Volume
V covers the various specific crystallization
processes such as precipitation and freeze crystallization.
The volume concentrates on the mechanisms and
processes relevant to the crystallization technique
rather than equipment design.
Volume
CR V Part 1 Cooling crystallization by direct
contact heat transfer. When
the vapour pressure of a solvent is too low for evaporative
cooling of a liquor during crystallization, the usual
cooling method adopted is to use a jacketed vessel or
similar device as a heat exchanger. There is an alternative
method, however, where the coolant is in direct contact
with the crystallizing liquid; this is termed direct
contact heat transfer. The main types of direct contact
heat transfer are reviewed in this report, followed
by a discussion of the theoretical aspects which specifically
apply to direct contact crystallization. The importance
of the interaction between the crystallizing liquor
and the coolant is highlighted. Several processes which
have been proposed for commercial application are discussed
as examples. The use of direct contact cooling will
also affect the crystal product quality and the report,
therefore, discusses its effects on parameters such
as crystal size, purity and habit.
Volume
CR V Part 2 Melt crystallization.
Melt crystallization was originally
developed as a small-scale process for ultra-pure chemical
production, but it is increasingly used on a large scale.
The boundary between melt crystallization and solution
crystallization is somewhat difficult to define, but there
are, practical differences in the growth and nucleation
kinetics and the factors affecting crystallizer design.
Various types of melt crystallization systems are discussed,
such as Zone Refining, Column and Roll crystallizers.
Design calculations for each of these are provided, highlighting
the particular aspects of crystallization theory relevant
to that process. The available equipment is reviewed,
and several examples of industrial melt crystallization
processes are also discussed.
Volume
CR V Part 3 Precipitation. Precipitation
(or fast reaction crystallization) is used to produce
a wide variety of products. Although the same fundamental
mechanisms as normal solution crystallization are involved,
their relative importance is different and this report
looks at the processes from the viewpoint of precipitation.
Since the processes are very rapid, the equilibrium and
non-equilibrium properties of the system are important,
particularly effects such as Ostwald Ripening which are
not normally encountered with slow solution crystallization.
Brownian motion and inter-particle forces become more
important at the small particle sizes encountered in precipitating
systems. With the high supersaturation levels generated,
primary nucleation is usually dominant over secondary,
and this is discussed along with crystal growth. Various
techniques for precipitation can be used (such as mixing,
reaction and salting-out), and the equipment required
and the advantages and disadvantages of each are discussed.
The report also contains a review of the use of precipitation
in the industrial production of various chemicals such
as magnesium hydroxide and proteins.
Volume
CR V Part 4 Freeze crystallization.
Freeze crystallization is
used as an alternative to evaporation or distillation,
and involves the cooling of liquor below the freezing
point of the solute. Cooling can be generated by evaporation,
or the use of a refrigerant either in direct contact with
the liquor, or indirectly using a heat exchanger. These
methods are discussed, and examples of industrial processes
using them are given. Eutectic freezing is also discussed
(where the solute and solvent both crystallize, but as
separate rather than mixed crystals). The report reviews
the various process operations for freeze crystallization
including the design of heat transfer systems, the separation
of product crystals, and the design of refrigeration cycles.
The report also discusses the economics and possible applications
of freeze crystallization.
Volume
CR V Part 5 Novel
crystallization techniques.
In
this new manual part a range of novel or new crystallization
techniques will be reviewed. Topics covered will include:
Section
1 : Chiral crystallization
Section 2 : Sonocrystallization
Section 3 : Supercritical crystallization
Section 4 : High pressure crystallization
Section 5 : Spherical & liquid membrane emulsion
crystallization
