Calcification Roasting-Microwave Acid Leaching of Vanadium from Vanadium-Bearing Steel Slag

Enhanced vanadium recovery from vanadium-bearing steel slag is essential in the sustainable use of metallurgical solid waste. This study uses microwave-assisted acid leaching on roasted clinker and systematically investigates it to enhance vanadium recovery; uses response surface methodology (RSM) to identify optimal parameters for leaching; and the influences of sulfuric acid concentration, leaching time, liquid-to-solid ratio (L/S ratio), and leaching temperature on vanadium dissolution are evaluated. The optimal leaching parameters are identified as an L/S ratio of 10:1, 41% sulfuric acid concentration, 65 min leaching time, and 92 °C leaching temperature, under which the highest vanadium extraction rate is 84.58%. Kinetic studies revealed that the leaching behavior during the initial 30 min followed a shrinking core model with fixed particle size. The vanadium microwave-assisted acid leaching process exhibited the observed activation energy (Ea) of 37.30 kJ·mol−1, following a kinetic order of 1.5392 relative to sulfuric acid concentration, implying that ion transport across the solid phase formed during the reaction determined the step that limits the reaction rate. The semi-empirical kinetic equation established in this study accurately describes the leaching behavior under different conditions. This research establishes a theoretical framework and technical reference for boosting vanadium recovery from steel slag, which uses microwave-assisted leaching technology.