Preparation of FeCl₃·6H₂O from NdFeB secondary waste slag by acid leaching-extraction method

For the recovery of large amounts of iron in NdFeB secondary waste slag, an acid leaching-extraction process was employed to prepare FeCl₃·6H₂O. Single factor experiments, thermodynamic and kinetic research were used to optimize the acid leaching conditions, achieving a leaching rate of Fe³⁺ exceeding 91%. A systematic study was conducted on the selective extraction performance of the LIU extractant towards Fe³⁺ in the hydrochloric acid wet leaching processing. After the three-stage cross-current extraction, the extraction rate of Fe³⁺ reached 98.78%, while other impurity ions were basically not extracted and retained in the raffinate. Distilled water was used for stripping. The stripping rate of Fe³⁺ reached 99.88% after the two-stage cross-current stripping. The products were characterized by ICP-OES, XRD, and SEM. The results showed that the product purity was over 99.8%, and the net profit exceeded 1 200 CNY/ton. Compared with other recycling processes, this technology forms a closed cycle with low costs and short duration, thereby providing an effective scheme for the treatment of secondary waste.