A novel process for recovery of tungsten and vanadium from a leach solution of tungsten alloy scrap

A process is developed in this study to recover tungsten and vanadium from a sodium tungstate solution containing 95 g/l WO3, 0.175 g/l V and some impurities. The solution is produced by roasting a tungsten alloy scrap and subsequently dissolving it in an alkali solution. The process to recover tungsten and vanadium involves three steps: purification and separation of vanadium from tungsten, recovery of vanadium, recovery of tungsten. For the recovery of vanadium, MgCl2 and ammonia solution are used in the purification step to precipitate the impurities and the vanadate. A small amount of acetic acid solution is then used to selectively dissolve the vanadium from the mixed residue and leave the impurities in the residue. Finally, NH4VO3 is precipitated by adding NH4OH to the solution, to achieve a vanadium recovery of 88.28%. For the recovery of tungsten, the sodium salt is converted to calcium salt after purification of the sodium tungstate solution. The CaWO4 is then converted to H2WO4 using a HCl solution, followed by dissolving in NH4OH solution and crystallization of APT. A tungsten recovery of over 85% is obtained. The purity of both the final tungsten and vanadium products has met the standard specifications.