Patents Assigned to Hampshire Chemical Ltd.
  • Patent number: 5571378
    Abstract: Process for high pH metal ion chelation in pulps. Extraction and removal of detrimental metal ions and organic solvent extractives prior to delignification and bleaching is carried out on pulp, preferably kraft pulp, at a pH over 5, more preferably a pH over 6, most preferably a pH of 7-9. Aqueous pulp is first brought to a pH of about 3-6 to cause chelation and desorption of metal ions from the fiber phase of the aqueous pulp, and at the same time implementing air entrainment and evaporation. The pH is then raised, and the extractable species are removed by dewatering and washing the pulp.
    Type: Grant
    Filed: October 27, 1994
    Date of Patent: November 5, 1996
    Assignee: Hampshire Chemical Ltd.
    Inventors: Arne Elofson, Arne Nordgren