Migration and coordination of vanadium separating from black shale involved by fluoride

With the rapid development of extraction technology of vanadium from black shale, more and more attention has been paid to its mechanism of vanadium separating. Among them, the release and oxidation process of vanadium separating from lattice and the ionic state of vanadium in the solution under the fluorine-containing system need to be revealed urgently to guide and improve the separation and purification of vanadium from black shale. In this study, the migration and coordination of vanadium leaching is preliminarily explored through experiments and simulation studies. Leaching kinetics analysis show that the release of vanadium from black shale is mainly controlled by chemical reaction under the direct acid leaching process. DFT simulations further confirm that the remove of structural oxygen atoms is the control step of vanadium release. Meanwhile, the destruction of V-O octahedron depends on the synergy of H+ and F- in turn, which pull vanadium away from mica interfaces in the form of six-coordinated [VF6]. The oxidation process of vanadium is mainly caused by the breaking of V-O bonds and the formation of V-F bonds. After transferring into a fluorine-containing solution, the ionic state of vanadium transforms constantly with the change of the concentration of H+ and F-, wherein the main reversible coordination process of V(IV) is: VF62 (sic) VF5 (sic) VF4 (sic) VF3+ (sic) VF3(OH) (sic) VOF2 (sic) VOF+ (sic) VO2+, and the main reversible coordination process of V(V) is: VF6- (sic) VF5 (sic) VF4+ (sic) VF4(OH) (sic) VOF3 (sic) VOF2+ (sic) VOF2(OH) (sic) VO2F (sic) VO2+. Above, the basic theory of vanadium separation from shale at atomic level has been studied systematically.

Automated summary

The mechanism of vanadium extraction from black shale involves the release and oxidation process, with the ionic state changing constantly in a fluorine-containing solution, indicating that successful release is achieved through a chemical reaction-controlled acid leaching process.