Separation of molybdenum(VI), rhenium(VII), tungsten(VI), and vanadium(V) by solvent extraction

Solvent extraction experiments were performed to separate Mo(VI), V(V), Re(VII), and W(VI) from two types of synthetic solutions. One was 1-5 M HCl solution containing Mo(VI), V(V), and Re(VII), and the other was a solution containing these four metals in the pH range 2-10. First, LIX 63 co-extracted Mo(VI) and V(V) from 1 M HCl solution, leaving Re(VII) in the raffinate. The two metals in the loaded LIX 63 were separated by selective stripping of V(V) with 6 M HCl solution. Second, LIX 63 selectively extracted both Mo(VI) and V(V) from the solution with an initial pH of 2, leaving Re(VII) and W(VI) in the raffinate. W(VI) was selectively extracted over Re(VII) from the Mo(VI) and V(V) free raffinate by Alamine 336. McCabe-Thiele diagrams for the extraction and stripping were constructed. Based on the results of this study, a process was proposed for the separation of the four metals from the second synthetic solution by solvent extraction and stripping.