Abstract: Dense rotary dried sodium tripolyphosphate (STPP) particles having a bulk density of at least 0.9 g/cc and a particle size distribution of 0 to 85% by weight +20 mesh, 15 to 100% by weight -20 +100 mesh and 0 to 20% by weight -100 mesh are moisturized by adding a sufficient amount of water to produce a material containing on the average between about 10% and about 30% by weight moisture. The moisturized material is calcined to a temperature within the range of from about 300.degree. to about 600.degree. C., to produce a granular STPP product having low friability, high absorptivity and a bulk density within the range of from about 0.65 to about 0.87 g/cc.

Abstract: Screen undersize sodium tripolyphosphate (STPP) particles are compacted, milled and moisturized by adding a sufficient amount of water thereon to produce a material containing on the average between about 15% and about 35% by weight moisture. The moisturized material is calcined to a temperature within the range of from about 300.degree. to about 600.degree. C., to produce a granular STPP product having a low friability, high absorptivity, and a bulk density within the range of from about 0.65 to about 0.87 g/cc.