Mechanism of Selective Chlorination of Fe from Fe2SiO4 and FeV2O4 Based on Density Functional Theory

Abstract

Vanadium slag is an important resource containing valuable elements such as Fe, V, Ti, and so on. A novel selective chlorination method for extracting these valuable elements from vanadium slag has been proposed recently. The proposed methods could recover valuable elements with a high recovery ratio and less of an environmental burden, while the study on the chlorination mechanism at the atom level was still insufficient. Fe2SiO4 and FeV2O4 are the two main phases of vanadium slag, and the iron element can be selectively extracted via the chlorination of NH4Cl. The NH4Cl decomposes into NH3 gas and HCl gas, which was the true chlorination agent. As a result, the chlorination reactions of Fe2SiO4 and FeV2O4 with HCl were firstly calculated using FactSage 8.0. Then, this paper studied the characteristics of HCl adsorption on the Fe2SiO4(010) surface and the FeV2O4(001) Fe-terminated surface mechanism of the selective chlorination of Fe from Fe2SiO4 and FeV2O4 via DFT calculations. The processes of chlorination of Fe2SiO4 and FeV2O4 involved the processes of removing O atoms from them with HCl gas. The iron in Fe2SiO4 was selectively chlorinated because HCl could adsorb on the iron site but could not adsorb on the silicon site. The iron in FeV2O4 was selectively chlorinated because the electronegativity gap between V and O was more significant than that between the Fe and O elements.