Desilication from Alkali Leaching Solution Containing Vanadium and Preparation of High Purity Vanadium Pentoxide

Using the alkaline leaching solution containing vanadium produced by a factory in Panzhihua as the raw material,the main impurities and the removal of silicon in the alkaline leaching solution were analyzed,and the influences of desilication agent species,dosage of desilication agent,pH of leaching solution,reaction temperature,reaction time and standing time on the desilication were studied.The results show that with Al₂(SO₄)₃·18 H₂O as the desilication agent at n(Al):n(Si)=0.7,10.5 of pH for leaching solution,30℃ of reaction temperature for 2 h and 16 h of standing time,the removal rate of silicon in the leaching solution is more than 97% coupled with less than 2% of vanadium loss rate.Furthermore,the Al content in vanadium solution after silicon removal is less than 0.005 g/L.The method can remove silicon effectively without additional impurities introduced into the solution,and the precipitates are easy to be settled and filtered.Vanadium pentoxide can be prepared from the leaching solution after removing silicon by acid precipitation of vanadium-redissolution-alkaline precipitation of vanadium,in which the content of silicon and aluminum is less than 0.002% and the purity is higher than 99.9%,exceeding the quality requirements of 99.0% grade V₂O₅ in the standard(YB/T 5304-2011).