Granted Patent
Utility
US 5,284,633 · App. 07/975,504
Solvent extraction of precious metals with hydroxyquinoline and stripping with acidified thiourea
Inventor:
David L. Gefvert
Patented Case
View Patent ↗
Granted: Feb 8, 1994
Filed: Nov 12, 1992
Inventor
David L. Gefvert
Assignee (at issue)
Sherex Chemical Co., Inc.
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.