The kinetics of oxidative leaching of vanadium trioxide

The oxidative leaching of vanadium trioxide was studied in sulfuric acid solutions from 30 degrees C to 90 degrees 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: partial derivative d/partial derivative t = 12,088 x exp (-4580/T) (C-Fe(III)/C-Fe(II))0.47 mu m/min. (C) 2014 Elsevier B.V. All rights reserved.