Vanadium Extraction from Refractory Stone Coal Using Novel Composite Additive

Based on the novel composite additive BaCO 3 /CaO for the vanadium extraction from the refractory stone coal, the vanadium leaching effect has been investigated and many technical conditions have also been optimized. The results indicated that an optimum vanadium leaching efficiency of 81.07% can be obtained under the conditions that the mass ratio of BaCO 3 to CaO was 1:9 with the total proportion of the raw ore was 5 wt.%, the roasting temperature was 850°C, the roasting time was 2 h, the sulfuric acid concentration was 15% (v/v), the leaching temperature was 95°C, the liquid-to-solid ratio was 4 mL/g, and the leaching time was 3 h. Meanwhile, the vanadium leaching mechanisms demonstrated that the composite additive BaCO 3 /CaO can destroy the lattice structure of muscovite and phlogopite with the production of BaSi 4 O 9 and Ca 2 Al 2 SiO 7 during the roasting process, which can therefore facilitate the release and extraction of vanadium.