Fmc Corporation

Paul L Hensler

Delmar F Church

Robert W Beger

Peter H Zeh

Gary E Wolfe

Hilary A Himpler

Mark A Bissell

Ronald E Arnold

Frederick J Kelso

A granular STPP suitable for detergent compositions which is non-caking in non-agitated water is produced by wetting anhydrous phase II STPP granules and drying the granules to remove free water. The resulting granules, when incorporated in detergent compositions, form a free flowing detergent slurry in detergent dispensing systems.

Sodium tripolyphosphate composition and method of producing it

Process for producing granular tetrasodium pyrophosphate having a bulk density of about 0.73 to about 0.84 g/ml and a dissolving time of about three minutes or less by heating crystalline disodium orthophosphate dihydrate at a slow heating rate, not over about 5.degree. C. per minute, until its temperature reaches about 130.degree. C. and then calcining it at about 350.degree. C. to about 550.degree. C. until it is converted to tetrasodium pyrophosphate.

Preparation of medium density, fast-dissolving, tetrasodium pyrophosphate

A process is provided for manufacturing tetrasodium pyrophosphate from sodium tripolyphosphate and a sodium salt capable of forming sodium carbonate on calcination. A compound capable of forming sodium carbonate is added to adjust the mol ratio to about 2, the mixture is milled and heated to from 300.degree. C. to 700.degree. C.

Process for manufacturing tetrasodium pyrophosphate

A process is provided for producing a powdered STPP hexahydrate particularly useful for use as a builder in a heavy duty detergent.

Process for preparing a sodium tripolyphosphate hexahydrate powder

The concentration of Phase II sodium tripolyphosphate in the sodium tripolyphosphate produced by spray drying a feed liquor comprising sodium orthophosphate, sodium pyrophosphate or mixture thereof, is increased to at least 90% by weight of sodium tripolyphosphate product, by seeding the feed liquor with Phase II material. Phase II yield is further increased by introducing with the feed liquor, in addition to the Phase II seed material, a minor amount of sodium sulfate. Hydrolysis of the Phase II seed is minimized by concentrating the Phase II seed in feed liquor in a separate feed tank at a lower temperature than the main feed line. Dispersing the Phase II seed in water, a dilute soda ash solution or an inert organic liquid and then injecting the dispersion into the feed liquor into the spray dryer promotes good contact between the seed and feed.

Production of Phase II sodium tripolyphosphate

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.

Preparation of granular sodium tripolyphosphate products

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.

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Lawrence, KS, United States of America

Paul L Hensler