US3903237A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recovering hexavalent chromium for reuse
Assignee: National Steel Corp
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Filing: 1973-06-04
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Granted: 1975-09-02
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Expires: 1993-06-04
Abstract
Abstract In recovering hexavalent chromium from chrome plated steel strip which is wetted with plating solution as a result of dragout from the plating process, an aqueous solution containing hexavalent chromium in relatively low concentration is concentrated in a process comprising treating in a first cation exchange zone, treating in an anion exchange zone, regenerating the anion exchange zone and treating the effluent of regeneration in a cation exchange zone different from the first cation exchange zone. The concentrated solution is passed to a storage zone and recirculation is carried out between the storage zone and the plating zone and solution is passed from the storage zone to an evaporation zone and more concentrated solution is passed from the evaporation zone to the storage zone. In regenerating the anion exchange zone, only a portion of the hexavalent chromium is removed.
Inventors
- 👤 Robert B Smith
- 👤 Richard K Dickey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:18
CPC Classifications
C; C01; C01G; C01G37/00; C01G37/003
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
368 words
METHOD OF PRODUCING AN AQUEOUS SOLUTION HAVING A CONCENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS (EXPRESSED AS CRO3) RANGING FROM 10 TO 50 GRAMS PER LITER FROM AN AQUEOUS SOLUTION COMPRISING A CENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS (EXPRESSED AS CRO3) ON THE ORDER OF 0.1 TO 0.3 GRAMS PER LITER AND CATIONS SELECTED FROM THE GROUP COMPRISING OF IRON IONS AND TRIVALENT CHROMIUM IONS, SAID METHOD COMPRISING A. TREATING THE SOLUTION COMPRISING A CONCENTRATION OF HEXAVALENT CHROIUMIN THE FORM OF ANIONS (EXPRESSED AS CRO3) ON THE ORDER OF 0.1 TO 0.3 GRAMS PER LITER AND CAUTIONS SELECTED FROM THE GROUP CONSISTING OF IRONS IONS AND TRIVALENT CHROIUM IONS IN A FIRST CATION EXCHANGE ZONE, WITH CATION EXCHANGE RESIN OF THE STRONG ACID TYPE AND IN THE HYDROGEN FORM TO REPLACE CATIONS WITH HYDROGEN IONS AND PRODUCE AN AQUEOUS EFFLUENT CONTAINING THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS AND HYDROGEN IONS, B. TREATING THE EFFLUENT FROM STEP (A) IN AN ANION EXCHANGE ZONE WITH STRONG BASE ANION EXCHANGE RESIN OF THE QUATERNARY AMMONIUM TYPE IN THE HYDROXIDE FORM TO REACT THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS IN EFFLUENT OF STEP (A) WITH THE RESIN, C. REGENERATING THE RESIN IN THE ANION EXCHANGE ZONE USING A REGENERATING AGENT COMPRISING ALKALI METAL PRODUCE AN AQUEOUS EFFLUENT COMPRISING ALKALI METAL CATIONS ORGINATING FROM THE ALKALI METAL HYDROXIDE AND A CONCENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS SUCH AS TO PROVIDE THE CONCENTRATION IN THE EFFLUENT PRODUCED IN STEP (D), D. TREATING THE EFFLUENT OF STEP (C) IN A SECOND CATION EXCHANGE ZONE WITH CATION EXCHANGE RESIN OF THE STRONG ACID TYPE IN THE HYDROGEN FORM TO REPLACE CATIONS WITH HYDROGEN IONS AND PRODUCE AN EFFLUENT WHICH IS AN ACIDIC AQUCOUS SOLUTION COMPRISING A CONCENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS (EXPRESSED AS CRO3) RANGING FROM 10 TO 50 GRAMS PERLITER, C. THE CATION EXCHAMGE RESIN OF STEP (A) BEING OXIDATIVE RESISTANT UNDER THE CONDITIONS OF STEP (A) BUT NOT UNDER THE CONDITIONS OF STEP (D), AND THE CATION EXCHANGE RESIN OF STEP (D) BEING OXIDATIVE RESITANT UNDER THE CONDITIONS OF STEP (D), WHEREBY ECONOMY IN RESIN COST IS ACHIVED.
Claim 2
Dependent Claim
368 words
METHOD OF PRODUCING AN AQUEOUS SOLUTION HAVING A CONCENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS (EXPRESSED AS CRO3) RANGING FROM 10 TO 50 GRAMS PER LITER FROM AN AQUEOUS SOLUTION COMPRISING A CENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS (EXPRESSED AS CRO3) ON THE ORDER OF 0.1 TO 0.3 GRAMS PER LITER AND CATIONS SELECTED FROM THE GROUP COMPRISING OF IRON IONS AND TRIVALENT CHROMIUM IONS, SAID METHOD COMPRISING A. TREATING THE SOLUTION COMPRISING A CONCENTRATION OF HEXAVALENT CHROIUMIN THE FORM OF ANIONS (EXPRESSED AS CRO3) ON THE ORDER OF 0.1 TO 0.3 GRAMS PER LITER AND CAUTIONS SELECTED FROM THE GROUP CONSISTING OF IRONS IONS AND TRIVALENT CHROIUM IONS IN A FIRST CATION EXCHANGE ZONE, WITH CATION EXCHANGE RESIN OF THE STRONG ACID TYPE AND IN THE HYDROGEN FORM TO REPLACE CATIONS WITH HYDROGEN IONS AND PRODUCE AN AQUEOUS EFFLUENT CONTAINING THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS AND HYDROGEN IONS, B. TREATING THE EFFLUENT FROM STEP (A) IN AN ANION EXCHANGE ZONE WITH STRONG BASE ANION EXCHANGE RESIN OF THE QUATERNARY AMMONIUM TYPE IN THE HYDROXIDE FORM TO REACT THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS IN EFFLUENT OF STEP (A) WITH THE RESIN, C. REGENERATING THE RESIN IN THE ANION EXCHANGE ZONE USING A REGENERATING AGENT COMPRISING ALKALI METAL PRODUCE AN AQUEOUS EFFLUENT COMPRISING ALKALI METAL CATIONS ORGINATING FROM THE ALKALI METAL HYDROXIDE AND A CONCENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS SUCH AS TO PROVIDE THE CONCENTRATION IN THE EFFLUENT PRODUCED IN STEP (D), D. TREATING THE EFFLUENT OF STEP (C) IN A SECOND CATION EXCHANGE ZONE WITH CATION EXCHANGE RESIN OF THE STRONG ACID TYPE IN THE HYDROGEN FORM TO REPLACE CATIONS WITH HYDROGEN IONS AND PRODUCE AN EFFLUENT WHICH IS AN ACIDIC AQUCOUS SOLUTION COMPRISING A CONCENTRATION OF HEXAVALENT CHROMIUM IN THE FORM OF ANIONS (EXPRESSED AS CRO3) RANGING FROM 10 TO 50 GRAMS PERLITER, C. THE CATION EXCHAMGE RESIN OF STEP (A) BEING OXIDATIVE RESISTANT UNDER THE CONDITIONS OF STEP (A) BUT NOT UNDER THE CONDITIONS OF STEP (D), AND THE CATION EXCHANGE RESIN OF STEP (D) BEING OXIDATIVE RESITANT UNDER THE CONDITIONS OF STEP (D), WHEREBY ECONOMY IN RESIN COST IS ACHIVED.
Claim 3
Dependent Claim
18 words
Method as recited in claim 1 in which in step (d) the cation exchange resin is highly cross-linked.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |