The mineral processing flow is grinding, size classification, ultrafine vertical mill, strong magnetic separation, flotation. In 2004, we carried out a ultrafine vertical mill experimental that replacing 1200mm ultrafine mill with 1500mm one. The result shows that processing capability increased by 30%. In recent years, the serious silting problem of 1500mm spiral chute has reduced the mineral classification efficiency greatly of which doesn't separate the concentrate, medium, and tailings ore accurately. Ore deposition not only influences efficiency but also reduce the spiral chute service life. The observation found that the ore mainly piles in the middle-lower part of the chute body, and the middle part of the cross-section. The reasons as follows, first of all, the placid chute curve and small inclination angle slow down the flow speed, and weak the fluidity, that easy to cause minerals deposition, especially in the middle-lower part of the spiral chute while mineral preliminary separating.