Method of bleaching pulp with ozone-chlorine mixtures
AssigneeKamyr, Inc.
InventorMichael D. Meredith
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Abstract
Ozone and chlorine are used to bleach cellulosic fibrous material pulp in the production of kraft pulp for paper and paper products, being applied together in a mixture. When the ozone and chlorine are applied simultaneously it is possible to achieve delignification to a greater extent than is possible utilizing chlorine at any level. The total chlorinated ring compounds in the bleach plant effluent are remarkably reduced utilizing the ozone-chlorine mixture, compared to all chlorine, with resulting decrease in the fish toxicity of the bleach plant effluent. Utilizing an O.sub.3 /Cl.sub.2 E.sub.o D bleaching sequence (only three stages) it is possible to obtain pulp with 90 TAPPI Absolute, or greater, brightness.
Claims10
A method of chlorine bleaching cellulosic fibrous material pulp at a consistency between about 1/2-15% solids during the production of kraft pulp without significantly affecting the degree of delignification produced by chlorine bleaching, comprising the step of:
- in the chlorine bleaching of kraft pulp at a consistency of about 1/2-15%, substituting ozone for a portion of the chlorine by providing a mixture of chlorine and ozone applied to the pulp simultaneously, the amount of ozone in the mixture being between 1-40% by volume.
Dependencies are inferred from the claim text.