Ammonia Direct Reduction of Iron Oxides — Kinetics Aspects and Process Development

Ammonia (NH3) has recently gained considerable interest as an alternative low-CO2 reductant in ironmaking. Compared to the use of hydrogen, ammonia offers advantages such as a significantly lower liquefaction temperature and higher hydrogen density for efficient storage and transportation without dissipating. The authors’ previous thermodynamic analysis concerning ammonia reduction of iron oxides showed that reduction at low temperatures (T < 850°C) represents a highly promising technique for decarbonizing the ironmaking industry. This article continues the authors’ investigations and discusses the reaction kinetics based on experiments in a thermogravimetric vertical resistant tube furnace in NH3 atmospheres at 650-850°C. Preliminary process development required for the further advancement of ammonia ironmaking is also discussed.