Gaseous and particulate chlorine emissions from typical iron and steel industry in China

Abstract

The accurate estimation of chlorine emissions is urgently needed to evaluate regional and global atmospheric chlorination. This study first reports on the gaseous/particulate phases of chlorine emissions from typical integrated steel industries, including the major manufacturing processes (i.e., sintering, ironmaking, and steelmaking) and self-owned coal-fired power plant (CFPP). The concentration of chlorine species emitted from the ironmaking/steelmaking processes and the self-owned CFPP is very low (<1 mg/Nm3). Owing to the combustion of chlorine-rich sinter raw materials, the sintering processes emitted unexpectedly high concentrations of chlorinated substances, including chlorinated very short-lived CH3Cl, CH2Cl2, C2H5Cl, and C2H4Cl2. Flue gas desulfurization (FGD) systems equipped on the sintering processes can slightly reduce chlorinated hydrocarbons emissions (ClVOCs). However, the chlorine species bonded in filterable/condensable particulate states (ClFPM/ClCPM) can be removed by high efficient systems (with efficiencies of 64.8–94.1% for ClFPM and 97.3–98.5% for ClCPM), relying on employed FGD technology. Owing to rapid rate at which FGD systems have been installed in China, ClInorganic gases, ClCPM, and ClFPM emissions from the sintering and iron industry in 2016 were reduced by 75.3%, 82.7%, and 45.6%, respectively. Our results indicate that the current ultralow-emission equipment facilitates the reduction in chlorine emissions from iron and steel industry, but subsequent retrofits should give greater consideration to the simultaneous removal of ClVOCs.