Developing a Low-Temperature, Carbon-Lean Hybrid Valorisation Process for Bauxite Residue (Red Mud) Towards Metallic Fe and Al Recovery

An Invitation on Characterization of H2-Reduced Bauxite Residue and Recovering Iron through Wet Magnetic Separation Processes

“…Under these optimum conditions (BR with 20 wt% NaOH at 500 • C for 2 h under 5 vol.% H 2 + 95 vol.% N 2 ), the conversion of hematite to magnetite reached a maximum of 96%. The detailed study of different parameters to find out the optimum reduction conditions was already discussed in the study by Pilla et al [9,[19][20][21][22][23][24]. Reduction under the above-mentioned conditions shows that the phases of hematite (Fe 2 O 3 ) and goethite (FeO(OH)) were transformed into magnetite (Fe 3 O 4 ) according to Equation (2) under H 2 .…”

“…The mineralogy of the raw BR, H 2 reduced BR, and magnetic and non-magnetic products was evaluated by X-ray diffraction (XRD) on a D2 phase diffractometer (Bruker D2 Phaser) and quantified (QXRD) by Rietveld analysis with TOPAS Academic [19][20][21]. The samples were measured between 10-65 • 2θ using CuK radiation with an accelerating voltage of 30 kV and a current of 10 mA, with a step size of 0.02 • and a counting duration of 0.8 s/step.…”

Optimization of Fe, Al, and Na Recovery from H2-Reduced Bauxite Residue (“Red Mud”) Using Response Surface Methodology (RSM)

“…In the Bayer process, about 1.5-2.5 tons of bauxite residue (BR) is generated as waste per ton of alumina, depending on the type of bauxite ore and process efficiency [1,2]. The global inventory of BR is estimated to be around 5.5 billion tons by 2022 [3,4], most of it being disposed in landfills [1]. BR's high alkalinity and fine particle size poses a potential risk to land, ecosystems, and groundwater.…”

“…BR is a potential polymetallic source for the recovery of different metals including rare earth elements, REEs. Therefore, extensive efforts have been undertaken to explore economic and environmentally sustainable approaches for maximizing the utilization of BR, particularly through the recovery of metals at lower temperatures [4][5][6][7][8][9]. In most studies, the single-factor method is commonly used for process optimization, while ignoring the mutual interactions among the variables.…”