Patents by Inventor Erhart K. Drechsel, deceased

Erhart K. Drechsel, deceased 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).

  • Production of phosphoric acid and additional products from phosphate ore
    Patent number: 4479923
    Abstract: Phosphate rock, including low grade phosphate ore, is treated to recover phosphoric acid and other valuable products by a series of steps including contacting phosphate ore with a weak phosphoric acid to form a suspension of at least a portion of the slimes contained in the ore so that the slimes can be separated from the ore, and separating the slimes to provide a deslimed phosphate ore. Deslimed phosphate rock is solubilized with phosphoric acid to convert at least a portion of the calcium contained in the rock and form a solution of monocalcium phosphate and phosphoric acid. After removal of solids, this solution can be treated with sulfuric acid in a gypsum crystallizer to form gypsum and the phosphoric acid product wherein filterable gypsum crystals are obtained by maintaining a total SO.sub.3 content of 1.5-4 wt. % in a first crystallizer and neutralizing the SO.sub.3 in a second crystallizer.
    Type: Grant
    Filed: July 6, 1983
    Date of Patent: October 30, 1984
    Assignee: Pennzoil Company
    Inventors: John B. Sardisco, Dysart E. Holcomb, Erhart K. Drechsel, deceased