Granted Patent
Utility
US 4,923,686 · App. 07/049,163
Process for the extraction of metal values
Inventors:
Raymond F. Dalton, Raymond R. Price, Peter M. Quan, David Stewart
Patented Case
View Patent ↗
Granted: May 8, 1990
Filed: May 13, 1987
Inventors
Raymond F. Dalton
Raymond R. Price
Peter M. Quan
David Stewart
Assignee (at issue)
IMPERIAL CHEMICAL INDUSTRIES LIMITED
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.