GB386208A - Process for the production of potassium carbonate - Google Patents

Abstract

Potassium carbonate is obtained by reacting an aqueous solution or suspension of potassium sulphate and alkaline-earth hydroxides with carbon monoxide or gases containing it and converting the resulting potassium formate into carbonate by calcination. The potassium formate solution resulting from the first step, after the separation of precipitated alkalineearth sulphate, is preferably treated with excess of potassium carbonate or bicarbonate to precipitate impurities, the purified solution containing formate and carbonate being evaporated to dryness for calcination ; or only sufficient potassium carbonate or bicarbonate to precipitate the impurities may be added to the solution, a further quantity of carbonate or bicarbonate being added to the dry product after evaporation. According to one example, an aqueous suspension of potassium sulphate and quick lime is treated with purified producer gas in an iron stirrer-autoclave at 200 DEG C. and 15 atmospheres pressure. The resulting solution is filtered from gypsum, evaporated to dryness and calcined. According to a second example, the potassium formate solution, prepared as in the foregoing example, after the separation of gypsum is heated and potassium carbonate or bicarbonate is added. Ferric oxide, alumina and calcium carbonate precipitate and the remaining solution is concentrated, whereupon unconverted potassium sulphate precipitates, is separated and returned to the process. The purified solution is dehydrated mixed with ground potassium carbonate and calcined.ALSO:Potassium carbonate is obtained by reacting an aqueous solution or suspension of potassium sulphate and alkaline-earth hydroxides with carbon monoxide or gases containing it and converting the resulting potassium formate into carbonate by calcination. The potassium formate solution resulting from the first step, after the separation of precipitated alkaline-earth sulphate, is preferably treated with excess of potassium carbonate or bicarbonate to precipitate impurities, the purified solution containing formate and carbonate being evaporated to dryness for calcination; or only sufficient potassium carbonate or bicarbonate to precipitate the impurities may be added to the solution, a further quantity of carbonate or bicarbonate being added to the dry product after evaporation. The calcination may be carried out in a continuous process in a rotary furnace with the gases of combustion in parallel flow. According to one example an aqueous suspension of potassium sulphate and quick lime is treated with purified producer gas in an iron stirrer-autoclave at 200 DEG C. and 15 atmospheres pressure. The resulting solution is filtered from gypsum, evaporated to dryness and calcined. According to a second example, the potassium formate solution, prepared as in the foregoing example, after the separation of gypsum is heated and potassium carbonate or bicarbonate is added. Ferric oxide, alumina and calcium carbonate precipitate and the remaining solution is concentrated, whereupon unconverted potassium sulphate precipitates, is separated and returned to the process. The purified solution is dehydrated, mixed with ground potassium carbonate and calcined.