Material falls the feed hopper, then enters the high-speed rotary sling wheel from center feeding hole, which is speeded immediately in the sling wheel. The speed can reach several dozens times of the gravity acceleration. Then it is thrown from the sling wheel. First, it is crushed with other rebounded material fell freely from the sling wheel. Then both of them are impacted to the material lining (rock-rock) or strike back block (rock-iron), rebounded and stroke to the top of eddy cavity in the inclined-up direction. Then it moves along deflection-down, and forms a continuous material curtain with the material from the impellers passage. Just like this, the material is stroke, rubbed, crushed twice or more, then is discharged from the down discharging hole.