Process for the delignification and bleaching of chemical and semi-chemical cellulosic pulps
Patent 4459174 Issued on July 10, 1984. Estimated Expiration Date: 
July 21, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
July 21, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3719552 Kraft pulp bleaching and recovery process Chlorine free process for bleaching lignocellulosic pulp Patent #: 4372812 InventorsAssigneeApplicationNo. 06/400380 filed on 07/21/1982US Classes:162/40, Without treatment or modification162/60, With washing162/65, Oxygen, ozone or air162/76, Acids, salts or esters162/78, Per-compound (e.g., peroxide, perborate)162/89Alkali metal, ammonium, alkaline earth metal or magnesium hydroxide or carbonate in at least one stageExaminersPrimary: Alvo, SteveAttorney, Agent or FirmInternational ClassD21C 9/10 (20060101)Foreign Application Priority Data1979-05-25 FRAbstractA process for the delignification and bleaching of chemical and semi-chemical cellulosic pulps in which the pulp is subjected to a treatment with oxygen and a subsequent treatment with peroxide. The effluent from the treatment with peroxide is at least partially recycled to the treatment with oxygen.Other References
Field of SearchOxygen, ozone or airPer-compound (e.g., peroxide, perborate) Alkali metal, ammonium, alkaline earth metal or magnesium hydroxide or carbonate Without treatment or modification Recirculation (includes separation from fibers) Acids, salts or esters Plural diverse stage treatment Alkali metal, ammonium, alkaline earth metal or magnesium hydroxide or carbonate in at least one stage | |
