Transactions of Nonferrous Metals Society of China (中国有色金属学报)•2026•DOI: 10.1016/S1003-6326(26)67068-9
Synergistic sulfidation roasting of heavy metal gypsum residue and secondary zinc oxide fume was proposed by using the research idea of 'waste to treat waste'. Thermodynamic studies indicated that the sulfidation of zinc oxide could be effectively enhanced by increasing the dosage of calcium sulfate and carbon powder in the range of 500−800 °C. The synergistic sulfidation experiments of heavy metal gypsum residue with secondary zinc oxide showed that the sulfidation rate of zinc reached 90.39% and the grain size of ZnS increased from 5 to 10 μm under the conditions of temperature 700 °C, carbon powder 30%, Na2CO3 10%, mass ratio of gypsum residue to secondary zinc oxide 1.4:1, roasting time 2 h and cooling rate 1 °C/min. Meanwhile, 76.32% F, 72.11% Cl and 93.41% As were removed. TG/DTG−DSC, 3D FTIR spectra and SEM analysis showed that the conversion of CaSO4 to CaCO3 and the avoidance of CO2 and SO2 production were achieved under optimized conditions. This study achieves efficient sulfidation of zinc as well as growth of ZnS grains, laying the theoretical and technological foundation for subsequent recovery of ZnS by flotation.
Journal of Central South University•2025•DOI: 10.1007/s11771-025-6044-x
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 ℃. 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 ℃ for 3 h. E−pH plots show that ZnS, PbS and Cu2S can be enriched in the leaching residue, under leaching conditions at 25 ℃, 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 ℃, 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.