Influence of CaO on Existence form of Vanadium-containing Phase in Vanadium Slag

Abstract

A novel de-Phosphorisation & V-extraction process (de-P & V-extraction) is proposed in which lime is added during the production of vanadium slag. This is expected to promote both phosphorus removal and environment-friendly vanadium extraction from the vanadium-containing hot metal simultaneously. The influence of CaO addition on the chemical components and mineralogical morphology of vanadium-containing phase in vanadium slags has been investigated by XRD and SEM/EDS. Results show that the increase in CaO contents changes both species of vanadium-containing phase and the morphologies of vanadium-containing spinels in vanadium slags. Vanadium concentrates as (Mn,Fe,Mg)V2O4 in the spinel phase in vanadium slag with CaO content less than 10 mass%. When CaO content is higher than 12.89 mass%, vanadium exists both as (Mn,Fe,Mg)V2O4 in dendritic-like spinel and as Ca3V2(SiO4)3 in goldmanite in the matrix. Precipitation of perovskite results in the dendritic-like shape of spinels while V 3+ diffusing away from spinel lattice leads to the formation of goldmanite Ca3V2(SiO4)3. Thermodynamic calculation of phase equilibrium has been conducted to understand the phase evolution. This work demonstrates the influence of CaO addition on the existence form of vanadium-containing phase in vanadium slag and thus provides the theoretical foundation for the proposed novel de-P & V-extraction process.

Structural Characterization of FeO–SiO₂–V₂O₃ Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

“…and spinel phase, meaning that the valences of V and Fe in the vanadium slag system are mostly + 3 and + 2 respectively. 5,[7][8][9][10][11] Recently, Fang 12) modelled the thermodynamic behavior of Fe, V and Cr in molten slag. It was found that under the conditions of practical refining of V-containing hot metal, where the log( f O 2 ) varies from − 11 to − 10 at the slag-metal reaction interface, the oxide forms of V and Fe can be assigned as VO 1.5 and FeO 1.05.…”

Phase Equilibrium Investigation for CaO-SiO₂-5wt.%MgO-20wt.%Al₂O₃-TiO₂ System Relevant to Ti-bearing Slag System

“…The Al-Ti diopside phase is one of the most common phases presented in Ti-bearing slag system and is characterized by the high solubility of Al 2 O 3 and TiO 2 . [34][35][36][37][38][39][40] In Fig. 2(f), four phases equilibria are detected for sample K15 at 1 300°C, except for the equilibrium phases mentioned for sample K12, the pseudobrookite solid solution phase with the fomula of (MT 2 , AT) ss is found, as marked in Fig.…”

Vanadium Extraction from a Fe–V (2.0 Mass%)–P (0.1 Mass%) Melt and Investigation of the Phase Relations in the Formed FeO–SiO2-Based Slag with 20 Mass% V

“…P is found to distribute into the augite phase in the BOF samples formed under these less-favorable process conditions. The average compositions of the augite [9,20] and fayalite [9,20] phases in these samples are presented in Table 8. Normalization was performed by taking the sum of the components as 100 mass%.…”