Time: 2022-04-29

Although the vertical mill developed relatively late, it has been widely used in the modern industrial raw material grinding production due to its excellent technical performance, especially in the grinding of cement clinker and slag, more and more vertical mills are used. . Today we share several factors that affect the operation and operation of vertical mills.
1. Characteristics of grinding materials
The characteristics of the grinding material mainly refer to the hardness, particle size, water content and grindability (Bond Gong index) of the material.
(1) The hardness of the grinding material
The hardness of the grinding material is usually characterized by the Mohs hardness (range 1-10), which varies with the type and content of the inclusions in the original ore. Generally speaking, the hardness of the material is high, the grindability is poor, and the wear is high, so the hardness of the material is directly related to the product output and the service life of the wear-resistant parts of the mill.
(2) The particle size of the grinding material
The particle size of the material can be reasonably controlled according to the fineness of the finished product. In principle, it is “more broken and less grinding”. The vertical mill has certain requirements for the particle size of the raw materials. Too large or too small particle size will destroy the gradation balance of the material layer on the grinding disc, which is not conducive to the normal operation of the mill. If the feed particle size is too large, the primary grinding efficiency will be reduced, the number of cycles of the material will be increased, and the grinding power consumption of the mill will be increased invisibly. When this problem is encountered in operation, appropriate material reduction should be carried out to stabilize the pressure difference and material layer of the mill. If the feed particle size is too small, the powdery material will inevitably increase. Due to the poor adhesion of fine particles and the effect of internal air flow, the fluidization trend of the material bed is obvious, so that the vertical mill cannot effectively bite into a large number of particle groups, resulting in material The layer is unstable, causing the mill to vibrate.
In the non-metallic mineral powder industry, the product fineness is generally relatively high. It is suggested that the control of the feeding particle size should be smaller (<30mm), which is more conducive to exert the ultra-fine grinding characteristics of the vertical mill and maximize the production capacity. Based on the debugging experience, the maximum particle size of the grinding material should not exceed 3% of the diameter of the grinding roller, and it can be appropriately controlled to be smaller.