Effectiveness of thermal treatment on Pb recovery and Cl removal from sintering dust

Sintering dust is considered as a hazardous waste material owing to its high heavy metal content. In this study, a new technology for the treatment of sintering dust via chlorination roasting was developed. The chlorination behavior of Pb at high temperatures was studied. The volatilization behavior of Pb and Cl was found using different analytical techniques, such as scanning electron microscopy and energy dispersive X-ray spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, X-ray fluorescence, and atomic absorption spectroscopy. In addition, the thermodynamics and kinetics of the chlorination mechanism of Pb at high temperatures were studied. Thermodynamic analysis results showed that quartz and the chlorinating agent played key roles in the process of chlorination. Compared with KCl and NaCl, CaCl₂ showed superiority in the chlorination. The phase transformation of sintering dust at different temperatures was analyzed. The volatilization rates of Pb and Cl reached 98.69 % and 84.55 %, respectively. The study of kinetics showed that the volatilization of PbCl₂ was controlled by diffusion, and the apparent activation energy is 7.97 kJ/mol. Finally, chlorination roasting residue can be recycled for iron and steel metallurgy.