The raw material is fed into the pneumatic pipeline through the rotary valve at the bottom of the feed bin, and is then drawn into the mill grinding chamber, where it is ground by the high speed rotating impact of the hammer heads on the hammer disc, and then lifted up to the wind classifier by the wind provided by the fan. The classifier circulates the coarse particles back to the grinding chamber for further grinding, and the fine powder of the desired particle size is pneumatically conveyed out of the mill, thus controlling the particle size of the output material to meet the requirements and uniform distribution. Finally, the fine powder is directly ejected by the fan to the flue gas pipe.