Sustainable Recovery of Vanadium from Stone Coal via Nitric Acid Oxygen Pressure Leaching

To overcome the low extraction efficiency and environmental concerns associated with traditional vanadium extraction methods, this study proposes an innovative nitric acid oxygen pressure leaching approach integrated with nitrogen recycling. Through systematic single-factor experiments and response surface optimization, key parameters, including nitric acid concentration, leaching temperature, liquid-to-solid ratio, and total pressure, were carefully evaluated and optimized. Under optimal conditions, consisting of 1.5 mol/L nitric acid, a temperature of 127.43 °C, a liquid-to-solid ratio of 5 mL/g, and a total pressure of 2 MPa, the vanadium leaching efficiency reached 73.1%. Cyclic leaching experiments confirmed the feasibility of nitrogen recycling. Characterization analyses by SEM-EDS, XRD, BET, and FTIR revealed that nitric acid oxygen pressure leaching significantly disrupted the mineral lattice structure, altering the coordination environment of metal ions and increasing surface porosity, thereby facilitating efficient vanadium dissolution from stone coal. This study provides valuable insights and establishes a scientific foundation for developing efficient, environmentally friendly, and economically viable vanadium extraction techniques from low-grade stone coal resources, thereby contributing to sustainable mining practices and resource utilization.