Impact of surface tension and viscosity on solids motion in a conical high shear mixer granulator



Surface tension and viscosity are the important properties of liquid binders affecting wet granulation processes. They could be used to control solids flow pattern and relative motion of particles for controlling wetting, granule growth, consolidation, and breakage. This study aims to investigate experimentally the impacts of the two properties with a conical high shear granulator. The results show significant effects of viscosity and surface tension on solids flow pattern and relative motion of particles. The relative importance of the two parameters, the surface tension and the viscosity, are found to vary with the axial and radial positions in the granulator. For example, the viscosity force decreases with an increase in the bed height in the axial direction (vertical plane). The viscosity force between particles coated with PEG4000 solution is in mN order, whereas that between particles coated with ethanol and water is in μN order. © 2009 American Institute of Chemical Engineers AIChE J, 2009