Effects of H2, CO, and a gas mixture on the reduction process of raw and pre-oxidized ilmenite concentrate powders

Herein, we reduce raw and pre-oxidized ilmenite concentrates by H2, CO, and a gas mixture (H-2/CO = 1) at different temperatures. The results show that the reduction rate of both concentrates increases with increasing H2 concentration. Furthermore, the reducing ability of the three types of reducing gases increases in the order of CO < H-2 < gas mixture. Moreover, we elucidate the coupling effect of H-2-CO on the reduction process and propose a comprehensive utilization index for hydrogen-rich reduction gas. The results indicate that H-2-CO coupling plays a positive role in both the concentrate reduction processes, improving the reduction rate and gas utilization efficiency. The maximum reducing gas comprehensive utilization indices for the hydrogen-rich reduction of the raw and pre-oxidized ilmenite concentrates are observed at 1000 and 950 C, respectively. Additionally, changing the reducing atmosphere and pre-oxidation treatment significantly affects the distribution of metallic iron in the product particles.