Unlocking Strategic Metals from Zinc Smelting Dust: Ultrasound-ClO₂ Synergy and Atomic-Scale Leaching Mechanisms

This study proposes an innovative ultrasonic-assisted ClO₂ oxidative leaching (UCL) process for Zn, In, and Ge synergistic recovery from zinc smelting dust (ZSD). Laser ablation inductively coupled plasma time-of-flight mass spectrometry reveals the synergistic association of In/Ge and Cu in sphalerite, which breaks through the limitations of the traditional characterization techniques for trace element analysis in ZSD. Through appropriate process parameters(0.12 mol/L NaClO₂, 600 W, 8:1 mL/g, 1.6 mol/L H₂SO₄, 80 °C, 40 min), efficient leaching of Zn(98.16%), In(93.18%), and Ge(92.78%) was achieved, with an increase in the efficiency of the process over the conventional leaching (CL) process of 6.43%-8.33%, while reducing oxidizer dosage by 40% and acid consumption by 20%. Density functional theory (DFT) shows that the coadsorption of H₂SO₄ and ClO₂ on the Cu-In/Ge codoped ZnS(110) surface induces synergistic charge transfer. Ultrasound enhanced this process through a dual intensification effect: (1) cavitation-induced microjet disrupts the mineral passivation layer and continuously exposes the fresh reaction interface; and (2) local high temperature and pressure promote complete contact between ClO₂ and H₂SO₄ with minerals, driving the sulfur phase transformation (S^2-→S⁰/SO₄^2-). This study provides a low-energy-consumption and high-recovery solution for efficiently recovering strategic metals in ZSD.