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<p>Extraction and mobilization of rare earth elements (REEs) from carbonatite-hosted deposits remains a major challenge due to the limitations of conventional acid-leaching processes. This study presents a potentially more environmentally compatible extraction approach for REE mobilization and capture from the Amba Dongar carbonatite complex, Gujarat, India, by integrating alkali roasting, water leaching, and clay-based adsorption–desorption. Inductively coupled plasma mass spectrometry (ICP-MS) analyses of carbonatite and carbonatite–fluorite samples revealed high total REE concentrations dominated by Ce and La. Alkali roasting with NaOH followed by water leaching effectively mobilized REEs under mild, acid-free conditions. Four natural clays—montmorillonite, bentonite, attapulgite, and kaolinite—were evaluated as low-cost adsorbents. Mineralogical and structural analyses using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy confirmed active surface and lattice sites responsible for REE uptake. Smectite clays (montmorillonite and bentonite) exhibited superior adsorption efficiency due to interlayer cation exchange, while attapulgite displayed moderate uptake but enhanced desorption associated with its channel-type morphology. Kaolinite exhibited the weakest performance due to its low cation exchange capacity. Ultraviolet–visible (UV–Vis) and fluorescence spectroscopy validated REE–clay interactions, displaying characteristic absorption (294, 343&#xa0;nm) and emission features (200–390&#xa0;nm). Overall, the observed adsorption hierarchy (montmorillonite ≈ bentonite &gt; attapulgite &gt; kaolinite) highlights the potential of this integrated approach as a preliminary and environmentally compatible framework for REE mobilization and selective capture from carbonatite-derived leachates.</p>

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Developing a clay-assisted method for REE recovery from Amba Dongar carbonatite

  • 期刊论文

  • 发表日期：

    2026年6月26日

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  • Ali H. Almohammed,
  • Uttam K. Bhui,
  • Dwijesh Ray,
  • N. Madhavan

摘要

Extraction and mobilization of rare earth elements (REEs) from carbonatite-hosted deposits remains a major challenge due to the limitations of conventional acid-leaching processes. This study presents a potentially more environmentally compatible extraction approach for REE mobilization and capture from the Amba Dongar carbonatite complex, Gujarat, India, by integrating alkali roasting, water leaching, and clay-based adsorption–desorption. Inductively coupled plasma mass spectrometry (ICP-MS) analyses of carbonatite and carbonatite–fluorite samples revealed high total REE concentrations dominated by Ce and La. Alkali roasting with NaOH followed by water leaching effectively mobilized REEs under mild, acid-free conditions. Four natural clays—montmorillonite, bentonite, attapulgite, and kaolinite—were evaluated as low-cost adsorbents. Mineralogical and structural analyses using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy confirmed active surface and lattice sites responsible for REE uptake. Smectite clays (montmorillonite and bentonite) exhibited superior adsorption efficiency due to interlayer cation exchange, while attapulgite displayed moderate uptake but enhanced desorption associated with its channel-type morphology. Kaolinite exhibited the weakest performance due to its low cation exchange capacity. Ultraviolet–visible (UV–Vis) and fluorescence spectroscopy validated REE–clay interactions, displaying characteristic absorption (294, 343 nm) and emission features (200–390 nm). Overall, the observed adsorption hierarchy (montmorillonite ≈ bentonite > attapulgite > kaolinite) highlights the potential of this integrated approach as a preliminary and environmentally compatible framework for REE mobilization and selective capture from carbonatite-derived leachates.