Effects of process parameters on granules properties produced in a high shear granulator

Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder. The dried granules have been analysed for their strength, density and size distribution. The results show that increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. The underlying cause is an increase in granule density. Granules are consolidated more at higher impeller speeds. Moreover, the granule size distribution seems not to be affected significantly by an increase in impeller speed. Granules produced with high binder viscosity have a considerably lower strength, wide strength distribution due to poor dispersion of binder on the powder bed. Binder addition methods have showed no considerable effect on granule strength or on granule size distribution.

Research highlights▶ Higher impeller speeds give rise to more consolidation and compaction of granules and produce granules with high strength and low porosity. ▶ Increasing the granulation time has a great affect on granules strength, until an optimum time has been reached. ▶ Interaction of binder viscosity and impellers peed was explained using concept of Stokes number. ▶ Binder addition methods have showed no considerable effect on granule properties such as granule strength or on size distribution.