Method and device for processing waste paper

Abstract

The invention relates to a method for processing waste paper according to the following steps: a) the waste paper is decomposed into fibres, b) the fibres are washed, c) the fibres are subjected to a dispersion process, d) the fibres are subjected to a flotation method, e) the fibres are processed for further treatment in a paper machine. The liquid from the fibres obtained in step b) is reintroduced into the fibre flow prior to step d). The invention also relates to a device for carrying out said method.

1 . A method for processing waste paper comprising the following steps:
 a) the waste paper is decomposed into fibres,   b) the fibres are subjected to a washing process,   c) the fibres are subjected to a dispersion,   d) the fibres are subjected to a flotation process,   e) the fibres are processed for further treatment in a paper machine,   wherein the liquid accumulating in step b) is supplied to the fibre stream again before step d).   
     
     
         2 . The method according to  claim 1 , characterised in that after step b) and before step c), the fibres are subjected to at least one thickening. 
     
     
         3 . The method according to  claim 2 , characterised in that the liquid accumulating during the at least one thickening is removed. 
     
     
         4 . The method according to  claim 2 , characterised in that the liquid accumulating during the thickening is supplied to the fibres again after step c). 
     
     
         5 . The method according to  claim 1 , characterised in that the fibres are subjected to at least one sorting before step b). 
     
     
         6 . The method according to  claim 5 , characterised in that the fibres are subjected to a coarse sorting and a fine sorting before step b). 
     
     
         7 . The method according to  claim 1 , characterised in that the fibres are subjected to at least one thickening after step d). 
     
     
         8 . The method according to  claim 7 , characterised in that the water accumulating during the at least one thickening carried out after step d) is supplied back to the fibre stream before step d). 
     
     
         9 . The method according to  claim 1 , characterised in that at least the liquid accumulating in step b) is subjected to a separate thickening and the thickened material is supplied to the fibre stream again before step d). 
     
     
         10 . The method according to  claim 9 , characterised in that the fibre stream accumulating after step c) is partially or completely used as filter aid for the separate thickening. 
     
     
         11 . The method according to  claim 9 , characterised in that the water accumulating during the separate thickening is supplied to the fibre stream again upstream of step b). 
     
     
         12 . A device for processing waste paper having the following features:
 a) a decomposition stage for decomposing the waste paper into fibres,   b) a washing stage for washing the fibres,   c) a dispersion stage for dispersing the fibres,   d) a flotation device for flotation of the fibres,   e) at least one processing stage for processing the fibres for further treatment in a paper machine,   wherein a line is provided for the liquid accumulating in the washing stage, which branches off from the washing stage and opens into the fibre stream again before the flotation device.   
     
     
         13 . The device according to  claim 8 , characterised in that at least one thickening stage is provided between the washing stage and the dispersion stage. 
     
     
         14 . The device according to  claim 9 , characterised in that a line for the liquid accumulating in the thickening stage branches off from the at least one thickening stage and opens into the fibre stream again before the flotation device. 
     
     
         15 . The device according to  claim 8 , characterised in that at least one sorting stage is provided before the washing stage. 
     
     
         16 . The device according to  claim 11 , characterised in that a coarse sorting stage and a fine sorting stage are provided. 
     
     
         17 . The device according to  claim 8 , characterised in that at least one thickening stage is provided after the flotation device. 
     
     
         18 . The device according to  claim 17 , characterised in that a line for the extracted water branches off from the at least one thickening stage and opens into the fibre stream before the flotation stage. 
     
     
         19 . The device according to  claim 8 , characterised in that a separate thickening stage is provided at least for the liquid accumulating in the washing stage. 
     
     
         20 . The device according to  claim 19 , characterised in that a line for at least some of the fibre stream accumulating after the dispersion stage is provided after the dispersion stage and opens into the thickening stage. 
     
     
         21 . The device according to  claim 19 , characterised in that a line branches off from the thickening stage and opens into the fibre stream at least one point upstream of the washing stage.