Abstract:In view of the problem that the concentration of silicon in the alkaline leaching solution of high chromium vanadium slag after leaching by submolten salt method is too high (4-8 g/L), and the presence of silicon will have a great impact on the subsequent separation of vanadium chromium, this paper conducted an experimental study on the removal of silicon from the oxygen-rich alkaline leaching solution of vanadium slag produced by an enterprise in Hebei Province. The effects of the type of precipitating agent, the amount of precipitating agent, the alkalinity of leaching solution, reaction time, precipitation temperature and standing time on the removal of silicon and the loss of vanadium and chromium were investigated. The results show that by using NaAlO2 as a desilicide and when n(Al):n(Si)=1.8, the concentration of hydroxylion (OH-) in the leaching solution is 7.5 mol/L, the reaction temperature is 85 °C, the reaction time is 1 h, and the standing time is 2 h, the removal rate of silicon in the alkaline leaching solution is 93.33%, and the concentration is reduced to 0.29 g/L. The loss of vanadium and chromium is less than 1%. The removal of silicon by this method has good effect, short time and less loss of vanadium and chromium. The leaching solution after removing silicon meets the requirements of subsequent extraction of vanadium and chromium.