Clean preparation of V2O3 by one-step molten salt electrochemical reduction of soluble NaVO3

Abstract

Vanadium oxides, such as V2O5 and V2O3, are important metallurgy products and mainly used to prepare V-based alloys for steelmaking. At present, vanadium oxides are mainly produced by complex sodium salt roasting process. Serious environmental pollution, such as emission of ammonia nitrogen wastewater and NH3, are restrictive problems. Here, a clean and sustainable method for V2O3 preparation is proposed by one-step molten salt electrochemical reduction of soluble NaVO3, i.e. an indispensable intermediate in traditional V metallurgy. The pollution issues are well solved. The theoretical decomposition voltages of different vanadate to various low-valence vanadium oxides were calculated. NaVO3 with a solubility of 14.7 wt% is the most suitable vanadate for the direct preparation of V2O3 by molten salt electrolysis. The effects of cathode structure, NaVO3 content, electrolysis temperature and voltage on current efficiency and electricity consumption were systematically studied. High-purity V2O3 with uniform particle distribution is obtained and the lowest electricity consumption is only 2.86 kWhkg−1. V2O3 is mainly produced by one-step electrochemical reduction of soluble NaVO3 through two-electron transfer process. The economic evaluation for ferrovanadium production is preliminarily carried out. Compared with the traditional process, the cost for ferrovanadium production is lower by the aluminothermic reduction of V2O3 which is prepared by clean one-step electrolysis of soluble NaVO3.