Quantitative characterization of mixing of dry powders in V‐blenders

Abstract

Experiments were conducted to determine the effect of rotation rate, fill level, and total number of revolutions on the mixing performance of a V‐blender. The experiments were performed using 66‐μm red and green glass beads. Mixture uniformity was quantified after each experiment by infiltrating the mixtures with a binder, and using image analysis to examine slices of the solidfied mixture. The mixing rate (as a function of total revolutions) was not affected by changing the rotation rate between 8 and 24 rpm. The mixing rate increased significantly as the fill percentage was decreased from 60% to 40% of the total vessel volume. In a symmetric blender such as a V‐blender, the rate of mixing is limited by the rate of mass transfer across the vessel plane of symmetry orthogonal to the axis of rotation. A one‐parameter model based on the amount of material that crossed the plane of symmetry per revolution displayed good agreement with the experimental data.