This paper focuses on the study of current knowledge regarding the use of hydrogen as a reducing agent in the metallurgical processes of iron and steel production. This focus is driven by the need to introduce environmentally suitable energy sources and reducing agents in this sector. This theoretical study primarily examines laboratory research on the reduction of Fe-based, metal-bearing materials. The article presents a critical analysis of the reduction in iron oxides using hydrogen, highlighting the advantages and disadvantages of this method. Most experimental facilities worldwide employ their unique original methodologies, with techniques based on Thermogravimetric analysis (TGA) devices, fluidized beds, and reduction retorts being the most common. The analysis indicates that the mineralogical composition of the Fe ores used plays a crucial role in hydrogen reduction. Temperatures during hydrogen reduction typically range from 500 to 900 °C. The reaction rate and degree of reduction increase with higher temperatures, with the transformation of wüstite to iron being the slowest step. Furthermore, the analysis demonstrates that reduction of iron ore with hydrogen occurs more intensively and quickly than with carbon monoxide (CO) or a hydrogen/carbon monoxide (H2/CO) mixture in the temperature range of 500 °C to 900 °C. The study establishes that hydrogen is a superior reducing agent for iron oxides, offering rapid reduction kinetics and a higher degree of reduction compared to traditional carbon-based methods across a broad temperature range. These findings underscore hydrogen’s potential to significantly reduce greenhouse gas emissions in the steel production industry, supporting a shift towards more sustainable manufacturing practices. However, the implementation of hydrogen as a primary reducing agent in industrial settings is constrained by current technological limitations and the need for substantial infrastructural developments to support large-scale hydrogen production and utilization.
This article examines the low-temperature reducibility of four types of iron ore pellets in a pure hydrogen atmosphere, with the aim of understanding the thermodynamic aspects of the process. The research focuses on optimizing conditions for pellet reduction in order to reduce CO2 emissions and improve iron production efficiency. Experimental tests were conducted at temperatures of 600 °C and 800 °C, supplemented by thermodynamic simulations predicting the equilibrium composition and energy requirements. Chemical and microstructural analyses revealed that porosity, mineralogical composition, and phase distribution homogeneity significantly affect reduction efficiency. High-quality pellets with low SiO2 content demonstrated the best reduction ability, while fluxed pellets with the presence of calcium silicate ferrites and pellets with a higher content of SiO2 showed lower reduction potential due to the presence of hard-to-reduce phases such as calcium silicate ferrites and iron silicates. The results highlight the importance of controlling process conditions and optimizing pellet properties to enhance the reduction process and minimize environmental impacts. This study provides valuable insights for the application of hydrogen reduction in industrial conditions, contributing to the decarbonization of the metallurgical industry.