chapter  4
20 Pages

Actual case examples

In the first half of the 20th century, processes were investigated to recover the potassium chloride from this brine as a vendable product (potash). Chemists at the Hebrew University in Jerusalem (M. Novominski, M. Langoski, and others) studied the entire relevant physical-chemical solids/liquid saturation system. They found that when the Dead Sea brine evaporated and gradually concentrated in a solar pond, salt (sodium chloride) reached first its saturation point and precipitated. Then carnallite (a hydrated double salt of magnesium and potassium chloride) was crystallized together with some more sodium chloride. The scientists also found that the mixture of the carnallite crystals and sodium chloride, obtained from solar ponds, could be leached at ambient temperatures with a large amount of water to leave a number of fine potash crystals with a rather low yield. Or the mixture could be leached alternatively with a limited amount of water at a higher temperature to decompose the carnallite and dissolve all the magnesium

chloride, allowing to separate by filtration the remaining solid sodium and potassium chlorides. These can be hot-leached and then the hot filtrate brine can be cooled and concentrated under vacuum in conventional equipment to crystallize the potash. The remaining brine can be recycled back into the solar pond to repeat the process.1