Patents by Inventor Donald A. Riva

Donald A. Riva has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Tar sands conditioning drum
    Patent number: 3984920
    Abstract: A rotating drum type muller is described for initial conditioning of mined tar sands by the hot water method for separation of bitumen from the sands wherein ablation of mined tar sand lumps into pulp is effected through the addition of hot water, steam and caustic.
    Type: Grant
    Filed: April 3, 1975
    Date of Patent: October 12, 1976
    Assignee: Shell Oil Company
    Inventors: Brian W. Raymond, Donald A. Riva, Frederick C. Stuchberry