Scaling up studies for mixing of granular materials in rotating drums

This study investigates the mixing of granular materials for rotating drums of different volumes which vary from 6.28 L to 402.12 L. Two groups of case studies are considered: Group I (constant particle diameter, d) and Group II (constant ratio of drum diameter to particle diameter, D/d). The results show that for Group I, the mixing performance deteriorates with drum size increasing. A correlation as a function of scale-up ratio and Froude number is proposed for mixing rate prediction. For Group II, at a constant Froude number, particle flow patterns and mixing performance are similar. The results also demonstrate that the scaled particle travel distances and displacements are affected by the ratio of D/d. For Group I, the scaled particle travel distances and displacements become more restricted as drums become larger, causing a delay in mixing. For Group II, similar particle travel distances and displacements are observed, hence the similar mixing performance.