Batch vs. Continuous Blending of Segregating Blends and the “Oka Ratio”
Sarang Oka, Ph.D.
Thursday June 30th 2016 @ 1PM EST
Binary powder mixtures with variable segregation tendencies were “mixed” in a tumbling batch blender and in a continuous convective tubular blender. The degree of homogeneity of the final blend obtained from the continuous blender was found to be much higher than that from the batch V-blender. A direct relationship was observed between the segregation index of freely-flowing mixtures and a new material property metric, the “Oka Ratio”, defined as the ratio of the median particle size and bulk density of the ingredients that constitute the mixture. Moreover, for freely flowing materials, the extent of non-homogeneity at the end of a batch blending process was found to be proportional to the segregation index of the mixture and thus consequently proportional to the material property metric. Results demonstrate the superior capability of continuous blenders compared to batch blenders in their ability to homogenize segregating mixtures.