METHOD OF OBTAINING EDIBLE AMMONIUM PHOSPHATES Russian patent published in 2009 - IPC C01B25/28 

FIELD: chemistry.

SUBSTANCE: invention relates to methods of obtaining edible ammonium phosphates, more specifically to monoammonium phosphate and diammonium phosphate from wet-process phosphoric acid, which are widely used in the food industry. The method of obtaining edible ammonium phosphates from evaporated wet-process phosphoric acid involves neutralisation with ammonia, crystallisation of ammonium phosphate from ammonium phosphate solution, separation of crystals from the mother solution with recycling of the latter. According to the invention, the evaporated phosphoric acid is diluted to concentration 23-25% P₂O₅. Calcium carbonate is added at ratio CaO/P₂O₅ = (0.03-0.05) : 1. The obtained mixture is neutralised in two stages, first to pH = 1.6-2.0 and then to pH = 4.2-4.5. The formed pulp is filtered with separation of ammonium phosphate solution. Monoammonium phosphate is crystallised. Crystals separated from the mother solution are dissolved in water and the solution is evaporated. The obtained purified ammonium phosphate solution is divided into two streams, one of which is channeled for production of monoammonium phosphate through crystallisation, and the second is ammoniated until obtaining diammonium phosphate. Evaporation is done and diammonium phosphate crystals are separated.

EFFECT: method increases cost effectiveness, simplifies process of purifying wet-process phosphoric acid, allows for obtaining high quality edible phosphates, versatile technology, which allows for obtaining two different products - monoammonium phosphate and diammonium phosphate in a single process.

3 cl, 1 tbl, 1 ex