Promoting the Calcified Roasting of Vanadium Slag Based on the CeO₂-Catalytic Oxidation Mechanism

Calcification roasting-acid leaching is a clean, efficient, and environmentally friendly process, but in the roasting process, the local temperature is often too high, the heat release is not timely, and the heat transfer is blocked. Furthermore, the material is easy to sinter, which affects the final vanadium extraction effect. In this paper, a small amount of CeO₂ was introduced in the roasting process of vanadium slag to promote the calcified roasting. The results showed that the vanadium leaching rate reached 93.17% with the addition of 0.1 wt % CeO₂ at a roasting temperature of 750 °C, which was higher than that obtained without CeO₂ addition (90.00%). The results of XPS, XRD, and SEM-EDS analyses confirmed that adding CeO₂ to the roasted clinker significantly increased the proportion of pentavalent vanadium to the total vanadium by up to 28.64%. O₂-TPD analysis revealed an enhanced chemisorbed oxygen with the CeO₂-assisted roasting, indicated the activation of oxygen by CeO₂, and resulted in an enhanced oxidation of vanadium. The work in this paper establishes an alternative route for catalytic oxidation-enhanced vanadium slag roasting, which can improve the utilization of vanadium slag at relatively lower temperatures under the action of CeO₂ and is of positive significance in solving the problems of sintering and energy consumption in the roasting process.