Phosphoric acid crystallization process

Details Phosphoric acid crystallization process Phosphoric acid crystallization process

1985-05-08

1987-04-07

Lacey, David L.

Chemistry: physical processes

Physical processes

Crystallization

23299, 23301, 423321R, 62532, B01D 902

Patent

active

046557890

ABSTRACT:
The present invention discloses a new method for obtaining a crystallized phosphoric acid of relatively high purity starting with conventional phosphoric acid. The new method is based on crystallization of orthophosphoric acid hemihydrate from the phosphoric acid. Massive nucleation which would lead to the formation of unprocessable masses is avoided in the new method by providing unusually large amounts of fine relatively pure seed crystals of orthophosphoric acid hemihydrate and operating the crystallization process under conditions which favor crystal growth on the seed crystals and disfavor the occurrence of secondary nucleation. To prevent the crystallizing magma from reaching a viscosity which would render further processing difficult the present invention provides for recycling raffinate in an amount sufficient to maintain the solids content of the crystallizing magma below about 40%.

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