LAUSR

Limiting the cracking of gibbsites during calcination can reduce the content of ultrafine particles in the smelter grade alumina product and increase the quality of products. However, the investigation on the cracking behaviour and mechanism of gibbsites during calcination remains a challenge. In this study, we focus on the cracking behaviour and mechanism of gibbsite grain boundary during calcination. We first observe the cracking behaviour of the gibbsite grain boundary during calcination and propose a cracking mechanism. Based on the observed crack evolution at the gibbsite grain boundary, we found that the cracking of gibbsite grain boundary is initiated on the surface of particles, and then the cracks grow into the inner side of particles with the calcination. We also investigate the impact of the crystallite size and the c-axis angle between crystallites on gibbsite grain boundary. As a result, the increased crystallite size and the c-axis angle between crystallites can result in increased crack size at the gibbsite grain boundary.