Rapid on-site monitoring of heavy metals in gold-mine tailings via filtered thin-layer deposition and low-power PEDXRF

Abstract

Direct quantification of heavy metals (Cu, Zn, Pb) in mineral slurries remains challenging due to high moisture content (>70%) and particle heterogeneity. This study introduces a novel filtration-based thin-layer deposition method coupled with low-power polarized energy-dispersive X-ray fluorescence (PEDXRF) for rapid on-site analysis of gold-mine tailing slurries. By optimizing filtration parameters (−70 kPa, 60 s), moisture was reduced to ∼20%, depositing a uniform analyte layer (≤33.60 mg cm⁻²) that minimized particle segregation and enhanced signal uniformity. Critical innovations include: particle size control (≤38 µm) reducing surface signal deviation to <9.44% (Cu), 4.16% (Zn), and 6.23% (Pb), low-power PEDXRF (60 kV, 800 µA) achieving ultra-low LODs (0.23 mg kg⁻¹ Cu, 0.16 mg kg⁻¹ Zn, 0.19 mg kg⁻¹ Pb) and linear calibration (R² > 0.99) via mass-adjusted certified reference materials. Validation against ICP-OES showed relative errors of 0.95–5.67% (Cu), 1.89–2.59% (Zn), and 4.67–9.96% (Pb), confirming field-deployable accuracy for real-time slurry monitoring in mineral processing.