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US 4,656,019 AGranted
Production of Phase II sodium tripolyphosphate
AssigneeFMC Corporation
InventorsPaul L. Hensler, Frederick J. Kelso, Gary E. Wolfe, Peter H. Zeh
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AssigneeFMC Corporation
InventorsPaul L. Hensler, Frederick J. Kelso, Gary E. Wolfe, Peter H. Zeh
Estimating the term…
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.
In a method of producing sodium tripolyphosphate wherein an aqueous feed liquor supplied to a spray dryer from a feed tank, comprising sodium orthophosphate, sodium pyrophosphate or a mixture thereof, is spray dried from spray nozzles in the spray dryer at a temperature below 450.degree. C., the improvement which comprises introduction with the feed liquor a minor but effective amount of a crystalline Phase II sodium tripolyphosphate seed, whereby the concentration of Phase II material in the sodium tripolyphosphate product is at least 90% by weight.
Dependencies are inferred from the claim text.