Purification of aqueous alkali metal chlorate solutions
AssigneeOlin Corporation
InventorsJerry J. Kaczur, David W. Cawlfield, Julian F. Watson
Life of this patent
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Abstract
A process for removing alkaline earth metal impurities (e.g. calcium and magnesium ions) from an aqueous alkali metal chlorate solution which includes adding sufficient alkali metal carbonate or hydroxide or both to the impure solution to raise the pH to above 9 and form alkaline earth metal precipitates which are then removed from the pH-adjusted solution (e.g. by microfiltration). This process can lower the level of these impurities from about 1-20 ppm to less than about 0.3 ppm or less.
Claims27
A process for removing alkaline earth metal impurities from an impure aqueous chlorate ion-containing solution having an alkali metal chlorate as the main salt comprising the steps of:
- (1) adding a sufficient amount of at least one alkali compound to said chlorate ion-containing solution to adjust the pH of said solution to about 9.5 to 13.5 and to form alkaline earth metal precipitates in said solution;
- said alkali compound selected from the group consisting of an alkali metal carbonate, alkali metal bicarbonate, alkali metal hydroxide, and mixtures thereof;
- and
- (2) separating said pH-adjusted aqueous alkali chlorate solution from said precipitated alkaline earth metal impurities;
- thereby forming a first purified pH-adjusted aqueous alkali chlorate solution having less than about 0.3 parts per million by weight of total alkaline earth metal impurities.
A process for regenerating a chelating ion exchange resin contaminated with alkaline earth metal impurities comprising the steps of:
- (1) contacting a chelating ion exchange resin contaminated with alkaline earth metal impurities with an aqueous chloric acid solution and removing said impurities from said resin;
- and
- (2) then contacting said resin with an aqueous solution selected from the group consisting of (a) water, (b) an alkali metal hydroxide solution, (c) an alkali metal chlorate solution, and (d) mixtures thereof, thereby removing substantially all of the remaining chloric acid from said chelating resin.
A process for removing alkaline earth metal impurities from an impure aqueous chlorate ion-containing solution having an alkali metal chlorate as the main salt, comprising the steps of:
- (1) adding a sufficient amount of alkali compound to said chlorate ion-containing solution to adjust the pH of said solution to about 9.5 to 13.5 and to cause the precipitation of alkaline earth metal compounds in said solution;
- said alkali compound selected from an alkali metal carbonate, alkali metal bicarbonate, alkali metal hydroxide, and mixtures thereof;
- and
- (2) separating said pH-adjusted aqueous alkali chlorate solution from said alkaline earth metal precipitates, thereby forming a first purified alkali metal chlorate solution having less than about 0.3 parts per million by weight of total alkaline earth metal ions;
- (3) contacting said first purified alkali metal chlorate solution with a chelating ion exchange resin to remove further amounts of alkaline earth metal impurities, thereby forming a second purified alkali metal chlorate solution having less than about 0.05 parts per million parts by weight of total alkaline earth metal impurities;
- and
- (4) contacting said chelating ion exchange resin which was contaminated with alkaline earth metal impurities from said first alkali metal chlorate solution with an aqueous chloric acid solution and removing said impurities from said resin;
- and
- (5) then contacting said, resin with an aqueous metal hydroxide solution to remove substantially all of the chloric acid from said resin thereby producing a regenerated resin.
A process for removing alkaline earth metal impurities from an impure aqueous chlorate ion-containing solution having an alkali metal chlorate as the main salt, comprising the steps of:
- (1) contacting said impure aqueous chlorate ion-containing solution with a chelating ion exchange resin, thereby producing a purified alkali metal chlorate solution having less than about 0.3 parts per million parts by weight of total alkaline earth metal impurities and leaving said alkaline earth metal impurities on said chelating resin;
- and
- (2) regenerating said chelating resin with an aqueous chloric acid solution to remove said alkaline earth metal impurities from said resin.
A process for producing aqueous chloric acid solutions comprising the step of:
- (1) passing a purified aqueous alkali metal chlorate-containing solution having less than about 0.3 parts per million parts by weight of total alkaline earth metal impurities therein through an electrolytic cell having a cation exchange membrane to produce an aqueous solution containing chloric acid and an aqueous solution containing alkali metal hydroxide.
A process for removing alkaline earth metal impurities from a chelating ion exchange resin comprising:
- contacting a chelating ion exchange resin contaminated with alkaline earth metal impurities with an aqueous chloric acid solution and then removing said impurities from said resin.
Dependencies are inferred from the claim text.