nhi has been producing various kinds of mills since 1950s, especially in the 1980s,by taking the opportunity of national reform and opening-up policy, nhi began to cooperate with foreign famous ball mill manufacturers to produce and introduced technology, such as the united statesa-ccompany, foster wheeler, mpsi company and france stene alstom. by means of cooperative production and technology introduction, the advanced technology of foreign ball mill is digested and absorbed, combined with the technical advantages of our company, the mill with large diameter and large specifications with independent intellectual property rights is gradually produced on the basis of the original innovation. from the originalφ4m ~ φ6m series, ag (sag) mills are gradually developed into φ6.4m, φ7m,φ7.5m,φ8m,φ8.53m,φ8.8m,φ9.15m,φ9.75m,φ10.37m,φ11m,φ12.2 m diameter series etc.