The product is impacted by the high speed grinding media, which causes the feed product to fracture and be thrown by the centrifugal force to the wall of the grinding chamber, which in turn, causes the product to fracture further. The fractured particles are entrained in the induced airflow liberating the outside wall of the internal baffle assembly, which is fitted with air baffles to laminar the air flow. The laminar airflow and particles pass to the internal classifier, which is rotating, in the same direction as the rotor disc. Oversized particles rejected by the centrifugal force applied by the classifying wheel are thrown to the inner wall of the baffle and move down by gravity and by the pressure created by the classifier. These oversized particles are then re-entrained into the grinding zone where further impact occurs.