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<p>A novel strategy is presented for extracting iron values from iron-lean red muds (RMs) based on blending RMs with red mill scale (MS) powders or Fe<sub>2</sub>O<sub>3</sub> in a range of proportions. Three red muds, namely RM1, RM2, and RM3 with low, medium, and high Fe<sub>2</sub>O<sub>3</sub> contents, respectively, were chosen; there were significant differences in their alumina, silica, and calcia contents as well. Carbothermic reduction of blends was carried out in a vertical Tamman resistance furnace at 1600–1650&#xa0;°C for 30 min; synthetic graphite was used as the reductant. Reaction products were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and elemental mapping. Iron-rich concentrates (Fe: 77.2–98.2 wt%) were produced in a variety of morphologies and sizes. RM compositions, nano/micro-particulate sizes of red MS, and proportions of major oxides (Fe<sub>2</sub>O<sub>3</sub>, SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, CaO) played a key role in iron recovery. Pick-up of Si by molten iron was also observed; Si levels were between 15.8 and 22 wt% (RM1 blends), 1.8–4.6 wt% (RM2 blends), and 7.2–8.1 wt% (RM3 blends). Concentration of CaO in the blends as compared to Al<sub>2</sub>O<sub>3</sub> and SiO<sub>2</sub> played a key role in controlling Si pick-up by molten iron. While low CaO levels in the blend favored assimilation of Si in molten iron, high CaO levels favored the assimilation of SiO<sub>2</sub> in calcium aluminate slag. This novel strategy lays the foundation for recovering iron resources from iron-lean RMs, enhancing recyclability, waste valorization, and significant reductions in vast RM reserves.</p> Graphic Abstract <p></p>

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A Novel Strategy for Extracting Iron Values from Iron-Lean Red Muds Toward Enhanced Resource Recovery and Recycling of Industrial Wastes

  • 期刊论文

  • 发表日期：

    2025年8月8日

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  • R. Khanna,
  • Y. Konyukhov,
  • K. Li,
  • D. Zinoveev,
  • Z. Liang,
  • N. Maslennikov,
  • I. Burmistrov,
  • J. Kargin,
  • M. Kravchenko,
  • P. S. Mukherjee,
  • J. Zhang

摘要

A novel strategy is presented for extracting iron values from iron-lean red muds (RMs) based on blending RMs with red mill scale (MS) powders or Fe2O3 in a range of proportions. Three red muds, namely RM1, RM2, and RM3 with low, medium, and high Fe2O3 contents, respectively, were chosen; there were significant differences in their alumina, silica, and calcia contents as well. Carbothermic reduction of blends was carried out in a vertical Tamman resistance furnace at 1600–1650 °C for 30 min; synthetic graphite was used as the reductant. Reaction products were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and elemental mapping. Iron-rich concentrates (Fe: 77.2–98.2 wt%) were produced in a variety of morphologies and sizes. RM compositions, nano/micro-particulate sizes of red MS, and proportions of major oxides (Fe2O3, SiO2, Al2O3, CaO) played a key role in iron recovery. Pick-up of Si by molten iron was also observed; Si levels were between 15.8 and 22 wt% (RM1 blends), 1.8–4.6 wt% (RM2 blends), and 7.2–8.1 wt% (RM3 blends). Concentration of CaO in the blends as compared to Al2O3 and SiO2 played a key role in controlling Si pick-up by molten iron. While low CaO levels in the blend favored assimilation of Si in molten iron, high CaO levels favored the assimilation of SiO2 in calcium aluminate slag. This novel strategy lays the foundation for recovering iron resources from iron-lean RMs, enhancing recyclability, waste valorization, and significant reductions in vast RM reserves.

Graphic Abstract