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US 4,869,783 AGranted
High-yield chemical pulping
AssigneeThe Mead Corporation
InventorsZenon C. Prusas, Clarence L. Oates
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Abstract
A chemical pulping process is disclosed wherein wood chips are partially defiberized such that the fibers in the chips are substantially separated from one another but sufficient interfiber bonding is maintained to preserve chip integrity and thereby provide chips having an open porous fibrous network; and the chips are subjected to chemical pulping at an elevated temperature to remove a majority of the lignin in the chips.
Claims10
A pulping process comprising the steps of:
- partially defiberizing wood chips such that the fibers in said chips are substantially separated from one another but sufficient interfiber bonding points are maintained within said chip to preserve chip integrity and therey provide a chip having an open porous fibrous network;
- said wood chips being partially defiberized by passing said chips through a screw press having a compression ratio of about 3/1 to 5/1 under a substantial back pressure;
- directly feeding said partially defiberized chips to a digester;
- subjecting said partially defiberized chips to chemical pulping at elevated temperature and pressure to provide a pulp having a Kappa value of about 45 to 70;
- further delignifying said pulp by reacting said pulp with oxygen in the presence of caustic;
- and
- bleaching said pulp.
4 more elements
Dependencies are inferred from the claim text.