METHOD OF PREPARING DODECAHYDRATE SODIUM PHOSPHATE Russian patent published in 2001 - IPC

FIELD: preparation of alkali metal phosphates for softening water, photography, laboratory practice, food and chemical industries. SUBSTANCE: method of preparing dodeca hydrate sodium phosphate comprises neutralizing phosphoric acid with sodium hydroxide at original sodium hydroxide to phosphoric acid molar ratio of (2.96-3.0):1 to form saturated solution having density of 1.25-1.3 g/cubic cm, heating said saturated solution to 100-105 C, maintaining it at given temperature for 30-40 minutes prior to crystallization and subsequently filtering it. Crystallization is carried out by cooling to 5-17 C, and commercial product is separated from mother liquor. EFFECT: reduced amount of impurities in final product and higher yield of final product due to preparing large crystals o dodecahydrate sodium phosphate of cubic or spherical from. 1 tbl