In this study,the formation mechanism and removal efficiency of polychlorinated dibenzo-p-dioxins, dibenzofurans(PCDD/Fs) achieved with bag filter(BF) in an electric arc furnace(EAF) in Taiwan is evaluated via intensive stack sampling and analysis.The results indicate that the PCDD/F concentration measured in the stack gas of the EAF investigated was 0.16 ng I-TEQ/m1,which was significantly lower than the PCDD/F emission limit(0.5 ng I-TEQ/m~3) set for existing EAFs in Taiwan.Due to the low operating temperature(<60℃) of the BF adopted by the EAF investigated,76%of total toxicity PCDD/Fs could be removed from the flue gas stream. In addition,the partitioning of PCDD/Fs between vapor and solid phase at different locations in EAF did not change significantly,while a reduction of solid-phase PCDD/Fs was observed at the outlet of BF.As the chlorination level of PCDD/Fs congener increases,the vapor pressure of PCDD/F congener decreases,resulting in the increase of PCDD/Fs existing in solid phase.Hence,the removal efficiencies of highly chlorinated congeners were significantly higher than that of lowly chlorinated congeners.PCDFs accounted for more than 85%of the TEQ in flue gas of the EAF investigated,among them 2,3,4,7,8-PeCDF(> 43%) was of the highest contribution.Overall,2,3,7,8-TCDD,2,3,7,8-TCDF and 2,3,4,7,8-PeCDF can serve as the unique congeners in the flue gas of the stainless steel EAF process. In this study, the formation mechanism and removal efficiency of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD / Fs) achieved with bag filter (BF) in an electric arc furnace (EAF) The results indicate that the stack gas of the EAF investigated was 0.16 ng I-TEQ / m1, which was significantly lower than the PCDD / F emission limit (0.5 ng I-TEQ / m ~ 3) set for existing EAFs in Taiwan. Due to the low operating temperature (<60 ° C) of the BF adopted by the EAF investigated, 76% of total toxicity PCDD / Fs could be removed from the flue gas stream. / Fs between vapor and solid phase at different locations in EAF did not change significantly, while a reduction of solid-phase PCDD / Fs was observed at the outlet of BF.As the chlorination level of PCDD / Fs congener increases, the vapor pressure of PCDD / F congener decreases, resulting in the increase of PCDD / Fs existing in soli d phase .ence, the removal efficiencies of highly chlorinated congeners were significantly higher than that of lowly chlorinated congeners. PCDFs accounted for more than 85% of the TEQ in flue gas of the EAF investigated, among them 2,3,4,7, 8-PeCDF (> 43%) was the highest contribution. Overall, 2,3,7,8-TCDD, 2,3,7,8-TCDF and 2,3,4,7,8-PeCDF can serve as the unique congeners in the flue gas of the stainless steel EAF process.