Besides the Waelz process, the submerged
arc furnace (
SAF) process has also been extensively used to retain metals from ashes and scraps in the metallurgical industry. However, very little is known about the formation and depletion of
polychlorinated dibenzo-p-dioxins and
dibenzofurans (
PCDD/Fs) from this thermal process. In this study, an electric
arc furnace (EAF) dust treatment plant adopting the
SAF process was investigated and compared to the plant adopting the Waelz process. The predominant contributor of
PCDD/F I-TEQ input was the EAF dusts, accounting for 98.4% of the total. The
PCDD/F contents in the generated fly ashes of the
SAF were extremely low, as almost all the organic compounds for
PCDD/F formation were decomposed by the high operating temperatures (1500-1700 °C) of the
SAF. Therefore, the
PCDD/F emission factor of the
SAF process (46.9 μg I-TEQ/tonne-EAF dust) was significantly lower than that of the Waelz process (840-1120 μg I-TEQ/tonne-EAF dust). Its
PCDD/F output/input ratios (0.23 and 0.50 based on mass and toxicity) were also lower than those of the Waelz process plant (0.62 and 1.19). Therefore, the
SAF process is superior to the Waelz process in reducing the potential of
PCDD/F formation.