Patents by Inventor David L. Donaldson

David L. Donaldson 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).

  • Method for treating liquid and semi-solid organic waste materials
    Patent number: 4509696
    Abstract: An apparatus and method for treating for disposal organic waste material carried within a sludge, by adding to the sludge an alkali metal silicate and a setting agent, is disclosed. The apparatus includes several mixers, each having a trough with an input end and a discharge end, at least one rotatable shaft mounted longitudinally along the trough, a plurality of blades mounted to the shaft, and a drive for rotating the shaft. The sludge is deposited within a first mixer, and then directed from the mixer into a tank. A series of chopper pumps recirculate the sludge into the tank, and alternatively, the sludge may be passed through an additional mixer. Leaving the tank, the sludge is directed into a second mixer at its input end. Water is introduced at the input end, and a setting agent is added along the trough at a point adjacent the input end. Further along the trough, an alkali metal silicate is introduced. The mixture is recovered from the second mixer, and carried to a remote location for setting.
    Type: Grant
    Filed: August 12, 1983
    Date of Patent: April 9, 1985
    Assignee: Chemfix Technologies, Inc.
    Inventor: David L. Donaldson
  • Apparatus for treating liquid and semi-solid organic waste materials
    Patent number: 4471916
    Abstract: An apparatus and method for treating for disposal organic waste material carried within a sludge, by adding to the sludge an alkali metal silicate and a setting agent, is disclosed. The apparatus includes several mixers, each having a trough with an input end and a discharge end, at least one rotatable shaft mounted longitudinally along the trough, a plurality of blades mounted to the shaft, and a drive for rotating the shaft. The sludge is deposited within a first mixer, and then directed from the mixer into a tank. A series of chopper pumps recirculate the sludge into the tank, and alternatively, the sludge may be passed through an additional mixer. Leaving the tank, the sludge is directed into a second mixer at its input end. Water is introduced at the input end, and a setting agent is added along the trough at a point adjacent the input end. Further along the trough, an alkali metal silicate is introduced. The mixture is recovered from the second mixer, and carried to a remote location for setting.
    Type: Grant
    Filed: August 30, 1982
    Date of Patent: September 18, 1984
    Assignee: Chemfix Technologies, Inc.
    Inventor: David L. Donaldson