Recovery of vanadium from stone coal acid leaching solution by coprecipitation, alkaline roasting and water leaching

The recovery of vanadium from stone coal acid leaching solution by coprecipitation, alkaline roasting and water leaching was studied. A method used to recover vanadium from stone coal acid leaching solution was developed, and it primarily included vanadium coprecipitation with iron in the solution, vanadium extraction by alkaline leaching from the precipitate, and vanadium pentoxide preparation with the alkaline leaching solution. Experiments found that the vanadium in stone coal acid leaching solution can be effectively enriched in the precipitate obtained by adding 3.64 g NaClO3 per liter solution with initial pH 1.73 under stirring for 0.5 h at 95 °C. By roasting the mixture of 25 g of the precipitate with 22.5 g NaOH at 170 °C for 1.0 h, and then water leaching the roasted mixture at 98 °C for 1.0 h under stirring with L/S ratio of 3.3:1 mL/g, 97.0% of vanadium was extracted from the precipitate. After purifying with MgCl2, the vanadium pentoxide with purity 99.3% was obtained by adding NH4Cl to precipitate ammonium vanadate from the solution at pH about 2.0, and then roasting the ammonium vanadate at 520 °C for 2.0 h. The essential components of the coprecipitate are KFe3(SO4)2(OH)6 and HNaV6O16·4H2O.