Preparation of granular sodium tripolyphosphate products

A continuous process for producing a granular sodium tripolyphosphate product having low friability, high absorptivity and a bulk density within the range of from about 0.65 g/cc to about 0.87 g/cc, which comprises continuously moisturizing an agitated feed material consisting essentially of sodium tripolyphosphate which, other than any portion of material recycled from this process, is a dense rotary dried material in essentially non-hydrated form 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, by adding a sufficient amount of water thereon to continuously produce a moisturized material containing between 10 and 30% by weight moisture, continuously calcining the moisturized material to a temperature within the range of from about 300.degree. to about 600.degree. C. and continuously recovering said granular sodium tripolyphosphate product.

A continuous process for producing a granular sodium tripolyphosphate product having low friability, high absorptivity, and a bulk density within the range of from about 0.65 g/cc to about 0.87 g/cc, which comprises continuously moisturizing an agitated feed material consisting essentially of dense rotary dried sodium tripolyphosphate together with recycled sodium tripolyphosphate produced in the process, said dense rotary dried sodium tripolyphosphate being in essentially non-hydrated form and 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, by adding a sufficient amount of water thereon to continuously produce a moisturized material containing between 10 and 30% by weight moisture, continuously calcining the moisturized material to a temperature within the range of from about 300.degree. C. to about 600.degree. C., continuously recovering said granular sodium tripolyphosphate product, and continuously recycling process undersize material to the moisturization step.

A process for producing a granular sodium tripolyphosphate product having low friability, high absorptivity, and a bulk density within the range of from about 0.65 g/cc to about 0.87 g/cc, which comprises moisturizing an agitated feed material consisting essentially of sodium tripolyphosphate which, other than any portion of material recycled from this process, is a dense rotary dried material in essentially non-hydrated form 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, by adding a sufficient amount of water thereon to produce an agglomerated material containing on the average between 10 and 30% by weight moisture, calcining the agglomerated material to a temperature within the range of from about 300.degree. to about 600.degree. C. and recovering said granular sodium tripolyphosphate product.