High-Temperature Hydrogen Reduction of Bauxite Residue for Iron Recovery

This paper is written by Arman et. al. and published in the proceedings of the 61st Conference of Metallurgists, Springer (978-3-031-17425-4).

In order to develop a low-carbon footprint process for industrial waste valorization of bauxite residue (BR), the hydrogen reduction of a mixture of BR (61 wt.%) and limestone (39 wt.%) was studied for the purpose of simultaneous production of iron and calcium aluminates. In this research, pellets were made and subsequently sintered at 1200 °C. The pellets were then reduced in pure hydrogen in a vertical tube furnace at 1170 °C, where hydrogen was introduced from the bottom to the pellets bed. The products of the reduction were characterized by X-ray diffraction (XRD) technique, which revealed the reduction of iron oxide phases to metallic iron. The co-existing phases were found to be 12CaO.7Al2O3 (Mayenite), CaSiO4, and CaTiO3 phases. Results indicated the fluxing of the BR by lime prevented the iron trapping in aluminate phases and hence all the iron contents can be reduced to metallic iron. Microstructural analysis was done by electron microscopy (SEM) on the sintered pellets and the corresponding reduced pellets. The preliminary results presented in this paper indicated the feasibility of iron production out of BR by this method.

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