Patent US3712939A successfully refreshed from Google Patents.
US3712939A
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US
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Method for recovering tantalum and/or columbium
Assignee: Umetco Minerals Corp
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Filing: 1971-03-29
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Granted: 1973-01-23
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Expires: 1991-03-29
Abstract
Abstract METHOD FOR RECOVERING TANTALUM AND/OR COLUMBIUM VALUES FROM INSOLUBLE RESIDUES OBTAINED FROM THE ACID LEACHING OF COLUMBIUM AND/OR TANTALUM CONTAINING ORE BY ACID TREATING THE RESIDUES AND CONTACTING THE RESULTING SLURRY WITH METHYL-ISOBUTYL KETONE.
Inventors
- 👤 R Capps
- 👤 G Harman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:43
CPC Classifications
C; C22; C22B; C22B34/00; C22B34/20; C22B34/24; C01; C01G; C01G33/00; C01G35/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |