Highlights

• Researchers discovered high REE concentrations in mining-impacted sediments with 89% recovery efficiency using EDTA extraction.
• Study demonstrates a dual-purpose method of environmental cleanup and resource recovery from mining sediments.
• Potential commercial pilot possible within 2-3 years, with significant implications for global rare earth element supply.

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A groundbreaking study published in the Journal of Hazardous Materials (opens in a new tab) (Vol. 496) presents a commercially promising, environmentally sound method to recover rare earth elements (REEs) from mining-impacted sediments using EDTA-based extraction. The study was led by Dr. De-Xiang Xu and a team from the South China Agricultural University in collaboration with Université de Lorraine and INRAE through the ECOLAND international joint laboratory.

The authors hypothesized that sediments impacted by ion-adsorption rare earth mining in southern China contain high concentrations of extractable REEs, and that EDTA-based ligand complexation can serve as a scalable and low-impact method for recovery.

Study Design

Researchers investigated reservoir sediments across heavily mined counties in southern China (Dingnan, Longnan, Xunwu). These sediments, sourced from REE-rich wastewater and colloidal material settling downstream of mining operations, were analyzed for REE concentration, speciation, and extractability.

The team conducted a full recovery process—from extraction using EDTA-Na₂ to purification via ammonium sulfate precipitation and oxalate calcination. A life cycle assessment (LCA) and cost-benefit analysis (CBA) were performed to benchmark the method against conventional recovery technologies.

Key Findings

• High REE Concentration: Sediments contained 1,290–3,200 mg/kg total REEs—up to 10x higher than control sites. Roughly 30% of the REEs were heavy rare earth elements (HREEs).
• Labile Speciation: Most REEs were found in exchangeable or reducible forms, enabling easy extraction without aggressive processing.
• EDTA Efficiency: EDTA-Na₂ extracted REEs with 89% recovery efficiency, yielding REO product purity above 95%.
• Low Environmental Impact: LCA showed EDTA extraction had a significantly lower ecological footprint than traditional acid leaching or thermal methods.
• Commercial Viability: CBA supports economic feasibility, especially where sediment volumes are high and tailings remediation is co-prioritized.

Implications & Timeline

This study positions sediment recycling as a dual-purpose opportunity: environmental cleanup and secondary resource recovery. Given the process maturity demonstrated in lab trials, a commercial pilot could be launched within 2–3 years, particularly in regions with decades of sediment accumulation from REE or uranium mining.

Limitations

• The process was tested in controlled lab environments; real-world sediment heterogeneity may require location-specific optimization.
• EDTA recovery and reuse were not fully addressed—crucial for cost control and minimizing chelator emissions.
• Commercial scaling requires regulatory alignment and infrastructure for sediment dredging and processing.

Conclusion

This study identifies a novel, high-grade unconventional REE source in mining-impacted sediments and validates EDTA ligand complexation as a commercially scalable, low-impact recovery method. As global REE demand grows and China tightens exports, such innovations may help diversify and decentralize supply.

Citation: Xu D-X, Cheng X-P, Huang C-L, et al. Recovery of rare earth elements from sediments affected by mining activities. Journal of Hazardous Materials. 2025;496:139223. https://doi.org/10.1016/j.jhazmat.2025.139223 (opens in a new tab)