Global demand for rare earth elements (REEs) has been on the rise due to recent rapid technological advancements. Even though most REEs are mainly recovered from rich ores and mineral deposits, recovery of REEs from secondary sources has attracted attention. However, low metal concentration, complex matrices and high levels of other impurities in mine wastes and tailings have remained the toughest challenges to overcome. The presence of low amount of valuable metals such as Sc requires utilization of very selective separation techniques such as ion exchange. A series of ion exchange resins (chelating, solvent impregnated and strongly acidic) were studied in the recovery of Sc from synthetic and actual pregnant leach solutions obtained from acid-leaching of coal fly ash. To the best of our knowledge, this paper exhibits the first attempt in selective recovery (from other REEs as well as major Fe and Al contaminations) of Sc in coal fly ash using ion exchange separation technique. With maximum capacity of ∼24 mg Sc/g resin, Sc was adsorbed quickly on phosphorus containing Lewatit® VP OC 1026 and TP 272 resins even in the presence of high levels of potentially interfering Fe³⁺ and Al³⁺ ions. Full elution of the adsorbed REEs from VP OC 1026 was achieved with 5 M H₂SO₄, with only minor Sc removal. While elution of Sc from these chelating resins has been reported to be challenging, Sc could be eluted almost completely with 2 M NH₄F. Recovery of REEs with 5 M H₂SO₄ from TP 272 resulted in co-elution of only 7% of the adsorbed Sc while the rest could be eluted efficiently with 6 M HNO₃.

由于最近的快速技术进步，全球对稀土元素 (REE) 的需求一直在上升。尽管大多数 REE 主要从富矿和矿床中回收，但从次要来源回收 REE 已引起关注。然而，矿山废物和尾矿中的低金属浓度、复杂的基质和高含量的其他杂质仍然是需要克服的最艰巨的挑战。少量有价金属（如 Sc）的存在需要使用非常有选择性的分离技术，如离子交换。研究了一系列离子交换树脂（螯合、溶剂浸渍和强酸性）从粉煤灰酸浸获得的合成和实际富集浸出溶液中回收 Sc。据我们所知，本文首次尝试使用离子交换分离技术选择性回收粉煤灰中的 Sc（从其他 REE 以及主要的 Fe 和 Al 污染物）。最大容量约为 24 mg Sc/g 树脂，即使在存在高水平潜在干扰 Fe 的情况下，Sc 也能快速吸附在含磷的 Lewatit® VP OC 1026 和 TP 272 树脂上³⁺和 Al ³⁺离子。从 VP OC 1026 中完全洗脱吸附的 REE 是用 5 MH ₂ SO _{4 实现的}，只去除了少量的 Sc。虽然据报道从这些螯合树脂中洗脱 Sc 具有挑战性，但 Sc 几乎可以用 2 M NH ₄ F完全洗脱。从 TP 272 中回收含有 5 MH ₂ SO ₄的 REE导致共洗脱仅 7%吸附的 Sc 而其余的可以用 6 M HNO ₃有效洗脱。