Study on zinc removal behavior in simulated pre-reduction sintering process

Abstract

In this study, blast furnace dust and iron concentrate were used as raw materials and graphite as reducing agent for mixed compacts. The briquettes were roasted in a high temperature tube furnace at 1200°C and kept for a certain time to simulate the pre-reduction sintering dezincification process. The reduced briquettes were characterized by X-ray diffraction, scanning electron microscopy, Energy Dispersive Spectroscopy and flame atomic absorption spectrometry. The effects of C/O molar ratio, basicity and pre-reduction time on the zinc removal rate and pre-reduction degree of the pre-reduction sintered products were studied, and the removal mechanism of zinc was further investigated. The results show that the pre-reduction sintering process can effectively achieve the zinc volatility removal while meeting the requirements of subsequent blast furnace production. The zinc removal rate of pre-reduced sintered products increased with the prolongation of pre-reduction time, increased first and then decreased with the increase of C/O molar ratio and basicity. The pre-reduction degree and Zn removal rate showed the same variation pattern. When the briquettes with C/O molar ratio of 1.0 and basicity of 1.9 were reduced for 20 min, the zinc removal rate and pre-reduction degree could reach 90.40% and 87.74%, respectively, indicating that a large amount of zinc was removed and most of the metallic iron had been reduced. The research results can provide some theoretical basis for industrial production.