Mitigation of CO2 Emissions Via Direct FeCO3 Reduction with Hydrogen

CO₂ breakthrough technologies are solver strategies that aim at reducing CO₂ emissions. In this regard, direct reduction of iron ore with hydrogen has great potential. Hydrogen is able to directly reduce siderite (FeCO₃) to elemental iron. The prove of concept for the direct reduction of siderite with hydrogen is shown in [1], [2]. A major question for the implementation of this technology is providing hydrogen for the reduction. For a first implementation the solution could be coker gas. Coker gas has hydrogen contents between 58-65%. By using coker gas, establishing the direct reduction of iron carbonate could be accomplished alongside the state of the art blast furnace process, which would provide a steady hydrogen supply.

We tested different gas compositions emulating coker gas in a bench scale fixed bed reactor. The main focus was placed on the methane content in the coker gas (15-25%). We found that methane in combination with hydrogen does not limit the reducing ability of hydrogen for siderite reduction; it is slightly reactive on its own. This means coker gas is a possible hydrogen source for the direct reduction of siderite.

[1] G. Baldauf-Sommerbauer, S. Lux, and M. Siebenhofer, “Sustainable iron production from mineral iron carbonate and hydrogen,” Green Chem., vol. 18, no. 23, pp. 6255–6265, 2016.

[2] S. Lux, G. Baldauf-sommerbauer, B. Ottitsch, A. Loder, and M. Siebenhofer, “Iron carbonate beneficiation through reductive calcination – Parameter optimization to maximize methane formation,” Eur. J. Inorg. Chem., no. 13, pp. 1748–1758, 2019.