Patents by Inventor Hannu Kurittu

Hannu Kurittu 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 of separating sodium hydroxide from white liquor or polysulfide liquor using diffusion dialysis
    Patent number: 5843316
    Abstract: The present invention relates to a method of processing white liquor obtained from the causticization stage of a pulp mill. According to the method, the white liquor, which principally contains sodium hydroxide (6) and sodium sulfide, is oxidized into polysulfide liquor (3), whereby the sodium sulfide is oxidized most advantageously with the help of a catalyst and an oxidizer such as air substantially into sodium polysulfide (7) and sodium thiosulfate. The method according to the invention is characterized in that the sodium hydroxide (6) contained in the white liquor is separated from the white liquor prior to the oxidizing step or from the polysulfide liquor (3) after the oxidizing step either entirely or partly by means of a diffusion dialysis process (4). The invention is further characterized in that the sodium hydroxide (6) separated from the white liquor is returned to the chemical circulation of the pulp mill.
    Type: Grant
    Filed: February 25, 1997
    Date of Patent: December 1, 1998
    Assignee: Enso-Gutzeit Oy
    Inventor: Hannu Kurittu
  • Method of separating sodium hydroxide from white liquor
    Patent number: 5510035
    Abstract: The present invention relates to a method of processing white liquor (3) obtained from the causticization step of a pulp mill, in which method infeed white liquor (3) principally contains sodium hydroxide (6) and sodium sulfide (7). The method according to the invention is characterized in that the sodium hydroxide (6) contained in the white liquor (3) is separated from the white liquor (3) either entirely or partly by means of a diffusion dialysis membrane process (4). The invention is further characterized in that the sodium hydroxide (6) separated from the white liquor (3) is advantageously entirely returned back to the chemical circulation of the pulp mill.
    Type: Grant
    Filed: October 18, 1994
    Date of Patent: April 23, 1996
    Assignee: Enso-Gutzeit Oy
    Inventors: Marjo Toronen, Hannu Kurittu