International Journal of Energy Research, Vol.44, No.6, 4861-4874, 2020
Synthesis of Ti(C, O, N) from ilmenite at low temperature by a novel reducing and carbonitriding approach
The clean and effective utilization of titanium-bearing minerals has challenged the titanium industry all over the world. In order to realize the high-efficiency, clean, and high value-added comprehensive utilization of ilmenite concentrate, a novel process has been proposed in this study by reducing and carbonitriding ilmenite with the CH4-N-2-H-2 gas mixture at low temperature. Carbonitride performance and mechanism have been investigated experimentally and theoretically. The obtained results showed that the reaction process could be divided into three stages: formation of metallic iron, reduction of titanium oxide to titanium suboxides, and formation of Ti(C, O, N). The metallic iron congregated at the first two stages, but dispersed once the Ti(C, O, N) formed. The effects of both reaction temperature and preoxidation treatment on the reaction have been studied as well. It was found that the increase of temperature was conducive to the formation of Ti(C,O), and the ilmenite could be reduced completely to Ti(C,O) at 1170 degrees C for 8 hours. The preoxidation treatment could improve the kinetics of reduction. At 1170 degrees C, the introduction of N-2 could apparently increase the reduction rate, with the complete reduction time decreasing from 8 hours in CH4-H-2 gas mixture to 3 hours in CH4-N-2-H-2 gas mixture. The proposed novel process has been assessed and it showed many potential advantages and feasibility.