Water leaching of vacuum distilled selenium residue for platinum group metals (PGMs) enrichment and recovery

Fig. 1: The dissolution kinetics of Pt and Pd contained in the water leached vacuum distillation residue (VDR) in aqua regia.
Fig. 1: The dissolution kinetics of Pt and Pd contained in the water leached vacuum distillation residue (VDR) in aqua regia.

CMI researchers at Missouri S&T conducted the research for this highlight

Innovation
Water leaching of vacuum-distilled selenium residue (VDR) removes sodium sulfate and other soluble impurities, thereby reducing the weight of the PGMs residue going for hydrometallurgical processing by over 60%.

Achievement

  • Water leaching of the VDR increased the concentration of PGMs and critical elements by at least two-fold, showing a significant grade improvement.
  • Aqua regia leaching of water‑treated VDR achieved target extraction efficiencies above 80% for Pt and Pd (Fig. 1), demonstrating effective dissolution kinetics.
  • All silver was recovered as pure AgCl during the aqua regia leaching (Fig. 2).

Significance and Impact
Unlocking secondary sources transforms a domestic copper‑processing byproduct into a viable source for Te, Pd, Pt, Ag, and Au, supporting U.S. supply chain diversification.

Hub Target Addressed
Improving the efficiency of PGM production from domestic sources.
 

Fig. 2: XRD of the aqua regia leach residue showing the absence of PGMs and Ag found as a chloride.
Fig. 2: XRD of the aqua regia leach residue showing the absence of PGMs and Ag found as a chloride.