Abstract: The selective grinding of diasporic bauxite with a 4.4 ratio of Al₂O₃ to SiO₂ from Henan Great Wall Aluminum Co. in a φ100 mm×150 mm ball mill was investigated. The results show that,at a grinding size of 50% -74 μm, its selective grinding effect is good, high material-ball ratio is benefit to vary grinding effect and the grinding concentration has little impact on the product size composition but high impact on the ratio of Al₂O₃ to SiO₂ of each size fraction of the product. With the grinding mediums filling ratio and medium size composition used in this test, at a material-ball ratio of  1.2, a 70% grinding concentration and grinding size of 50% -74 μm, in the course size fraction of the product, the +0.18 mm Al₂O₃-SiO₂ ratio is greater than 7.5, the yield of the fractions is 27% and the Al₂O₃ recovery is 30%.

Key words: Ball mill, Bauxite, Selective grinding, Ratio of Al₂O₃ and SiO₂