Discrete particle simulation for mixing of granular materials in ribbon mixers: a scale-up study

This work presents a numerical study of particle mixing and scale-up of ribbon mixers with four sizes (mixer A - 5.62 L, mixer B - 49.02 L, mixer C - 142.91 L, and mixer D - 482.32 L). The results show that the mixing performance becomes worse with the mixer size increasing. A correlation is proposed to predict the mixing rate as a function of the scale-up ratio and Froude number. The top-bottom initial loading condition of granular materials mix much faster than the side-side and front-back loading conditions. With the mixer size becoming larger, the total mixing time increases significantly. The power consumption per unit mass for the four mixers is in this order: mixer A > mixer D > mixer C > mixer B. The results suggest that scale-up is necessary to save mixing time and power consumption and reduce additional operating costs such as labour and down-time.