Materials first enter jaw crusher to be crushed to smaller size. Then they are lift to storage room by elevator. Vibrating feeder will feed materials into grinding chamber evenly and gradually. After being grinded, the powder will be blowed to cyclone by blower. Then the material will be transferred to storage room through pipes, and then will be discharged as final products. The whole process works in a negative pressure environment. First, through pipes, the air from the blower enters the cyclone collector above the storage room along with powder, and then returns to the blower through return pipe. In the way, air can be recycled. There is a powder locking equipment under the cyclone, which isolates the outside positive air pressure and the negative air pressure inside cyclone. And this ensures high productivity. In addition, the residual air and dust under the main unit will be transferred to dust catcher equipment through pipes and be cleaned there. The clean air will be discharged so that environment will be protected.