Dual role of dissolved oxygen in sulfidation-xanthate flotation of anglesite from zinc leaching residue

The recovery of valuable anglesite (PbSO 4 ) from zinc leaching residue (ZLR) via sulfidation-xanthate flotation is hindered by poorly understood dissolved oxygen (DO) effects. This study clarifies the dual role of DO across sulfidation and xanthate adsorption stages. Micro-flotation experiments revealed that minimizing DO during the sulfidation stage reduced Na 2 S dosage, while optimal anglesite recovery required controlled DO levels (5.0–6.0 ppm) during xanthate conditioning stage. For sulfidation stage, zeta potential and XPS analysis revealed gradual surface oxidation with increasing DO, though PbS species remained relatively stable (0.2–6.0 ppm DO). For PAX conditioning stage, adsorption quantity, QCM-D and FTIR measurements revealed that 6.0 ppm DO enhanced xanthate adsorption on sulfurized anglesite. Bench-scale tests with nitrogen-regulated DO (1.8–4.2 ppm in sulfidation; 4.2–6.0 ppm in PAX conditioning) achieved higher Pb grade (23.3 % vs. 19.4 %) with comparable Pb recovery (60.9 % vs. 60.6 %), alongside a 26.7 % reduction in Na 2 S dosage (14,600 to 10,700 g/t). These findings establish DO as a pivotal operational parameter for balancing surface oxidation and xanthate adsorption, offering a reagent-saving strategy for anglesite recovery from ZLR.