Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1997-01-24
1999-07-13
Silverman, Stanley S.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162 3011, 162239, 210686, 423181, D21C 1100
Patent
active
059221712
ABSTRACT:
Sodium chloride is removed from pulping chemicals used in a Kraft pulping process by the use of a snake-cage polyelectrolyte ion exchange resin, coupled with removal of sulfide prior to treatment, or treatment of chemicals which are already low in sulfide. In one aspect of the invention, dust is collected from exhaust gases produced in the black liquor recovery cycle and is dissolved in water to produce a solution containing sodium chloride and sodium sulfate. The solution is filtered to yield a solid product and a filtrate solution. The filtrate solution is fed to an ion exchange unit which removes chloride and produces a purified sodium sulfate product. The sodium chloride is removed from the ion exchange resin by water elution, and useful recovered chemicals are recycled to the recovery cycle of the Kraft process. In one embodiment, only a portion of the dust is dissolved so that the solid product produced by filtering is primarily sodium sulfate, and that sodium sulfate is recycled to the recovery cycle of the Kraft process. In another aspect of the invention, white liquor from the pulping process is treated directly after oxidizing sulfide to sulfate. After removal of sodium chloride in the ion exchange unit, the treated white liquor can be used as a source of sodium hydroxide for oxygen delignification, and the effluent from the oxygen delignification stage can be returned to the process.
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Berry Richard McKinnon
Brown Craig J.
Paleologou Michael
Sheedy Michael A.
Thompson Rokhsareh
Eco-Tec Limited
Nguyen Dean T.
Pulp and Paper Research Institute of Canada
Silverman Stanley S.
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