Mid-Alumina grinding balls refer to materials such as bauxite, roller powder, industrial alumina powder, and high-temperature calcined Alpha alumina powder as raw materials, after batching, grinding, milling (pulping, mud making), forming, and drying , Sintering and other processes, mainly used as a grinding medium and widely used ball stone. According to different alumina content, it can be divided into medium-aluminum balls, medium-high aluminum balls and high-aluminum balls. Generally, we classify those with 68% alumina content as medium-aluminum balls. Some types mainly made by hand by some special ceramic factories.