Patent ID: 6217622
Filing Date: 2001-04-17
Classification: C01F

Abstract:
A method of forming and partially classifying a precipitate containing large, coarse and fine particles from a supersaturated precipitating mother slurry, comprising separating the supersaturated precipitating mother slurry into a plurality of separate streams, separately and simultaneously introducing each stream as a slurry feed into a vessel provided with an agitated lower zone and a quiescent upper zone to form said precipitate, continuously removing product slurry as an underflow from the agitated lower zone of each vessel, and continuously removing spent liquor as an overflow from said quiescent upper zone, wherein said slurry feed, said underflow and said overflow are maintained such that said large and coarse particles accumulate as a slurry in the agitated lower zone of each vessel and only said fine particles exit said vessel with said overflow after migrating through said quiescent upper zone.