Chemical Equilibrium and Energy Consumption Analysis on Biomass and Iron Oxides Direct Reduction Ironmaking Process

Biomass ironmaking is crucial for carbon reduction in the ironmaking industry. To understand this process better, the iron production capacity and energy requirements of biomass were studied. A thermodynamic equilibrium model and energy consumption model for the biomass and iron oxide reduction system at 100–1300 °C was established by the minimum free Gibbs energy method. The effects of factors such as biomass type, temperature, and initial amount of iron oxide on the system were analyzed. The research results indicated that the maximum ironmaking capacity of biomass was determined by the element content of carbon, hydrogen and oxygen in biomass and temperature. The equilibrium H2/(H2 + H2O) and CO/(CO + CO2) at the maximum iron yield were affected not by the biomass species and element content, but by temperature. The reduction capacity of the ten selected biomass types decreased with a temperature increase from 700 °C to 1300 °C. For the 1 kg of pine sawdust and iron oxide system, the maximum equilibrium state amount of metallic iron was 23.05 mol at 718 °C, and the minimum system energy consumption per ton Fe was 1.16 GJ at 800 °C and 1.18 GJ at 900 °C. These research results will provide a key basis for a deeper understanding of the intrinsic mechanism of biomass ironmaking.