Abstract:In order to solve the problems of low content of qualified particle size, high content of over-ground product in first grinding stage, and low copper recovery in the No. 1 beneficiation plant, Dahongshan copper mine, Yuxi Mining Co., LTD. The optimal ratio of steel ball in the mill was derived on the properties of feed, the semi-theoretical formula of ball diameter and the principle of accurate make-up ball, and the laboratory tests and industrial tests were carried out. The initial loading scheme of steel balls as m(Φ70)︰m(Φ50)︰m(Φ40)︰m(Φ30)=15︰25︰35︰25 was deduced according to the above parameters, and the results of both the laboratory tests and industrial tests shown that this scheme can increase the content of -0.020+0.010 mm selectable particle size and -0.074+0.018 mm easily selectable particle size, meanwhile the phenomenon of overgrinding was effectively reduced. In addition, the research can reduce the media loss, improve the recovery rate of copper concentrate and realize the destination of cost reduction and efficiency increasing.