New Strategy for Recovering Pb, Fe, and Zn from Blast Furnace Dust and Zinc Oxide via Ammonia-Acid Co-leaching

Zinc-containing solid wastes (ZCSW) from the steel industry pose significant environmental risks due to hazardous heavy metals like zinc, iron, and lead. This study proposes a synergistic ammonia-acid leaching strategy for co-processing blast furnace dust (BFD) and secondary zinc oxide (SZO) to achieve resource recovery and pollution mitigation. The ammonia leaching selectively extracted 70.62–88.08% of Zn while suppressing Fe and Pb dissolution, facilitated by optimized (NH 3 ·H 2 O]/[NH 4 HCO 3 ] ratios (1:1) and pH (9.84). Subsequent acid leaching (3.24 mol·L -1 HCl, 50°C) effectively dissolved residual Zn (95.7%) and Pb by leveraging BFD’s reducibility to oxidize refractory ZnS in SZO. Selective metal recovery was achieved through pH-controlled precipitation: Fe 3 ⁺ was removed as Fe 2 O 3 at pH 5, Pb via Zn displacement, and ZnCO 3 via ammonium bicarbonate addition. The integration of BFD enhanced ZnS leaching efficiency, while mixed waste ratios (e.g., 3:1 BFD/SZO) optimized elemental separation, converting residues into Fe-enriched (73.42%) materials. This waste-to-waste approach enables simultaneous Zn, Fe, and Pb recovery with <1% residuals, offering a sustainable solution for ZCSW management by bridging resource scarcity and environmental challenges.