Patent ID: 8721999
Filing Date: 2014-05-13
Classification: C01C,C01D,C01F,Y02P

Abstract:
1. A process for the simultaneous production of sulphate of potash (SOP), ammonium sulphate, surface modified magnesium hydroxide and/or magnesium oxide being characterized in the co-generation of the said products using kainite mixed salt and ammonia as the only consumable raw materials, the said process comprising the following steps: a) converting in a first reaction zone, kainite mixed salt into schoenite by the process of aqueous leaching, wherein the aqueous leaching process comprises reacting kainite mixed salt with water and SOP end liquor of step (e) followed by separating the pure schoenite and schoenite end liquor (SEL); b) treating the clear schoenite end liquor obtained in step (a) with aqueous CaCl c) subjecting the desulphated schoenite end liquor obtained in step (b) to evaporation to obtain solid carnallite and liquor rich in MgCl d) decomposing the carnallite obtained in step (c) with water to recover KCl and carnallite decomposed liquor (CDL) containing MgCl e) treating the pure schoenite of step (a) with KCl obtained in step (d) to produce sulphate of potash (SOP) while recycling the SOP end liquor in the process of step (a); f) washing the gypsum recovered in step (b) to minimize adhering impurities; g) contacting in a second reaction zone gypsum obtained in step (f) with liquor ammonia or recycled ammonium sulphate mother liquor obtained in step (i) and carbon dioxide obtained in step (k) to produce ammonium sulphate solution and by-product CaCO h) filtering out the CaCO i) evaporating the neutralized filtrate obtained in step (h) to recover ammonium sulphate while recycling the ammonium sulphate mother liquor in step (g); j) washing the CaCO k) bottling the CO l) slaking the lime generated in step (j) with decarbonated water and treating with CDL generated in step (d) and/or MgCl m) adding a surface modifying agent to facilitate filtration of Mg(OH) n) separating the surface-modified Mg(OH) o) calcining the Mg(OH)