A study on the zinc removal kinetics and mechanism of zinc-bearing dust pellets in direct reduction

Zinc-bearing dusts from steel plants were classified as hazardous solid waste, but are important secondary resources to extract iron and zinc through direct reduction technology. In this study, three kinds of Zinc-bearing dusts from a steel plant were made into carbon-containing pellets and reduced at 1323 K-1473 K. The results showed that the efficiency of zinc removal was controlled by the Jander three-dimensional diffusion. The mechanism of zinc removal from the pellets was analyzed by optical microscope, scanning electron microscope, energy dispersive spectrometer, X-ray diffraction and thermodynamic calculation. It was found that the zinc element in the zinc-bearing dust pellets presented in the form of zinc ferrite, hardystonite and zinc chloride. The process of the zinc removal from the pellets in direct reduction could be divided into four stages according to the efficiency of zinc removal and the microstructure of the reduced pellets. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study demonstrates that direct reduction technology can efficiently extract iron and zinc from zinc-bearing dusts, with the efficiency of zinc removal controlled by Jander three-dimensional diffusion. Analysis of the microstructure and elemental composition of the pellets showed that zinc in the dust exists in different forms, and the process of zinc removal can be divided into four stages based on the efficiency and microstructure of the reduced pellets.