The purpose of this study was to investigate the effects of metal oxides and smelting dust on the formation of sulfur trioxide during copper, lead, zinc smelting process and flue. Focusing on the effects of SO₂ concentration, O₂ concentration, and temperature on SO₂ oxidation conversion rate under homogeneous test conditions, and under various metal oxide oxidation conditions, further in dust (mainly electric dust removal ash in copper, lead, zinc smelting process), which were studied by single factor experiment test. The results showed that the effect of heterogeneous catalytic oxidation on SO₂ conversion rate is much greater than that of pure gas phase oxidation. The addition of five pure metal oxides such as Fe₂O₃, CuO, Al₂O₃, ZnO, and CaO obviously promoted the SO₂ conversion rate under different conditions. At different temperatures, the ability of metal oxides to promote SO₂ conversion is ranked: Fe₂O₃ > CuO > CaO > ZnO > Al₂O₃. The catalytic oxidation of copper, lead, and zinc smelting dust to SO₂ conversion rate was studied, and the conclusion was drawn that the metal oxides that promoted SO₂ conversion rate in copper smelting dust were Fe₂O₃, Al₂O₃, ZnO, CaO, and the main substance was Fe₂O₃; the metal oxides that promoted SO₂ conversion in zinc smelting dust were Fe₂O₃, Al₂O₃, ZnO, CaO, CuO, and the main substances were Fe₂O₃ and ZnO; the metal oxides that promoted SO₂ conversion rate in lead smelting dust were Fe₂O₃. Whether metal oxides or copper, zinc, lead smelting dust in the experiment, Fe₂O₃ displayed the strongest catalytic oxidation capacity.

The thermodynamic equilibrium of the gas-phase system in lead smelting flue gas was studied using FactSage 8.2 software, and the effects of temperature, the main components of the gas phase, and other factors on the SO₃ content in the equilibrated flue gas were investigated. In addition, experimental research was conducted on a solid-phase catalysis experimental platform to investigate the effect of lead smelting ash on SO₂ catalytic oxidation. The results show that temperature and initial O₂ content in flue gas have a significant impact on the equilibrium concentration of SO₃, while the initial SO₂ content in flue gas has a relatively small impact on the equilibrium concentration of SO₃; the fly ash from the lead smelting flue promotes the conversion of SO₂ to SO₃ in the flue gas. SO₃-suppression experiments show that PbS can adequately inhibit SO₃ formation in a simulated flue gas environment, and the content of SO₃ after adding PbS under different oxygen contents and SO₂ atmospheres does not exceed 0.6%. Through the method of thermodynamic simulation and experimental verification, this study reveals the catalytic oxidation mechanism of SO₂ in lead dust and proposes the use of PbS as an in situ SO₃ inhibitor.