Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – With regeneration – reclamation – reuse – recycling or...
Patent
1996-03-28
1997-12-23
Chin, Peter
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
With regeneration, reclamation, reuse, recycling or...
162 79, 162DIG8, D21C 1100
Patent
active
057003505
ABSTRACT:
Improved environmentally acceptable process for retaining chelant-containing effluent within pulp bleach plants, particularly total chloride-free bleaching sequence plants using a chelating agent closed re-cycle process. The process involves treating a pulp liquor in an acidic or near neutral stage with an effective chelating amount of a chelating agent to form a soluble, chelated metal species; removing the pulp to provide a chelated metal species-containing solution; treating this solution in an alkaline stage in the presence of sufficient Ca ions with an effective amount of an alkaline liquor to effect displacement of metals from the chelated metal species and precipitation of the metals as solids in alkaline solution; removing the solids from the alkaline solution to provide a metal-free, chelating agent-containing solution; and recycling the metal-free solution to the pulp liquor.
REFERENCES:
patent: 5401362 (1995-03-01), Lindberg
patent: 5545331 (1996-08-01), Guess
Brooks, et al: "Filtrate Recycle and Metals Management in TCF Bleach Plants", International Non-Chlorine Bleaching Conference Proceedings, paper 8-1, Mar. 1995.
Maples, et al: BFR:"A New Process Toward Bleach Plant Closure", International Pulp Bleaching Conferecne, p. 253, Jun. 1994.
Lindberg, et al: "Strategies for Metal Removal Control in Closed Cycle Mills", International Pulp Bleaching Conference, pp. 293-302, 1994.
Chemetics International Company Ltd.
Chin Peter
Nguyen Dean T.
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