Evolution of Viscosity and Structure Property during Aluminothermic Reduction of Vanadium‐Enriched Slag

Abstract

Aluminum dross is a promising reductant for extracting vanadium to enable the direct production of ferrovanadium alloy in pre‐reduced vanadium‐rich slag (PVS). The evolution of the viscosity of PVS is measured with various A/M ratios (w(Al2O3)/w(FeO + Cr2O3 + MnO + V2O3 + Al2O3)), representing different reduction stages. The compositions and structural properties of the melts are analyzed using X‐ray powder diffraction, scanning electron microscopy, and Raman spectroscopy. The results show that with an increase in the mass ratio of Al2O3 to (FeO+Cr2O3+MnO+V2O3+Al2O3) in the slag transformed from a solid–liquid mixture to a single liquid phase at 1873 K. When A/M increases from 0.29 to 0.53, Q0 and Q1 polymerize into Q2, resulting in a slow increase in viscosity from 0.091 to 0.158 Pa s. As A/M further increased to 1.00, Q0 disappeared, Q3 appeared, and the fraction of Al–O–Si increased to 37.7%, indicating that the simple aluminosilicate structural units are polymerized into complex structural units. Meanwhile, the viscosity increases to 0.338 Pa s. Al2O3 acts as a network former and strengthens the degree of polymerization of the melt. The variation ranges of the apparent activation energy, structural complexity, and the average number of non‐bridging oxygen are 139.23–215.12 kJ mol−1, 0.57–2.97, and 2.16–1.05, respectively.