Abstract: The present invention concerns a granular material conditioner for optimising grain sizes of granular materials comprising two discs which are rotatable relative to each other and which are arranged in substantially mutually parallel relationship, a granular material inlet through which granular material can be passed into the conditioner into an annular gap between the two discs, and a catch container for receiving the granular material which issues from the gap between the two discs by virtue of centrifugal force. According to the invention it is proposed that the catch container has an elastic curtain, wherein the curtain is spaced at least portion-wise from the catch container wall and limits the trajectory of the granular material issuing from the gap.