On the one hand, reduce the grinding amount, on the other hand, recover useful minerals in time, which can improve the grinding efficiency of vertical roller mill. The influence of improving classification efficiency on grinding efficiency is self-evident.High classification efficiency means that the qualified particle size can be discharged timely and efficiently, while low classification efficiency means that most qualified particle size products cannot be discharged and returned to vertical roller mill for regrinding, which is easy to cause over grinding.In production, two-stage classification or improved classification equipment can be used to improve classification efficiency and vertical roller mill grinding efficiency accordingly.