Process for making a granular product containing sodium triphosphate

In the process for making a hydrated product consisting completely or partially of sodium triphosphate for use in detergent and cleaning compositions by initially mixing pulverulent sodium triphosphate containing less than 22 wt.-% water, alone or in admixture with at least one further pulverulent constituent of the detergent or cleaning composition, with water for hydrating the sodium triphosphate and compressing the mixture obtained;

• the improvement which comprises premixing a feed material comprising sodium triphosphate consisting essentially of Na.sub.5 P.sub.3 O.sub.10 and having a water od crystallization content less than 5 wt.-% and a particle size smaller than 0.3 mm with a quantity of water sufficient to increase the water content of the resulting mixture relative to the feed material and the water of crystallization content of the compressed product, relative to the feed material;
• admitting continuously the said resulting mixture to a roller press;
• compressing said resulting mixture in the roller press under a linear pressure of 10,000-20,000 KN per cm roller length to a solid sheet, whereby any incompletely fixed water in the thus-compressed mixture is essentially completely linked as hexahydrate, and ultimately crushing the said solid sheet to desired fineness with the resultant formation of a dry final product whose water content is essentially completely in the form of water of crystallization, said dry final product having an apparent density between 700 and about 1100 g/l.