<p>Vanadium-bearing slags serve as a dominant industrial source for vanadium extraction. Varying cooling regimes for the hot vanadium-bearing slags after converting result in different phase formations in the cooled slags, which further determines the transition of vanadium-containing phases to soluble vanadate during roasting. In this study, two sets of experiments were designed to synergistically regulate the phase formations in the hot vanadium-bearing slags during the cooling and the phase transitions during the subsequent roasting. The samples from cooling to roasting were investigated by multiple advanced characterizations including SEM-EPMA, XPS, XRD and FTIR as well as thermodynamic analysis. The results of cooling experiments showed that, rapid cooling prompted retention of more V₂O₃ into the liquid phase instead of forming the spinel. Rapid cooling at a higher temperature to avoid the formation of olivine could maintain the high reactivity, thus facilitating the subsequent roasting kinetics. Based on the results of roasting experiments, the highly reactive vanadium-bearing slags without olivine showed shorter roasting time and improved vanadium enrichment. Those findings, within an integrated design of cooling and roasting steps coupled with the previous converting and the subsequent leaching steps, provide a significant whole process design for vanadium extractions from the hot vanadium-bearing slags.</p>