Process-resolved characterization and plant-level inventory of multi-pollutant emissions from China's coking industry

Process-specific multi-pollutant emissions, trace-element phase partitioning, and long-term mitigation potential in China's coking industry remain insufficiently resolved. This study aimed to integrate process-resolved field measurements with a dynamic plant-level emission inventory and scenario analysis to identify major emission characteristics and mitigation priorities. Size-segregated particulate matter, water-soluble ions, and trace elements were measured at coal charging, coke oven flue gas, dry quenching, and coke pushing units in two representative enterprises. A plant-level inventory covering 307 enterprises during 2012-2024 was subsequently developed, and emissions were projected to 2050. Total PM concentrations ranged from 3.12 to 37.72 mg/m3, sulfate accounted for 28-59% of the measured ionic mass, and As and Cd were preferentially associated with PM2.5. The operationally defined condensable fraction contributed 44.5-57.4% of total measured trace-element concentrations in coke oven flue gas. In 2022, national emissions were estimated at 159.8 kt PM, 66.6 kt SO2, 82.3 kt NOx, 1,928.6 kt CO, 32.6 kt NH3, 838.3 kt VOCs, 4.24 kt PAHs, and 707.6 t trace elements. Under the BACT scenario, PM, SO2, NOx, and trace-element emissions were projected to decline to 15.5 kt, 14.6 kt, 7.4 kt, and 88.1 t, respectively, by 2050. These results identify process-, region-, and technology-specific priorities for controlling fine particles, condensable fractions, and fugitive emissions from China's coking industry.