production of two alkali salt a combination of ion exchange and kristallimisprotsessi

摘要

The invention relates a process for producing an alkali metal nitrate and an alkali metal phosphate in the same process from a phosphate raw material and a nitrate raw material comprising the steps of: a) reacting the phosphate raw material with the nitrate raw material to provide an aqueous nitrophosphate feed, optionally followed by the separation of solid material, b) introducing the aqueous nitrophosphate feed into a first ion exchange step comprising an alkali metal-loaded cationic exchange resin for exchanging cations present in the feed with alkali metal ions present on the resin to obtain a stream enriched in alkali metal ions, c) subjecting the stream from step (b) to a first crystallization under such conditions that an alkali metal nitrate is crystallized and separating the crystallized alkali metal nitrate from the mother liquor, d) introducing the mother liquor from step (c) into a second ion exchange step comprising an alkali metal-loaded cationic exchange resin for exchanging cations present in the mother liquor with alkali metal ions present on the resin to obtain a phosphate containing stream enriched in alkali metal ions, and e) subjecting the stream from step (d) to a second crystallization under such conditions that an alkali metal phoshate is crystallized and separating the crystallized alkali metal phosphate from the mother liquor.