Detoxification of Ion-Adsorption Rare Earth Elements Low-Level Radioactive Residues via Mild Alkali–Carbonate: Uranium Extraction and Multi-Metal Recovery
Experimental study reveals efficient uranium extraction from rare earth residues using mild alkali-carbonate leaching, suggesting a scalable pathway for industrial detoxification.
Key Points
To develop a mild, atmospheric-pressure alkaline leaching process for selectively extracting uranium and aluminum from low-level radioactive rare earth residues to satisfy environmental regulatory thresholds.
Leached Al(III) from ion-adsorption rare earth element low-level radioactive residues using dilute NaOH under atmospheric pressure.
Selectively leached U(VI) using a NaHCO3–Na2CO3 buffer solution at pH 9–10 and temperatures ≤90 °C under atmospheric pressure.
Evaluated the reaction mechanisms and performed a techno-economic assessment of the stepwise mild alkaline disposal process.
Selective NaHCO3–Na2CO3 buffer leaching achieved 95.8% U(VI) extraction, decreasing residue uranium-specific activity from 13.9 to 0.72 Bq·g–1, beneath the 1 Bq·g–1 regulatory limit.
The stepwise process cumulatively removed ~88 wt% Al and ~97 wt% U, yielding a residue mass reduction of ~77 wt% and upgrading the rare earth element grade from 0.88 to 2.23 wt%.
Deep extraction was driven by the stabilization of soluble [UO2(CO3)3]4– complexes while simultaneously inhibiting insoluble Na2U2O7 precipitation.