Dynamic emission evolution and synergistic effect of heavy metals and primary air pollutants in China's iron and steel industry

Abstract

At present, most reductions in heavy metals (HMs) emissions in the iron and steel industry (ISI) are attributable to synergistic decreases resulting from the implementation of dust removal, desulfurization, and denitrification facilities. However, the correlation between HMs and primary air pollutants (PAPs) emissions remains understudied. In this study, we systematically investigated the spatiotemporal evolutionary dynamics of HMs and PAPs emissions, as well as their synergistic effects, using an established long-time-series HMs and PAPs emission inventory based on a facility-level point source activity database. The results showed that HMs and PAPs emissions from the ISI in China were estimated at 1445.8 t and 1327.1 kt in 2023, respectively. Basic oxygen furnace and electric arc furnace processes were identified as the primary sources of HMs emissions. The Beijing–Tianjin–Hebei region and the Yangtze River Delta were identified as the main areas with high levels of HMs and PAPs emissions. Spring and summer were also identified as the primary seasons associated with elevated HMs and PAPs emissions. From 2013 to 2023, emission reductions of HMs ranged from 21.2% to 81.1%, while reductions of PAPs ranged from 37.0% to 87.0%. Among the PAPs, NO_x exhibited the greatest synergistic reduction potential with HMs, whereas PM demonstrated the strongest synergistic effects with HMs. End-of-pipe treatment levels (65.9%–85.7%) and energy intensity (13.5%–33.4%) were identified as the primary drivers of synergistic emission reductions. These findings provide data support for the formulation of targeted policies aimed at achieving synergistic emission reductions of HMs and PAPs in the ISI.