Abstract： To investigate the effect of sloping angles of vertical turbine classifiers outer tube body on classification efficiency, a self-made CP-20 jet mill was used to crush and classify river sands at different sloping angles to obtain the optimal sloping angles based on the analysis of flow field, classification performance and problems of the vertical turbine classifiers. The results show that for the river sands, the classification efficiency increases first and then decreases with the increase of sloping angles between 0 and 15°, and the optimal sloping angle is 9°.

Keywords: turbine classifier; outer tube body; classification performance; sloping angle