US 8,262,851 B2Granted

Processes and systems for the pulping of lignocellulosic materials

AssigneeAndritz Inc.

InventorsJohann Aichinger, Eric Xu, Marc J. Sabourin

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Abstract

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.

Claims8

Dependent claims

An alkaline peroxide mechanical pulping process comprising the steps of:

(a) preconditioning a lignocellulosic chip material by adding chemical stabilizers selected from the group consisting of diethylene triamine pentaacetic acid (DTPA), ethylene diamine tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), silicate and MgSO4 to a non-compressive digester containing the lignocellulosic chip material to be preconditioned in the presence of liquor to achieve a liquor to wood ratio in the digester of between about 0.5:1 to about 5:1 to form a preconditioned liqnocellulosic chip material;
(b) discharging the preconditioned lignocellulosic chip material from the digester without the use of a screw mechanism to a fiberizer, and mechanically breaking apart the preconditioned lignocellulosic material in the fiberizer to obtain a fiberized lignocellulosic material;
(c) washing the fiberized lignocellulosic material,
(d) feeding the washed fiberized lignocellulosic material to a high consistency refiner;
(e) treating the washed and fiberized lignocellulosic material with alkali peroxide chemicals for a time and under conditions sufficient to obtain a pulp therefrom;
(f) retaining the pulp in a high consistency tower for a time sufficient to allow chemical reactions to complete;
and thereafter
(g) transferring the pulp from the high consistency tower to downstream processes and recovering the pulp therefrom.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/826,837Filed 18 Jul 2007 · us provisional application
Priority: 10 Aug 2006
Published: US 2008/0035286 A114 Feb 2008
Granted: 11 Sep 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

D21C 3/02
Pulping cellulose-containing materials: with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
D21C 9/1042
Other features in bleaching processes: use of chelating agents
D21C 9/16
Bleaching ; Apparatus therefor: with per compounds
D21C
Production of cellulose by removing non-cellulose substances from cellulose-containing materials