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<p>The refractory nature of cerium dioxide (CeO<sub>2</sub>) in roasted rare earth concentrates remains a significant bottleneck for efficient extraction. This study proposes a synergistic HCl–H<sub>2</sub>O<sub>2</sub> leaching system and elucidates its underlying interfacial mechanism beyond conventional process optimization. Systematic characterization reveals that roasting at 550&#xa0;°C for 2 hours triggers partial fluorination loss (10.04 pct) and atomic dissociation, creating a highly reactive surface characterized by abundant dangling bonds and high-energy states. We demonstrate that the introduction of H<sub>2</sub>O<sub>2</sub> acts as a site-specific reductant, facilitating the Ce<sup>4+</sup> to Ce<sup>3+</sup> transition. This transition not only increases the density of proton-active sites but also enables the saturation of vacant bonding orbitals of surface anions by adsorbed H<sup>+</sup>, significantly lowering the interfacial energy barrier for mineral dissolution. Under the optimized conditions (7 mol/L HCl, 80&#xa0;°C, 40 minutes, and a liquid-to-solid ratio of 3:1), the rare earth leaching efficiency reached 83.67 pct, while achieving exceptional selectivity by suppressing fluorine co-extraction to a mere 0.21 pct. This work provides a new theoretical perspective on mineral surface state regulation, offering a robust strategy for the clean and efficient processing of complex rare earth resources.</p>

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Enhanced Leaching of Oxidatively Roasted Rare Earth Concentrate Using HCl–H2O2 System

  • 期刊论文

  • 发表日期：

    2026年4月27日

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  • Xiaodong Wang,
  • Xiaowei Zhang,
  • Feng Guo,
  • Ruifeng Ma,
  • Zhaogang Liu,
  • Yanhong Hu,
  • Jinxiu Wu

摘要

The refractory nature of cerium dioxide (CeO2) in roasted rare earth concentrates remains a significant bottleneck for efficient extraction. This study proposes a synergistic HCl–H2O2 leaching system and elucidates its underlying interfacial mechanism beyond conventional process optimization. Systematic characterization reveals that roasting at 550 °C for 2 hours triggers partial fluorination loss (10.04 pct) and atomic dissociation, creating a highly reactive surface characterized by abundant dangling bonds and high-energy states. We demonstrate that the introduction of H2O2 acts as a site-specific reductant, facilitating the Ce4+ to Ce3+ transition. This transition not only increases the density of proton-active sites but also enables the saturation of vacant bonding orbitals of surface anions by adsorbed H+, significantly lowering the interfacial energy barrier for mineral dissolution. Under the optimized conditions (7 mol/L HCl, 80 °C, 40 minutes, and a liquid-to-solid ratio of 3:1), the rare earth leaching efficiency reached 83.67 pct, while achieving exceptional selectivity by suppressing fluorine co-extraction to a mere 0.21 pct. This work provides a new theoretical perspective on mineral surface state regulation, offering a robust strategy for the clean and efficient processing of complex rare earth resources.