Abstract:Three materials including coarse semolina， coarse middling， and fine middling were taken as raw materials. The most commonly used purifier in China was used， and the influence of air volume on the separating efficiency of materials with different natures was studied by adjusting the air volume. The results indicated that as the air volume increased， the sifting rate of coarse semolina increased first significantly and then decreased significantly， and the ash reduction rate increased first significantly and then decreased significantly.The separating efficiency of the material increased first significantly and then decreased significantly. The sifting rate of coarse middling increased first significantly and then decreased significantly， and the ash reduction rate increased first and then decreased. The separating efficiency of the material increased first significantly and then decreased significantly. The changing trend of the two indicators was not significant. The sifting rate of fine middling decreased， and the ash reduction rate increased. The separating efficiency of the material increased first and then decreased， and the changing trend of the three indicators was not significant. The coarse semolina， coarse middling， and fine middling had the best separating efficiency within the range of air volume of 2 114-2 509 m3/h， 1 978-2 154 m3/h， and 881-1 041 m3/h， respectively. The separating efficiency of the three materials in descending order was as follows： coarse semolina > coarse middling > fine middling.