DE102009005909A1 - Fiber suspension stream treating method for packaging paper, involves dividing fiber suspension stream into two partial streams before flotation that is only present in partial streams with dispersion - Google Patents

Abstract

The method involves dividing a fiber suspension stream (1) into two partial streams (2, 3) before a flotation (4). Dispersion (12) is passed through one of the partial streams (2). The partial streams are combined in the dispersion. The floatation is only present in the partial streams with the dispersion. The floatation is carried out before the dispersion of the former partial stream. The former partial stream is concentrated and dehydrated with the dispersion after the floatation and before the dispersion.

Description

The The invention relates to a method for treating at least one partially made of waste paper pulp suspension stream, which is divided into several sub-streams, wherein at least one, but not all partial streams undergo dispersion and the partial streams are combined after dispersion become.

in the Generally, the total fiber flow in fiber processing guided through all process steps. Especially expensive are the thickening and the dispersion.

at the recycling of waste paper for packaging papers it is known to fractionate the total pulp flow and the to separately treat resulting sub-fractions.

Since this is still associated with high operating and system costs, is in the EP 1731662 proposed to disperse only a partial flow after a first flotation.

The The object of the invention is without significant impairment the quality of the finished pulp suspension, the plant and reduce operating costs even further.

According to the invention was the task is solved in that the division of the partial streams before a first flotation takes place and this first flotation only is present in the partial streams with dispersion.

in this connection was recognized that it is usually sufficient, only part of the Float suspension or flow through a first To send flotation. Because of the lower flow rate can the flotation carried out in the partial stream with dispersion smaller which has a significant impact on costs.

there the flotation should take place before the dispersion of the partial stream and the partial stream with dispersion before dispersion and preferably be thickened after flotation.

Furthermore should the partial stream with dispersion before the dispersion and preferably be dehydrated after thickening.

In Dependence on the quality of the treatment Pulp suspension and the required parameters of the finished Pulp suspension may be advantageous if the partial flow with dispersion before dispersion and preferably before Thickening undergoes a sorting.

Of Further, the partial stream should be dispersed without dispersion by fractionation guided and the rejection of fractionation preferably be passed into the partial stream with dispersion.

These Fractionation can be due to the lower flow rate accordingly be made smaller and with higher fabric densities respectively. In addition, the higher fabric densities of up to 6% increase the fractionation effect.

The in the partial stream without dispersion remaining accepting the fractionation is essentially formed by short fibers. By adding it is the case of the rejection formed essentially by long fibers an enrichment of long fibers in the partial stream with dispersion.

Around to ensure adequate treatment of the reject This should be before thickening, especially before a possible existing sorting led to the partial flow with dispersion become.

there It may be beneficial if the reject is only after the flotation is conducted into the partial flow with the dispersion.

Of Furthermore, it can be advantageous in many cases if the partial stream without dispersion, preferably after fractionation is passed through a thickening.

in the The result is a large proportion of short fibers of the pulp suspension to be treated passed through the first flotation, which increases the yield.

in the Interest of a comprehensive treatment should be the pulp suspension stream after merging the partial flows a second Go through flotation.

In Dependence on the circumstances and the requirements it may also be advantageous to use several partial streams with dispersion and / or to form a plurality of partial streams without dispersion.

For the fractionation is preferably the basket sorting as well the slot sorting with a slot width of particular less than 0.2 mm.

following the invention should be closer to an embodiment be explained. In the attached drawing the figure shows a plant schematic.

In a dissolution stage 14 is made of virgin fibers, waste paper and water a Faserstoffsuspensi on generated in the form of a pulp suspension stream 1 for further processing by several treatment stages is performed.

At the resolution level 14 closes a coarse sorting 15 to remove larger impurities in the form of a hydrocyclone or heavy duty cleaner followed by a basket sorter.

This is followed by the division of the pulp suspension stream 1 in two sub-streams 2 . 3 , wherein the main part of the pulp stream 1 in the main substream 2 is dispersed.

The ratio between the partial flows 2 . 3 can be exemplified by a valve 16 in a partial flow 3 Taxes.

After division, the main partial stream to be dispersed becomes 2 through a first flotation 4 to remove impurities such as ink particles, adhesives, plastic particles and resins.

