Separation of vanadium and tungsten from a sodium tungstate solution

Three methods have been developed in this study to recover vanadium from a sodium tungstate solution containing 95 g/L WO3, 0.175 g/L V and some impurities. In the case of method 1 and method 2, the Na2WO4 solution was treated with Ca(OH)(2) to convert tungsten and vanadium into the calcium salts after removal of impurities. The formic acid (method 1) or acetic acid (method 2) was then employed to selectively dissolve vanadium from the mixed calcium salts. In the case of method 3, MgCl2 and hydrated ammonia were firstly employed to precipitate both impurities and vanadate. An acetic acid solution was then used to selectively dissolve vanadium from the mixed residue. Tungsten and vanadium was finally recovered respectively with the form of ammonium para-tungsten and ammonium metavanadate in all of methods.