Granted Patent
Utility
US 5,651,947 · App. 08/553,175
Recovery of zinc from sulphidic concentrates
Inventors:
Michael J. Collins, Donald K. Kofluk
Patented Case
View Patent ↗
Granted: Jul 29, 1997
Filed: Nov 7, 1995
Inventors
Michael J. Collins
Donald K. Kofluk
Assignee (at issue)
698638 Alberta Ltd.
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.