Granted Patent
Utility
US 4,988,487 · App. 07/426,624
Process for recovering metal values such as scandium, iron and manganese from an industrial waste sludge
Inventors:
Wen-Chao Lai, William J. Rourke, Samuel Natansohn
Patented Case
View Patent ↗
Granted: Jan 29, 1991
Filed: Oct 24, 1989
Inventors
Wen-Chao Lai
William J. Rourke
Samuel Natansohn
Assignee (at issue)
GTE Laboratories Incorporated
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.