## 3 Results and Discussion
### Sorption Properties
#### 3.2.6 Application to Ore Raffinate  
The ore was collected in the Abu Zenima area (in Southwestern Sinai, Egypt, Figure S19) in a mineralogical Adedia formation (described in Section SD). This ore is mainly comprised of phosphate minerals (iron, aluminum, magnesium, and rare earths) associated with aluminosilicate (Table S9). In addition to these major elements, the mineralization is also characterized by noticeable amounts of titanium, uranium, and lead. The acidic leaching of the ore was processed at 150 \({}^{\circ}\)C in an agitated tank reactor for 2 h using concentrated sulfuric acid (200 g H\({}_{2}\)SO\({}_{4}\) L\({}^{-1}\)). The solid/liquid ratio was set to 1/3. The composition of the leachate is summarized in Table S10. The most remarkable concentrations were those of iron (i.e., 20.8 g Fe L\({}^{-1}\)), aluminum (i.e., 8.17 g Al L\({}^{-1}\)), calcium \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Cycle**} & \multicolumn{4}{c}{**MC**} & \multicolumn{2}{c}{**MC-UR**} & \multicolumn{2}{c}{**MC-UR/S**} \\ \cline{2-9}  & & **SE (\%)** & **DE (\%)** & **SE (\%)** & **DE (\%)** & **SE (\%)** & **DE (\%)** \\ \hline \multirow{2}{*}{1} & Aver. & 16.1 & 100.6 & 45.9 & 99.9 & 71.8 & 100.4 \\  & Std. Dev. & 0.6 & 0.5 & 0.5 & 1.1 & 1.5 & 0.5 \\ \hline \multirow{2}{*}{2} & Aver. & 15.6 & 99.8 & 45.2 & 100.3 & 71.7 & 100.2 \\  & Std. Dev. & 0.4 & 0.7 & 0.4 & 0.1 & 1.5 & 0.9 \\ \hline \multirow{2}{*}{3} & Aver. & 15.5 & 100.3 & 44.9 & 100.6 & 70.8 & 99.7 \\  & Std. Dev. & 0.6 & 0.2 & 0.7 & 0.4 & 1.1 & 0.5 \\ \hline \multirow{2}{*}{4} & Aver. & 15.1 & 100.5 & 44.6 & 100.0 & 70.2 & 100.0 \\  & Std. Dev. & 0.7 & 0.5 & 1.0 & 0.9 & 0.8 & 0.5 \\ \hline \multirow{2}{*}{5} & Aver. & 14.7 & 99.9 & 44.2 & 100.0 & 69.7 & 100.3 \\  & Std. Dev. & 0.7 & 0.4 & 0.8 & 0.5 & 0.8 & 0.2 \\ \hline \multirow{2}{*}{Loss (5 th/1 st) (\%)} & 8.7 & - & 3.8 & - & 3.1 & - \\ \hline \hline \end{tabular}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{Exp. Cond. for sorption—C\({}_{0}\): 0.366 mmol Ce L\({}^{-1}\): pH\({}_{0}\): 5; SD: 0.4 g L\({}^{-1}\); time: 24 h; v: 210 rpm; T: 22 \(\pm\) 1 \({}^{\circ}\)C. Exp. Cond. for desorption—eluent: 0.2 M HCl; SD: 2 g L\({}^{-1}\): time: 2 h; v: 210 rpm; T: 22 \(\pm\) 1 \({}^{\circ}\)C.} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Reuse of sorbents in the recovery of Ce(III)—sorption (SE, %) and desorption (DE, %) efficiencies for five successive cycles. (i.e., 1.17 g Ca L\({}^{-1}\)), and manganese (i.e., 0.98 g Mn L\({}^{-1}\)). The acidic leachate also contains high concentrations of REEs, with the global REE index being close to 8.7 g REE L\({}^{-1}\), which is, notably, comprised of neodymium (i.e., 0.98 g Nd L\({}^{-1}\)) and cerium (i.e., 0.43 g Ce L\({}^{-1}\)). Uranium is another important element identified in the leachate (i.e., 200 mg U L\({}^{-1}\)), which serves to decrease the possible contamination of the valorized REEs with hazardous radio-elements (potentially including thorium). A pre-treatment of the leachate was conducted at pH 1.8 using an Amberlite IRA-400 column (quaternary ammonium salt resin). The uranyl removal reached 81%, while the loss in the REEs and cerium was less than 5% (up to 11% for neodymium). The high concentration of iron in the residue of the sorption may interfere with the further steps in the valorization of strategic metals. After controlling the pH to 4, 98.8% of the residual iron was precipitated (global loss, GL: 98.9%). This step hardly changed the residual concentrations of U (GL: 83.5%) and the REEs (GL: 9.3%), including 10.1% for Ce(III) and 18.1% for Nd(III). The next step in the process consists of the recovery of the REEs using a strong cation exchange resin (bearing sulfonic groups), Dowex 50X8, at pH 4. The resin collected 93.7% of the REEs contained in the residue of the pH 4 precipitation step, and 84.8% for Ce(III) and 87.2% for Nd(III) (Table S11). The residual concentrations of REEs stand at 498.6 mg REE L\({}^{-1}\) (58.8 mg Ce L\({}^{-1}\) and 102.7 mg Nd L\({}^{-1}\)).