Process for obtaining desalted water from zirconium-containing wash water
AssigneeHenkel AG & Co. KGaA
InventorsJan-Willem Brouwer, Jens Krömer
Life of this patent
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Abstract
A method for recovering demineralized water from zirconium-containing rinse water having a pH lower than 6.0, wherein a) the rinse water has added to it an aqueous solution of Ca(OH)2 containing no more than 0.1 wt% undissolved Ca(OH)2, in a quantity such that the pH of the rinse water rises to a value in the range from 6.2 to 8.0, b) a precipitate that forms is separated from the rinse water, and c) the rinse water from which the precipitate was removed in step b) is subjected to an ion exchange method or to reverse osmosis.
Claims14
A method for recovering demineralized water from zirconium-containing rinse water having a pH lower than 6.0, comprising steps of:
- a) treating zirconium-containing rinse water having a pH lower than 6.0 by adding an aqueous solution of Ca(OH)2 containing no more than 0.1 wt% undissolved Ca(OH)2 in a quantity such that pH of treated rinse water rises to a value in a range from 6.2 to 8.0 and a precipitate forms;
- b) separating the precipitate from the treated rinse water, and
- c) subjecting the treated rinse water from which the precipitate was removed in step b) to an ion exchange method or to reverse osmosis thereby producing demineralized water.
A method for conversion treatment comprising steps of:
- a) contacting a metal surface with a zirconium-containing treatment solution;
- b) rinsing the metal surface with water thereby generating zirconium-containing rinse water having a pH lower than 6.0;
- c) treating zirconium-containing rinse water by adding an aqueous solution of Ca(OH)2 containing no more than 0.1 wt% undissolved Ca(OH)2 in a quantity such that pH of treated rinse water rises to a value in a range from 6.2 to 8.0 and a precipitate forms;
- d) separating the precipitate from the treated rinse water, and
- e) subjecting the treated rinse water from which the precipitate was removed in step b) to an ion exchange method or to reverse osmosis;
- f) re-using the treated rinse water from step e) in preparing process solutions or for rinsing metal surfaces in the method for conversion treatment.
Dependencies are inferred from the claim text.