PROCESS FOR RECOVERY OF SULPHATE OF POTASH

摘要

A novel integrated process for the recovery of sulphate of potash (SOP) from sulphate rich bittern is disclosed. The process requires only bittern and li me as raw materials. Kainite type mixed salt is obtained by fractional crystallization of the bittern. Kainite is converted to schoenite with simultaneous removal of NaCl by processing it with water and end liquor obtained from reaction of schoenite with MOP for its conversion to SOP. The end liquor from kainite to schoenite conversion (SEL) is used for the recove ry of MOP. SEL is desulphated and supplemented with MgC12using end bittern generated in the process of making carnallite. The carnallite is decomposed to get crude potash which in turn processed to get MOP. The carnallite decompos ed liquor produced in the decomposition of carnallite is reacted with hydrated lime for preparing CaC12 solution and high purity Mg(OH)2 having low boron content. The CaC12 solution is used for desulphatation of SEL producing high purity gypsum as a byproduct. It is shown that the liquid streams containing potash are recycled in the process, the recovery of potash in the form of SO P is quantitative.