A Comparative Study of Extracting Vanadium from Vanadium Titano-Magnetite Ores: Calcium Salt Roasting Vs Sodium Salt Roasting

In this study, a new vanadium extraction process from vanadium titano-magnetite(VTM) featuring calcification roasting and (NH4)2C2O4 solution leaching has been proposed. Compared with the traditional sodium roasting, the calcification roasting can avoid the production of waste gas and the sodium free tailings can be used for iron recovering by steel-making. However, the leaching rate of (NH4)2C2O4 was lower than that in sodium salt roasting-waterleaching. The reaction kinetics and mechanism of these two process were studied and compared in detail. It was found thatCaV2O6was formed during calcification and the porous structure of calcine facilitated the mass transfer. In the subsequent (NH4)2C2O4 leaching, theCaC2O4was formed and it would precipitate at the calcine particle surface and pores, which hindered the vanadium leaching. The leaching kinetics study showed that the diffusion through the solid product layer was the rate-determiningstep. Mechanical activation method was proposed to improve the leaching reaction kinetics in this work. It has been evident to be an effective method to intensify the leaching process. Under the optimal roasting and leaching conditions, the vanadium leaching rate could reach 81%, which was similar to that of the sodium salt roasting process. This is a promising alternative process for vanadium extraction from high grade VTM.