Separation of Vanadium and Tungsten from Sodium Molybdate Solution by Solvent Extraction

Solvent extraction experiments have been performed, to separate vanadium (V) and tungsten (W) from a synthetic solution containing macroamounts of molybdenum (Mo), in order to determine the effects of solution pH, extractant type and concentration, and stripping reagent. Only V was selectively extracted by 5,8-diethyl-7-hydroxydodecane-6-oxime (LIX 63) from the solution at the equilibrium pH 8.0. Stripping of the loaded LIX 63 with dilute NaOH solution led to complete stripping of V. After removal of V, the highest separation factor between W and Mo was obtained at the equilibrium pH 7.7, by extraction with Aliquat 336. The addition of tributyl phosphate (TBP) to the tricaprylmethylammonium chloride (Aliquat 336) had a profound effect on the separation of the W and Mo by stripping with sulfuric acid solution. In the same H₂SO₄ concentration range, Mo and W were not stripped from the loaded Aliquat 336 alone, while Mo was selectively stripped over W from the loaded mixture of Aliquat 336 and TBP. A process was proposed to separate V and W from Mo solution by solvent extraction.