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Patent US3598718A successfully refreshed from Google Patents.
US3598718A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solvent extraction of coal
Assignee: Universal Oil Products Co
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Filing: 1969-08-18
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Granted: 1971-08-10
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Expires: 1989-08-18
Abstract
Abstract COAL IS CONVERTED TO LIQUID PRODUCTS UTILIZING A TWOSTAGE SOLVENT EXTRACTION PROCESS WHEREIN THE LIQUID COAL PRODUCTS ARE SEPARATGED FROM UNREACTED COAL AND ASH WITHOUT REQUIRING FILTRATION. THE COAL IS FIRST CONTACTED WITH CONVENTIONAL COAL SOLVENTS, SUCH AS TETRAHYDRONAPHTHALENE UNDER HYDROGEN PRESSURE; THE SOLVENT IS REMOVED VIA FRACTIONATION; AND HYDROGEN-RICH COAL COMPONENTS PRODUCED ARE RECOVERED FREE OF PARTICULATE MATTER BY SOLVENT EXTRACTION WITH A LIGHT AROMATIC OR KETONE SOLVENT.
Inventors
- 👤 William K T Gleim
- 👤 Richard S Corey
- 👤 Frederick J Riedl
- 👤 George R Sunagel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:51
CPC Classifications
C; C10; C10G; C10G1/00; C10G1/006
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) | 1974-08-09 | 1975-02-08 | 1975-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-09 | 1979-02-08 | 1979-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-09 | 1983-02-08 | 1983-08-10 | $7700.00 | Window Closed / Lapsed |