Influence of pollutants' control facilities on PM_2.5 profiles emitted from an iron and steel plant

A typical long process in an iron and steel plant has been investigated with four main manufacturing processes, and nine sample sites were selected, in order to provide a comprehensive understanding of the PM_2.5 profile changes caused by the pollutants' control facilities. The result shows pollutants' control facilities have not only affected PM_2.5 concentrations, but also the PM_2.5 profiles. PM_2.5 concentration was increased 1.89 times after Flue gas desulfurization (FGD) in the sintering process, the Ca content in PM_2.5 increased to 21.1% caused by the desulfurizing agent; compared with electrostatic precipitator (ESP), bag filter (BF) is more effective for removal of fine particles, especially the condensable particles. The chemical compositions of Cl, K, Pb and Sb decreased after ESP in the sintering process, Fe decreased to 38.0% after ESP in the pelletizing process, and [Formula: see text] and Organic carbon (OC) increased in both processes. Different from ESP, Fe content increased obviously after BF in both blast furnace and converter processes, while S, K, [Formula: see text], and OC are all decreased after BF. The coefficient of divergence (CD) values has been calculated at 0.42∼0.60, showing giant influences of pollutants' control facilities on PM_2.5 chemical profiles. Sixteen Polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 have been analysed, the result shows that de-dusting facilities (ESP and BF) are quite effective for PAHs removal, and the PAHs' concentration significantly increased after FGD. More efforts are still needed to complete the accurate profile data with the rapid development of pollutants' control technologies.