(19)
(11) EP 0 395 792 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
16.01.1991 Bulletin 1991/03

(43) Date of publication A2:
07.11.1990 Bulletin 1990/45

(21) Application number: 89117233.0

(22) Date of filing: 18.09.1989
(51) International Patent Classification (IPC)5: D21C 9/10, D21C 9/147
(84) Designated Contracting States:
AT BE CH DE ES FR GB GR IT LI NL SE

(30) Priority: 04.05.1989 FI 892151

(71) Applicant: ENSO-GUTZEIT OY
FIN-00160 Helsinki (FI)

(72) Inventors:
  • Vaheri, Marja
    SF-02210 Espoo (FI)
  • Miikki, Kari
    SF-55100 Imatra (FI)
  • Jokela, Veikko
    SF-55330 Tiuruniemi (FI)
  • Ruohoniemi, Kimmo
    SF-55800 Imatra (FI)

(74) Representative: Weitzel, Wolfgang, Dr.-Ing. 
Friedenstrasse 10
89522 Heidenheim
89522 Heidenheim (DE)


(56) References cited: : 
   
       


    (54) Procedure for the bleaching of pulp


    (57) The invention concerns a procedure for the bleaching of pulp using oxygen as an oxidating bleaching chemical. The essen­tial features of the invention are that oxygen is used in the first oxidation stage of the bleaching process, that the pulp is subjected to enzyme treatment, and that after oxygen bleaching and enzyme treatment, the pulp is washed. According to the invention, the subsequent oxidation stages can be implemented using bleaching chemicals containing chlorine, e.g. chlorine gas and/or chlorine dioxide. The use of enzymes allows partial burning of the washings and enables the amounts of toxic compounds in the spent bleach liquor to be reduced, simultaneously lowering its chemical oxygen demand.





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