Patent US3856916A successfully refreshed from Google Patents.
US3856916A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing chromium sulphate from residual solutions containing hexavalent chromium compounds
Assignee: Produits Chimiques Ugine Kuhlmann
•
Filing: 1973-04-12
•
Granted: 1974-12-24
•
Expires: 1993-04-12
Abstract
Abstract A process for preparing chromium sulphate from residual solutions containing hexavalent chromium compounds, wherein, firstly, the hexavalent chromium from the residual solution to be treated is extracted and fixed, by known means notably by contacting the said solution either with an ion exchange resin or with a water-insoluble organic solvent, then the hexavalent chromium thus fixed by the resin or organic solvent is reextracted. Said reextraction according to the improved process of the invention, is carried out with a solution of sulphur dioxide in the presence of sulphuric acid to directly recover a chromium sulphate solution.
Inventors
- 👤 R Lefrancois
- 👤 J Denoyers
- 👤 M Gabriel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:50
CPC Classifications
C; C01; C01G; C01G37/00; C01G37/08
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
99 words
IN A PROCESS FOR PREPARING A CHROMIUM SULPHATE FROM RESIDUAL SOLUTIONS CONTAINING HEXAVALENT CHROMIUM COMPOUNDS COMPRISING CONTACTING A RESIDUAL SOLUTION CONTAINING HEXAVALENT CHROMIUM COMPOUNDS AT PH IN THE RANGE OF 0 TO 6 WITH AN ANIONIC EXCHANGE RESIN WHEREBY HEXAVALENT CHROMIUM IS FIXED ON SAID ANIONIC EXCHANGE RESIN, ELUTING AND ANION EXCHANGE RESIN CONTAINING FIXED HEXAVALENT CHROMIUM BY CONTACTING WITH AN AQUEOUS ELUTION SOLUTION CONTAINING A REDUCING AGENT, AND RECOVERING AN AQUEOUS SOLUTION CONTAINING A CHROMIUM SULPHATE, THE IMPROVEMENT CONSISTING OF ULTILIZING AN AQUEOUS SOLUTION OF SULPHUR DIOXIDE IN THE PRESENCE OF SULPHURIC ACID AS SAID AQUEOUS ELUTION SOLUTION.
Claim 2
Dependent Claim
99 words
IN A PROCESS FOR PREPARING A CHROMIUM SULPHATE FROM RESIDUAL SOLUTIONS CONTAINING HEXAVALENT CHROMIUM COMPOUNDS COMPRISING CONTACTING A RESIDUAL SOLUTION CONTAINING HEXAVALENT CHROMIUM COMPOUNDS AT PH IN THE RANGE OF 0 TO 6 WITH AN ANIONIC EXCHANGE RESIN WHEREBY HEXAVALENT CHROMIUM IS FIXED ON SAID ANIONIC EXCHANGE RESIN, ELUTING AND ANION EXCHANGE RESIN CONTAINING FIXED HEXAVALENT CHROMIUM BY CONTACTING WITH AN AQUEOUS ELUTION SOLUTION CONTAINING A REDUCING AGENT, AND RECOVERING AN AQUEOUS SOLUTION CONTAINING A CHROMIUM SULPHATE, THE IMPROVEMENT CONSISTING OF ULTILIZING AN AQUEOUS SOLUTION OF SULPHUR DIOXIDE IN THE PRESENCE OF SULPHURIC ACID AS SAID AQUEOUS ELUTION SOLUTION.
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein said aqueous elution solution is recirculated for further elution after cooling and Addition of sulphur dioxide.
Claim 4
Dependent Claim
45 words
The process of claim 1 wherein said aqueous elution solution of sulphur dioxide in the presence of sulphuric acid contains from 2 to 20 g/l of sulphuric acid and an amount of sulphur dioxide corresponding to a molar range SO2:H2SO4 of from 3.06 to 3.45:1.
Claim 5
Dependent Claim
25 words
The process of claim 1 wherein said anionic exchange resin is in the sulphate form prior said contacting step and subsequent to said eluting step.
Claim 6
Dependent Claim
104 words
A PROCESS FOR PREPARNG A CHROMIUM SULPHATE FROM RESIDUAL SOLUTIONS CONTAINING HEXAVALENT CHROMIUM COMPOUNDS COMPRISING CONTACTING AN AQUEOUS ACIDIC RESIDUAL SOLUTION CONTAINING HEXAVALENT CHROMIUM COMPOUNDS WITH A WATERINSOLUBLE ORGANIC SOLVENT CAPABLE OF DISSOLBING HEXAVALENT CHROMIUM COMPOUNDS AND RESISTING OXIDATION IN A STRONGLY ACID MEDIUM, SEPARATING SAID ORGANIC SOLVENT CONTAINING HEXAVALENT CHROMIUM COMPOUNDS DISSOLVED THEREIN FROM THE AQUEOUS ACIDIC RESIDUAL SOLUTION DEPLETED IN HEXAVALENT CHROMIUM COMPOUNDS, EXTRACTING SAID ORGANIC SOLVENT CONTAINING HEXAVALENT CHROMIUM COMPOUNDS CONTACTING WITH AN AQUEOUS EXTRACTION SOLUTION OF SULPHUR DIOXIDE IN THE PRESENCE OF SULPHURIC ACID, SEPARATING THE EXHAUSTED ORGANIC SOLVENT FOR RECYCLING, AND RECOVERING AN AQUEOUS SOLUTION CONTAINING A CHROMIUM SULPHATE.
Claim 7
Dependent Claim
104 words
A PROCESS FOR PREPARNG A CHROMIUM SULPHATE FROM RESIDUAL SOLUTIONS CONTAINING HEXAVALENT CHROMIUM COMPOUNDS COMPRISING CONTACTING AN AQUEOUS ACIDIC RESIDUAL SOLUTION CONTAINING HEXAVALENT CHROMIUM COMPOUNDS WITH A WATERINSOLUBLE ORGANIC SOLVENT CAPABLE OF DISSOLBING HEXAVALENT CHROMIUM COMPOUNDS AND RESISTING OXIDATION IN A STRONGLY ACID MEDIUM, SEPARATING SAID ORGANIC SOLVENT CONTAINING HEXAVALENT CHROMIUM COMPOUNDS DISSOLVED THEREIN FROM THE AQUEOUS ACIDIC RESIDUAL SOLUTION DEPLETED IN HEXAVALENT CHROMIUM COMPOUNDS, EXTRACTING SAID ORGANIC SOLVENT CONTAINING HEXAVALENT CHROMIUM COMPOUNDS CONTACTING WITH AN AQUEOUS EXTRACTION SOLUTION OF SULPHUR DIOXIDE IN THE PRESENCE OF SULPHURIC ACID, SEPARATING THE EXHAUSTED ORGANIC SOLVENT FOR RECYCLING, AND RECOVERING AN AQUEOUS SOLUTION CONTAINING A CHROMIUM SULPHATE.
Claim 8
Dependent Claim
28 words
The process of claim 5 wherein said sulphuric acid in said aqueous extraction solution is formed in situ during said extracting step by oxidation of said sulphur dioxide.
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) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |