Crystallization is the (natural or artificial) process of formation of solid
crystals precipitating from a
solution,
melt or more rarely
deposited directly from a
gas. Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs. In
chemical engineering crystallization occurs in a crystallizer. Crystallization is therefore an aspect of
precipitation, obtained through a variation of the
solubility conditions of the
solute in the
solvent, as compared to precipitation due to chemical reaction.