Claims
- 1. A process for removing chromium containing anions from used rinse water from a chrome treatment operation and producing a concentrated solution of chromic acid, in which the used rinse water is passed through a cation exchange bed to remove cation impurities and then through an anion exchange bed in hydroxyl form from the top to remove chromium containing anions, a concentrated aqueous alkali metal hydroxide solution is then passed from a reservoir through said anion exchange bed from the bottom to produce a concentrated solution of chromium containing anions at the top of said anion exchange bed, said concentrated solution of chromium containing anions is then passed directly to and through a second cation exchange bed in hydrogen form from the bottom to produce at the top of said second cation exchange bed a concentrated solution of chromic acid, and displacement water is then passed through said second cation exchange bed and directly to and through the anion exchange bed in the same flow path as but in a direction opposite to the direction in which said concentrated solution of chromium containing anions and said alkali metal hydroxide solution passed through said beds, to displace the liquids remaining in said beds and connecting conduits into the reservoir for said alkali metal hydroxide solution.
- 2. A process as claimed in claim 1, in which said displacement water is city water.
- 3. A process as claimed in claim 1, in which said displacement water is a dilute chromic acid solution.
- 4. A process as claimed in claim 1, in which said alkali metal hydroxide is sodium hydroxide.
- 5. A process as claimed in claim 1, in which an aqueous solution of sulphuric acid is passed through the second cation exchange bed from the top following passage of the displacement water therethrough and said bed is rinsed with city water from the top following passage of the sulphuric acid therethrough.
Parent Case Info
This is a continuation of application Ser. No. 637,605, filed Dec. 4, 1975, which is a continuation of application Ser. No. 249,857, filed May 3, 1972, now abandoned.
US Referenced Citations (8)
Non-Patent Literature Citations (1)
Entry |
Krug, "Galvanotechnik", vol. 55, 1964, pp. 295-300. |
Continuations (2)
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Number |
Date |
Country |
Parent |
637605 |
Dec 1975 |
|
Parent |
249857 |
May 1972 |
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