Extraction and selective stripping of molybdenum(VI) and vanadium(IV) from sulfuric acid solution containing aluminum(III), cobalt(II), nickel(II) and iron(III) by LIX 63 in Exxsol D80

5,8-diethyl-7-hydroxydodecane-6-oxime (LIX 63), a commercially available reagent, has been used in this work to investigate the extraction of molybdenum(VI) and vanadium(IV) from sulfuric acid solution in the presence of various other metals, such as aluminum(II), cobalt(II), nickel(II) and iron(III). Molybdenum(VI) and vanadium(IV) were extracted preferentially and separated completely from the coexisting metals involved at low pH (e.g., around 1.5) with LIX 63 dissolved in Exxsol D80, Vanadium(IV) in the loaded organic phase was selectively stripped by contacting with a 2 M sulfuric acid solution and isolated from molybdenum(VI). Molybdenum(VI) in the organic solvent, after the removal of vanadium(lV), was easily stripped by employing an aqueous ammonia solution as stripping agent and excellent phase separation performance (rapid phase separation, no formation of a second organic phase and no generation of an emulsion) in the stripping process was observed in all cases. A special emphasis, at least as an example of potential application, has been put on the extraction recovery of molybdenum(VI) and vanadium(IV) with LIX 63 extractant from the acidic sulfate liquor containing a sufficient quantity of aluminum(III), an appreciable amount of cobalt(II) and nickel(II), as well as a small amount of iron(III), resulting from the sulfuric acid leaching of spent hydrodesulfurization catalysts. The results obtained using the synthetic solution are in good agreement with those using the real leach liquor.