The analysis of mixing performance of sand and gravel in a rotating drum by DEM

Material mixing in a rotating drum is a complex movement process, and the material mixing uniformity impacts product quality. The mixing of sand and gravel in the rotating drum was simulated by the discrete element method to study the quantitative relationship between the mixing uniformity and its influencing factors and analyze the mixing performance. The quantitative relationships between mixing uniformity and rotation speed of the rotating drum, material filling rate, and distance of rods inside the rotating drum were established based on the response surface method. Results indicate that the rotation speed of the rotating drum has the most significant influence on the mixing uniformity, followed by the distance of rods inside the rotating drum, and the material filling rate has a minor influence on the mixing uniformity. The interaction between the three factors significantly affects the mixing uniformity. The areas where the particles move in the rotating drum are divided into active and inactive areas. Rods inside the rotating drum can accelerate the movement of the particles in the inactive area, relieve particle segregation and promote particle mixing.