Process for preparing medium density granular sodium tripolyphosphate

A method of preparing granular sodium tripolyphosphate of medium density which comprises spraying onto rotating finely divided sodium tripolyphosphate particles having a size distribution of at least 50% by weight -100 mesh, 0 to 25% by weight -50+100 mesh and 0 to 25% by weight +50 mesh, an aqueous spray solution of sodium orthophosphate having a concentration of from about 20 to 65% by weight until the total amount of dissolved solids sprayed is between 8 and 15% by weight based on the total weight of sodium tripolyphosphate to be produced, to form an agglomerated product and calcining the agglomerated product at a temperature of 300.degree. to 600.degree.C to produce granular sodium tripolyphosphate having a bulk density between about 0.50 and 0.80 grams per cubic centimeter and a particle size of -20+100 mesh.