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US 4,268,486 AGranted
Selective chromate removal from a chlorate solution
AssigneeOlin Corporation
InventorsManfred G. Noack, Steven A. Manke
Life of this patent
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Abstract
A method has been devised for removing hexavalent chromium from concentrated aqueous alkali metal chlorate solutions by reacting the solution with a hydrazine compound and separating trivalent chromium compound from the solution. Alkali metal hypohalites may be simultaneously removed from the chlorate solution by reaction with excess hydrazine compound.
Claims18
A process for removing hexavalent chromium from an impure aqueous solution which comprises:
- (a) reacting a hydrazine compound with said impure aqueous solution, said impure aqueous solution containing from about 100 to about 750 grams of alkali metal chlorate per liter and from about 20 to about 400 grams of alkali metal chloride per liter, said reaction being carried out at a pH in the range from about 6.0 to about 7.5 to form an aqueous slurry of solid particles of trivalent chromium compound in an aqueous solution of alkali metal chlorate, alkali metal chloride, and a nitrogen-containing compound;
- and
- (b) separating said solid particles of trivalent chromium compound from said aqueous solution;
- and
- wherein said hydrazine compound selectively reduces hexavalent chromium to trivalent chromium to achieve hexavalent chromium removal without reducing said alkali metal chlorate or said alkali metal chloride.
2 more elements
Dependencies are inferred from the claim text.