Patent ID: 7217366
Filing Date: 2007-05-15
Classification: C01G,C22B,Y02P

Abstract:
1. A process for reducing the content of alkali metal impurities in ammonium metallate solutions comprising: (a) providing a membrane having a retentate side and a permeate side; (b) contacting a feed solution comprising ammonium metallate and alkali metal impurities with the retentate side of said membrane; (c) withdrawing a permeate from the permeate side of said membrane; and (d) withdrawing a retentate from the retentate side of said membrane, wherein said retentate comprises an amount of alkali metal impurities that is reduced relative to said feed solution, and said permeate comprises an amount of alkali metal impurities that is substantially equivalent to the difference between the amount of alkali metal impurities present in said feed solution and said amount of alkali metal impurities present in said permeate.