A new approach to optimising the life and performance of worn liners in ball mills: Experimental study and DEM simulation

Abstract

The need to improve and sustain the capacities of grinding mills over a longer time while mitigating the operating costs, is of prime concern in the milling industry today. This has emerged in the wake of escalating costs of liner material and increased mill down times alongside power expenditures. One possible way of addressing this issue is through proper design and selection of liners/lifters. The practice in the industry has hitherto been to rely on experience for liner selection, which limits the possibility of applying novel techniques that may enhance mill performance. Our recent experience suggests that there is an opportunity to improve the liner performance and life using retrofits. However, the challenge lies in selecting an efficient profile and configuration for the retrofits. The Discrete Element Method is emerging as a tool that holds possibilities for exploration of various profiles by simulation. This paper presents an experimental investigation and the corresponding numerical simulation of a new approach of optimising the performance of liners over an extended life period. An integrated aim is to assess the ability of 3D DEM simulator to model the effect of lifter profile on mill load behaviour and hence its potential as a tool for design optimisation of mill liners. Two liner profiles, bevel and bevel retrofitted with detachable cone-shaped lifters are utilised in the investigation. A comparison of the measured to the simulated results shows a fairly good match in terms of load position and power draw at sub-critical speeds. In both cases there is a discernible improvement in mill load behaviour and power draw with the optimised liner which clearly indicates the benefit of liner retrofits.