The particle mixing was studied in a cylindrical stirred tank with elliptical dished bottom by experiments and simulations. The impeller types used were double helical ribbon (HR) + bottom HR

pitched blade ribbon + bottom HR

inner and outer HR + bottom HR

and pitched blade ribbon + Pfaudler + bottom HR labeled as impellers I to IV

respectively. The quantitative correlations among the rotational speed

fill level and power consumption for impeller I and impeller Ⅱ were obtained by experiments to validate the discrete element method (DEM) simulations. The particle mixing at different operating conditions was simulated via DEM simulations to calculate the mixing index using the Lacey method

which is a statistical method to provide a mathematical understanding of the mixing state in a binary mixture. The simulation results reveal that as the rotational speed increases

the final mixing index increases

and as the fill level increases

the final mixing index decreases. At the same operating conditions

impeller Ⅲ is the optimal combination

which provides the highest mixing index at the same revolutions.