Evaporation of Seawater or Brine
In hot countries with a dry climate or a long summer, salt is mass-produced by the evaporation of seawater or brine, obtained from salt lakes or brine wells. In this process, the brine left huge shallow ponds called salt pans to evaporate the water using heat energy from the Sun (Figure 2.3)
The evaporation process will concentrate the brine so that suspended impurities (e.g. sand and clay) and less soluble salts(e.g. calcium carbonate and calcium sulfate) can be removed. The concentrated brine is then run through a series of crystallising pans. As evaporation continues, sodium chloride gets deposited on the crystallising pans.
The sodium chloride in each of the crystallising ans is raked into rows. After days of draining, the sodium chloride is collected into heaps and drained again. Finally, the salt is lifted from the crystallising pans and dried(Figure 2.4)
In industrial countries, the salt is mechanically harvest and washed with saturated brine. After that, the salt is washed with freshwater before being stored for use, sale or further processing.