A novel process of gradient oxidation roasting-acid leaching for vanadium extraction from stone coal

Efficient green vanadium extraction is a research direction of stone coal. This study focuses on efficient green vanadium extraction of stone coal. A gradient oxidation roasting-acid leaching (GORA) process was proposed, which is additive-free and effectively improves the leaching efficiency with preliminary oxidation and further high-temperature reoxidation. The results of this study showed that 95.59 % of −0.074 mm particles were the most appropriate. The suitable roasting temperature and time for preliminary oxidation roasting were 650 °C and 0.5 h, respectively. A porous structure was formed with a specific surface of 2.61 m2/g, and a total pore volume of 0.0164 cm3/g. Further, the optimal conditions of high-temperature reoxidation roasting were 850 °C, 3 h, 35 % O2, and 600 ml/min. The best V2O5 leaching rate of the GORA was 68.89 %, which was 36.23 % higher than that of the raw ore. It was discovered that stone coal could withstand high temperatures without sintering after preliminary roasting. High-temperature reoxidation is a prerequisite for destroying the lattice of vanadium-bearing minerals and promoting vanadium release. Meanwhile, the loose and porous honeycomb particle products promoted subsequent gas–solid and liquid–solid reactions. Therefore, this study provides a novel and effective method for extracting vanadium from stone coal.