Potential application of Bayer alumina with high Na2O content

Abstract

Bayer alumina with high Na2O content is hardly used. In this paper, Bayer alumina with a pseudomorphic structure was used as raw material, which is pressed and sintered at high temperatures without any sintering aid. The effects of Na2O content on the densification behavior, microstructure, and physical properties of the pseudomorphic structure were studied. Bayer alumina with high Na2O content is often used as a low-grade raw material because Na2O inhibits the densification process of spherical Bayer alumina particles. However, the sintering mechanism of Bayer alumina particles with pseudomorphic structure is significantly different from that of spherical Bayer alumina particles. With the increase of Na2O doping amount, the linear shrinkage increases, and the degree of densification decreases. Tabular grains grow in the pseudomorphic structure, forming an interlocking network structure, inhibiting pore shrinkage and significantly improving mechanical properties. This study provides a theoretical basis for the rational application of low-grade Bayer alumina with high Na2O content and realizes the high-value utilization of low-cost materials.