Study on the influence of the discharge end cover structure of SAG mill on the discharge capacity

Abstract

The SAG mill’s discharge end cover, which comprises the slurry lifters, the grate liners, and other structures, significantly impacts the machine’s discharge capacity. The working performance of the current SAG mill when the radial structure and arc structure were adopted in the lifting bars of the grate liners and slurry lifters, respectively, was compared to investigate the influence of the discharge end cover structure on the discharging capacity and optimize the design of the end cover structure. Additionally, a new arc structure for the lifting bar was designed. The discharge process of the ore particles passing through the discharge end cover in the SAG mill was simulated using the discrete element method (DEM). The analysis included the discharging rate, discharging efficiency, and flow characteristics of the ores under the three lifting bar structures, as well as the impact of the lifting bar structure and the arrangement of the discharge holes of grate liners on the discharging capacity. The results demonstrate a positive correlation between the effective discharge hole area of grate liners and discharge rate. When adopting the arc lifting bars, the grate liners have a larger effective discharge hole area and a stronger discharge capacity than the radial lifting bars. The new design arc structure for lifting bars largens the effective discharge hole area and enhances the discharge capacity of the grate liners when compared to the original arc structure of lifting bars. The ore particle backflow phenomenon will be evident in the discharge process of the slurry lifters when the lifting bars of the slurry lifters adopt a radial structure; on the other hand, the arc structure can effectively mitigate the backflow issue and increase the discharge rate. Based on the observation that the arrangement of discharge holes on the grate liners greatly affects the discharging rate of the grate liners, a strategy for arranging the discharge holes is suggested to maximize the discharging capacity of the SAG mill. In addition, a comparison between the findings of the discrete element simulation and the experimental data confirms the viability of the simulation approach.