The rare earth elements (REE) play an important role in modern technology due to its wide applicability in various sectors of the world economy. The REE configures a select group of elements with exceptional properties physicochemical, catalytic, electrical, magnetic, and optical attributes [1]. Usually, the REEs are obtained from ore concentrates. However, secondary sources, such as effluents resulting from acid mining drainage (AMD) [2], could be an alternative to the conventional mining and represent an important source of these elements [3]. 

The current work addresses the study of the recovery of rare earth elements (REE) from acid mine drainage (AMD) by using cationic exchange resin. The acid water was obtained from one closed uranium mine at Caldas Municipality (Brazil). The total REE concentration was approx. 0,90 mmol/L, i.e, the sum of the concentrations of lights REE (LREE) and heavies REE (HREE), total impurities 12,9 mmol/L (Al; Ca; Mg; Mn and Zn), sulfate 10 mmol/L, fluoride 5,26 mmol/L, iron <0.09 mmol /L, and the pH around 3.4. 

The loading experiments were carried out in columns at a temperature of 25±1⁰C and the cation exchange resins used were Dowex 50WX8, Lewatit MDS 200H, and Purolite C160. The best results for loading capacity and percentages of efficient removal (%) for total REE and impurities were obtained for the resin Lewatit MDS 200H with 0,566 mmol/g (92%) (LREE = 0,501 + HREE = 0,065) and 1,64 mmol/g (60%), respectively. The selectivity of the resins for the REE can be described as LREE > HREE. Regarding the impurities (Ca, Mn, Mg, Zn, and Al), the resin presents greater loading for calcium and aluminum. The elution experiments with inorganic and organic acids showed that hydrochloric acid and EDTA were more appropriate for the desorption and/or separation of the REE.