Patents by Inventor Erwin A. Letzgus

Erwin A. Letzgus 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).

  • Process for producing magnesium aluminate spinel
    Patent number: 3950504
    Abstract: Disclosed is the production of high purity magnesium aluminate spinel by blending alumina as ESP fines with a finely divided source of magnesia in a MgO:Al.sub.2 O.sub.3 weight ratio of between about 0.4 to 0.8 and firing the blend at 900.degree.C. or above.
    Type: Grant
    Filed: September 26, 1974
    Date of Patent: April 13, 1976
    Assignee: Quigley Company, Inc.
    Inventors: Jeffrey H. Belding, Erwin A. Letzgus