Determining an Appropriate range for the Number of Cuboid Lifters in Ball Mills using DEM

The number of lifters in the liner of ball mills and the mill rotation speed are among the most significant factors affecting the behavior of grinding charge (balls) and their motion trajectory, and consequently, the comminution mechanism in these mills. In this research, in order to find a suitable range for the number of lifters in the liner of ball mills, the DEM method is utilized. Initially, a pilot-scale ball mill with dimensions of ۲.۰ m × ۱.۱۱ m without any lifter is simulated. Afterwards, by adding, respectively, ۱, ۲, ۴, ۸, ۱۶, ۲۰, ۲۶, ۳۰, and ۳۲ cuboid lifter(s) with dimensions of ۲ m × ۵ cm × ۵ cm, nine other separate simulations are performed. The influences of the number of cuboid lifters on the two new factors introduced here, namely ‘head height’ (HH) and ‘impact zone length’ (IZL) at various mill speeds, that is, ۷۰% and ۸۰% of its critical speed (CS) are investigated. The results indicate that in order to find a suitable range for the number of lifters in the liner of ball mills, it is necessary to consider these two parameters simultaneously as the criteria for selecting the appropriate range, That is, liners that simultaneously produce both a higher HH and a greater IZL are more suitable for use in the industry. The results also demonstrate that the suitable range for the number of cuboid lifters in the liner of ball mills is between ۱۶ and ۳۲, which field research on the ball mills of three different plants in the industry confirms the accuracy of the results obtained in this research. Unlike the previous research works, it has now been shown that the number of ball mill lifters does not only depend on the diameter of the mill but also depends on the width, height, angle of the lifter, and generally on the type of lifter.

Keywords:

DEM simulation , ball mills , Number of Lifters , Head height (HH) , Impact zone length (IZL)