Method for producing high-purity iron oxide red by utilizing iron waste slag of rare earth smelting

The invention discloses a method for producing high-purity iron oxide red by utilizing iron waste residues of rare earth smelting, and relates to the field of rare earth smelting. According to the method, ferric hydroxide can be heated and crystallized in a sodium hydroxide solution, heating is continued, and the ferric hydroxide is decomposed and converted into acid-insoluble crystal form ferric oxide hydrate under the action of high-temperature pyrolysis; according to the principle that rare earth elements are converted into rare earth hydroxide in the process, selective leaching separation is carried out by utilizing the solubility difference of the rare earth elements and the rare earth hydroxide under the acidic condition. According to the method, the iron waste residues generated in rare earth wet smelting can be heated to different temperatures in a sodium hydroxide solution in two stages to obtain the crystal form hydrated ferric oxide, so that the solubility of iron and non-iron elements under the ac