Selective separation of vanadium from molybdenum by electrochemical ion exchange

This paper presents the results of work on the selective electrochemical elution of vanadium co-adsorbed with molybdenum on Amberlite IRA 94S resin. A three-compartment cell equipped with an RVC (Reticulated Vitreous Carbon) cathode mixed with ion exchange resin and two Ti-Pt anodes separated by a Daramic diaphragm was used. In the process, the pentavalent vanadyl anion is selectively desorbed with respect to molybdenum after its reduction to a tetravalent vanadyl cation. The subsequent elution can therefore produce a pure molybdenum solution. At 323 K, using a 30 g.l(-1) H2SO4 eluant and a decreasing current intensity, 93% V and only 7% Mo is eluted from the resin initially loaded with 1.25 equivalent (Mo7O246-+HV10O285-) l(-1) which corresponds to 9.3 kg V and 130 kg Mo m(-3) of wet settled resin. The further elution of molybdenum with an alkaline solution leads to the recovery of a pure molybdate solution characterized by a molar Mo/V ratio of 1000/1 after a post-precipitation at pH 8. (C) 1998 Elsevier Science B.V.