High-yield semi-chemical carbonate pulping process
AssigneeDomtar Inc.
InventorJan S. Temler
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Abstract
High-yield pulp suitable for the production of corrugating medium is produced by cooking hardwood chips at a temperature 180.degree.-192.degree. with sodium carbonate solutions of a concentration 65 to 120 g/l as Na.sub.2 O, at a liquor to wood ratio of 1.2-2.5, and mechanically refining the cooked chips in a primary refining stage to a C. S. Freeness less than 480, and then refining the pulp in a secondary refining stage.
Claims9
A method of producing high-yield semi-chemical pulp suitable for the manufacture of corrugating medium comprising mixing hardwood chips with a liquor consisting essentially of an aqueous solution of sodium carbonate having a concentration of carbonate between 65 and 120 grams per liter expressed as Na.sub.2 O, cooking the chips with said liquor at a temperature between 170.degree. C. and 200.degree. C. to a pulp yield of about 70-85%, separating the cooked chips from residual liquor and immediately thereafter passing said chips to a primary refining state, mechanically refining the cooked chips in said primary refining state to a pulp of a C.S.F. value not greater than 480, and mechanically refining said pulp in a secondary refining stage.
Dependencies are inferred from the claim text.