The quality of materials processed by vertical roller mill is poor and there are many material impurities: when the materials processed by vertical roller mill contain sediment and other impurities, especially when there is a large amount of sediment, the material concentration in vertical roller mill will become higher and the material fluidity will become worse, resulting in stone discharge in the discharge of vertical roller mill operation. 

It can be improved by increasing the make-up water and reducing the ore feeding. Poor grindability: quartz stone is mainly composed of SiO2, with high hardness and poor grindability. Therefore, the impact force can be increased by increasing the steel ball diameter to increase the steel ball weight. 

At the same time, the feeding amount should be reduced, the output of vertical roller mill should be reduced, and the residence time of quartz in vertical roller mill should be prolonged to improve the grindability of materials.