Effect of Low-Carbon Atmosphere on Ti(C,N) Formation in Vanadium Titanomagnetite Blast Furnace

To support green transition of vanadium titanomagnetite blast furnace smelting, various low-carbon blast furnace atmospheres, including oxygen-enriched air injection (CO–N 2 ), oxygen-enriched H 2 -rich air injection (CO–H 2 ), and H 2 -rich air injection (CO–H 2 –N 2 ) were investigated to gain insight on the Ti(C,N) formation mechanisms. In this study, thermogravimetric analysis was first employed to investigate the kinetics of the TiO 2 reaction. Arrhenius-based kinetic modeling revealed that these reactions are primarily controlled by solid-state diffusion, and N 2 directly nitrides titanium oxides to TiN, and the activation energy decreases with increasing N 2 content. In contrast, H 2 lowers the activation energy of the reaction and promotes the reduction of TiO 2 to lower-valence oxides. Then, the carbothermic reduction of TiO 2 -bearing slags was investigated. Chemical composition analysis, XRD, and EPMA-WDS mapping demonstrated pronounced atmosphere-dependent variations in the formation of TiC/N phases. In CO–N 2 atmospheres, Ti(C,N) content decreases with increasing CO content and Ti(C,N) tends to agglomerate. With pure CO, only a few, sparsely dispersed TiC particles were detected. Whereas in CO–H 2 atmospheres, increasing the H 2 concentration markedly enhanced TiC formation, yielding uniformly dispersed particles with slight clustering. Therefore, the overall atmosphere effect on the amount of TiC/N formation follows the order: 100 pct CO < 80 pct CO–20 pct H 2  < 80 pct CO–20 pct N 2  < 60 pct CO–40 pct H 2  < 60 pct CO–40 pct N 2  < 30 pct CO–70 pct N 2 atmosphere (conventional blast furnace atmosphere). Graphical