Raw material after crushed by stone crusher is transported to raw material storage hopper by conveyoring stytem. Electromagnetic feeder feeding raw material to ceramic ball mill evenly. Grinding high aluminum balls obtain huge impact force by rotation of ball mill to drop down to crush and grind materials into fine powder. the ground material is sucked to the air classifier, where the coarse and fine powders is separated by the centrifugal force and draft force, the qualified powder is collected by collector and the oversized particle is resend to the ball mill to regrind by screw conveyor. The whole process is under negative pressure state ,form closed circular system.