Life cycle assessment of ultra-low treatment for steel industry sintering flue gas emissions

The largest contributor to pollutant emissions is the sintering process in steel industry. Ultra-low emission policy for the Chinese steel industry states that emission concentrations of particulatematter, SO2 and NOx should not exceed 10, 35 and 50mg/m(3) respectively. The emission concentrations of the steel industry are the same as the ultralow emission policy for the coal-fired power industry, but the pollutant control technologies of the two industries are different. Life cycle assessmentmethod is applied to analyze the latest ultra-lowtreatment process for sintering flue gas emissionswhich includes electrostatic precipitation, ozone oxidation, wet desulfurization, wet denitration, condensation dehumidification and wet electrostatic precipitation. Following this novel ultra-low emission treatment, the concentrations of particulatematter, SO2, NOx, and PCDDs in the sintering flue gas decreased very significantly, attaining the new emission standard. With 1 ton of sinter as the functional unit and cradle to gate as the systemboundary, the environmental impact of the process is 0.1811 and the total economic cost is 172.79 RMB, of which internal cost is 34.64 RMB and external cost is 138.15 RMB. The main environmental impacts result from applying the wet denitration and ozone oxidation processes. Sodium sulfite in the wet denitration process, and electricity and liquid oxygen in the ozone oxidation process are the key inputs that cause environmental impact. These findings are useful for a further optimization of the ultra-low emissions process from both the environmental and economic perspective, which is applicable in other regions of the world. (C) 2020 Elsevier B.V. All rights reserved.