(211d) Direct FeCO3 Reduction with H2

The iron- and steel industry has a huge potential for reduction of CO₂ emissions [1]. Direct reduction of siderite ore (FeCO₃) to elemental iron may make use of H₂, cutting down CO₂ emissions by up to 60 %.

Direct FeCO₃ reduction with H₂ was investigated in terms of FeCO₃ conversion and the amount of elemental Fe in the solid product. Five factors were tested for their influence on the reduction of a FeCO₃-ore from the Erzberg in Austria: process temperature, particle size, initial mass of the ore, gas flow and hydrogen concentration. The reaction kinetics were investigated with models from Khawam and Flanagan [2].

The investigation of direct FeCO₃ reduction with hydrogen was based on Design of Experiments. The factors process temperature, particle size, gas flow and the interaction of gas flow*temperature and gas flow*gas flow were identified as strong impact on FeCO₃ conversion. The sigmoidal curve of the A4 model (Avrami-Erofeyev) [2] represents the experimental data of FeCO₃ conversion vs. time best. The limiting effect of the temperature on maximum FeCO₃ conversion was included in the model.

The information on the process parameters and the reaction rate law is needed for process and plant design for direct FeCO₃ reduction with H₂.

[1] M. A. Quader, S. Ahmed, R. A. R. Ghazilla, S. Ahmed, and M. Dahari, “A comprehensive review on energy efficient CO2 breakthrough technologies for sustainable green iron and steel manufacturing,” Renew. Sustain. Energy Rev., vol. 50, pp. 594–614, 2015.

[2] A. Khawam and R. D. Flanagan, “Solid-State kinetic Models: Basic and Mathematical Fundamentals,” J.Phys.Chem.B, vol. 110, no. 35, pp. 17315–17328, 2006.