AN X-RAY TOMOGRAPHY STUDY OF THE EFFECT OF PROCESSING TIME ON GRANULE STRUCTURE IN HIGH SHEAR MELT GRANULATION

摘要

X-ray tomography was used to evaluate the effect that granulation time has on the internal structure of granules made from comminuted limestone and polyethylene glycol; in a vertical-axis high-shear mixer. The presence of a core of melting binder was observed at the earlier granulation times and due to the low impeller speeds the cores were still present after granulation times of up to 15 minutes. The presence of a core of binder proves that immersion is the prevalent nucleation mechanism in the experiments performed. When the impeller speed is increased the core of binder is squeezed towards the surface of the granules and disappears.