Investigation of mixing homogeneity of binary particle systems in high-shear wet granulator by DEM

Abstract

To provide a theoretical foundation and a good understanding for the real manufacturing granulation process, this paper investigates the effect of particle properties on the mixing process in the high-shear wet granulator, a common equipment in one of the key technologies in the growth of the pharmaceutical industry that has rarely been used to examine particle mixing-related problems in previous numerical simulations. The discrete element method (DEM) and the relative standard deviation (RSD) to explore binary particle systems with a range of sizes, densities, and volume fractions, and measure the mixing homogeneity of the particles. Results show that, for binary particle systems, particle size, density, and volume fraction all significantly affect mixing homogeneity, with good mixing occurring for a single size and a 1:1 volume fraction for the same density. Similar Brazil nut effect and Reverse-Brazil nut effect occurrences were discovered for many particle systems at various stages. There is a size threshold for a given binary particle system. Then, in a binary system, particles of a single size and density had nearly similar vertical driving forces, and these forces may vary by up to 10 times with changes in size or density. In the end, granular temperature rises with radial position and reaches its highest point at the pelletizer’s wall and the top of the impeller. Density has less of an impact on granule velocity fluctuation than size.