Abstract
In this paper, the author carried out a study to examine the crystallization of the brine produced in the salt-field of Ako (W) Salt Manufacturing Factory when it was concentrated in the crystallizer of the factory. The purpose of this study was to examine the quality of salt-field brine (WS, June 1966), ion-exchange membrane brine (WI, January 1968) and their mixture (WM, October 1967) and to make a comparison on the alteration of their chemical composition in case they were crystallized in the same vacuum evaporation system plant.
Also, the high caking tendency of the salt manufactured at the W factory in 1964-65 were examined, and the following results were obtained:
1. Mother liquid in the crystallizer of this factory was in the range of concentrating process between a1 and a2 where the liquid was saturated with sodium chloride only, or it was in the range over a2 where the liquid was saturated with sodium chloride and magnesium sulfate or its double salt.
2. Differing from those observed in other factories, the concentrating process of the brine in the crystallizer of this factory showed a tendency of containing more sulfate ion than the concentrating process of sea water.
3. The precipitates of the mother liquid were composed of sodium chloride, calcium sulfate and a little amount of glauberite in the early stage of concentrating process, and in the late stage they were composed of sodium chloride, polyhalite (K2SO4·MgSO4·2CaSO4·2H2O) and magnesium sulfate.
4. The high caking tendency was attributed to the high purity of salt, and the small size of particles and the high content of sulfate ion.
