Efficient recovery of copper, lead and zinc from heavy metal gypsum residue and zinc-containing fume by synergistic sulfidation-acid leaching
摘要
In this study, a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume. The equilibrium phase composition of the sulfidation reaction and calculations of the thermodynamic stability region show that 89.36% Zn, >99% Pb and >99% Cu of gypsum residue and zinc-containing fume can be sulfured to ZnS, PbS and Cu2S, under sufficient sulfur partial pressure, low oxygen partial pressure and 400–1000 °C. Sulfidation roasting experiments show that the sulfidation rate of Cu, Pb and Zn reach 81.43%, 88.25% and 92.31%, respectively, under the roasting conditions of material mass ratio of 30 g: 10 g, carbon dosage of 3.75 g, roasting temperature of 800 °C for 3 h. E–pH plots show that ZnS, PbS and Cu2S can be enriched in the leaching residue, under leaching conditions at 25 °C, pH<4 and −0.4 V<φ(E)<0.04 V. The leaching experiments showed that the sulfide is retained in the leaching residue, while the leaching rates of Cu, Pb and Zn are 1.94%, 2.05% and 1.51%, respectively, under the conditions of 25 °C, CHCl of 0.5 mol/L, L/S of 5 mL/g, stirring rate of 300 r/min, and stirring time of 30 min. This study provides a new approach for the synergistic disposal of gypsum residue and zinc-containing fume.