Granted Patent
Utility
US 4,268,380 · App. 06/062,092
Froth flotation process
Inventor:
Douglas R. Shaw
Patented Case
View Patent ↗
Granted: May 19, 1981
Filed: Jul 30, 1979
Inventor
Douglas R. Shaw
Assignee (at issue)
Pennwalt 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.