Extraction of tungsten and vanadium from spent selective catalytic reduction catalyst for stationary application by pressure leaching process

This paper presents the direct extraction, which works by means of pressure leaching, of vanadium and tungsten from the spent SCR catalysts using a caustic soda. The experimental parameters were concentration of NaOH (aq), the particle size of the feedstock, the temperature, and the S/L ratio. The results of an assessment of the proposed method found that pressure leaching using a caustic soda can more effectively dissolve vanadium and tungsten from the spent SCR catalysts than atmospheric alkaline leaching. The dissolution efficiency of vanadium and tungsten tended to increase with an increase in the concentration of NaOH (aq), a higher temperature and a decrease in the particle size of the feedstock used. The S/L ratio, which affected the dissolution efficiency of vanadium and tungsten, differed depending on the concentration of NaOH (aq). The optimum conditions for the extraction of vanadium and tungsten by pressure leaching were as follows: concentration of NaOH (aq), 3 mol/L; temperature, 250 degrees C; particle size distribution; <150 mu m; S/L ratio, 0.4. With these optimum conditions, the dissolution efficiency of vanadium and tungsten were found to be 91.5% and 87%, respectively. The established method for the direct extraction of vanadium and tungsten from spent SCR catalysts is effective and environmentally sound compared to atmospheric alkaline leaching. (C) 2018 Elsevier Ltd. All rights reserved.