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<p>High-iron bauxite residue (BR), a highly caustic byproduct of the Bayer process, presents both an environmental challenge and a promising polymetallic resource. This study proposes a potentially ecofriendly, efficient, and low-chemical-consuming roasting–leaching process for simultaneous recovery of alumina (Al<sub>2</sub>O<sub>3</sub>) and soda (Na<sub>2</sub>O) while upgrading the residue for dual applications—as a feedstock for direct reduced iron (DRI)/smelting and as a high-performance catalytic material. Water leaching at 60&#xa0;°C for 30&#xa0;min confirmed that roasting at 950&#xa0;°C with a CaO/BR ratio of 0.125&#xa0;g/g and a Na₂CO₃/BR ratio of 0.5&#xa0;g/g provides optimal conditions, enabling &gt; 80% recovery of both Al<sub>2</sub>O<sub>3</sub> and Na<sub>2</sub>O while increasing iron oxide (Fe₂O₃) content from 49.3 wt% to 60 wt%. Without lime addition, a Na₂CO₃/BR ratio of 0.75&#xa0;g/g yields 87% alumina recovery but causes major soda loss (− 52.7%), despite enriching Fe₂O₃ to 65.8 wt%. Extending the roasting time beyond 3&#xa0;h further improves overall recovery. The process enables &gt; 90% soda regeneration and produces alumina of 97 wt% purity through carbon dioxide (CO₂) bubbling of the sodium aluminate liquor. After extraction, the residue is substantially iron-enriched with enhanced porosity, making it suitable for ironmaking as well as low-cost catalytic applications. It contains ~ 14.1 wt% lime (CaO), which can reduce external flux demand and associated calcination energy during sintering and pelletization, while the low residual soda (~ 0.44 wt%) becomes negligible upon dilution with iron ore feed. The alumina obtained demonstrates the potential of BR as a secondary resource contributing to global aluminum demand, while regenerated soda can be directly recycled, potentially reducing chemical consumption and operational costs.</p> Graphical abstract <p></p>

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Selective Recovery of Alumina and Soda from Iron Rich Bauxite Residue via a CaO–Na2CO3 Roasting Route: Phase Evolution Insights

  • 期刊论文

  • 发表日期：

    2026年7月28日

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  • Gautam Behera,
  • Veerababu Gollapalli,
  • Manish Kumar Kar,
  • Mehmet Ali Recai Önal,
  • Raghuram Peddinti,
  • Chenna Rao Borra

摘要

High-iron bauxite residue (BR), a highly caustic byproduct of the Bayer process, presents both an environmental challenge and a promising polymetallic resource. This study proposes a potentially ecofriendly, efficient, and low-chemical-consuming roasting–leaching process for simultaneous recovery of alumina (Al2O3) and soda (Na2O) while upgrading the residue for dual applications—as a feedstock for direct reduced iron (DRI)/smelting and as a high-performance catalytic material. Water leaching at 60 °C for 30 min confirmed that roasting at 950 °C with a CaO/BR ratio of 0.125 g/g and a Na₂CO₃/BR ratio of 0.5 g/g provides optimal conditions, enabling > 80% recovery of both Al2O3 and Na2O while increasing iron oxide (Fe₂O₃) content from 49.3 wt% to 60 wt%. Without lime addition, a Na₂CO₃/BR ratio of 0.75 g/g yields 87% alumina recovery but causes major soda loss (− 52.7%), despite enriching Fe₂O₃ to 65.8 wt%. Extending the roasting time beyond 3 h further improves overall recovery. The process enables > 90% soda regeneration and produces alumina of 97 wt% purity through carbon dioxide (CO₂) bubbling of the sodium aluminate liquor. After extraction, the residue is substantially iron-enriched with enhanced porosity, making it suitable for ironmaking as well as low-cost catalytic applications. It contains ~ 14.1 wt% lime (CaO), which can reduce external flux demand and associated calcination energy during sintering and pelletization, while the low residual soda (~ 0.44 wt%) becomes negligible upon dilution with iron ore feed. The alumina obtained demonstrates the potential of BR as a secondary resource contributing to global aluminum demand, while regenerated soda can be directly recycled, potentially reducing chemical consumption and operational costs.

Graphical abstract