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US 4,196,043 AGranted
Kraft pulp bleaching and recovery process
AssigneeScott Paper Company
InventorRudra P. Singh
Life of this patent
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Abstract
A Kraft pulp bleaching process comprising from one to about three treatments with ozone and a final treatment with an alkaline peroxide solution, the treatments being separated by an alkaline extraction, wherein effluent from the bleach treatments is utilized in subsequent bleaching operations or in the chemical recovery system of a Kraft pulping process.
Claims8
In a method of kraft wood pulping including a kraft chemical recovery system and a kraft wood pulp bleaching operation, the improvement which comprises bleaching the kraft wood pulp by a sequence of treatments comprising:
- from one to about three treatments with ozone;
- a final treatment with an alkaline peroxide solution;
- separating the treatments with alkaline extractions;
- recycling effluent from the alkaline extractions and alkaline peroxide treatment to reduce the fresh water requirements of the bleaching operations;
- and
- introducing effluent from the bleaching operation into the kraft pulp chemical recovery system;
- wherein the method is free of any treatments employing chlorine or chlorine-containing compounds and;
- whereby the need for treating the effluent being introduced into the kraft pulp chemical recovery system for the removal of chlorine containing salts is eliminated.
5 more elements
Dependencies are inferred from the claim text.