Patent US3709978A successfully refreshed from Google Patents.
US3709978A
Expired / Lapsed
US
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Process for purifying industrial waste gases containing hydrogen fluoride
Assignee: Universal Oil Products Co
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Filing: 1970-11-09
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Granted: 1973-01-09
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Expires: 1990-11-09
Abstract
Abstract A MULTI-STAGE METHOD FOR SCRUBBING A WATE GAS STREAM CONTAINING HF AND SO2 SUCH AS FROM THE ALUMINUM PRODUCTION INDUSTRY WHERE ALUMINUM DUST CAN ALSO BE PRESENT. CONTROL OF WASH STREAMS IS MAINTAINED TO PRECLUDE TOO MUCH HF REACHING THE SECOND STAGE WASHING ZONE CAUSE SODIUM FLUORIDE TO PRECIPITATE AND THEN BLOCK VALVES AND PIPING. A COMBINED EFFLUENT FROM EACH WASH STAGE IS PASSED TO A NEUTRALIZATION ZONE WHERE AN ALKALINE STREAM SUCH AS CAUSTIC SODA WILL CAUSE PRECIPITATION OF SODIUM FLUORIDE AND SODIUM SULPHATE ALONG WITH ENTRAINED DUST OR ALUMINUM PARTICULATES.
Inventors
- 👤 H Predikant
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:51
CPC Classifications
B; B01; B01D; B01D47/00; B01D47/06
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) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |