US3689370A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for purifying hydrofluoric acid by distillation with an oxidizing agent and a ferrous salt
Assignee: Daikin Industries Ltd
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Filing: 1971-02-17
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Granted: 1972-09-05
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Expires: 1991-02-17
Abstract
Abstract IN PURIFYING HYDROFLURIC ACID CONTAINING ARSENIC AND/OR ANTIMONY COMPOUNDS AS IMPURITIES BY TREATING IT WITH ALKALI METAL PERMANGANATE AND/OR DICHROMATE AND DISTILLING THE RESULTANT LIQUID, THE PRESENT PROCESS IS CHARACTERIZED IN THAT SAID DISTILLATION IS CONDUCTED IN THE PRESENCE OF AN INORGANIC FERROUS SALT.
Inventors
- 👤 Yonosuke Osaka
- 👤 Kinya Watanabe
- 👤 Kohji Tamura
- 👤 Heikitsu Sonoyama
- 👤 Satoru Matsuda
- 👤 Masao Haruhana
- 👤 Hideo Matoba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:31
CPC Classifications
C; C01; C01B; C01B7/00; C01B7/19; C01B7/191
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) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |