METHOD OF SODIUM ORTHO-PHOSPHATES PREPARING FOR PRODUCTION OF SODIUM POLYPHOSPHATES Russian patent published in 1994 - IPC

FIELD: chemical technology. SUBSTANCE: phosphoric acid is extracted from solution with organic solvent, and organic phase containing phosphoric acid is carried out with disodium phosphate aqueous solution at 20-40 C. Obtained solution of monosodium phosphate is divided for two parts at mass ratio 1: 5. Five mass parts of prepared solution are treated with soda, and disodium phosphate solution is formed, which is divided for two parts at mass ratio 1,5: 1. One mass part of disodium phosphate solution is mixed with one mass part of monosodium phosphate solution. Obtained mixture is removed as an end product ( mass ratio of disodium phosphate to monosodium phosphate is 2,36). Residual part of disodium phosphate solution is fed for reextraction. Saturated concentration of disodium phosphate solution obtained after treatment with soda is maintained at the range 7,1-35,5% by weight depending upon temperature of solution obtained. EFFECT: improved method of production. 3 cl