Process for the production of potassium sulfate

A process for producing potassium sulfate, which comprises:

• (a) forming a starting mixture comprising carnallite, potassium chloride, kieserite and residual quantities of less than 15% by weight rock salt by electrostatically separating a ground crude potassium salt;
• (b) contacting said starting mixture with a potash magnesia liquor at a temperature of about 20.degree.-40.degree. C. to form a slurry containing up to 70 mole MgCl.sub.2 /1000 H.sub.2 O, said contacting resulting in the decomposition of the carnallite and the dissolution of the rock salt contained in said starting mixture;
• (c) separating the slurry formed in step b) into a magnesium chloride solution and a solids portion containing a mixture of kieserite and potassium chloride;
• (d) mixing the solids portion obtained in step c) with a sulfate liquor containing 18-45 mole MgCl.sub.2 /1000 H.sub.2 O at a temperature of about 75.degree.-110.degree. C. to convert the solids portion into a mixture of langbeinite and potassium chloride;
• p1 (e) cooling the mixture obtained in step d) to a temperature between about 15.degree.-60.degree. C. to form slurry containing a potassium-magnesium double sulfate salt and potassium chloride;
• (f) separating the slurry formed in step e) into a potash magnesia liquor portion and a double sulfate saltcontaining solids portion;
• (g) mixing the solids portion obtained in step f) with water to convert the double sulfate salt contained in said solids portion into potassium sulfate;
• and
• (h) separating the potassium sulfate formed in step g) from the sulfate liquor associated therewith.