Method and arrangement in making of mechanical pulp

A mechanical pulping and pulping technology, applied in the regeneration of pulping liquid, textile and papermaking, fractionation/concentration of waste liquid, etc., to achieve the effect of improving cleanliness and reducing demand

Inactive Publication Date: 2005-12-28
METSO PAPER INC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But because in the solution described in this publication, the bleaching agent is already added to the pulp, a significant amount of the extract is dissolved in the process water, and it is not possible to remove the extract sufficiently efficiently by membrane filtration
[0014] Furthermore, th

Method used

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  • Method and arrangement in making of mechanical pulp
  • Method and arrangement in making of mechanical pulp

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Embodiment Construction

[0044] By way of an example, Figure 1 illustrates the pulping process schematically. As shown in Figure 1, pulp is produced from a mechanical pulp, ie, fiber separation, such as from a mill 1 or refiner, generally at a consistency of about 0.1% to 0.8%. The mechanical pulp preparation process used can be, for example, thermomechanical pulping (TMP), grinding (GW / SGW; groundwood / groundwood), pressure grinding (PGW: pressure groundwood) or thermal grinding ( TGW; thermal groundwood pulp). The mechanical pulping process can also be chemi-thermomechanical pulping (CTMP) or chemi-mechanical pulping (CMP), which do not use bleaching agents in refining. By defibration, the pulp is introduced into a thickening 2, for example into a disc filter. During the thickening step the consistency of the pulp is generally raised to about 6-12% and the pulp is generally directed to intermediate storage 3 . The thickened filtrate is introduced into the white water tank 4, from where it is led b...

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Abstract

It is an object of the present invention to provide a method and apparatus for preparing mechanical pulp which reduces the amount of organic dissolved colloids by treating part of the process water during the pulping process. According to the method, the treatment is carried out by the following steps: the process water filtrate is separated from the pulp to be prepared by a press (5) located before the bleaching step, and the process water filtrate is introduced into the pretreatment (8) , in this pretreatment (8), the process water to be treated is classified to separate long fibers therefrom. The filtrate that has passed through said pretreatment (8) is introduced into membrane filtration (9) in which at least a portion of the organic dissolved colloids contained in said process water is combined with the remaining The process water is separated. The membrane filtration concentrate, i.e. the colloidal solute separated from the process water, is introduced for further processing, and the leachate, the process water that has been filtered through the membrane, is introduced back into the pulping process. The apparatus of the present invention includes a unit that can perform the method of the present invention.

Description

technical field [0001] The present invention relates to a method and a device for producing mechanical pulp, said method and device being described in the preambles of the appended independent claims. Background technique [0002] When preparing mechanical pulp used in the production of wood-based fiber webs such as paper and board webs, ie defibration, 20 kg to 50 kg of wood-derived substances are dissolved and dispersed per ton of wood. These wood-derived substances are accumulated during the pulping process. These substances derived from wood are commonly referred to as dissolved colloidal substances (DCS). [0003] During the preparation of mechanical pulp, the group of compounds obtained from wood and dissolved in white water is usually: carbohydrates, lignin, fat-soluble extractives (resin, bitumen) and inorganic salts (ash). Fat-soluble extracts are colloidal, while carbohydrates and lignin are dissolved compounds. [0004] When wood is defibrated during the produc...

Claims

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Application Information

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IPC IPC(8): D21C11/00
CPCD21C11/0028D21C11/005D21C11/122
Inventor 帕西·努尔米宁蒂莫·苏特拉基莫·科斯基宁
Owner METSO PAPER INC
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