Modeling and simulation of samarium and neodymium separation by a solvent extraction process

The demand for permanent magnets is expected to increase in the 2021–2030 decade, which will require a commensurate increase in the production of samarium (Sm) and neodymium (Nd). Since these metals are considered critical and due to their abundance in Brazilian territory, the Brazilian government and mining companies must master the refining of these metals through autochthonous technologies. Thus, we developed a process to separate the light (La, Ce, Pr and Nd) from the medium (Sm, Eu and Gd) and heavy (Tb-Lu and Y) rare earth elements (REE) with D₂EHPA by empirical modeling of solvent extraction (SX) processes. The experimental methodology included three phases: equilibrium data acquisition from batch experiments, solvent extraction simulation, and continuous process trials to validate the model on a mini-pilot scale. Our simulation predicted 99.5% Sm organic recovery and 80% Nd aqueous recovery in a seven-stage process and 0.30 A/O ratio, validated in the continuous trial. This work paves the way for establishing Brazilian technology to obtain the constituent elements of permanent magnets.