Effect of Temperature on CH₄/CO Carburization Process of Hydrogen‐Based Direct Reduced Iron Pellets

Abstract

Cementite (Fe3C) has a high combined‐carbon content, which not only increases the carbon content but also provides a heat source and shortens the smelting time. Besides, the CO generated by carbon oxidation can stir the molten pool. It is beneficial to the formation of foaming slag and the removal of inclusions. To study the formation behavior of cementite and surface‐deposited carbon during the carburizing process of hydrogen‐reduction pellets under different conditions, the effects of temperature and carburizing gas composition on the carburizing rate of hydrogen‐reduction pellets are studied. The results show that the carburization rate of CH4 gas is proportional to the carburization temperature. The carburization rate of CO gas is inversely proportional to the temperature, and almost no carburization occurs at 900 °C. The contents of cementite and deposited carbon in different weight gain samples are compared by X‐ray diffraction (XRD) refinement and high‐pressure air gun injection. The analysis revealed that CH4 gas is easier to form deposited carbon in the later stage of carburizing at 900 °C. It provides a theoretical basis for the control of the carburization behavior of hydrogen‐based pellets.