Estimation of Liner Design in a Tube Mill by Discrete Element Method

Abstract

Tube mills having four kinds of liner designs (MODEL I, II, III and IV) were modelled to evaluate the effect of liner design on the impact energy by the Discrete Element Method (DEM). The ball charge motion was simulated, and the impact energy of balls was calculated. The charge motions of MODEL I (duolift), III (step wave liner) and IV (lifter liner) were cataracting and cascading, and motion in MODEL II (steps) seemed to be cascading under the condition of N/N_C = 0.72 (N_C: critical rotational speed). MODEL I, III and IV gave larger impact energy than that of MODEL O (without liner). MODEL III had the largest E_n (normal component of impact energy) in all mills; and it was 32% superior to MODEL O. The distribution of E_n shifts to high-energy range when the mill had liner. The effective area for the grinding in MODEL I, III and IV were around toe of ball charge due to cataracting motion. Therefore, the grinding performance will be improved by the liner, especially design of MODEL III is the best according to this analysis.