NL8300025A - METHOD FOR PROCESSING OLD PAPER - Google Patents

Description

Ρ Ρ Kon / HPJS / Voithl 6

Method for processing old paper.

The invention relates to a method for manufacturing fibrous dust from waste paper, in particular cleaned from printing ink, according to the preamble of claim 1.

Such a method is known from German patent specification 2.3X1.674.

When processing old paper with a printing ink removal step, it is required for this separation step to dissolve the printing ink from the fibers, since only in this state can the printing ink particles be removed from the fiber suspension by a flotation or washing process.

Dissolving of the printing ink particles from the fibers generally takes place in an alkaline environment, within a temperature range of 40 ° -70 ° C. Often additional detergents to aid in the dissolution of the ink are added.

When processing offset printed matter, for example newspapers, telephone books, etc., especially if they have been stored for a longer period of time, as well as special printed matter that is printed with dyes on a plastic basis, for example xerox and other copy paper, the described method remains defective. .

The reaction of the fibrous suspension in a high dust density range, as described, for example, in German patents 2,339,591 (Lausch), 2,311,674 (Berndt) and 2,803,804 (Kriebstein), although the dissolution of the printing ink is enhanced, but there is, nevertheless, a range of printing products, these methods also unsatisfactory, especially if the decolorized fiber 30 is used to produce high quality papers.

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The object of the invention is to provide a method for the processing of waste paper, which makes it possible, also from paper, xerox and other copied paper printed in particular by the offset method, to obtain a fiber raw material for the production of high-quality papers. free.

This object is achieved in a method of the above-mentioned kind by the characterizing part of claim 1. A preferred embodiment of the method is described in claims 2 and 3.

Surprisingly, the method according to the invention provides the possibility of obtaining a paper fiber fabric of high brightness and whiteness by flotation or washing the difficult starting materials mentioned. ....

The defibrillation devices used according to the invention, including the extensively introduced and known one or two-axis fiber or disc defibrillation device, which have been introduced in the art, have hitherto been or have been utilized for a paper fiber raw material having a obtain a certain structure, for instance a certain degree of grinding, or to finely distribute bitumen, wax or latex substances in the suspension by the dispersion achieved during the passage of the fiber suspension through the defibrillation device, 2.5 in order to avoid disturbing, in particular avoid optical influence. Immediately prior to the printing ink removal from the fiber slurry, these devices have not been used anywhere.

The method according to the invention is based on the idea of allowing the temperature increase and action or the fiber suspension to take place at high concentrations for a very short time. The supply of heating steam can expediently be carried out in the feed worm of the existing shredding device, if such a device is available, as is the case, for example, with uniaxial or disk shredding devices. These devices work optimally at completely determined concentrations, which are known in the art, however, and are between about 18 and 35%. It is expedient to supply the chemicals to the device or feed worm 8300025 Μ -3-, however it may be advantageous in certain cases to add the chemicals as well as those for bleaching or flotation as well as alkali for heating the fabric add.

The invention will be elucidated hereinbelow with reference to the appended drawing, in which the course of the method is schematically shown in an exemplary embodiment.

In a conventional manner in a device 1 for dissolving material, the old paper is dissolved at a concentration between 4 and 25%. It is then led via a pump 3 into sorting devices, which are summarized here as a group and indicated by 2. These sorting devices can be seven, so-called sorters, as well as vertical classifiers, but also hydrocyclones. The sorted and thus pre-cleaned material then enters a thickening device 4 and after the thickening device, the dust consistency according to the shedding device 7 used being optimally between 18 and 35% in the feed worm 6 of the shedding device 7, which here is a uniaxial shredder is indicated. In the feed worm 6, in addition to steam via the line 11, also the chemicals for bleaching, such as, for example, peroxide, and for flotation, as well as substances with foaming and coauguration properties, such as, for example, soaps or fatty acids, are added up to about 2%, as well as 1% alkali, for example in the form of NaOH, as well as possibly also about 1.5% water glass in addition to complexing agents under conditions. In order to be able to maintain the required temperatures in the shredder 7, the feed mold 6 or conically tapering or 30 can be carried out with worm passes becoming increasingly narrow towards the drive end, so that the pressure in the shredder can be maintained by the compression of the suspension.

