An Overview of H2 and CH4 as Environmentally Sustainable Alternative Reductants to C for Chromite Smelting

Abstract

The application of hydrogen (H₂) and methane (CH₄) as gaseous reductants for pure chromite (FeCr₂O₄) is reviewed in four theoretical approaches. These approaches are evaluated against the conventional process, where the sole reductant is a solid carbon (C) source. The sustainability is measured by gaseous carbon monoxide (CO(g)) formation, determined by the reaction stoichiometry of each theoretical approach. Decreased CO(g) formation is critical for alleviating the adverse environmental impact of ferroalloy production. The prereduction of FeCr₂O₄ by H₂, followed by reduction by CH₄ shows the largest decrease in CO(g) formation, i.e., a 75% decrease, compared to the conventional process. Furthermore, the H₂-based prereduction and CH₄-based primary reduction occur at lower temperatures than C-based reduction, due to kinetic advantages, and thus decrease energy consumption. The overview discusses the environmental impact of substituting C with H₂ and CH₄ and briefly discusses how it can be implemented in industry.