Andritz Inc.

Xu, Eric Chao

Eric Chao Xu

Marc J Sabourin

Thomas Pschorn

Johann Aichinger

Martin Herkel

The present disclosure relates to a system and process in which pulp is produced using a chemical mechanical pulping process, during which lignocellulosic material undergoes fiberization without chemical impregnation. Chemical treatment of the lignocellulosic material is performed during or after fiberization of the material to become fiber bundles.

Chemical treatment of lignocellulosic fiber bundle material, and methods and systems relating thereto

A non-compression vessel, such as a digester, is employed for the chemical preconditioning of the chips followed by a fiberizing device to break the preconditioned chips down to fiber bundles, which are then washed before a high consistency chemical treatment. The digester may be one such as used in conventional chemical pulping of wood with or without screens for the extraction of chemical. If extracted this chemical could be recirculated to the digester with treatment in the circulation loop such as heating or the addition of dilution or other chemicals. This digester may be hydraulic or vapor phase (that is contain a vapor space within the digester), and operate in either a continuous or batch fashion. This digester allows for the discharge of material without the use of a screw mechanism. The digester treated material is then defiberized to convert the chips into course fiber bundles, which then is washed and dewatered. The washed and dewatered pulp is then treated with alkali peroxide chemicals to develop brightness and other pulp properties.

Processes and systems for the pulping of lignocellulosic materials

The invention combines the step of adding chemicals such as alkaline peroxide to an intermediate line after refining, with the step of applying chemicals such as alkaline peroxide as a pre-treatment before primary refining and/or applying chemicals such as alkaline peroxide at the primary refiner. This is implemented in the preferred embodiment, by pre-treating feed material, refining the materials into a pulp in a superatmospheric refiner, and adding chemicals in the post refining blowline.

Multi-stage AP mechanical pulping with refiner blow line treatment

A process for applying chemicals, such as an alkaline peroxide pretreatment () to lignocellulosic material before chemical refining and at the primary refiner (). The preferred embodiment comprises (i) preconditioning at temperatures below 95&#xb0; C., especially below 80&#xb0; C., (ii) limiting the time and/or temperature in the refiner, (iii) reaction quench to maintain temperatures below 80&#xb0; C., and (iv) subsequent high consistency bleaching ().

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Miamisburg, OH, United States of America

Eric Chao Xu