Studies on recovery of vanadium from calcium complex vanadate salt

The complex calcium vanadate salt-a Bayer's process discard from the Indian Aluminium Company plant at Muri has been examined for the recovery of vanadium. The salt analysed 46.04% CaO 4.86% V2O5, 3.49% P2O5, 9.98% Al2O3, 2.32% free alkali, 0.82% F and 30.29% L.O.I. Soda ash roasting of the salt followed by aqueous leaching was initially attempted and it was found that a Na/V feed ratio of 15.29:1 is necessary to convert 80% of vanadium to water soluble vanadate after roasting for one hour at 800°C. Leaching of the complex salt with sulphuric acid extracted all the vanadium and phosphate in the leach liquor from which a quantitative separation of vanadium from phosphate is accomplished by neutralisation of the leach liquor to pH 6. The precipitated phosphate may be used as a fertiliser, while vanadium from the solution could be precipitated either as ammonium vanadate by treatment with ammonium chloride, or as V2O5 by sulphuric acid treatment. (Mr. P.V. Vishwanathan, Junior Technical Assistant, Mr. R.N. Misra and Mr. P.P. Bhatnagar, Scientists, National Metallurgical Laboratory, Jamshedpur)