Recovery of vanadium and molybdenum from heavy oil desulphurization waste catalyst

Abstract Sodium chloride-water vapour roasting of calcined catalyst for 2 h at 850°C (water vapour pressure 0.253 bar, N 2 atmosphere) and subsequent leaching of the roasted catalyst with water at its boiling point for 1 h dissolved 81.85% V and 81.78% Mo and minor amounts of other constituents. The separation of V from the leach solution has been carried out efficiently by precipitation (as NH 4 VO 3 ), liquid-liquid extraction using di(2-ethylhexyl)phosphoric acid (D2EHPA) and tri-n-octylamine (TOA) and subsequent strippings and precipitations. The overall recoveries of V and Mo from the waste catalyst are 75.5 and 77%, respectively.