Low valency vanadium produced in the insufficient sodium roasting process affects the improvement of vanadium leaching rate. Anthraquinone-2

6-disulfonic acid disodium salt (ADA) or tannin as oxygen carrier was added into the water leaching process to transfer oxygen and to strengthen the air oxidation process of low valency vanadium. Phases of reaction system were analyzed using XRD

SEM

UV and UV-Vis DRS. The reaction mechanism of the process was also studied to prove its theoretical feasibility. Low valency vanadium was effectively oxidized by ADA or tannin

and vanadium leaching ratios increased from initial 89.47% to 92.84% and 93.64%

while vanadium contents in the leaching residue reduced from 1.1% to 0.52% and 0.47%

respectively. It also proved that catalysts had no negative effect on the consequential process.