Effects of blender rotational speed and discharge on the homogeneity of cohesive and free-flowing mixtures.

The roles of blender rotational speed and blender discharge on the homogeneity of free-flowing art sand and of a cohesive placebo formulation were investigated in the tote blender. For three practical operating speeds, 6, 10, and 14 RPM, spanning the entire range of commercial equipment, the homogeneity of the free-flowing mixture was independent of rotational speed and blender size. On the other hand, the homogeneity of the cohesive pharmaceutical powder mixture was dependent on vessel rotational speed in a complex fashion, with 10 RPM producing a better final mixture than either 5 or 15 RPM. The homogeneity of the free-flowing sand mixture was preserved when discharged into a vertical bin, while the homogeneity of the fine pharmaceutical powder mixture significantly improved after discharge from the tote blender. Copyright 2002 Elsevier Science B.V.