Optimization and kinetic analysis of co-extraction of vanadium(IV) and chromium(III) from high chromium vanadium slag with titanium dioxide waste acid

Conventional methods for the co-extraction of vanadium (V) and chromium (Cr) from high chromium vanadium slag (HCVS) are normally accompanied with the formation of toxic V(V) and Cr(VI) residues and wastewater. In this study, a new process for the co-extraction of V(IV) and Cr(III) from HCVS with titanium dioxide waste acid (TWWA) by direct pressurized leaching is proposed to eliminate the looming threat of toxic V(V) and Cr(VI) formation. To gain insights into the mineralogical characteristics and liberation behavior of HCVS, mineral liberation analysis (MLA) was performed. Subsequently, the response surface methodology (RSM) was used to optimize the leaching conditions and delve into investigate the kinetics of V in the pressurized acid leaching process. By optimizing the leaching conditions, the leaching efficiencies of V, Cr, Fe, Mn, and Ti were 97.98%, 92.01%, 94.70%, 91.03%, and 0.56%, respectively. Kinetic analysis showed that the chemical reaction was the controlling step of the leaching process. Notably, this method ensures the efficient leaching of valuable metals, and the valence states present in the leach solution are V(IV), Cr(III), and Fe(II). By mitigating the generation of toxic residues and reducing the pollution burden on the environment, this study makes a compelling case for the sustainable and environmentally responsible extraction of V and Cr from HCVS.