Method for efficiently preparing iron phosphate dihydrate from red mud

The invention discloses a method for efficiently preparing iron phosphate dihydrate by using red mud, which comprises the following steps: obtaining a red mud leaching solution after acidolysis reaction, reducing the red mud leaching solution to convert ferric iron into ferrous ions, and adding an organic solvent to separate out the ferrous ions by using the principle that the ferrous ions have different solubility in a specific organic solvent. And after the ferrous oxide ions become ferric iron, carrying out homogeneous precipitation reaction with a phosphorus source, and cleaning and drying the precipitate to obtain the iron phosphate dihydrate. According to the method provided by the invention, chloride is obtained through acid leaching, different solubility of ferrous chloride, aluminum chloride, calcium chloride, magnesium chloride and the like in a specific organic solvent is innovatively utilized, the polarity characteristic of ferrous chloride is combined, ferrous chloride is rapidly separated out, a