In contrast, the other partial flow 3 not floated, but in a fractionation 5 in the form of a cyclone, a washing device or a basket sorter. When using a hydrocyclone, the consistency should preferably be less than 1.5%. While the accruing accept 7 in the form of short fibers as a partial stream 3 is continued, the reject gets 6 in the form of long fibers in the parallel, to be dispersed partial stream 2 ,

The addition of the reject 6 may be immediately after or before the first flotation 4 respectively.

In this way it is possible the flotation 4 and the fractionation 5 on the relatively low flow rates of the corresponding partial flows 2 . 3 to cut and thus minimize.

In addition, the fractionation 5 be operated with much higher fabric densities, which enhances the fractionation effect.

After fractionation 5 can the consistency of the concept 7 and thus the partial flow 3 still through a thickening 9 be increased before this partial flow 3 again with the other partial flow 2 after its dispersion 12 is mixed.

While the non-dispersible substream 3 contains essentially short fibers, accumulate in the partial stream to be dispersed 2 in particular by the admixture of the reject 6 predominantly long fibers.

The long fiber partial flow 2 can after the flotation 4 and the blending of the reject 6 if necessary by a sorter 8th be performed in the form of a basket sorter.

Following should be the long fiber partial flow 2 through a thickening 10 For example, a disc filter and drainage 11 For example, a screw press be passed before this partial flow 2 into a disperser 12 arrives.

Because the short fiber partial flow 3 is not floated, the yield of the treatment process increases.

Often, however, it is advantageous for the achievement of predetermined parameters of the pulp suspension to float them at least a second time. In this case, then the total pulp suspension flow 1 , ie after mixing of the partial streams 2 . 3 , as indicated in the figure, by another flotation 13 be guided.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - EP 1731662 [0004]

Claims (13)

Process for the treatment of a pulp suspension stream formed at least partially from waste paper ( 1 ), which is divided into several sub-streams ( 2 . 3 ), wherein at least one but not all partial streams ( 2 ) a dispersion ( 12 ) and the partial flows ( 2 . 3 ) after dispersion ( 12 ), characterized in that the division of the partial flows ( 2 . 3 ) before a first flotation ( 4 ) and this first flotation ( 4 ) only in the partial streams ( 2 ) with dispersion ( 12 ) is available. Method according to claim 1, characterized in that the flotation ( 4 ) before dispersion ( 12 ) of the partial flow ( 2 ) he follows. Method according to claim 1 or 2, characterized in that the partial flow ( 2 ) with dispersion ( 12 ) before dispersion ( 12 ) and preferably after flotation ( 4 ) is thickened. Method according to one of the preceding claims, characterized in that the partial flow ( 2 ) with dispersion ( 12 ) before dispersion ( 12 ) and preferably after thickening ( 10 ) is drained. Method according to one of the preceding claims, characterized in that the partial flow ( 2 ) with dispersion ( 12 ) before dispersion ( 12 ) and preferably before thickening ( 10 ) a sorting ( 8th ) goes through. Method according to one of the preceding claims, characterized in that the partial flow ( 3 ) without dispersion by fractionation ( 5 ) and the reject ( 6 ) of fractionation ( 5 ) preferably in the partial flow ( 2 ) with dispersion ( 12 ). Method according to claim 6, characterized in that the reject ( 6 ) before thickening ( 10 ), especially before sorting ( 8th ) in the partial flow ( 2 ) with dispersion ( 12 ) to be led. Method according to claim 6, characterized in that the reject ( 6 ) after flotation ( 4 ) in the partial flow ( 2 ) with the dispersion ( 12 ) to be led. Method according to one of the preceding claims, characterized in that the partial flow ( 3 ) without dispersion ( 12 ), preferably after fractionation ( 5 ) by thickening ( 9 ) to be led. Method according to one of the preceding claims, characterized in that the pulp suspension stream ( 1 ) after merging the partial flows ( 2 . 3 ) a second flotation ( 13 ) goes through. Method according to one of claims 6 to 10, characterized in that the fractionation ( 5 ) is designed as Korbfraktionierung. Method according to one of claims 6 to 11, characterized in that the fractionation ( 5 ) is designed as a slot sorting, wherein the slot width is preferably smaller than 0.2 mm. Method according to one of claims 6 to 10, characterized in that the fractionation ( 5 ) with a hydrocyclone, wherein the consistency is preferably less than 1.5%.