Process for the preparation of potassium sulphate from bittern

摘要

Process for the production of potassium sulphate from sea saline mother liquor (bitters) by evaporation in solar ponds in three different evaporation sections (basins) with gradual crystallization of sodium chloride - sodium chloride + MgSO4 · hydrates and a potassium-containing mineral mixture from the components carnallite - kainite, magnesium sulphate hydrates and sodium chloride, harvesting from the mixture resulting from the third evaporation section and its gradual conversion to potassium sulphate via the intermediate product Schönite, characterized in that by mixing bitters and in-process solutions during the production of potassium sulphate, the solution to be evaporated is reduced to a molar ratio of KCl: MgSO4: MgCl2 such as 1: 1.8 to 2, 2: 3.5 to 4 moles and through ongoing analytical control and, if necessary, correction of the concentration of MgCl2 and MgSO4 in the brines, a crystallization mixture is obtained which is a natural kainite mineral KCl: MgSO4 · 2.75 H2O has the corresponding molar ratio KCl: MgSO4 = 1: 1 with a deviation of ± 5 percent, whereupon this mixture of different salts is further processed into potassium sulfate using a known method analogous to natural kainite.