Patent US3847757A successfully refreshed from Google Patents.
US3847757A
Expired / Lapsed
US
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Recovering chromium values for stabilization of tin-plate surfaces
Assignee: National Steel Corp
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Filing: 1973-06-04
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Granted: 1974-11-12
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Expires: 1993-06-04
Abstract
Abstract Chromium values are recovered from wash water following a chemical treatment step in electrotinplating lines in a process comprising treating in a cation exchange zone, treating in an anion exchange zone, regenerating the anion exchange zone, treating effluent from said regeneration in a cation exchange zone and passing effluent from the cation exchange zone to a storage zone, passing effluent from said regeneration to the storage zone without intermediate cation exchange treatment.
Inventors
- 👤 R Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:53
CPC Classifications
C; C25; C25D; C25D21/00; C25D21/16; C25D21/22; B; B01; B01J; B01J49/00; B01J49/05; B01J49/08
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
204 words
METHOD FOR RECOVERING HEXAVALENT CHROMIUM FROM SOLUTION WETTING TIN PLATE SURFACES AFTER ELECTROCHEMICAL TREATMENT UTILIZING AS AN ELECTROLYTE AN ACIDIC AQUEOUS SOLUTION COMPRISING SODIUM DICHROMATE COMPRISING THE STEPS OF A. WASHING SAID SURFACES TO RECOVER AN AQUEOUS SOLUTION CONTAINING CATIONS AND ANIONS INCLUDING ANIONS CONTAINING HEXAVALENT CHROMIUM; B. TREATING AQUEOUS SOLUTION RECOVERED FROM SAID WASHING STEP WITH CATION EXCHANGE RESIN IN A CATION EXCHANGE ZONE TO REPLACE CATION WITH HYDROGEN IONS TO PRODUCE AN AQUEOUS EFFLUENT CONTAINING HYDROGEN IONS AND ANIONS INCLUDING ANIONS CONTAINING HEXAVALENT CHROMIUM C. TREATING SAID EFFLUENT WITH ANION EXCHANGE RESIN IN AN ANION EXCHANGE ZONE TO REPLACE ANIONS WITH HYDROXYL IONS THEREBY RECOVERING HEXAVALENT CHROMIUM IN THE RESIN IN SAID ANION EXCHANGE ZONE AND PRODUCING A DEMINERALIZED WATER EFFLUENT; D. REGENERATING THE RESIN IN SAID ANION EXCHANGE TO PRODUCE AN EFFLUENT FROM SAID ANION EXCHANGE ZONE COMPRISING AN AQUEOUS SOLUTION CONTAINING SODIUM IONS AND ANIONS CONTAINING HEXAVALENT CHROMIUM; E. TREATING EFFLUENT FROM STEP (D) WITH CATION EXCHANGE RESIN IN A CATION EXCHANGE ZONE TO REPLACE CATIONS WITH HYDROGEN IONS AND PRODUCE AN EFFLUENT AND PASSING THE PRODUCED EFFLUENT INTO AN ELECTROLYTE STORAGE ZONE; F. PASSING EFFLUENT FROM STEP (D) INTO THE ELECTROLYTE STORAGE ZONE WITHOUT AN INTERMEDIATE CARTION EXCHAGE TREATMENT.
Claim 2
Dependent Claim
204 words
METHOD FOR RECOVERING HEXAVALENT CHROMIUM FROM SOLUTION WETTING TIN PLATE SURFACES AFTER ELECTROCHEMICAL TREATMENT UTILIZING AS AN ELECTROLYTE AN ACIDIC AQUEOUS SOLUTION COMPRISING SODIUM DICHROMATE COMPRISING THE STEPS OF A. WASHING SAID SURFACES TO RECOVER AN AQUEOUS SOLUTION CONTAINING CATIONS AND ANIONS INCLUDING ANIONS CONTAINING HEXAVALENT CHROMIUM; B. TREATING AQUEOUS SOLUTION RECOVERED FROM SAID WASHING STEP WITH CATION EXCHANGE RESIN IN A CATION EXCHANGE ZONE TO REPLACE CATION WITH HYDROGEN IONS TO PRODUCE AN AQUEOUS EFFLUENT CONTAINING HYDROGEN IONS AND ANIONS INCLUDING ANIONS CONTAINING HEXAVALENT CHROMIUM C. TREATING SAID EFFLUENT WITH ANION EXCHANGE RESIN IN AN ANION EXCHANGE ZONE TO REPLACE ANIONS WITH HYDROXYL IONS THEREBY RECOVERING HEXAVALENT CHROMIUM IN THE RESIN IN SAID ANION EXCHANGE ZONE AND PRODUCING A DEMINERALIZED WATER EFFLUENT; D. REGENERATING THE RESIN IN SAID ANION EXCHANGE TO PRODUCE AN EFFLUENT FROM SAID ANION EXCHANGE ZONE COMPRISING AN AQUEOUS SOLUTION CONTAINING SODIUM IONS AND ANIONS CONTAINING HEXAVALENT CHROMIUM; E. TREATING EFFLUENT FROM STEP (D) WITH CATION EXCHANGE RESIN IN A CATION EXCHANGE ZONE TO REPLACE CATIONS WITH HYDROGEN IONS AND PRODUCE AN EFFLUENT AND PASSING THE PRODUCED EFFLUENT INTO AN ELECTROLYTE STORAGE ZONE; F. PASSING EFFLUENT FROM STEP (D) INTO THE ELECTROLYTE STORAGE ZONE WITHOUT AN INTERMEDIATE CARTION EXCHAGE TREATMENT.
