Method for utilizing flue gas sulfuric acid

The invention discloses a method for utilizing flue gas sulfuric acid. The method comprises the following steps of: a), adding ammonium salt into vanadium liquid, and adding an oxidizing agent to obtain mixed liquid; and b), regulating a pH value of the mixed liquid by flue gas sulfuric acid, performing molybdenum precipitation, filtering molybdenum precipitation liquid, and washing and drying a filtering cake to obtain ammonium polyvanadate, wherein the oxidizing agent is a substance which does not introduce impurities into a molybdenum precipitation system; and the addition amount of the oxidizing agent can prevent the generation of low-price vanadium during molybdenum precipitation. By the method, the molybdenum precipitation is performed completely, and the molybdenum precipitation effect is superior to industrial sulfuric acid molybdenum precipitation; and because a small quantity of oxidizing agent is added, the cost of flue gas sulfuric acid is reduced, and the total production cost is reduced. By the method, ammonium polyvanadate is prepared by flue gas sulfuric acid in a molybdenum precipitation mode, so that the application of flue gas sulfuric acid is widened, the production cost of preparing ammonium polyvanadate is reduced, and the method has good popularization and application prospect.