## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element** & **Earth Crust (ppm)** & **Ore A.0 (ppm)** & **Tailing A.1 (ppm)** & **Enrichment (\%)** \\ \hline La & 30 & 70.18 & 3.85 & 233.92 \\ Ce & 60 & 144.72 & 6.08 & 241.19 \\ Pr & 6.7 & 16.19 & 0.66 & 241.7 \\ Nd & 27 & 65.49 & 2.60 & 242.57 \\ Sm & 5.3 & 12.5 & 0.63 & 236.34 \\ Eu & 1.3 & 3.04 & 0.17 & 233.93 \\ Gd & 4 & 9.19 & 0.57 & 229.94 \\ Tb & 0.7 & 1.68 & 0.08 & 236.74 \\ Dy & 3.8 & 8.75 & 0.54 & 230.37 \\ Ho & 0.8 & 1.82 & 0.12 & 227.96 \\ Er & 2.1 & 4.44 & 0.45 & 211.51 \\ Tm & 0.3 & 0.64 & 0.06 & 215.14 \\ Yb & 2 & 4.18 & 0.44 & 209.22 \\ Lu & 0.7 & 1.69 & 0.07 & 241.36 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Concentration of REEs in the materials A.0 and A.1 compared to the average in the Earth’s crust. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Element** & **Bastnasite** & **Monazite** & **A.0** & **A.2** & **B** & **C** & **Bastnasite** & **Monazite** \\  & **(ppm)** & **(ppm)** & **(ppm)** & **(ppm)** & **(ppm)** & **(ppm)** & **(\%)** & **(\%)** \\ \hline La & 3903.2 & 3279.1 & 70.1 & **96.5** & 12.8 & 19.1 & 2.47\% & 2.94\% \\ Ce & 12,378.0 & 10,987.9 & **144.7** & 137.1 & 21.1 & 37.3 & 1.17\% & 1.32\% \\ Pr & 233.6 & 188.8 & **16.2** & 13.3 & 2.3 & 4.4 & 6.93\% & 8.58\% \\ Nd & 2187.5 & 2227.0 & **65.5** & 54.8 & 7.4 & 18.4 & 2.99\% & 2.94\% \\ Sm & 161.2 & 434.4 & **12.5** & 12.3 & 1.3 & 3.6 & 7.75\% & 2.88\% \\ Eu & 29.4 & 14.2 & 3.1 & **3.5** & 0.3 & 0.8 & 11.90\% & 24.65\% \\ Gd & 58.9 & 715.7 & 9.2 & **13.5** & 1.1 & 3.6 & 22.92\% & 1.89\% \\ Tb & - & 83.9 & 1.6 & **2.0** & 0.1 & 0.5 & - & 2.38\% \\ Dy & - & 1309.0 & 8.7 & **12.4** & 0.7 & 2.8 & - & 0.95\% \\ Ho & - & 374.8 & 1.8 & **2.9** & 0.1 & 0.5 & - & 0.77\% \\ Er & 148.7 & 809.2 & 4.4 & **9.5** & 0.3 & 1.6 & 6.39\% & 1.17\% \\ Tm & - & 188.2 & 0.6 & **1.5** & 0.0 & 0.2 & - & 0.80\% \\ Yb & - & 870.7 & 4.2 & **9.1** & 0.2 & 1.3 & - & 1.05\% \\ Lu & - & 261.7 & **1.7** & 1.2 & 0.1 & 0.2 & - & 0.65\% \\ Total & 19,100.7 & 21,745.1 & 344.5 & 369.8 & 47.7 & 94.5 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Comparison between the concentrations of the five materials and the mineral exploitation materials. None of the proportions found in the five cases exceeded the exploitable concentrations in nature for the minerals bastnastic and monazite; therefore, it was not immediately feasible to recover them. However, depending on the cut-off laws and the ore price, the process may be feasible. Regarding the analyzed samples, tailings A.2 and ore A.0, both from the same iron ore deposit, were the most favorable for possible exploitation, depending on the future REE market development. Comparing the ore from which the flotation tailings were obtained with magnetic separation tailings, the quantity of REEs was at least 6x greater in the magnetic tailings, which made the quantities of many elements in flotation tailings irrelevant by comparison. Sample A.2 had approximately a quarter of the concentration of europium and gadolinium in relation to that which was exploitable for monazite. These were the highest concentrations of all the samples in relation to the levels of exploitation. Europium is one of the most critical REEs and is quoted in the markets at $38.83 per kg in the oxide form. Gadolinium's price is $20.31 per kg; it has a large market since it is one of the REEs that has the most applications [80]. REEs from tailings are not a viable alternative, except for those from magnetic separation tailings, where the recovery of rare earths would not only be technically feasible but would also have a great positive environmental impact by helping to reduce the volume of waste and pollution linked to it. The potential impact of this waste on the market depends on its availability to cover significant shares. In the treatment of iron ore, every ton of iron processed generates an estimated average of 360 kg of tailings.