Process for pretreating wood chips for pulping
First Claim
1. A process for producing a cellulose pulp from wood chips, comprising:
- (1) prewashing the wood chips with a cooking liquor;
(2) crushing the prewashed wood chips in a liquid phase to open up the fiber structure of the wood chips in the direction of the length of the fibers;
(3) delignifyina the wood chips obtained in step (2) with the cooking liquor to obtain cellulose pulp; and
(4) optionally, bleaching the cellulose pulp.
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Accused Products
Abstract
The invention relates to a process and apparatus for pretreating pulp raw material, to be subsequently prepared in a chemical pulping process, and for preparing cellulose pulp from a fibrous starting material. According to the process the starting material is delignified to yield a chemical cellulose pulp, and the obtained pulp is bleached when desirable. According to the invention the starting material is crushed in cooking liquor prior to delignification in order to open its fiber structure. The apparatus of the invention comprises a frame (21), to which to adjacent first rolls (12; 22, 23) have been fitted, which form a first pair of rolls with the rolls arranged to distance from each other in such a manner that a gap clearance is formed between their outer mantles. The rolls are caused to rotate by a means of power transmission, which causes the raw material to be crushed inside the gap between the rolls where a liquid pocket is formed, from which liquid is absorbed into the fiber material being treated. The invention provides even cooking of the raw material under mild conditions.
51 Citations
15 Claims
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1. A process for producing a cellulose pulp from wood chips, comprising:
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(1) prewashing the wood chips with a cooking liquor;
(2) crushing the prewashed wood chips in a liquid phase to open up the fiber structure of the wood chips in the direction of the length of the fibers;
(3) delignifyina the wood chips obtained in step (2) with the cooking liquor to obtain cellulose pulp; and
(4) optionally, bleaching the cellulose pulp. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification