Electrolytic preparation and characterization of VCr alloys in molten salt from vanadium slag.

Vanadium slag contains several critical elements like V, Ti, Cr, Fe and Mn. In our previous work, V and Cr have been enriched by selective chlorination, increasing from 10.05% to 14.95% and 5.84%–8.69% separately. V and Cr still maintain the trivalence state in molten salt. In the current work, the electrodeposition behaviors of V3+ and Cr3+ in NaCl–KCl molten salt at 800 °C were investigated using cyclic voltammetry (CV) and square wave voltammetry (SWV) with a tungsten electrode. It was found that the reduction processes of V3+ and Cr3+ consist of two steps, M3+/M2+, M2+/M. The diffusion coefficients of V3+ and Cr3+ in NaCl–KCl molten salt were measured by CV. The effect of VCl 3 /CrCl 3 mass ratio on VCr alloy was investigated by a two-electrode under constant voltage. Pure Cr can be obtained at 2.8 V in the NaCl–KCl molten salt, while VCr alloy (3.71 mass % V-94.28 mass% Cr-2.01 mass % O) was obtained when electrolysis voltage was controlled to 2.8 V at 800 °C. The composition of VCr alloy can be designed by changing the molten salt composition. This method can be applied for direct preparation of VCr alloy from vanadium slag, thus offering the use of low cost raw materials with direct environmental benefits. • The main composition of chlorinated vanadium slag were the VCl 3 and CrCl 3. • The electrochemical behaviors of V3+ and Cr3+ in molten salt were investigated. • The diffusion coefficients of V3+ in NaCl–KCl molten salt were 8.72✕10−5 cm2s−1. • The diffusion coefficients of Cr3+ in NaCl–KCl molten salt were 26.5✕10−5 cm2s−1. • Alloys with different ratios of V to Cr were prepared. [ABSTRACT FROM AUTHOR]