Selective Recovery of Low-Concentration Light Rare Earth Ions from High-Concentration Ammonium Sulfate System by Coordination Ability

The selective extraction of low-concentration light rare earth ions(LREs) by 1,7-diaza-15-crown-5 ether(2N15C5) from complex ammonium sulfate solutions containing multiple impurity ions was studied, which provides a new method for efficient separation of Ln 3+ from the tail liquid wastewater discharged from in-suit leaching of ion-adsorbed rare earth ores. Liquid–liquid extraction experiments showed that impurity ions affect the extraction distribution of LREs via inducing the formation of rare earth ammonium sulfate compound salts, and the single-stage extraction coefficients of LREs were 2.20 for aluminum (Al) and 7.80 for iron (Fe) under the condition of pH 1.5 ± 0.5 and [SO 4 2− ] T /∑[Ln 3+ ]