US3885018A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Regenerating anion exchange zone containing hexavalent chromium
Assignee: National Steel Corp
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Filing: 1973-06-04
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Granted: 1975-05-20
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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
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:37
CPC Classifications
C; C01; C01G; C01G37/00; C01G37/003; B; B01; B01J; B01J49/00; B01J49/05; B01J49/07
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
217 words
METHOD BOTH FOR RECOVERING CHROMIUM FROM STRONG BASE ANION EXCHANGE RESIN WHICH HAS BEEN USED IN THE HYDROXIDE FORM TO REMOVE THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS FROM A SOLUTION AND FOR REGENERATING THE RESING FOR REUSE FOR REMOVING HEXAVALENT CHROMIUM IN THE FORM OF ANIONS FROM A SOLUTION; COMPRISING THE STEPS OF A. INTRODUCING WATER INTO A COLUMN CONTAINING THE RESIN THEREBY BACKWASHING THE RESIN TO REMOVE EXTRANEOUS SOLIDS AND RESIN FINES, B. REMOVING RESIDUAL BACKWASH WATER, C. PASSING AQUEOUS ALKALI METAL HYDROXIDE INTO COLUMN CONTAINING THE RESIN AND PROVIDING EFFLUENT FROM THE COLUMN CONTAINING FROM ABOUT 90 TO ABOUT 95% OF THE HEXAVALENT CHROMIUM PRESENT IN THE COLUMN WHILE LEAVING IN THE COLUMN ALKALI METAL CATIONS AND THE REMAINDER OF THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS TO THEREBY OPTIMIZE THE CONCENTRATION OF HEXAVALENT CHROMIUM IN THE EFFLUENT, D. INTRODUCING WATER INTO THE COLUMN AND RECIRCULATING RESULTING LIQUID BETWEEN THAT COLUMN AND A COLUMN CONTAINING CATION EXCHANGE RESIN OF THE STRONG ACID TYPE IN THE HYDROGEN FORM TO REACT HEXAVALENT CHROMIUM IN THE FORM OF ANIONS WITH THE ANION EXCHANGE RESIN AND TO REACT THE ALKALI METAL CATIONS WITH THE CATION EXCHANGE RESIN, TO ESTABLISH A CONTINUING 5 TO 10% LEVEL OF HEXAVALENT CHROMIUM IN THE ANION EXCHANGE RESIN THEREBY CONSERVING CHROMIUM.
Claim 2
Dependent Claim
217 words
METHOD BOTH FOR RECOVERING CHROMIUM FROM STRONG BASE ANION EXCHANGE RESIN WHICH HAS BEEN USED IN THE HYDROXIDE FORM TO REMOVE THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS FROM A SOLUTION AND FOR REGENERATING THE RESING FOR REUSE FOR REMOVING HEXAVALENT CHROMIUM IN THE FORM OF ANIONS FROM A SOLUTION; COMPRISING THE STEPS OF A. INTRODUCING WATER INTO A COLUMN CONTAINING THE RESIN THEREBY BACKWASHING THE RESIN TO REMOVE EXTRANEOUS SOLIDS AND RESIN FINES, B. REMOVING RESIDUAL BACKWASH WATER, C. PASSING AQUEOUS ALKALI METAL HYDROXIDE INTO COLUMN CONTAINING THE RESIN AND PROVIDING EFFLUENT FROM THE COLUMN CONTAINING FROM ABOUT 90 TO ABOUT 95% OF THE HEXAVALENT CHROMIUM PRESENT IN THE COLUMN WHILE LEAVING IN THE COLUMN ALKALI METAL CATIONS AND THE REMAINDER OF THE HEXAVALENT CHROMIUM IN THE FORM OF ANIONS TO THEREBY OPTIMIZE THE CONCENTRATION OF HEXAVALENT CHROMIUM IN THE EFFLUENT, D. INTRODUCING WATER INTO THE COLUMN AND RECIRCULATING RESULTING LIQUID BETWEEN THAT COLUMN AND A COLUMN CONTAINING CATION EXCHANGE RESIN OF THE STRONG ACID TYPE IN THE HYDROGEN FORM TO REACT HEXAVALENT CHROMIUM IN THE FORM OF ANIONS WITH THE ANION EXCHANGE RESIN AND TO REACT THE ALKALI METAL CATIONS WITH THE CATION EXCHANGE RESIN, TO ESTABLISH A CONTINUING 5 TO 10% LEVEL OF HEXAVALENT CHROMIUM IN THE ANION EXCHANGE RESIN THEREBY CONSERVING CHROMIUM.
Claim 3
Dependent Claim
15 words
Method as recited in claim 1, in which the alkali metal hydroxide is sodium hydroxide.
Claim 4
Dependent Claim
19 words
Method as recited in claim 1, in which in step (b) residual backwash water is removed utilizing pressurized air.
Claim 5
Dependent Claim
33 words
Method as recited in claim 3 in which liquid resulting in the column containing the anion exchange resin from passing aqueous alkali metal hydroxide thereinto is removed from the column utilizing pressurized air.
Claim 6
Dependent Claim
60 words
Method as recited in claim 4 in which subsequent to the removal of liquid resulting in the column containing the anion exchange resin from passing aqueous alkali metal hydroxide thereinto and prior to step (d), rinse water is introduced into that column and resulting solution is removed utilizing pressurized air to provide a portion of the effluent of step (c).
Claim 7
Dependent Claim
25 words
Method as recited in claim 5 in which the rinse water and pressurized air are introduced into the column containing the anion exchange resin simultaneously.
Claim 8
Dependent Claim
36 words
Method as recited in claim 1 in which the water introduced in step (d) is passed through a column containing cation exchange resin of the strong acid type in the hydrogen form prior to such introduction
Claim 9
Dependent Claim
19 words
Method as recited in claim 1 wherein in step (c) the effluent contains about 95% of the hexavalent chromium.
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) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |