Patents by Inventor Bob L. Caldwell

Bob L. Caldwell 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 pelletizing a sulphur-bentonite clay mixture and the product formed thereby
    Patent number: 4133669
    Abstract: A process for pelletizing a mixture of elemental sulphur and bentonite clay to produce a water degradable prill includes adding dry clay dust to molten sulphur at an elevated temperature to provide a molten sulphur-clay mixture, forming droplets of the mixture, providing a liquid fertilizer coolant at a temperature lower than the freezing temperature of the sulphur-bentonite mixture, feeding the droplets into the coolant, passing the droplets through the coolant for a time sufficient to anneal the droplets into pellets, and removing the annealed pellets from the coolant.
    Type: Grant
    Filed: April 20, 1977
    Date of Patent: January 9, 1979
    Assignees: Agri-Prassco Joint Venture, Agri-Sul Equipment
    Inventors: Bob L. Caldwell, Ronald B. Fletcher