Claim 3
Dependent Claim
30 words
Method as recited in claim 1 in which the steps (e) and (f) are carried out to provide a pH ranging from 2 to 6 in said electrolyte storage zone.
Claim 4
Dependent Claim
29 words
Method as recited in claim 2 in which steps (e) and (f) are carried out to provide a pH ranging from 3 to 4 in said electrolyte storage zone.
Claim 5
Dependent Claim
26 words
Method as recited in claim 3 in which steps (e) and (f) are carried out to provide a pH of 3.5 in said electrolyte storage zone.
Claim 6
Dependent Claim
42 words
Method as recited in claim 1 in which said regeneration step is carried out to provide in the effluent from the regenerating step a concentration of anions containing hexavalent chromium expressed as grams of CrO3 per liter ranging from 20 to 40.
Claim 7
Dependent Claim
15 words
Method as recited in claim 5 in which said concentration ranges from 25 to 35.
Claim 8
Dependent Claim
29 words
Method as recited in claim 6 in which said effluent from the regneration step is recovered in a collecting zone prior to being subjected to steps (e) and (f).
Claim 9
Dependent Claim
81 words
Method as recited in claim 1 in which said regeneration is carried out to provide effluent from said anion exchange zone containing from about 90 to about 95 percent of the hexavalent chromium present in said anion exchange zone just prior to initiation of regeneration and in which water is introduced into said anion exchange zone subsequent to the recovery therefrom of the effluent of regeneration and recirculation is carried out between said anion exchange zone and a cation exchange zone.
Claim 10
Dependent Claim
40 words
Method as recited in claim 8 in which said regeneration is carried out to provide effluent from said anion exchange zone containing about 95 percent of the hexavalent chromium present in said zone just prior to the initiation of regeneration.
Claim 11
Dependent Claim
16 words
Method as recited in claim 1 in which step (a) comprises spray washing with demineralized water.
Claim 12
Dependent Claim
36 words
Method as recited in claim 1 in which solution treated in step (b) is an aqueous solution containing cations and hexavalent chromium in the form of anions recovered from step (a) and also from other sources.
Claim 13
Dependent Claim
189 words
Method of treating aqueous solution containing cations and hexavalent chromium in the form of anions to produce an electrolyte suitable for use in a chemical treatment step in an electrotinplating line, comprising the steps of a. treating said aqueous solution with cation exchange resin in a cation exchange zone to replace cations with hydrogen ions to produce an aqueous effluent containing hydrogen ions and anions including anions containing hexavalent chromium; b. treating said effluent with anion exchange resin in an anion exchange zone to replace anions with hydroxyl ions thereby recovering hexavalent chromium in the resin in said anion exchange zone and producing a demineralized water effluent; c. regenerating the resin in said anion exchange zone to produce an effluent from said anion exchange zone comprising an aqueous solution containing sodium ions and anions containing hexavalent chromium; d. treating effluent from step (c) with cation exchange resin in a cation exchange zone to replace cations with hydrogen ions and produce an effluent and passing the produced effluent into an electrolyte storage zone; e. passing effluent from step (c) into an electrolyte storage zone without an intermediate cation exchange treatment.
Claim 14
Dependent Claim
189 words
Method of treating aqueous solution containing cations and hexavalent chromium in the form of anions to produce an electrolyte suitable for use in a chemical treatment step in an electrotinplating line, comprising the steps of a. treating said aqueous solution with cation exchange resin in a cation exchange zone to replace cations with hydrogen ions to produce an aqueous effluent containing hydrogen ions and anions including anions containing hexavalent chromium; b. treating said effluent with anion exchange resin in an anion exchange zone to replace anions with hydroxyl ions thereby recovering hexavalent chromium in the resin in said anion exchange zone and producing a demineralized water effluent; c. regenerating the resin in said anion exchange zone to produce an effluent from said anion exchange zone comprising an aqueous solution containing sodium ions and anions containing hexavalent chromium; d. treating effluent from step (c) with cation exchange resin in a cation exchange zone to replace cations with hydrogen ions and produce an effluent and passing the produced effluent into an electrolyte storage zone; e. passing effluent from step (c) into an electrolyte storage zone without an intermediate cation exchange treatment.
Claim 15
Dependent Claim
29 words
Method as recited in claim 12 in which steps (d) and (e) are carried out to provide a pH ranging from 2 to 6 in said electrolyte storage zone.
Claim 16
Dependent Claim
29 words
Method as recited in claim 13 in which steps (d) and (e) are carried out to provide a pH ranging from 3 to 4 in said electrolyte storage zone.
Claim 17
Dependent Claim
42 words
Method as recited in claim 12 in which said regeneration step is carried out to provide in the effluent from the regenerating step a concentration of anions containing hexavalent chromium expressed as grams of CrO3 per liter ranging from 20 to 40.
Claim 18
Dependent Claim
15 words
Method as recited in claim 15 in which said concentration ranges from 25 to 35.
References Cited (Backward Citations)
US3681210A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-11-11 | 1978-05-13 | 1978-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-11 | 1982-05-13 | 1982-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-11 | 1986-05-13 | 1986-11-12 | $7700.00 | Window Closed / Lapsed |