Sep 13, 2017 Operating efficiency, based upon using operating work indices, is also a useful tool in comparing the variations in grinding mill operations such as mill speed, mill size, size of grinding media, mill discharge arrangements, liner designs etc. by David April 15, 2018 September 13, 2017 Categories Grinding Tags 998 Post navigation.Differences Between Vertical Grinding Mill and Ball Mill. 12. Vertical grinding mill has expensive wear parts, but compare with ball mill’s whole maintenance of mill, lifter, and classifier, it is stiller cheaper and simpler than ball mill. The above are the main differences between vertical mills and ball mills.