to enable the required heat treatment of the particulate material 6 to be safely and reliably carried out according to the invention it is therefore determined after a first measuring interval 40 for example after a half hour that the entry temperature 4 has dropped therefore this temperature information is used to slow by an adjustable value the revolution speed of the motor 20 of the screw drive 7 by means of the revolution speed controller 22 which is for example configured as a frequency converter therefore however the particulate material 6 now remains longer in the screw drive 7 of the separator 2 which would lead to an increase in the content of dry matter of the particulate material 6 the increase in the content of dry matter of the particulate material 6 means however also an increase in the torque which acts on the screw drive 7 thus the torque controller 21 can counteract said increase in torque and lower the torque which acts on the screw drive 7 in this manner the content of dry matter of the particulate material 6 is kept constant overall less particulate material is discharged to the litter reclamation plant 3 as a result of.