• Optimal roasting conditions (850°C, 2 h, CaO-to-slag ratio 0.3) yield a vanadium leaching efficiency of 92.5%.
• The activation energy of the leaching process is 45.2 kJ/mol, indicating a chemically controlled reaction.
• Phase transformations during roasting and leaching were identified, providing insights into the reaction mechanism.
• The study offers a theoretical foundation for improving vanadium recovery in industrial practice.