Solid state reaction of CaO-V₂O₅ mixture: A fundamental study for the vanadium extraction process

The aim of this study was to investigate the phase transformation and kinetics of the solid-state reaction of CaO-V₂O₅, which is the predominant binary mixture involved in the vanadium recovery process. Thermal analysis, X-ray diffraction, scanning electron microscope and energy dispersive spectrometry were used to characterize the solid-state reaction of the samples. The extent of the solid reaction was derived using the preliminary quantitative phase analysis of the X-ray diffractograms. The results indicate that the solid reaction of CaO-V₂O₅ mixture is significantly influenced by the reaction temperature and CaO/V₂O₅ mole ratio. The transformation of calcium vanadates goes through a step-by-step reaction of CaO-V₂O₅, CaO-CaV₂O₆, and CaO-Ca₂V₂O₇ depending on the CaO/V₂O₅ mole ratio. The kinetic data of the solid reaction of CaO-V₂O₅ (1:1) mixture was found to follow second order reaction model. The activation energy (E_α) and the pre-exponential factor (A) were determined to be 145.38 kJ/mol, and 3.67×108 min^-1, respectively.