Verfahren zur Herstellung von hydratisiertem Natriumtripolyphosphat

1,193,043. Hydrating sodium tripolyphosphate. FMC CORP. 16 July, 1968 [28 July, 1967], No. 33734/68. Heading C1A. Anhydrous sodium tripolyphosphate is hydrated by distributing water uniformly over agitated particles of anhydrous tripolyphosphate, at least 10% by wt. of which have a size below 100 U.S. mesh, the water being added in an amount of at least 80% but not in excess of 105% of that theoretically required to produce the hexahydrate, and at such a rate as to keep the temperature below 80‹ C. The water is preferably 80-98% of the theoretical, and may be sprayed on to the particles in an inclined rotary tube. The product may be dried at below 80‹ C. by showering it through a stream of air having an inlet temperature of 75-85‹ C. If may then be ground and screened to a product size of - 20 + 60 mesh, fines being recycled. The starting material may be obtained by drying and calcining a solution of H 3 PO 4 and Na 2 CO 3 having an Na/P ratio of 1À67 to give a mixture of Phase I and II which is then ground to the required size. The product has a bulk density of 0À65-0À9 g/cc.