Effect of sintering behavior and phase evolution on glass-ceramics entirely derived from ferrochrome slag and fluorite tailings

Abstract

The recycling of solid waste is widely regarded as the one of the most crucial issues of sustainability. This is particularly evident in the industrial sector, where the production of slags is huge and their handling presents a significant challenge. In this study, solid wastes from the industrial sector, namely ferrochrome slag (Fs) and fluorite tailings (Ft), were employed for the preparation of glass-ceramics by the sintering method. Three glasses were prepared by using the melt-quenching method, with a weight ratio of 60∼70 % Fs and 40∼30 % Ft (designated S30, S35, and S40, where the higher number indicates a greater Fs content). The sintering and crystallization behaviors of these glasses were characterized by hot-stage microscopy (HSM) and differential thermal analysis (DTA). It was observed that S40 glass exhibited a weak sintering capacity in comparison to that of S30 and S35 glass, which can be attributed to the robust crystallization propensity of S40 glass. The coarser glass frits were subjected to sintering experiments at varying temperatures, which demonstrates that the predominant crystalline phase is augite and that Cr2O3 remains present in all sintered samples. Besides, a transition of the Cr2O3 crystal into uvarovite was observed in S40 glass sintered at 1050 °C. The sintering time controlling experiment demonstrated that both wollastonite and the Ca-rich flow formed during sintering are vital for the formation of uvarovite. The formation of uvarovite can enhance the hardness of GCs. All GCs samples sintered at 1050 °C and 1120 °C exhibit comparable mechanical performance.