DISCRETE ELEMENT METHOD – COMPUTATIONAL FLUID DYNAMICS MODELLING OF FLOW BEHAVIOUR IN A STIRRED MILL – EFFECT OF OPERATION CONDITIONS

摘要

Stirred mills are increasingly used in the mineral industry for a range of milling duties from fine tocoarse grinding. This work investigated the particle and fluid flow in a stirred millusing a combineddiscrete element method (DEM) and computational fluid dynamics (CFD) approach. The effect ofoperation conditions such as millloading and disc rotation speed was studied. The flow propertieswere analysed in terms of flow velocity, power draw, collision frequency and collision energy. Bothparticle and fluid flows showed different flow patterns at different millloadings. Higher mill loadingshowed an increased collision frequency and decreased collision energy within the particle flow.The regions with high impact energy were also observed near the disc and mill chamber at a highloading. Both collision energy and collision frequency increased with increasing mill speed. Energyconsumption increased faster with mill loading than total impact energy, which reduced mill energyefficiency. The results obtained for the particle-fluid system were qualitatively comparable withthose obtained from dry systems under similar operating conditions. The findings would be useful tounderstand and optimise operation condition for improved grinding performance.