nucleus formation must first occur, before crystal growth starts. New nuclei may continue to form while the nuclei present are ...