Abstract: Process for the manufacture of potassium sulphate from solutions containing magnesium chloride and potassium chloride from solutions, more particularly from mother liquors issuing from the treatment of carnallite. According to this process sodium sulphate and potassium chloride are added to the solutions so as to precipitate sodium chloride and schoenite (K.sub.2 SO.sub.4.MgSO.sub.4.6H.sub.2 O) and the schoenite is treated in a known manner to produce potassium sulphate.

Abstract: In a treatment of carnallitic ores by treatment with a decomposition-brine containing amounts of MgCl.sub.2, KCl and NaCl suitable for precipitating artificial sylvinite in a solution of MgCl.sub.2 saturated in KCl and NaCl, the improvement of adding to said decomposition-brine a collector, e.g., a fatty amine acetate, for the flotation of KCl and a source of gas, preferably a gas-liberating additive such as H.sub.2 O.sub.2, so as to contact newly formed crystal nucleii of KCl selectively with said collector and to contact bubbles of said gas with said collector so as to form a froth enriched in KCl simultaneously with the decomposition of said carnallite, the process being particularly useful for treatment of underground carnallitic ore whereby the froth and brine are withdrawn at the surface, separated, and the brine, after make-up additions, is recycled to the ore formation.