The kinetics of oxidative leaching of vanadium trioxide

The oxidative leaching of vanadium trioxide was studied in sulfuric acid solutions from 30 °C to 90 °C. This study was performed in three stages. First, the kinetics of leaching using oxygen was investigated. It was shown that this oxidative leaching is chemically-controlled with an activation energy of around 69 kJ/mol. Secondly, vanadium(III) oxidative leaching was studied using ferric ions and oxygen. The presence of ferric enhanced kinetics significantly. Finally, oxidative leaching using a constant ferric–ferrous ratio from 1 to 300 was investigated. Potassium permanganate (KMnO4) was found to be a suitable oxidant for controlling solution potential. The oxidation rate using a constant ferric–ferrous ratio was very sensitive to temperature, giving a large activation energy (38 kJ/mol) and was proportional to the Fe(III)/Fe(II) ratio to the power of 0.47. The leaching rate using the shrinking sphere model was modeled as: ∂ d ∂ t = 12 , 088 × exp − 4580 T C Fe III C Fe II 0.47 μm min .