The increasing demand for rare earth elements (REEs) has led to the exploration of mining tailings as a potential secondary source. This study offers novel insights into the recovery of REEs from Fe-rich mine tailings sourced from a weathered carbonatite deposit. The REEs were recovered by selectively removing Fe impurities after acid-leaching. The paper details the comprehensive methodologies employed, including initial hydrochloric acid leaching and variable optimization such as acid concentration, liquid-to-solid ratio, temperature, and time. An alkali pre-treatment using NaOH was also investigated to assess its impact on the efficiency of REEs recovery. The study reveals that pH plays a significant role in the selective removal of Fe impurities and offers avenues for the production of high-purity, industry-grade REEs. The work is particularly ground-breaking in its exploration of selective Fe removal using a combination of dilute ammonium hydroxide and ammonium chloride. Through this method, a significant milestone was achieved: the precipitated solid primarily contained Fe (>96%), with minimal loss of REEs (only 0.22%) at a solution pH of 3.25 at 40 °C. This study is the first to demonstrate such high selectivity in the removal of Fe from acid leach liquors of this nature.

对稀土元素 (REE) 的需求不断增加，促使人们对采矿尾矿作为潜在的二次来源进行探索。这项研究为从风化碳酸岩矿床的富铁尾矿中回收稀土元素提供了新的见解。酸浸后通过选择性去除铁杂质来回收稀土元素。本文详细介绍了所采用的综合方法，包括初始盐酸浸出和变量优化，例如酸浓度、液固比、温度和时间。还研究了使用 NaOH 的碱预处理，以评估其对 REE 回收效率的影响。研究表明，pH 在选择性去除铁杂质方面发挥着重要作用，并为生产高纯度工业级稀土元素提供了途径。这项工作在探索使用稀氢氧化铵和氯化铵的组合来选择性去除铁方面尤其具有开创性。通过这种方法，实现了一个重要的里程碑：沉淀的固体主要含有 Fe (>96%)，在 40 °C 溶液 pH 值为 3.25 时，稀土元素损失最小（仅 0.22%）。这项研究首次证明了从这种性质的酸浸液中去除铁具有如此高的选择性。