(536c) Novel Technique for Improving Granular Mixing in Rotating Cylinders

Granular materials are widely used in industries such as cement, fertilizers, pharmaceuticals, construction, mining, and agricultural. Rotating cylinders are commonly used in the chemical and process industries as kilns, mixers, dryers, reactors, and granulators to process granular materials. Good cross-sectional mixing in the cylinders is important for product quality and efficient operation in terms of energy usage for continuous flow systems. Granular mixtures of particles with different properties (e.g., size, density) tend to spontaneously segregate. In this work, we study the radial segregation, transverse and azimuthal mixing in a rotating cylinder with an impeller. The radial profiles are obtained by sampling. Results are analyzed qualitatively with the profiles and quantitatively with mixing index, quantified in terms of segregation index which is a measure of relative proportion of small particles in the segregated core in an arbitrary segregated state to complete segregated state. Digital images are taken to qualitatively study the improvement of mixing for a cylinder with and without a rotating impeller. At a given impeller and cylinder speed, the extent of mixing was found to increase with increasing size of the impeller. For a given impeller size, the extent of mixing was found to increase with increasing speed of impeller rotation. No improvement of extent of mixing for regular pentagon as compared to circular geometry was observed.