Abstract: The exploratory experiments of precipitating vanadium which simulated the process conditions in a vanadium plant with the indexes of vanadium loss and cost were respectively tested with industrial sulfuric acid and flue-gas sulfuric acid in laboratory.The technology optimizations were studied by selecting the experimental group with the lowest vanadium loss and cost.The results indicate that the vanadium loss and cost are the lowest by one-step vanadium precipitation with flue-gas sulfuric acid,and the optimum processes are as follows:the pH of vanadium-containing solution is adjusted to 2.2 after adding the precipitation agent and the precipitation is proceeded 1 hour at 99℃ or 100℃.The vanadium loss and cost per 1 000 kg V₂O₃ are respectively 3.06 kg and 763.18 RMB yuan by the optimum processes,which are much less than the processes with industrial sulfuric acid.The new technology,which has been applied to industry,can wholly satisfy the production requirements with 0.31 g/L vanadium in the upper-liquor of precipitating vanadium process.Meanwhile,the purity,size distribution and bulk density of the final product V₂O₃ by the new technology are at the same level as those of the V₂O₃ by vanadium precipitation with industrial sulfuric acid.