Integrated process of production of potassium sulphate and ammonium sulfate from kainite mixed salt

An integrated process for the production of potassium sulphate and ammonium sulfate from a kainite mixed salt, dispensing with magnesium hydroxide production, the process comprising the steps of:

• i. adding hydrochloric acid in calcium carbonate to produce 30-40% w/v concentrated calcium chloride and pressurized carbon dioxide (CO2);
• ii. decomposing the kainite mixed salt with water to obtain solid schoenite and schoenite end liquor (SEL) as a liquid stream;
• iii. desulphatizing the SEL as obtained in step (ii) using the calcium chloride as obtained in step (i) to produce desulphated SEL and gypsum;
• iv. subjecting the gypsum as obtained in step (iii) and the pressurized CO2 as released in step (i) together with ammonia for the production of ammonium sulphate liquor and solid calcium carbonate, the latter being recycled in step (i);
• v. producing carnallite from the desulphated SEL as obtained in step (iii), decomposing the carnallite to obtain carnallite decomposed product (CDP) along with carnallite decomposed liquor (CDL), the latter being recycled in desulphated SEL;
• vi. wet sieving the CDP as obtained in step (v) followed by aqueous leaching of fines fraction, obtained upon wet sieving, to obtain potassium chloride (KCl) (purity >98%);
• vii. utilizing the potassium chloride, as obtained in step (vi) in the preparation of sulphate of potash (SOP) from the schoenite as obtained in step (ii).