The recovery of vanadium from spent catalyst: a case study

Recovery of vanadium from spent industrial catalysts is being widely practiced worldwide, as the material is available in large quantities with appreciable vanadium content. However, due to diversity in characteristics, many of these spent catalysts do not respond to the already established extraction methods, and separate studies are necessary to deal with specific cases. This article describes a process for vanadium recovery from a typical spent catalyst of ∼2·5%V₂O₅ content. The material was first water leached at room temperature in the presence of Na₂SO₃, whereby >99% of vanadium was brought into the solution. After solid–liquid separation, the pH of the solution was raised to 8·5, with the addition of NaOH resulting in a precipitate, which, after drying, contained ∼25%V₂O₅. Roasting the solid with Na₂CO₃ at 700°C for 30 min followed by water leaching yielded a concentrated vanadium bearing solution from which vanadium was separated as ammonium vanadate by adding NH₄Cl. The ammonium vanadate product after heating in air contained 92·6%V₂O₅. Various parameters during Na₂SO₃ leaching of spent catalyst were studied. Na₂CO₃ roasting of the vanadium enriched product and ammonium vanadate precipitation were optimised.