Abstract: In order to achieve the effective separating of alumina and silica minerals existing in diasporic bauxite, the cyclonic separation method was adopted to study these minerals separation characteristics, and the separation mechanism was analyzed preliminarily. The results showed the increase of apex diameter can make the LZVV shrink, and is advantageous to increase the recovery of Al₂O₃ in underflow and to reduce the A/S of overflow, however the separation precision decreases with the decreasing of the A/S of underflow; the changing of feed pressure can not effect the spatial locality of LZVV basically, however its increase has advantageous influence on the cyclonic separation of minerals with adequate cone angle, and so the separation effect can be improved.