Effect of gas mixtures on the reduction and carburization behaviors of vanadium titanomagnetite pellets in H ₂ -CO-CH ₄ -H ₂ O-CO ₂ -N ₂ atmospheres

The reduction and carburization behavior of vanadium titanomagnetite pellets in gas-based shaft furnace is critical for enhancing the smelting efficiency of vanadium titanomagnetite. The effects of CH 4 , H 2 O and CO 2 on the metallization rate, cementite (Fe 3 C) content and free carbon content of direct reduced iron (DRI) were investigated under a simulated gas-based shaft furnace atmosphere (H 2 -CO-CH 4 -H 2 O-CO 2 -N 2 ). When the CH 4 content is in the range of 3% to 9% and the CO 2 content is within 0% to 5%, the metallization rate of DRI consistently exceeds 91.90%. As the H 2 O content increases from 0% to 5%, the metallization rate of DRI varies between 89.21% and 95.36%. The contents of Fe 3 C and free carbon increase as the CH 4 content increases and the H 2 O and CO 2 content decrease. When the CH 4 content exceeds 7%, the cementite content surpasses 21.75%. Besides, the microscopic and macroscopic characteristics of the DRI were also analyzed using a digital microscope and a scanning electron microscope in this paper.