Emission characteristics and removal efficiencies of SO2, NOx, particulate matter, and dioxins in iron ore sintering after ultra-low emission transformation

Abstract

Iron ore sintering, as the dominant pollutant source in China's iron and steel industry, is responsible for substantial emissions of SO₂, NO_x, particulate matter (PM), and dioxins, posing critical challenges to air quality. This study evaluated the performance of ultra-low emission transformation, a nationwide initiative to further restrict industrial emissions through advanced air pollution control technologies, in controlling multi-pollutant emissions from sintering flue gas. The results demonstrated that ultra-low emission transformation significantly reduced the concentrations of SO₂, NO_x and PM, in sintering flue gas, with emission factors after transformation plummeting to 0.007, 0.005, and 0.002 kg/t-iron ore, respectively, representing reductions of 98.8–99.2 % compared to pre-transformation scenario. The electrostatic precipitator showed a multi-pollutant controlling ability, exhibiting 34.1 %, 93.1 %, 93.0 %, and 93.8 % of SO₂, PM, dioxins mass concentration and dioxins I-TEQ removal efficiency, respectively. Meanwhile, the semi-dry flue gas desulfurization achieved81.7 % and 82.3 % dioxins removal efficiency. Notably, the unexpected increase in dioxin emissions across selective catalytic reduction, attributed to temperature-dependent catalytic reformation, provides critical insights for optimizing air pollution control device configurations to avoid trade-offs in multi-pollutant control. This work provides industrial-scale evidence supporting China's ultra-low emission transformation policy in iron ore sintering, offering a technically available pathway to reconcile emission reduction targets with sustainable steel production.