Behind the shredder, in which the suspension 35 remains for a maximum of about 5 (possibly up to 10) minutes, it is again brought to a very low consistency with the withdrawn liquid from the thickener 4 via the line 10 as well as additional water to a consistency of 1 to 1, Diluted 8% and floated in the flotator 8. It consists of the primary cells 8 'as well as by the schematically indicated secondary cells 8' * in which the extracted foam is floated once more. The cleaned suspension then enters a thickener 9, for instance a belt pressure filter, 5, achieving such a high consistency that the suspension becomes stackable, i.e. occupies a small space. Furthermore, the further processing, i.e. the preparation of the fibrous materials for the paper machine, can take place.

For the sake of completeness, it is pointed out that alkali, such as sodium hydroxide, and also peroxide can already be supplied to the device 1 intended for dissolving the material. The supply of the waste paper to the device 1 is effected dry, for example via the conveyor belt shown 12. ......

It is further pointed out that the time in which the heating takes place is very short in the chosen method in the relevant form of the hand fiber device.

In principle it will not exceed 1 minute, or preferably half a minute 20. As a result, the material does not lose its firmness. Also, the total transit time through the worm and the shredder is relatively short and in any case less than 12 minutes. Generally, this transit time is about 5 minutes. This short time is necessary from the same viewpoint.

The whiteness achieved is very high and is above 60%. The boundary condition for whiteness is exceeded by about 3% points. The well-known Elrepho device (Filter FMY) was used for this.

The shredders are known from the various literature references. For example, a single-disk shredder is known from "Das Papier", 1981, pages 67 to 73, in particular pages 71, Figures 10 and 11. A single-shaft shredder is known from " Voith Sonderdruck "Nr. 2018, W. Musselman: Ueber die Aufbereitung von Altpaper in Heiss-zerfaserungsanlagen, in particular page 9, images 11 and 12.

As already described at the beginning, 8300025 -5- J *. These shredders have heretofore been used for completely different purposes, especially to disperse printing ink or impurities in the fiber slurry, ie to distribute them finely, so that the optical influence of the filling can no longer be seen as disadvantageously. By the method according to the invention, on the other hand, against the hitherto held opposite view of the professional world, a fiber material with a good structure is produced, which can be used as starting material for the production of paper. The art world has hitherto believed that when high temperatures are used with simultaneous intensive mechanical treatment, as is the case in shredders of the aforementioned type, the printing ink is even more firmly bonded to the fibers and thereby in itself very difficult to get rid of ink starting material, a removal of printing ink is no longer possible.

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Claims (7)

1. A method for producing, in particular, ink-cleaned fiber dust from waste paper by dissolving the paper, cleaning the fiber suspension by sorting it in sorting sieves or cyclones and by removing the printing ink by flotation or washing, as well as optionally bleaching, characterized in that the fiber suspension between the cleaning step (2) and the printing ink removal step (8) at a dust consistency of more than 15% on a defibing step in a defibers (?) and thereby on a heat operating at temperatures in excess of 85 ° C, optionally coupled with heating in a feed worm (6) of the defibing step, so that the heat effect is approximately at most equal to the transit time through the defibering step and then up to a flotation time - 15 required consistency to be diluted and floated or subjected to a wash step, Method according to claim 1, characterized in that the passage of the fibrous material through the defibrillation device (7) takes place under the action or addition of alkali. Method according to claim 1 or 2, characterized in that the temperature of the heat-acting step is below 150 ° C. 4. Method according to any one of claims 1-3, characterized in that the dust concentration in the shredder is between 18 and 35%. Method according to any one of claims 1 to 4, characterized in that the dust concentration when dissolving the old paper is between 4 and 25%. Method according to any one of claims 1 to 5, 30, characterized in that simultaneously with the addition of alkali *, also that of the required bleaching chemicals and detergents takes place, or that before the flotation. 7. Device for the production of, in particular, ink-cleaned fiber fabrics from waste paper by dissolving the paper, cleaning the fiber suspension 8300025 -7->. -Τ ', * by sorting them into sorting sieves and cyclones and removing the printing ink by flotation or washing, and bleaching if necessary, characterized in that between the cleaning steps (2) and the printing ink removal step (8), a shredder 5 (7) for the processing of the fibers for suspension, as well as before a steam pipe (13) for heating steam are placed next to this or thereafter. 10 8300025 ----- -