METHOD OF PRODUCING SODIUM TRIPOLYPHOSPHATE FROM WET-PROCESS PHOSPHORIC ACID Russian patent published in 2010 - IPC C01B25/41 

FIELD: chemistry.

SUBSTANCE: invention relates to production of phosphorus salts, particularly sodium tripolyphosphate, which is used in food, household and chemical industries. The method of producing sodium tripolyphosphate involves neutralisation of wet-process phosphoric acid with calcined soda to molar ratio Na₂O : P₂O₅ = 1.63 - 1.70 and subsequent thermal treatment of sodium phosphates. In this process neutralisation takes place in a single step, while keeping temperature of the process, time and concentration of acid within limits necessary for obtaining concentration of disodium phosphate of not more than 36% in a neutral solution.

EFFECT: temperature of the process is varied from 70 to 90°C, duration of the process from 90 to 120 minutes and concentration of acid from 35 to 50% H₃PO₄.

2 cl, 1 tbl, 1 ex