After cooling, filtrating and drying, the compressed air will form supersonic airflow through nozzle and the airflow will rip into the crushing chamber. At the ground area, the materials will be brought by accorlerated airflow and produce violent collision attrition, and shearing to be superfine-ground. The crushed materials will be transported to the classifying-sections by the updraft and the coarse particles and fine powders will be separated by centrifugal force of classifying wheels and draught of blower. The qualified fine powders will enter the bag collector and the cyclone for collection. The purified gas will be discharged from the fan.