US3784669A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Recovery of metal values from chrome etching solutions
Assignee: United States Department of the Interior
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Filing: 1972-10-03
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Granted: 1974-01-08
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Expires: 1992-10-03
Abstract
Abstract CHROMIUM AND COPPER ARE RECOVERED, AS OXIDES, FROM SPENT CHROME ETCHING SOLUTIONS BY MEANS OF A PROCESS COMPRISING THE STEPS OF: (1) ADDITION OF A REDUCING SUGAR TO REDUE CR(VI) TO CR(III) AND TO COMPLEX CR(III) AND CU VALUES IN SOLUTION, (2) ADDITION OF BASE TO RAISE THE PH TO A VALUE OF ABOUT 10 TO 12, TO REDUCE THE COPPER AND PRECIPITATE IT AS CU2O, (3) SEPARATING THE PRECIPITATED CU2O, (4) HEATING THE REMAINING SOLUTION AT A TEMPERATURE OF ABOUT 50 TO 70*C. FOR A PERIOD SUFFICIENT TO BREAK THE CR(III) COMPLEX, AND (5) ADJUSTING THE PH OF THE SOLUTION TO A VALUE OF ABOUT 6 TO 9 TO PRECIPITATE THE CHROMIUM AS HYDROUS CHROMIUM OXIDE.
Inventors
- 👤 Iii C Elges
- 👤 P Haskett
- 👤 D Bauer
- 👤 R Lindstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:54
CPC Classifications
C; C01; C01G; C01G3/00; C01G3/02; C01G37/00; C01G37/02; C01P; C01P2006/00; C01P2006/80; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/911; Y10S210/912; Y10S210/913
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |