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US 4,376,099 AGranted
Process for recovering Cr(VI) ions from a chlorate cell liquor
AssigneeThe Japan Carlit Co., Ltd.
InventorsHideo Yamamoto, Isao Isa, Morioki Shibuya
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Abstract
From a chlorate cell liquor containing an alkali metal chlorate, an alkali metal chloride and Cr(VI) ions, Cr(VI) ions are recovered by means of a combination of simple chemical procedures and re-used in an electrolysis step for manufacturing an alkali metal chlorate.
Claims8
A process for recovering Cr(VI) ions which comprises the steps of:
- (1) acidifying a Cr(VI) ions-containing chlorate cell liquor containing an alkali metal chlorate and an alkali metal chloride to a pH-value of from 1 to 5 and passing through an anion exchange resin bed to produce a chlorate cell liquor from which most of Cr(VI) ions are separated;
- (2) regenerating the anion exchange resin bed by passing through it an eluent of an aqueous alkali metal hydroxide solution of 0.05-1.0 mole per liter containing an alkali metal chloride of 1.0-5.0 moles per liter and an alkali metal chlorate of 0.1-5.0 moles per liter to remove the adsorbed Cr(VI) ions therefrom;
- and
- (3) returning the effluent from the regeneration stage of the anion exchange resin bed to an electrolysis step.
1 more element
A process for recovering Cr(VI) ions which comprises the steps of:
- (1) acidifying a Cr(VI) ions-containing chlorate cell liquor containing an alkali metal chlorate and an alkali metal chloride to a pH-value of from 1 to 5 and passing through an anion exchange resin bed to produce a chlorate cell liquor from which most of the Cr(VI) ions are separated;
- (2) feeding said chlorate cell liquor from which most of Cr(VI) ions have been removed to a single generator-crystallizer for manufacturing chlorine dioxide therefrom;
- (3) regenerating the anion exchange resin bed by passing through it an eluent of an aqueous alkali metal hydroxide solution of 0.05-1.0 mole per liter containing an alkali metal chloride of 1.0-5.0 moles per liter and an alkali metal chlorate of 0.1-5.0 moles per liter to remove the adsorbed Cr(VI) ions therefrom;
- and
- (4) returning the effluent from the regeneration stage of the anion exchange resin bed to an electrolysis process.
2 more elements
A process for recovering Cr(VI) ions which comprises the steps of:
- (1) adding an aqueous alkali metal chloride and/or an alkali metal chlorate solution containing a barium salt soluble in water to a Cr(VI) ion-containing chlorate cell liquor containing an alkali metal chlorate and an alkali metal chloride at a pH-value above 7 to precipitate barium chromate;
- (2) filtering the precipitate of barium chromate to produce a Cr(VI) ion-substantially free chlorate cell liquor;
- (3) dissolving the precipitate of barium chromate in an aqueous hydrochloric acid solution weaker than 6 normal;
- (4) passing said aqueous hydrochloric acid solution containing barium ions and Cr(VI) ions through a cation exchange resin bed to adsorb barium ions and obtaining an aqueous hydrochloric acid solution containing Cr(VI) ions;
- (5) regenerating said cation exchange resin bed by passing through it an eluent of an aqueous alkali metal chloride and/or alkali metal chlorate solution to remove barium ions therefrom;
- (6) returning said aqueous alkali metal chloride and/or alkali metal chlorate solution containing barium ions to the precipitation step described in the step (1);
- and
- (7) returning the aqueous hydrochloric acid solution containing Cr(VI) ions to an electrolysis step for manufacturing an alkali metal chlorate.
5 more elements
A process for recovering Cr(VI) ions which comprises the steps of:
- (1) acidifying a Cr(VI) ion-containing chlorate cell liquor containing an alkali metal chlorate and an alkali metal chloride to a pH-value of from 1 to 5 and passing through an anion exchange resin bed;
- (2) adding an aqueous alkali metal chloride and/or alkali metal chlorate solution containing a barium salt soluble in water to the effluent passed through the anion exchange resin bed at a pH-value of above 7 to precipitate barium chromate;
- (3) filtering the precipitate of barium chromate to produce a Cr-(VI) ion-substantially free chlorate cell liquor;
- (4) dissolving the precipitate of barium chromate in an aqueous hydrochloric acid solution at a concentration weaker than 6 normal;
- (5) passing said aqueous hydrochloric acid solution containing barium ions and Cr(VI) ions through a cation exchange resin bed to adsorb barium ions and obtaining an aqueous hydrochloric acid solution containing Cr(VI) ions, which is named a first solution;
- (6) regenerating said cation exchange resin bed by passing through it an eluent of an aqueous alkali metal chloride and/or alkali metal chlorate solution to remove barium ions therefrom;
- (7) returning said aqueous alkali metal chloride and/or alkali metal chlorate solution containing barium ions to the precipitation step described in the step (2);
- (8) regenerating the anion exchange resin bed by passing an eluent of an aqueous alkali metal hydroxide solution of 0.05-1.0 moles per liter containing an alkali metal chloride of 1.0-5.0 moles per liter and an alkali metal chlorate of 0.1-5.0 moles per liter, the effluent being named a second solution;
- and
- (9) returning the first solution and the second solution to an electrolysis step for manufacturing alkali metal chlorate after mixing thereof.
7 more elements
Dependencies are inferred from the claim text.