Recovery and separation of Fe and Mn from simulated chlorinated vanadium slag by molten salt electrolysis

Abstract

Tailings from the vanadium extraction process are discarded each year as waste, which contain approximately 30wt% of Fe. In our previous work, we extracted Fe and Mn from vanadium slag, and Fe and Mn existed in the form of FeCl₂ and MnCl₂ after chlorination by NH₄Cl to achieve effective and green usage of waste containing Fe and Mn. In this work, square wave voltammetry (SWV) and cyclic voltammetry (CV) were applied to investigate the electrochemical behaviors of Fe²⁺ and Mn²⁺ in NaCl-KCl melt at 800°C. The reduction processes of Fe²⁺ and Mn²⁺ were found to involve one step. The diffusion coefficients of FeCl₂ and MnCl₂ in molten salt of eutectic mixtures NaCl-KCl molten salt were measured. The electrodeposition of Fe and Mn were performed using two electrodes at a constant cell voltage. The Mn/Fe mass ratio of the electrodeposited product in NaCl-KCl-2.13wt%FeCl₂-1.07wt%MnCl₂ was 0.0625 at 2.3 V. After the electrolysis of NaCl-KCl-2.13wt%FeCl₂-1.07wt%MnCl₂ melted at 2.3 V, the electrolysis was again started under 3.0 V and the Mn/Fe mass ratio of the electrodeposited product was 36.4. This process provides a novel method to effectively separate Fe and Mn from simulated chlorinated vanadium slag.

Keywords

vanadium slag / molten salt electrolysis / separation / electrochemical analysis

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