Page 194 - Academic Press Encyclopedia of Physical Science and Technology 3rd Chemical Engineering

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Encyclopedia of Physical Science and Technology EN004D-ID159 June 8, 2001 15:47

Crystallization Processes

Ronald W. Rousseau
Georgia Institute of Technology

I. Objectives of Crystallization Processes
II. Equilibrium and Mass and Energy Balances
III. Nucleation and Growth Kinetics
IV. Purity, Morphology, and Size Distributions
V. Crystallizer Configuration and Operation
VI. Population Balances and
Crystal Size Distributions

GLOSSARY tallizing species; includes both homogeneous and het-
erogeneous nucleation mechanisms.
Crystallizer The vessel or process unit in which crystal- Secondary nucleation The formation of crystals through
lization occurs. mechanisms involving existing crystals of the crystal-
Growth The increase in crystal size due to deposition of lizing species.
solute on crystal surfaces. Solubility The equilibrium solute concentration. The di-
Magma The mixture of crystals and mother liquor in the mensions in which solubility is expressed include, but
crystallizer. are not limited to, mass or mole fraction, mass or mole
Mode of crystallization The means by which a thermo- ratio of solute to solvent, and mass or moles of solute
dynamic driving force for crystallization is created. per unit volume of solvent or solution.
Mother liquor The liquid solution from which crystals Supersaturation The difference between existing and
are formed. equilibrium conditions; the quantity represents the
MSMPR crystallizer A vessel operating in a continuous driving force for crystal nucleation and growth.
manner in which crystallization occurs and whose con-
tents are perfectly mixed. As a result of perfect mixing,
all variables descriptive of the mother liquor and crys- CRYSTALLIZATION PROCESSES addressed in this
tals are constant throughout the vessel and are identical discussion are used in the chemical, petrochemical, phar-
to corresponding variables in the product stream leav- maceutical, food, metals, agricultural, electronics, and
ing the vessel. other industries. Moreover, the principles of crystalliza-
Nucleation The formation of new crystals. tion are important in all circumstances in which a solid
Primary nucleation The formation of crystals by mech- crystalline phase is produced from a fluid, even when the
anisms that do not involve existing crystals of the crys- solid is not a product of the process. Much has been done

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