Promoting the reduction reactivity of magnetite by introducing trace-K-ions in hydrogen direct reduction

Abstract

Hydrogen metallurgy exhibits considerable potential for application in the steel industry. However, it is restricted by the low utilization efficiency of hydrogen owing to the poor kinetic conditions and low reduction efficiency, which limit the development of ironmaking via hydrogen direct reduction. Therefore, improving the reduction efficiency of hydrogen direct reduction is critical. In this study, the reactivity of magnetite was considered. The impregnation of trace K+ (0.8 wt%) was found to significantly promote the reduction efficiency, and a possible mechanism was proposed. The increase in the metallization ratio from 88.51% to 99.43% indicated that the 0.8 wt% K+-promoted magnetite exhibited an improved reaction efficiency due to its higher reactivity. Furthermore, modified magnetite reacted under a broader range of gas conditions, e.g., the partial pressure of hydrogen could be reduced to 57%. According to the refined X-ray diffraction patterns, the promotion of the reduction reactivity could mainly be attributed to the increased Fe–O bond polarities, in addition to the solid-state diffusion of O2−, due to the formation of more oxygen vacancies. An enhanced reduction efficiency during hydrogen direct reduction was realized, which could provide promising guidance for the green, sustainable development of hydrogen direct reduction.