Breakdown of gibbsite particles during calcination is one of the main contributor to superfines in smelter grade alumina. Understanding the breakage behaviour and mechanism can guide the controlling of superfine generation. Extensive work has been carried out to characterise SGA’s breakage, yet key challenge remains in understanding the breakage behaviour and mechanism.
In this study, internal morphology change of calcined gibbsite was studied by focus iron beam (FIB) – scanning electron microscope (SEM) and 3D tomographic images by phase segmentation. The formation of internal cracks at the bulk phase were found on particles without surface cracks. These results indicate that cracks are initiated in the bulk of crystallite, and grow towards the surface.