(19)
(11) EP 0 383 999 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
12.12.1990 Bulletin 1990/50

(43) Date of publication A2:
29.08.1990 Bulletin 1990/35

(21) Application number: 89117235.5

(22) Date of filing: 18.09.1989
(51) International Patent Classification (IPC)5: D21C 9/10, D21C 9/14
(84) Designated Contracting States:
AT BE CH DE ES FR GB GR IT LI NL SE

(30) Priority: 14.02.1989 FI 890700

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

(72) Inventors:
  • Vaheri, Marja
    SF-02210 Espoo (FI)
  • Jokela, Veikko
    SF-55330 Tiuruniemi (FI)
  • Miikki, Kari
    SF-55100 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 an oxidating bleaching chemical containing chlorine. The essential features of the invention are that the chemi­cal used in the oxidation stage has a chlorine dioxide con­tent of at least 50 %, that the pulp is subjected to enzyme treatment either in conjunction with or before the oxida­tion, and that, after the oxidation and enzyme treatment, the pulp is treated with an alkali. The use of enzymes re­duces the amount of chlorophenols and other forms of organi­cally bound chlorine in the spent bleach liquor, simulta­neously lowering its chemical oxygen demand.





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