A mill and operating method for using grinding bodies for grinding a grinding stock. Grinding bodies that have passed through the through the product outlet enter an upwardly inclined discharge pipe from where, when the grinding body mill is at a standstill, the grinding bodies are directed out of the discharge pipe through the product outlet into a rotor body of the separating device. When operation of the grinding body mill is resumed, the grinding bodies are conveyed back into the grinding chamber owing to the rotation of the rotor body.