Method of bleaching kraft pulp employing chlorine dioxide/chlori

Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Gas – vapor or mist contact

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162 78, 162 89, D21C 914, D21C 9153

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active

061530514

ABSTRACT:
A method for improving the preparation of chemical cellulosic wood pulp for use in papermaking, and specifically to enhancement of the quality of a kraft pulp which has been subjected to a chlorine dioxide/chlorine bleaching stage and thereafter subjected to ozonation prior to an extraction stage in the bleaching sequence. The improved pulp of the present invention exhibits reduced total organically bound chlorine residues in the wood pulp and adsorbed organic halides (AOX) in the effluent, and has good brightness and viscosity. The advantages of the present invention may be accomplished by means of a bleaching sequence that employs a minimum of stages, namely (D.fwdarw.C)ZED or D.sub.c ZED with attendant relatively lower capital investment than heretofore possible.

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