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<p>This study presents an in-depth analysis of thermally assisted beneficiation of a low-grade iron ore (goethite/hematite, 54.8 wt pct Fe) powder sourced from the Pilbara region in Western Australia. It was calcined in an electrically heated pilot-scale drop tube reactor (DTR) at relatively low temperatures (300&#xa0;°C, 400&#xa0;°C, and 500&#xa0;°C), coupled with wet high-intensity magnetic separation to determine iron upgrade and recovery, and impurities removal. Various characterization techniques, including thermogravimetric analysis (TGA), X-ray diffraction, nitrogen adsorption, scanning electron microscope with energy dispersive X-ray spectroscopy, and X-ray fluorescence, were used to study the impact of flash heating on ore conversion, changes in ore mineralogy, and chemical-physical characteristics. It was found that the degree of conversion (calcination <i>via</i> goethite dehydroxylation) and mineralogy are strongly influenced by both heating rate (<i>HR</i>) and particle residence time (<i>τ</i>); samples heated under conditions relevant to flash heating in the DTR (<i>HR</i> of 30 to 50&#xa0;°C/s; <i>τ</i> in the order of minutes) exhibited different thermal decomposition behaviors to samples heated slowly in a TGA (<i>HR</i> of 5 to 40&#xa0;°C/min; <i>τ</i> in the order of hours). The analysis also shows that the proposed thermally assisted beneficiation method produces a hematite-rich concentrate with an iron upgrade and recovery of up to 60 wt pct and 94 pct Fe, respectively, and a high specific surface area (fivefold increase).</p> Graphical abstract <p></p>

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Thermally Assisted Beneficiation of a Low-Grade Iron Ore Powder in a Pilot-Scale Drop Tube Reactor: Effects on Ore Upgrading, Mineralogy and Chemical-Physical Characteristics

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月26日

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  • Renae Lillian O’Hara,
  • Nigel John Cook,
  • Elliott William Lewis,
  • Maziar Arjomandi,
  • Geoffrey Brooks,
  • Alfonso Chinnici

摘要

This study presents an in-depth analysis of thermally assisted beneficiation of a low-grade iron ore (goethite/hematite, 54.8 wt pct Fe) powder sourced from the Pilbara region in Western Australia. It was calcined in an electrically heated pilot-scale drop tube reactor (DTR) at relatively low temperatures (300 °C, 400 °C, and 500 °C), coupled with wet high-intensity magnetic separation to determine iron upgrade and recovery, and impurities removal. Various characterization techniques, including thermogravimetric analysis (TGA), X-ray diffraction, nitrogen adsorption, scanning electron microscope with energy dispersive X-ray spectroscopy, and X-ray fluorescence, were used to study the impact of flash heating on ore conversion, changes in ore mineralogy, and chemical-physical characteristics. It was found that the degree of conversion (calcination via goethite dehydroxylation) and mineralogy are strongly influenced by both heating rate (HR) and particle residence time (τ); samples heated under conditions relevant to flash heating in the DTR (HR of 30 to 50 °C/s; τ in the order of minutes) exhibited different thermal decomposition behaviors to samples heated slowly in a TGA (HR of 5 to 40 °C/min; τ in the order of hours). The analysis also shows that the proposed thermally assisted beneficiation method produces a hematite-rich concentrate with an iron upgrade and recovery of up to 60 wt pct and 94 pct Fe, respectively, and a high specific surface area (fivefold increase).

Graphical abstract