Granted Patent
Utility
US 4,322,284 · App. 06/118,860
Solvent refining of coal using octahydrophenanthrene-enriched solvent and coal minerals recycle
Inventors:
Shirley C. Tsai, Howard G. McIlvried
Patented Case
View Patent ↗
Granted: Mar 30, 1982
Filed: Feb 5, 1980
Inventors
Shirley C. Tsai
Howard G. McIlvried
Assignee (at issue)
Gulf Research & Development Company
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.