Recovery of saleable salts from occurring natural brines representing the quinary aqueous system Na-K-Mg-Ca-Cl

Potassium chloride (KCl) accounts for most of the potassium (K) used in world agriculture and represents 96% of the world potash capacity. The other 4% includes potassium sulfate (K₂SO₄), potassium nitrate (KNO₃) and potassium-magnesium based salts. In this sense, the prediction of the solubility of electrolytes in aqueous solutions is important to provide data for processes that extract potassium salts from multicomponent brines. In this work, Pitzer's and Harvie's models were used to calculate the amount and composition of crystallized salts after water evaporation. The process involved four crystallization steps starting from multicomponent brines represented by the quinary Na-K-Ca-Mg-Cl aqueous system at 20°C. The temperature of 20°C was chosen because it is the average process brine temperature in many dry salt lakes. The Pitzer's and Harvie's models allowed performing a material balance in solar ponds producing saleable salts like sodium, potassium, magnesium and calcium chlorides. (author)