Mineralogical characterisation of vanadium slag under different treatment conditions

Abstract

Synthetic vanadium slags were melted at 1673 K and then cooled to a predetermined temperature at different cooling rates. The mineralogical phases and crystallisation behaviour were investigated based on optical microscopy, SEM, EDS and XRD analyses. The results show that spinels and silicates were the major phases in the complex vanadium slag samples, and V is enriched in the spinel phases, i.e. Fe x V 32x O 4 and Mg x (V,Ti) 32x O 4 . The apparent diameter of spinel crystal grains decreases with increasing cooling rate, e.g. from 14 to 5 mm at 1523 K. Crystal grain size increases significantly with increasing holding time. It is also found that the grain sizes of spinels at higher temperatures, 1573 and 1623 K, are considerably smaller than at lower temperatures, 1473 and 1523 K. At lower temperature, large blocked spinel crystals between grey silicate phases are formed, whereas there only a few smaller blocked spinels when performed at higher temperature. Better control of the process cooling parameters will benefit vanadium slag quality.

Growth of spinel crystals in vanadium slag and their characterization

“…In a previous work, we used 10 g slag mixture and a 70 mm×10 mm×10 mm corundum porcelain boat to do the same experiment. The result showed that the grain size of spinels was no more than 6 µm on the condition of quenched in water directly and could reach 20 µm with slow cooling rates [12]. The result showed obvious consistency with Barolin's reports [13].…”

Viscosity Property and Structure Analysis of FeO–SiO₂–V₂O₃–TiO₂–Cr₂O₃ Slags

“…Thus, the dynamics condition for vanadium-extraction becomes worse, and the yield ratio of vanadium is decreased. [11][12][13][14] Though the viscosity of Cr 2 O 3 -bearing slag would decease with increasing of the temperature, the oxidation of vanadium would be suppressed according to the selective oxidation theory, and thus the practical blowing smelting temperature is usually controlled below 1 653 K. [15][16][17] Therefore, study on the influence of Cr 2 O 3 on the properties of FeO-SiO 2 -V 2 O 3 (-TiO 2 ) system slag is very important to improve the blowing smelting technology for the vanadium-extraction from the chromiumbearing hot metal.…”

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.…”