filter cakes of the filter plates and of the residual filtration element 36 as well as to removal of the cakes via the outlet of the disk valve and the discharge conduit 60 into a receptacle disposed therebelow in the event that the speed for the agitator 53 needs to be less or greater the rotation can by means of the speed regulatable drive motor 55 or the infinitely variable gearing be respectively adjusted to the centrifugal force required for centrifuging the filter cake as soon as the filter cakes are discharged and removed from the discharge region and while the bottom plate 30 is still raised the filter unit 21 is still rotating and the reversing valve 17 is opened wash liquid is withdrawn from the tank of the dosing device 12 by means of the pump 13 via the line 16 and the slurry line 14 and wash liquid is supplied via the filtrate withdrawal line 15 with the reversing valves 19 20 being opened and the gas outlet 65 and the reversing valves 18 19a being closed a portion of this wash liquid passes via the valve 37 the bore 34a the annular channel 34 and the channels 35 to the residual filtration element 36 and exits the latter into the filter housing after washing has been effected with the wash liquid just like the.