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<p>Thermally assisted beneficiation of a low-grade goethite-hematite ore powder (51.5 wt pct Fe), coupled with magnetic separation, was investigated using two heating strategies, and in the temperature range 300–700 °C. Heating was applied via a novel high-flux radiation method (10–50 °C/s) and slow convective heating using a muffle furnace (~1 °C/s) and a thermogravimetric analyser (~0.1 °C/s), followed by natural cooling, to systematically assess for the first time the coupled effects of temperature and heating/cooling rates on beneficiation performance, ore microstructure, and mineralogy. At 500 °C, the extent of goethite dehydroxylation was reduced at heating rates &gt;20 °C/s, while at 700 °C, full conversion occurred across all methods, though rapid heating achieved decomposition significantly faster. Heating rate also strongly influenced ore microstructure, with high-flux radiation treatments yielding up to 30 pct greater surface area than slow-heated samples. XRD, electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS) were employed to analyse these changes. Rapid heating further enhanced magnetic susceptibility, raising ore grade to 58 wt pct Fe and achieving recovery above 90 pct, suggesting that optimised high-flux heating can markedly improve magnetic separation efficiency.</p> Graphical Abstract <p></p>

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Thermally Assisted Beneficiation of Low-Grade Iron Ore Powder: Influence of Heating Rate on Upgrade, Microstructure, and Mineralogy

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月7日

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  • Yuecheng Lin,
  • Leok Lee,
  • Elliott Lewis,
  • Nigel Cook,
  • Woei Saw,
  • Graham J. Nathan,
  • Alfonso Chinnici

摘要

Thermally assisted beneficiation of a low-grade goethite-hematite ore powder (51.5 wt pct Fe), coupled with magnetic separation, was investigated using two heating strategies, and in the temperature range 300–700 °C. Heating was applied via a novel high-flux radiation method (10–50 °C/s) and slow convective heating using a muffle furnace (~1 °C/s) and a thermogravimetric analyser (~0.1 °C/s), followed by natural cooling, to systematically assess for the first time the coupled effects of temperature and heating/cooling rates on beneficiation performance, ore microstructure, and mineralogy. At 500 °C, the extent of goethite dehydroxylation was reduced at heating rates >20 °C/s, while at 700 °C, full conversion occurred across all methods, though rapid heating achieved decomposition significantly faster. Heating rate also strongly influenced ore microstructure, with high-flux radiation treatments yielding up to 30 pct greater surface area than slow-heated samples. XRD, electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS) were employed to analyse these changes. Rapid heating further enhanced magnetic susceptibility, raising ore grade to 58 wt pct Fe and achieving recovery above 90 pct, suggesting that optimised high-flux heating can markedly improve magnetic separation efficiency.

Graphical Abstract