Abstract: A method and apparatus for washing a filter fabric (3) of a filter press. The method includes filtering a material to be filtered containing a liquid and solids through the filter fabric (3) in a filter cell (20), retaining the solids on a surface of the filter fabric (3) thereby forming a filter cake (18) on the filter fabric (3), discharging the filter cake (18) from above the filter fabric (3) to one side of the filter press only, conveying an area of the filter fabric (3) soiled during the previous filtration step to a washing cell (21) for washing the soiled area of the filter fabric (3) and washing the soiled area of the filter fabric (3) in washing cell (21).

Abstract: The invention concerns a method for controlling a press filter, said press filter having electric motors for operating said press filter. At least one of said electric motors of said press filter is driven by a frequency filter. A logic control unit is used for sending a program-controlled analog signal to said frequency converter. The output current from said frequency converter having a frequency proportional to the magnitude of said analog signal received from said logic control unit is used for driving the press filter's electric motors, whose rotational speeds thereby become proportional to the drive current frequency. A desired electric motor is individually started by way of applying power to the motor via a switch element which is activated by a signal from the logic control unit.

Abstract: The invention concerns a filtering procedure by which the solid matter and the fluid contained in a sludge are separated in a box filter. The sludge is passed in the filter into a filtering space (2) between two opposite filter cloths (3), where the fluid is separated, whereupon the cake (13) of solid matter produced is dried by passing a stream of air through it. The essential feature of the invention is that the drying is performed by passing a stream of air into the cake (13) first from one side and then from the opposite side of the filtering space (2) in such manner that the air flows in opposite directions through the cake during these drying phases. Penetrating through the filter cloth (3) into the cake, the air causes the cake to be detached from the cloth. When the filtering space is opened, the cake thus detached and dried can be removed directly without specific detaching efforts.

Abstract: The invention concerns a pneumatic classifying procedure and apparatus for dividing particulate material into a fine product consisting of lighter particles and a coarse product consisting of heavier particles. The classification takes place in a cylindrical classifying space (1) in which can be established a centrifugal field with the aid of tangential supply of the material to be classified or with the aid of a mechanical rotor, the field separating the fine product into the center of the classifying space and the coarse product to its outer margin. It is essential in the invention that the coarse product is removed with the aid of a separate gas flow which is tangential to the centrifugal field. The gas flow runs in a passage (11) which is tangential to the classifying space (1) at the site of the coarse product removal aperture (9).

Abstract: The present invention seeks to provide a method for treating the cellulose obtained from the cellulose cooking process for paper-making purposes. According to this method, the cellulose is separated from black liquor or other similar waste slurry produced in the cooking process by means of compression and washed, bleached and dried, and an essential feature of the present invention is that all the phases of treatment are carried out in a pressure filter (4). The treatment is performed so that black liquor or similar waste slurry is first compressed from the cellulose pulp slurry, whereafter the resulting cellulose cake is washed by conducting washing liquid into the filter, after which the cellulose is bleached by treating the cake with one or several bleaching chemicals led into the filter and by re-washing, if necessary, the cake between the various bleaching phases, and finally, the cellulose cake is dried and removed from the filter.