Selective Extraction of Vanadium from Vanadium-Bearing Stone Coal by a Two-Stage Leaching Process

The current study presents a two-stage leaching process for selective extraction of V from vanadium-bearing stone coal. The mechanisms and influence factors of the acid leaching and baking processes were investigated. The results showed that iron phosphate and iron oxides could dissolve in dilute sulfuric acid and V released from muscovite during sulfuric acid baking process. Particularly, in the first stage, 83.03% of Fe was removed with 5.72% of V loss under the most suitable leaching conditions (concentration of H₂SO₄ of 20%, leaching time 2 h and leaching temperature 90°C). In the second stage, the leaching efficiency of V reached 95.97% at the optimal conditions (3 mL H₂SO₄ per 10 g Fe removal residue, baking time 80 min, baking temperature 230°C). Moreover, the mass ratio of V to Fe in V-rich leaching solution could achieve 6.71, which was conductive to separate of V from the acid leaching solution.