Granted Patent
Utility
US 4,508,701 · App. 06/480,735
Extraction of tungsten from spent or scrap catalyst materials
Inventors:
John Goddard, William N. Johnson
Patented Case
View Patent ↗
Granted: Apr 2, 1985
Filed: Mar 31, 1983
Inventors
John Goddard
William N. Johnson
Assignee (at issue)
Union Carbide Corporation
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.