Post digestion treatment of cellulosic pulp to minimize formatio

Details Post digestion treatment of cellulosic pulp to minimize formatio Post digestion treatment of cellulosic pulp to minimize formatio

1992-02-28

1999-03-02

Alvo, Steven

Paper making and fiber liberation

Processes of chemical liberation, recovery or purification...

With washing

162 65, 162 89, D21C 902, D21C 912, D21C 914, D21C 9153

Patent

active

058765611

ABSTRACT:
A post-digestion treatment method for cellulosic pulps which reduces the generation of dioxins and other chlorinated organics in the pulp, treatment effluent and/or the paper product produced from the pulp. In the treatment, the pulp, following digestion, is washed with a liquid that is essentially free of dioxins or dioxin precursors and simultaneously adjusted in consistency to at least a medium, and preferably a high consistency. Thereafter, the pulp is contacted with a chlorination agent selected from the group consisting of gaseous chlorine dioxide, gaseous chlorine, and gaseous chlorine dioxide which contains a minor amount of gaseous chlorine.

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Technical News Note, "Swedes Investigate Dioxin", Paper Technology, p. 36, Dec./Jan. 1989.
Hise, Ronnie G and Hintz, Harold L., "The Effect of Brownstock Washing on the Formation of Chlorinated Dioxins and Furans During Bleaching", TAPPI Journal, pp. 185-190, Jan. 1990.
Granum, F.; Hasvold, K.; Loras, V. and Soteland, N., "Influence of Bleaching Chemicals and Sequences on Some Properties of Sulphite Pulps", Journal of Pulp and Paper Science, pp. J 25-J 29, Mar. 1984.

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