Reduction of Basic Iron Ore Sinter under Blast Furnace Wall and Center-Simulated Conditions in CO–CO2–H2–H2O–N2 Gas

Abstract

Abstract

This study examines how varying conditions at the center and wall of a blast furnace (BF) impact the reduction of iron ore sinter in a gas containing hydrogen and water vapor. Sinter samples are isothermally reduced at 700–1100 °C using a BF simulator to assess reduction rates and extent. Characterization techniques analyze the reduced samples’ mineralogical, physical, and microstructural changes. Results indicate that metallic iron formed at 700 °C in samples reduced under BF center conditions but is absent up to 900 °C in BF wall conditions. Metallic iron is initially formed at the periphery and propagated inward as temperature increased. The sinter's non-homogeneous structure hinders uniform gas diffusion, with unfused iron ore content obstructing reducibility. The skeletal density of reduced samples correlated with the degree of reduction. The reduction of magnetite to metallic iron through wüstite is observed. Wüstite reducibility was better than calcium ferrite. No carbon deposition is observed in all testing conditions. Comparisons to acid iron ore pellets suggest charging the sinter to the BF center and pellets to the wall, with a recommendation to minimize unfused iron ore in the sinter charge for improved reducibility.