Characterizing the emissions of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) from electric arc furnaces during steel-making

Abstract

The amount of steel produced using electric arc furnaces (EAFs) has been increasing in recent years. In this study, stack gases from EAFs in steelmaking plants were analyzed to determine if they are also dominant sources of polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/F) emissions in China. Isotope dilution high-resolution gas chromatography high-resolution mass spectrometry for qualitative and quantitative analysis of PBDD/F congeners revealed that the mean PBDD/F mass concentrations were 271.1–9467.8 pg Nm−3 for the preheating stages (PS) of three EAF plants and that the corresponding toxic equivalents (TEQs) were 10.8–971.2 pg TEQ Nm−3. The PBDD/F mass concentration from the smelting stage (SS) at plant E3 was 261.9 pg Nm−3 (4.5 pg TEQ Nm−3). The PBDD/F emission factors (EF) during the preheating stage for the three plants were 0.0356–1.51 μg TEQ t−1, and the EF was 0.0359 μg TEQ t−1 during the E3 smelting stage. PBDD/Fs were found to contribute 2.39–67.85% to the total mass and 2.84–57.68% to the total dioxin TEQ. These wide fluctuations were caused by differences in the composition of feeding materials and the working temperature of bag filters. Overall, the results indicate that PBDD/F emissions from EAF steelmaking should receive increased attention. The PBDD/F congener patterns among the three EAF plants were variable, possibly because of differences in raw materials. The results presented herein will facilitate assessment of the contribution of EAFs to total PBDD/F emissions in China and investigations of PBDD/F emissions at different stages of steelmaking processes using EAFs.