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Abstract <p>Bauxite Residue (BR), a waste from the alumina industry, provides a promising avenue for the recovery of valuable metals. Building on prior laboratory-scale studies, this work demonstrates a pilot scale process involving H<sub>2</sub> reduction of BR using a tilted rotary induction furnace, continued with wet milling and magnetic separation. This approach enables the extraction of Fe as magnetite, Al, and Na as sodium aluminate while generating non-magnetic tailings (Ca, Si, Ti). A comprehensive series of pilot scale H<sub>2</sub> reduction trials were conducted with various process parameters such as H<sub>2</sub> amounts, furnace inclination angle, H<sub>2</sub> pressure, and reduction time to maximize magnetite and sodium aluminate formation in the roasted BR pellets. After optimal H<sub>2</sub> reduction conditions (600&#xa0;°C, 20 wt% NaOH, and 5 vol% H<sub>2</sub> at 20 LPM for 4&#xa0;h at horizontal furnace position and crucible rotation), the roasted intermediate pellets underwent wet milling for 30&#xa0;min followed by wet magnetic separation (0.15&#xa0;T) in lab scale setups. The separation step could achieve a maximum recovery of 77.8% Fe with a concentration of 55%, an Al recovery of 54.7% (with an Al<sub>2</sub>O<sub>3</sub> concentration of 127.6&#xa0;g/L), and Na recovery of 67% (with Na<sub>2</sub>O concentration of 120&#xa0;g/L). The limited recoveries of Al and Na were primarily attributed due to the formation of undissolved sodium aluminum silicate phases and ultra-fine particles. The process has the potential to scale up, minimize waste, and recover valuable materials thereby making a direct contribution to more sustainable practices in the alumina industry.</p> Graphical Abstract <p></p>

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Pilot Scale Hydrogen (H2) Reduction of Bauxite Residue for the Production of Magnetite and Water-Soluble Sodium Aluminate

  • 期刊论文

  • 发表日期：

    2025年3月20日

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  • Ganesh Pilla,
  • Glenn Beersaerts,
  • Tobias Hertel,
  • Yiannis Pontikes

摘要

Abstract

Bauxite Residue (BR), a waste from the alumina industry, provides a promising avenue for the recovery of valuable metals. Building on prior laboratory-scale studies, this work demonstrates a pilot scale process involving H2 reduction of BR using a tilted rotary induction furnace, continued with wet milling and magnetic separation. This approach enables the extraction of Fe as magnetite, Al, and Na as sodium aluminate while generating non-magnetic tailings (Ca, Si, Ti). A comprehensive series of pilot scale H2 reduction trials were conducted with various process parameters such as H2 amounts, furnace inclination angle, H2 pressure, and reduction time to maximize magnetite and sodium aluminate formation in the roasted BR pellets. After optimal H2 reduction conditions (600 °C, 20 wt% NaOH, and 5 vol% H2 at 20 LPM for 4 h at horizontal furnace position and crucible rotation), the roasted intermediate pellets underwent wet milling for 30 min followed by wet magnetic separation (0.15 T) in lab scale setups. The separation step could achieve a maximum recovery of 77.8% Fe with a concentration of 55%, an Al recovery of 54.7% (with an Al2O3 concentration of 127.6 g/L), and Na recovery of 67% (with Na2O concentration of 120 g/L). The limited recoveries of Al and Na were primarily attributed due to the formation of undissolved sodium aluminum silicate phases and ultra-fine particles. The process has the potential to scale up, minimize waste, and recover valuable materials thereby making a direct contribution to more sustainable practices in the alumina industry.

Graphical Abstract