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.
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