Patents by Inventor Donald L. Stewart, Jr.

Donald L. Stewart, Jr. 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).

  • Patent number: 5227143
    Abstract: A process is disclosed for treating salt-containing aluminum dross to remove potassium and sodium chloride salts therefrom. The process generally comprises treating the dross in a first treating step with a leaching solution having a pH maintained in the range of about 6-7 to remove a portion of the salt content thereof; filtering the residual solids from the first leaching solution; and treating the filtered solids in a second treating step with a second leaching solution having a pH maintained above about 8, and preferably above about 9. The pH of the first leaching solution is maintained in the desired range by the addition of hydrochloric acid, and the pH of the second leaching solution is maintained in the desired range by the addition of potassium and/or sodium hydroxide.
    Type: Grant
    Filed: September 26, 1991
    Date of Patent: July 13, 1993
    Assignee: Aluminum Company of America
    Inventors: Donald L. Stewart, Jr., Jan H. L. vanLinden
  • Patent number: 5198200
    Abstract: A process for the recovery of metallic aluminum, mixtures of salts, and an aluminum oxide-metallic aluminum product from secondary aluminum dross. The process includes treating the dross with leach water to dissolve the salt content. Magnesium chloride is preferably added to the leach water to maintain the pH in the range of about 7-8.5, thereby reducing ammonia production in the treating step and enhancing recovery of metallic aluminum.
    Type: Grant
    Filed: September 9, 1991
    Date of Patent: March 30, 1993
    Assignee: Aluminum Company of America
    Inventors: Daniel Yerushalmi, Gerald E. Carkin, Jr., Donald L. Stewart, Jr., Jan H. L. Van Linden
  • Patent number: 4761207
    Abstract: A continuous salt-based process is provided for melting and reclaiming aluminum from aluminum scrap containing impurities including heating a molten salt in a heat bay, mixing the heated salt with aluminum scrap or skim in a charge bay to form a molten charge mixture, separating aluminum from impurities in the charge bay by coalescing aluminum to form a molten aluminum metal pad, chlorinating a portion of the charge mixture from the charge bay to form a chlorinated salt mixture and metal chlorides, removing metal chlorides from the salt mixture, and feeding the salt mixture back to the heat bay. In one aspect, the chlorinating step of the present invention includes introducing carbon monoxide or, preferably, solid carbon to control oxide concentration. The process further comprises adding fluorides and removing metal chlorides from the salt to maintain a preferred salt composition.
    Type: Grant
    Filed: April 20, 1987
    Date of Patent: August 2, 1988
    Assignee: Aluminum Company of America
    Inventors: Donald L. Stewart, Jr., Jan H. L. VanLinden
  • Patent number: 4758316
    Abstract: A process is provided for melting and reclaiming aluminum and lithium from aluminum-lithium scrap including heating a molten salt in a heat bay, mixing the heated salt with aluminum-lithium scrap in a charge bay to form a molten mixture, separating aluminum from impurities in the charge bay by coalescing aluminum to form a molten aluminum metal pad, chlorinating a portion of the charge mixture from the charge bay to form a chlorinated salt mixture and metal chlorides, removing metal chlorides from the salt mixture, removing lithium from the salt mixture, and feeding the salt mixture back to the heat bay. In one aspect, the chlorinating step of the present invention includes introducing carbon monoxide or, preferably, solid carbon to control oxide concentration. The process, in other aspects, further includes adding fluorides and recovering lithium and removing metal chlorides from the salt to maintain a preferred salt composition.
    Type: Grant
    Filed: April 20, 1987
    Date of Patent: July 19, 1988
    Assignee: Aluminum Company of America
    Inventors: Donald L. Stewart, Jr., Jan H. L. VanLinden
  • Patent number: 4385964
    Abstract: A method is disclosed for preventing the condensation of aluminum chloride (AlCl.sub.3) in a fractional distillation column which is operated to separate a fraction which does not include AlCl.sub.3 from a mixture containing AlCl.sub.3 and other metal chlorides and which is operated at temperatures which include the sublimation or melting points of AlCl.sub.3 at the operating pressure of the column. According to this method, titanium tetrachloride (TiCl.sub.4) is maintained in the column in an amount at least as great, by weight, as the amount of AlCl.sub.3 contained in the mixture.
    Type: Grant
    Filed: May 26, 1982
    Date of Patent: May 31, 1983
    Assignee: Aluminum Company of America
    Inventors: Roger C. Johnson, Donald L. Stewart, Jr., Utah Tsao, David A. Wohleber
  • Patent number: 4349420
    Abstract: Metal chlorides such as aluminum chloride (AlCl.sub.3) are separated from a mixture containing metal chlorides including AlCl.sub.3 and ferric chloride (FeCl.sub.3). In order to effect this separation, the mixture is subjected to a fractional distillation process utilizing an array of distillation columns. According to this process, the mixture is introduced into a first distillation column which is operated at temperatures and pressures sufficient to separate FeCl.sub.3 from the mixture while avoiding the formation of a solid solution of FeCl.sub.3 and AlCl.sub.3 within the column. At least one additional distillation column is then employed to separate metal chlorides from the remaining mixture from the first column.
    Type: Grant
    Filed: January 12, 1981
    Date of Patent: September 14, 1982
    Assignee: Aluminum Company of America
    Inventor: Donald L. Stewart, Jr.