Patents Examined by Thi D. Dang
  • Interstage treatment of mechanical pulp
    Patent number: 4718980
    Abstract: A two-stage pulp refining system in which the fibrous material from the first stage refiner is in contact with an alkaline bleaching solution between refining stages at a temperature of 32.degree.-96.degree. C. and at a consistency of 15-25% on an oven dry basis. The material is then diluted and then pressed to a consistency of at least 20% and passes through the second stage refiner.
    Type: Grant
    Filed: December 30, 1985
    Date of Patent: January 12, 1988
    Assignee: Weyerhaeuser Company
    Inventors: Leonard E. Lowrie, William L. Duncan