The ball mill is widely used to grind various ores and other materials in mining, building materials, chemical industries, etc. The ball mill can be divided into dry type and wet type according to the milling method; grid type and overflow type or center-discharge and side-discharge type according to the ways of discharge; bearing-mill and bearing pad millaccording to the different methods of supporting; rim drive and center drive according to the different ways of transmission. Large mill 3 meters above is especially configured with jack-up devices for easy maintenance; the dynamical pressure bearing and the static pressure bearing can operate stably.