Granted Patent
Utility
US 4,306,899 · App. 06/214,821
Method for preheating pulverous materials prior to their introduction into a melting furnace
Inventor:
Raymond S. Richards
Patented Case
View Patent ↗
Granted: Dec 22, 1981
Filed: Dec 10, 1980
Inventor
Raymond S. Richards
Assignee (at issue)
Owens-Illinois 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.