Experiments demonstrate efficient water reuse and iron recovery in rare earth element extraction, suggesting a pathway for sustainability.
The NdFeB magnetic material is widely used in modern industry and electronics. Recycling spent magnets containing 30–40 wt.% Rare Earth Elements (REEs) and 60–70 wt.% iron is essential for resource recovery. This study focuses on treating wastewater from hydrometallurgical REE extraction to enable water reuse and iron recovery. Experiments investigated the influence of temperature (25–60 °C) and oxalic acid concentration (50–120% stoichiometric amount) on iron precipitation as the main focus. Optimal iron recovery of 85.3% and 86.8% was achieved at 25 °C using 80% and 100% stoichiometric oxalic acid, respectively. Simultaneously, praseodymium removal exceeded 94%. The Differential Scanning Calorimetry (DSC) analysis identified a peak between 168.8 °C and 245 °C, with the peak temperature recorded at 214.5 °C, indicating the optimal calcination temperature for iron oxalate. This was confirmed through oven testing and X-ray Diffraction (XRD) analysis. The treated effluent exhibited a Chemical Oxygen Demand (COD) of 418 mg/L, with residual Fe and Pr concentrations significantly reduced to 5.7 mg/L and 4.3 mg/L, respectively. This approach demonstrates an efficient method for wastewater treatment and resource valorization, promoting sustainability in the recycling sector.
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Ullah et al. (2026) studied this question.
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