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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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  • Summary
  • 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, the problem associated with the solution described in this publication is that since the process water separated from the pulp by pressing is introduced directly to the membrane filter, a significant amount of fibers valuable and useful for papermaking is also extracted from this Process removal

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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

The object of the present invention is a method and arrangement in making of mechanical pulp to reduce the amount of organic dissolved and colloidal substances in the pulp making process water by treating a part of the process water. According to the method the treating is carried out by leading the process water filtrate, separated from the pulp by a press located before bleaching, to pre-treatment, where elongated fibres are fractionated from the process water to be treated. The filtrate that has passed the pre-treatment is led to membrane filtration, where at least part of the organic dissolved and colloidal substances included in the process water are separated from the rest of the process water. The membrane filtration concentrate i.e. the colloidal and dissolved substances separated from the process water, is led to further treatment and the permeate i.e. the process water that has passed the membrane filtration is led back to the pulp making process. An arrangement according to the present invention comprises means to carry out the method according to the 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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