Key Takeaways & Executive Findings
- •• Lower vanadium valence (V3+ > V4+ > V5+) enhances solid solubility in Fe2TiO5, explaining reduced extraction efficiency in calcification roasting. • Insufficient oxidation of vanadium during roasting increases vanadium retention in Fe2TiO5, a key factor limiting vanadium recovery. • Optimized conditions (higher temperature, V2O3 as vanadium source, high-purity argon atmosphere) increase vanadium solubility in Fe2TiO5. • High-temperature dissociation in air facilitates vanadium release from Fe2TiO5, offering a potential strategy to improve extraction rates.
Abstract
Vanadium is a strategic metal in many countries, and it is mainly extracted from vanadium slag produced in titanomagnetite metallurgy. The traditional sodium roasting process for vanadium extraction poses environmental threats, and a green calcification process has been proposed. However, the vanadium extraction rate in the calcification process is much lower than in the sodium roasting process, which is related to vanadium solid solubility in Fe2TiO5. Previous studies about vanadium behavior in Fe2TiO5 were conducted in air, with a vanadium oxidation state of V5+. Vanadium with lower oxidation states has been detected in the tailings in the calcification process. The present paper studied the effects of vanadium oxidation states on the solid solubility in Fe2TiO5 through solid-state reaction, X-ray diffraction characterization, transmission electron microscopy characterization, X-ray photoelectron spectroscopy analysis, and solid solution modeling. The relative interaction values between vanadium oxides and Fe2TiO5 are obtained as |LV2O3| > |LV2O4| > |LV2O5|, indicating that vanadium with lower valence is preferable to be solid dissolved in Fe2TiO5. The results imply that insufficiently oxidized vanadium increases the vanadium content in the Fe2TiO5 phase during vanadium slag’s calcification roasting. Besides, experimental conditions optimization shows that higher experimental temperature, vanadium introduction as V2O3, and a high-purity argon atmosphere would lead to higher vanadium solubility in Fe2TiO5, and high temperature is beneficial for the release of vanadium from vanadium-containing Fe2TiO5 when dissociated in air.
1. Introduction
Vanadium is a strategic metal in many countries, and it is primarily used in steel, nonferrous metal alloys and catalysts, and recently in energy storage, like redox flow batteries [1–3]. The production of vanadium is constantly increasing in recent decades owing to its expanding applications, from 72000 t in 2010 to about 130000 t in 2024 [4].
The world’s vanadium supply is mainly derived from vanadium slag produced in titanomagnetite metallurgy, accounting for about 70% of the world’s total vanadium production [5]. The typical chemical compositions of vanadium slag include V2O3 8.77wt%–15.78wt%, Cr2O3 < 9.45wt%, FeO 23.50wt%–48.21wt%, SiO2 13.16wt%–20.88wt%, TiO2 9.90wt%–14.60wt%, MnO 4.94wt%–11.35wt%, Al2O3 < 3.47wt%, MgO < 4.01wt%, CaO 1.67wt%–3.02wt%, and P2O5 < 0.12wt% [6]. In vanadium slag, vanadium accompanied with Ti and Cr is mainly concentrated in the spinel phases of (Fe,Mn)2(V,Ti)O4 and (Fe,Mg,Mn)(V,Cr)2O4, where vanadium valences are V4+ and V3+ [7–8]. Vanadium-containing phases are wrapped in other phases in vanadium slag, including olivine ((Fe,Mg)2SiO4), fayalite (Fe2SiO4), augite (Ca(Fe,Mg)Si2O6), diopside (Ca(Fe,Al)2SiO6), etc. [7].
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Zhengpei Yan, Shili Zheng, Yang Zhang (2025). Effects of vanadium valences on the solubility in Fe2TiO5 for helping to understand calcification roasting of vanadium slag. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-025-3184-9
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Frequently Asked Questions
What is the main finding of this study?
The study reveals that vanadium with lower valence (V3+) has higher solid solubility in Fe2TiO5 compared to higher valences (V4+, V5+), which explains why insufficient oxidation during calcification roasting leads to higher vanadium retention in Fe2TiO5 and lower extraction rates.
How does vanadium valence affect its solubility in Fe2TiO5?
The relative interaction values indicate that V2O3 (V3+) has the highest solubility, followed by V2O4 (V4+), and V2O5 (V5+) has the lowest. This suggests that lower valence vanadium is more readily incorporated into the Fe2TiO5 lattice.
What experimental conditions increase vanadium solubility in Fe2TiO5?
Higher experimental temperature, introducing vanadium as V2O3, and using a high-purity argon atmosphere were found to increase vanadium solubility in Fe2TiO5.
Why is the vanadium extraction rate lower in calcification roasting compared to sodium roasting?
The lower extraction rate is partly due to vanadium being retained in the Fe2TiO5 phase during leaching. This study shows that lower valence vanadium is more soluble in Fe2TiO5, and insufficient oxidation during roasting increases this retention.
What is the significance of this research for vanadium production?
The findings provide insights into optimizing calcification roasting conditions to minimize vanadium loss in Fe2TiO5, potentially improving vanadium recovery and reducing environmental impact compared to traditional sodium roasting.
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