The recovery of rare earth metals from WEEE leaching solution via liquid-liquid extraction

The recovery of rare earth metals (REMs) from end-of-life products, such as Waste Electrical and Electronic Equipment (WEEE), is drawing great attention as an attractive strategy for promoting the sustainable development. The hydrometallurgical technique of solvent extraction has been reported to be one of the most interesting method to recover REMs. However, when applied to WEEE, this process is challenged by the heterogeneous composition of electronic waste, completely different from other solid matrices, and it still has much rooms of improvements. This study investigated the extraction, stripping and recovery of REMs from a WEEE leaching solution using Versatic 10 as carrier in the organic phase and oxalic acid as stripping agent. A factorial design was carried out to evaluate the simultaneous effects of factors as the feed phase pH and the concentrations of both extractant and organic phase modifier in the extraction process. Cerium, lanthanum and yttrium were extracted at high percentages using 200 mM of Versatic 10, loaded by 100 mM of TBP in kerosene at pH 7. Moreover, 750 mM of oxalic acid successfully stripped and recovered 7.63 and 13.82 mg/kg of lanthanum and yttrium, respectively.