Modeling and Assessment of Ammonia Direct Reduction for Decarbonizing Iron Production
Xuesong Lu1, Dorcas Tuitoek1, Binjian Nie1
1Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, U.K.
ACS Omega
|July 24, 2026
Summary
Ammonia shows promise for green steel production, offering an alternative to hydrogen. A new model simulates ammonia reduction in shaft furnaces, optimizing conditions for high metallization and low nitridation rates.
Area of Science:
- Materials Science
- Chemical Engineering
- Metallurgy
Background:
- Ammonia is a viable low-carbon reductant for green steel, especially where renewable energy is scarce.
- Existing experimental studies lack a comprehensive model for simulating ammonia reduction in industrial shaft furnaces.
Purpose of the Study:
- To develop and validate a mathematical model for ammonia reduction of iron ore in a shaft furnace.
- To investigate the impact of process conditions and gas recycling on reduction efficiency.
Main Methods:
- Developed a 1D plug-flow model incorporating kinetics of ammonia decomposition, direct reduction, and nitridation.
- Included mass and heat transfer using a grain model at the pellet scale.
- Calibrated the model with Thermogravimetric Analysis (TGA) data and performed numerical simulations.
Main Results:
- Ammonia-based iron ore reduction is highly endothermic, requiring significant heat input.
- High inlet gas temperatures (>900 °C) promote high metallization and low nitridation.
- Gas recycling with a purge stream achieved >0.90 metallization and <0.10 nitridation.
Conclusions:
- The developed model accurately simulates ammonia reduction in industrial shaft furnaces.
- Optimized process conditions, including high temperature and gas recycling, are crucial for efficient green steel production using ammonia.
- This research provides insights for industrial reactor design and supply chain analysis for ammonia-based steelmaking.
