Synthesis of MgAl2O4 Powder in KCI-LiCl-KF System Molten Salt

Molten salt synthesis of MgAl2O4 powder from industrial alumina and light calcined MgO in KCl, LiCl, and KCl-LiCl media, and the influence of KF at 500-1 000 ℃ were investigated. Synthesized powders were characterized by means of XRD, laser particle analyzer, and SEM, and the synthesis mechanism of MgAl2O4 was discussed as well. The results show that (1) the molten salt composite (KCl-LiCl) is more favorable for the synthesis of MgAl2O4 than single molten salt (LiCl or KCl), and LiCl is more favorable than KCl; (2) KF can accelerate the formation of MgAl2O4 and decrease its forming temperature; (3) synthesis of MgAl2O4 powder in the molten salts without KF is controlled by "template-growth" mechanism, but in the molten salts with KF, it is controlled by "template-growth" and "dissolution-precipitation" mechanism.