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<p>A high-Fe weathered carbonatite RE flotation tailings sample was examined for its potential for iron recovery while simultaneously enriching the rare earth elements (RE) in the residue. The sample contained 48.5&#xa0;pct Fe<sub>2</sub>O<sub>3</sub> and 8.4&#xa0;pct total REO, with the main Fe-rich mineral being goethite (FeO.OH) and with RE mainly in a monazite (RE-PO<sub>4</sub>) phase. Hydrogen was tested as a possible reductant at high temperatures to investigate the reduction and metallization behavior of iron in the goethite. <i>In situ</i> high-temperature X-ray diffraction (HTXRD) analysis results from heating the sample to 1000&#xa0;°C in an inert atmosphere showed that the goethite was transformed into hydro-hematite (Fe<sub>2−x</sub>(OH)<sub>x</sub>O<sub>3−x</sub>) and then hematite (Fe<sub>2</sub>O<sub>3</sub>). Following a comprehensive thermodynamic assessment to understand the iron reduction mechanism by hydrogen and its potential interaction with RE-phosphate phases, hydrogen reduction experiments were carried out at 700&#xa0;°C, 800&#xa0;°C, 900&#xa0;°C, and 1000&#xa0;°C for 4&#xa0;hours in a vertical tube furnace using a 50:50 mix of H<sub>2</sub> and Ar gases. Characterization results showed that the iron in the goethite was reduced into metallic Fe, Fe(P), and Fe<sub>3</sub>P, depending on the reduction temperature and duration, although some Fe remained in fayalite and hercynite phases. The implications for iron recovery from the reduced tailings are discussed.</p>

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Reduction of Iron Contained in Goethite-Rich Rare Earth Tailings by Hydrogen Gas

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年11月18日

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  • Deddy C. Nababan,
  • Mark I. Pownceby,
  • Warren J. Bruckard,
  • Aaron Torpy,
  • Nicholas D. Owen,
  • Nathan A. S. Webster,
  • Hyun Sik Park,
  • Jungho Heo,
  • Baek Seunghyeon,
  • Sujeong Lee

摘要

A high-Fe weathered carbonatite RE flotation tailings sample was examined for its potential for iron recovery while simultaneously enriching the rare earth elements (RE) in the residue. The sample contained 48.5 pct Fe2O3 and 8.4 pct total REO, with the main Fe-rich mineral being goethite (FeO.OH) and with RE mainly in a monazite (RE-PO4) phase. Hydrogen was tested as a possible reductant at high temperatures to investigate the reduction and metallization behavior of iron in the goethite. In situ high-temperature X-ray diffraction (HTXRD) analysis results from heating the sample to 1000 °C in an inert atmosphere showed that the goethite was transformed into hydro-hematite (Fe2−x(OH)xO3−x) and then hematite (Fe2O3). Following a comprehensive thermodynamic assessment to understand the iron reduction mechanism by hydrogen and its potential interaction with RE-phosphate phases, hydrogen reduction experiments were carried out at 700 °C, 800 °C, 900 °C, and 1000 °C for 4 hours in a vertical tube furnace using a 50:50 mix of H2 and Ar gases. Characterization results showed that the iron in the goethite was reduced into metallic Fe, Fe(P), and Fe3P, depending on the reduction temperature and duration, although some Fe remained in fayalite and hercynite phases. The implications for iron recovery from the reduced tailings are discussed.