Under the condition of the same feed particle size, the production capacity of the ultrafine vertical mill decreases with the increase of the fineness of grinding products. The finer the grinding product requirements, the more the productivity decreases. 

It should be noted that when the grinding products are required to be coarse, the variation of mill productivity with feed particle size is obvious, while when the grinding products are required to be fine, the variation of mill productivity with feed particle size is not very prominent. 

When the feeding particle size, i.e. the grinding particle size, is small, the grinding fineness is easy to achieve. However, the fineness and productivity are contradictory. 

However, for the coarse grinding process, the influence of the fineness change of grinding products on the mill productivity is not as obvious as that of fine grinding.