A novel type of extraction-precipitation strategy based on phosphate was developed to recover rare earth (RE, i.e., La, Ce, Nd, and Pr) from waste nickel-metal hydride (NiMH) batteries. This method does not require saponification and organic solvents. The novel phosphates, i.e., dibenzyl phosphate (DBP), diphenyl phosphate (DPP), triphenyl phosphate (TPP) were studied as extraction-precipitants. DBP has high precipitation efficiencies for RE³⁺, which can reach 97.84%, 100%, 100% and 99.77%, respectively. In addition, the precipitation efficiencies of Mn²⁺, Co²⁺ and Ni²⁺ are less than 1.75%. DBP-RE has the largest particle size (D10 = 52.6 μm, D50 = 135.35 μm, D90 = 296.08 μm), which is much larger than the precipitations formed by NH₄HCO₃, H₂C₂O₄, CaO and MgO. The larger precipitation particle sizes contribute to improving the solid-liquid separation efficiency. With 3 mol/L hydrochloric acid, the stripping efficiency of DBP-RE reaches 98.60%, and the purity of recovered RE is 99.85%. The regenerated DBP can be directly used for the recycling extraction. Therefore, the novel extraction-precipitation strategy is a green and sustainable separation method.

开发了一种基于磷酸盐的新型萃取-沉淀策略，用于从废镍金属氢化物 (NiMH) 电池中回收稀土（RE，即 La、Ce、Nd 和 Pr）。该方法不需要皂化和有机溶剂。研究了新型磷酸盐，即磷酸二苄酯（DBP）、磷酸二苯酯（DPP）、磷酸三苯酯（TPP）作为萃取沉淀剂。DBP对RE ³⁺的沉淀效率高，分别可达97.84%、100%、100%和99.77%。此外，Mn ²⁺、Co ²⁺和Ni ²⁺的析出效率均小于1.75%。DBP-RE 的粒径最大 ( D 10 = 52.6 μm, D 50 = 135.35 μm, D90 = 296.08 μm)，远大于NH ₄ HCO ₃、H ₂ C ₂ O ₄、CaO和MgO形成的沉淀。较大的沉淀粒径有助于提高固液分离效率。用3 mol/L的盐酸，DBP-RE的反萃取效率达到98.60%，回收的RE纯度为99.85%。再生后的 DBP 可直接用于回收提取。因此，新颖的萃取-沉淀策略是一种绿色且可持续的分离方法。