The utilization of bauxite residue (BR) through iron oxide reduction and leachable alumina phase
formation by hydrogen reduction were studied experimentally. Three different types of pellets were
made: one from bauxite residue, and the other two via calcite addition with varying CaCO3 amounts.
All pellets were isothermally reduced by H2 gas in a thermogravimetry furnace at constant temperature
under fixed hydrogen flow rate and retention times. X-ray diffraction (XRD) and Scanning electron
microscopy (SEM), coupled with Energy dispersive spectroscopy (EDS), were used for the phase
and microstructural analysis. It was found that the formation of dominant phases during reduction is
dependent on the reduction temperature and the quantity of CaCO3 addition. The relative intensity of
iron is constant for all reduced pellets at constant reduction temperature. There is no mayenite phase
in the reduced BR pellets, but with the addition of calcite, a small amount of mayenite phase starts to
appear, which increases with more calcite addition. In addition, similar metallic iron recoveries were
observed for all reduced pellets, while the calcite-added ones had better composition for further alumina
recovery.