Granted Patent
Utility
US 4,287,159 · App. 06/186,948
Extraction process for the recovery of tungsten from low level sources
Inventors:
Samuel Natansohn, Sophia R. Su
Patented Case
View Patent ↗
Granted: Sep 1, 1981
Filed: Sep 15, 1980
Inventors
Samuel Natansohn
Sophia R. Su
Assignee (at issue)
GTE Laboratories Incorporated
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.