| Summary: | 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. Fe<sub>2</sub>SiO<sub>4</sub> and FeV<sub>2</sub>O<sub>4</sub> are the two main phases of vanadium slag, and the iron element can be selectively extracted via the chlorination of NH<sub>4</sub>Cl. The NH<sub>4</sub>Cl decomposes into NH<sub>3</sub> gas and HCl gas, which was the true chlorination agent. As a result, the chlorination reactions of Fe<sub>2</sub>SiO<sub>4</sub> and FeV<sub>2</sub>O<sub>4</sub> with HCl were firstly calculated using FactSage 8.0. Then, this paper studied the characteristics of HCl adsorption on the Fe<sub>2</sub>SiO<sub>4</sub>(010) surface and the FeV<sub>2</sub>O<sub>4</sub>(001) Fe-terminated surface mechanism of the selective chlorination of Fe from Fe<sub>2</sub>SiO<sub>4</sub> and FeV<sub>2</sub>O<sub>4</sub> via DFT calculations. The processes of chlorination of Fe<sub>2</sub>SiO<sub>4</sub> and FeV<sub>2</sub>O<sub>4</sub> involved the processes of removing O atoms from them with HCl gas. The iron in Fe<sub>2</sub>SiO<sub>4</sub> was selectively chlorinated because HCl could adsorb on the iron site but could not adsorb on the silicon site. The iron in FeV<sub>2</sub>O<sub>4</sub> was selectively chlorinated because the electronegativity gap between V and O was more significant than that between the Fe and O elements.
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