Abstract: In order to reduce the ball milling medium consumption and grinding power consumption in the second-stage grinding operation of Sizhou concentrator，aiming at the shortcomings of high selfconsumption and high grinding power consumption of traditional grinding medium steel balls in the grinding process，the experimental study on the substitution of alumina ceramic balls for steel balls was carried out. Through the ratio test of alumina balls with different ball diameters in the laboratory and the compari⁃ son test of grinding medium filling rate in the production site，it is concluded that when the mass ratio of ball diameters of 35 mm and 25 mm are 6∶4 and the filling rate of grinding medium is 36%，the content of -0.074 mm in grinding products is the highest and the grinding process is the most stable. By analyzing the comparative test data of steel ball and alumina ball production，it can be seen that alumina ball can reduce the unit consumption of grinding power by about 30% and the unit consumption of medium by 66%. The economic benefit is remarkable and has the value of popularization.

Key words: second stage grinding, alumina ball, energy consumption, grinding medium, economic benefits