Increased feed particle size is often due to malfunctions in the crushing system’s screen equipment or screen breakage. Increased ore hardness may be caused by differences in the ore face or by the blending process. In both cases, the grinding process will change accordingly: firstly, the discharge particle size will become coarser, and secondly, the amount of returned sand will increase. The solutions are to increase the discharge concentration and the overflow concentration of the classifier, thus reducing the amount of returned sand. If the fineness issue cannot be resolved, the feed rate can be appropriately reduced.