Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Continuous chemical treatment or continuous charging or...
Patent
1994-07-18
1996-06-04
Lacey, David L.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Continuous chemical treatment or continuous charging or...
162 39, 162 45, 162 86, D21C 326
Patent
active
055229581
ABSTRACT:
A method for the production of kraft pulps in a digester, by modifying the cooking chemical concentration, and lignin concentration profiles during the cook, has provided extended delignification and improved selectivity in a simpler way than has previously been possible. The cooking is performed at an elevated temperature in two stages. The first stage liquor is a mixture of 1) the spent liquor of the second stage and 2) a portion of the conventional charge of fresh cooking chemicals needed for the complete cook. The second stage liquor is made up by adding an aqueous diluent, for example, fresh water or washing filtrate to the remaining portion of the fresh cooking chemicals.
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Lacey David L.
Nguyen Dean T.
Pulp and Paper Research Institute of Canada
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