Evolution of Viscosity and Structure Property of Vanadium Slag during Iron‐Extracting Reduction Process

Abstract

Photovoltaic cutting waste (PCW) is a promising prereductant to enrich vanadium and to extract iron present in vanadium slag. To understand the kinetic conditions during the reduction and separation of Fe from vanadium slag when using PCW as a reductant, the evolution of the viscosity with decreasing FeO contents is measured. The composition and structure of the melt are analyzed using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. The results show that the slag comprises a solid–liquid mixture system during the entire prereduction at 1873 K. At this temperature, as the FeO/SiO2 mass ratio decreases from 2.18 to 0.30, the solid–liquid ratio of the slag decreases from 21.5% to 1.9%, and the viscosity of the slag increases from 0.12 to 0.47 Pa s, indicating that the silicate structure of the melt significantly affects the slag viscosity, while the effect of the spinel phase is limited. The transition of the dominant silicate structure from FeO to SiO2 results in a significant decrease in the amount of the simple unit Q0 as well as the occurrence of the more complex structural unit Q3, suggesting a significant enhancement of the degree of polymerization in the vanadium slag.