Abstract: The stone coal from Yunxi，Hubei was selected as raw materials.The influence of additive-free roasting technique on the mineral phase，vanadium speciation and bioleaching vanadium process was investigated.The detection methods of X-ray fluorescence (XRF),X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyze the ore stone coal and the roasted residue.The results showed that ①the vanadium leaching rate could reach 92.62% and the highest concentration of Si was 53.93 mg/L，when the sample was roasted at 900 ℃ for 2 h.After leaching，the maximum of Al and Fe in the system was less than 10 mg/L and 2 mg/L，respectively.②The V was chiefly present in the residual fraction in the stone coal，which account for 88.62%.The content of V increased to 85.52% in the extractable fraction and it is only 9.28% in the residual fraction after additive-free roasting in 900 ℃.③the additive-free roasting caused the changes of the hydrogen bonding of interlayer water in muscovite and the disappearance of OH; the unstable of structure of alumina tetrahedron; the distorted and collapsed of basic composition unit; the reduced of chemical bond energies of the vanadium and around elements，which weaken the bond of vanadium.It provided favorable conditions for bioleaching process.

Key words: Vanadium-bearing stone coal, Additive-free roasting, Bacillus mucilaginosus, Bioleaching, BCR-sequential extraction