Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
169 words
A method of removing chromate from aqueous solutions of alkali metal chlorate and alkali metal chloride which comprises in an exhaustion stage (1) passing said aqueous solution of alkali metal chlorate and alkali metal chloride acidified with hydrochloric acid to a pH of not less than 0.5 through an anion exchange resin bed to remove chromate therefrom and produce an essentially chromate free aqueous solution containing alkali metal chlorate and alkali metal chloride, and in a regeneration stage (2) passing an aqueous solution of alkali metal hydroxide and alkali metal chloride through said resin bed to remove chromate therefrom, (3) passing an aqueous solution of alkali metal chloride acidified with hydrochloric acid to a low pH through said resin bed to convert said resin to acid form and (4) passing an aqueous solution of essentially chromate free alkali metal chlorate and alkali metal chloride acidified with hydrochloric acid to a pH value not less than 0.5, through said resin bed to saturate said resin bed with alkali metal chlorate.
Claim 2
Independent Claim
169 words
A method of removing chromate from aqueous solutions of alkali metal chlorate and alkali metal chloride which comprises in an exhaustion stage (1) passing said aqueous solution of alkali metal chlorate and alkali metal chloride acidified with hydrochloric acid to a pH of not less than 0.5 through an anion exchange resin bed to remove chromate therefrom and produce an essentially chromate free aqueous solution containing alkali metal chlorate and alkali metal chloride, and in a regeneration stage (2) passing an aqueous solution of alkali metal hydroxide and alkali metal chloride through said resin bed to remove chromate therefrom, (3) passing an aqueous solution of alkali metal chloride acidified with hydrochloric acid to a low pH through said resin bed to convert said resin to acid form and (4) passing an aqueous solution of essentially chromate free alkali metal chlorate and alkali metal chloride acidified with hydrochloric acid to a pH value not less than 0.5, through said resin bed to saturate said resin bed with alkali metal chlorate.
Claim 3
Dependent Claim
34 words
A process as claimed in claim 1 in which the aqueous solution of alkali metal chlorate and alkali metal chloride from which chromate is to be removed is the product of an electrolytic cell.
Claim 4
Dependent Claim
25 words
A process as claimed in claim 1 where the aqueous solutions from steps (2), (3) and (4) are passed as feedstock to an electrolytic cell.
Claim 5
Dependent Claim
14 words
A process as claimed in claim 1 in which the alkali metal is sodium.
Claim 6
Dependent Claim
32 words
A process as claimed in claim 4 in which a portion of the essentially chromate free aqueous solution of sodium chlorate and sodium chloride from step (1) is used in step (4).
Claim 7
Dependent Claim
27 words
A method as claimed in claim 4, in which the solutions indicated under (2), (3) and (4) are entirely used as feed stock for an electrolytic cell.
Claim 8
Dependent Claim
23 words
A process as claimed in claim 4 in which the pH in steps (1), (3) and (4) is not numerically greater than 3.
Claim 9
Dependent Claim
27 words
A method as claimed in claim 5 in which the solutions indicated under (2), (3) and (4) are entirely used as feed stock for an electrolytic cell.
Claim 10
Dependent Claim
27 words
A method as claimed in claim 7, in which the solutions indicated under (2), (3) and (4) are entirely used as feed stock for an electrolytic cell.
Claim 11
Dependent Claim
27 words
A method as claimed in claim 1 in which the flow of the solution in the regenerating stage is counter to the flow in the exhaustion stage.
Claim 12
Dependent Claim
18 words
A process as claimed in claim 1 in which the anionic exchange resin is a weakly basic resin.
Claim 13
Dependent Claim
27 words
A method as claimed in claim 1 in which the bed contains a vertical staggered column having longitudinally spaced recesses extending completely around the side walls thereof.
Claim 14
Dependent Claim
24 words
A method as claimed in claim 1 in which the product effluent is fed to a chlorine dioxide generator for production of chlorine dioxide.