Example - Crystallisation of Sodium Chloride

Vacuum-cooling crystallisation is the preferred cooling crystallisation method under continuous operation. Because cooling is generated by adiabatic expansion of the solvent no cooling surfaces can be incrusted. Vacuum-cooling becomes uneconomical only if cooling has to be effected at very lotv temperatures. 

From there the separation station is served which consists of a hydrocyclone, a washing-thickener and a centrifuge. In the washing thickener, the highly impure mother liquor is exchanged against the fresh feed liquor, before the suspension 

A plant of this type was erected for the treatment of 601 h concentrated liquor from a solar pond on the coast of the Mediterranean Sea. The plant is producing 2.5 th grain-size salt of 2 mm average crystal size and 6.51 h of normal vacuum salt. Per hour it consumes lit of steam and evaporates 341 of water. By 

Bamforth, A.W. (1965) Industrial Crystallization, Leonard Hill, London. 

(1969) KristaUisation, Springer-Verlag, Berlin, Heidelberg, New York. 

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