Example Crystallization of Table Salt

The unit operation crystallization belongs to the oldest technologies used by humans. Quite a number of early civilizations were formed in coastal areas with 

Sea salt consists of quite large single crystals randomly grown together. Inclusions of mother liquor inside the crystals or between the grown-together crystals, as well as gypsum as cocrystals, are reasons for the limited purity of around 98 wt%. 

In many cases, therefore, salt from solar ponds is processed downstream by some purification steps. These are, for example, a combined grinding and washing process or even the complete recrystallization by the evaporative vacuum crystallization. A modern alternative is the combination of the energy-saving solar pond concentration with industrial crystallization. In such cases, the seawater 

In order to make negligible any dilution by rainfall, the final solar pond brine is collected in 10 m deep tanks, before the brine is eventually used as feed stream for the crystallization plant constantly all over the year. The clear advantage of this alternative is the improvement in regard to salt quality and particle size distribution (uniformity and particle size as well) that helps to approach a more genera] market than before. 

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