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AssigneeAhlstrom Machinery Inc.
InventorsAuvo K. Kettunen, Kaj O. Henricson, Aki H. Vilpponen, Jian E. Jiang, Bruno S. Marcoccia
Estimating the term…
Chemical (typically kraft) pulp having enhanced intrinsic fiber strength and bleachability compared to pulp produced using conventional or modified kraft cooking is produced by using high alkali and/or pH cooking. After being impregnated with a first cooking liquor (e.g. white liquor) having low effective alkali, the first liquor is extracted from the pulp, and it is impregnated with a second cooking liquor having an effective alkali concentration of at least 25 g/l and cooked at cooking temperature (e.g. 140.degree.-190.degree. C.) to produce a spent second cooking liquor having a residual effective alkali concentration of at least about 15 g/l, which is then extracted from the pulp. The spent second liquor may be used to preheat incoming white liquor, and then flashed and used as the first liquor. The pH of the first liquor is typically less than about 13.0, and the residual pH of the spent second liquor is about 13.0 or more.
A method of producing chemical pulp having enhanced intrinsic fiber strength from comminuted ceIlulosic fibrous material, comprising the steps of continuously and sequentially:
A kraft pulp with enhanced intrinsic fiber strength and bleachability compared to kraft pulp produced by conventional and modified cooking, said pulp produced by the steps of continuously and sequentially:
Dependencies are inferred from the claim text.