In this paper, we proposed a novel method to prepare MgO-Al₂O₃-SiO₂ (MAS) glass-ceramics through direct heat treatment with the slag of laterite ore. First, the Ni-Fe alloy and slag glass were prepared simultaneously by this method, and the yield rate of Ni-Fe alloy was up to 95.69%. Then, the MAS glass-ceramics can be obtained by direct heat-treating for the slag glass. The energy consumption of glass-ceramics production was much lower than that in traditional method to make full use of the thermal energy of the molten slag. The crystallization behavior of the glass-ceramics was investigated by XRD, DSC and FESEM. The results demonstrate that many phase-separated droplets appear in the slag glass. During the heat treatment, the phase-separated droplets as favorable nucleation sites to inducing crystallization. The crystallinity and crystallite size of the samples exhibits an increasing tendency with the increase of heat treatment temperature and time.
The crystalline phases of glass-ceramics were two different compositions magnesium aluminum silicates (MgAl₂Si₄O₁₂ and (Mg,Al)SiO₃). The activation energies of the slag glass were calculated by Kissinger and Ozawa method, which were 308.81 and 309.36 kJ·mol^-1, respectively. And the crystallization mechanism of the glass-ceramics was dominated by both the surface crystallization and bulk crystallization with one-dimensional growth.

Keywords: Slag of laterite ore, Droplet phase separation, Crystallization, Glass-ceramics