Patent US3502271A successfully refreshed from Google Patents.
US3502271A
Expired / Lapsed
US
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Iron ore treating process
Assignee: University of Minnesota Twin Cities
•
Filing: 1967-05-29
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Granted: 1970-03-24
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Expires: 1987-05-29
Abstract
No abstract record available.
Inventors
- 👤 Ronald Martin Hays
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:30
CPC Classifications
B; B03; B03D; B03D1/00; B03D1/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2075466A
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US2352324A
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US2526519A
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US2558635A
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US2551893A
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US2557059A
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US2570120A
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US3067957A
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US3337328A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-03-23 | 1973-09-22 | 1974-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-03-23 | 1977-09-22 | 1978-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-03-23 | 1981-09-22 | 1982-03-24 | $7700.00 | Window Closed / Lapsed |