Abstract Acid mine leachate (AML) may be a significant source of rare earth and other critical elements needed for the manufacturing of advanced electronics and renewable energy technologies. A systematic study was performed on a natural leachate collected from a coal preparation plant that treated bituminous coal containing elevated amounts of pyrite. The leachate contained 1.96 ppm total REEs, 2.52 ppm Zn, 2.15 ppm Ni, 1.22 ppm Cu, 0.77 ppm Co, and 25 ppm Mn. Sequential precipitation using simple pH control generated a pre-concentrate containing 0.82% total REEs, 1.08% Zn, 0.91% Ni, 0.50% Cu, 0.34% Co, 7.1% Mn. The pre-concentrate was further treated by re-dissolution using a 10 M HNO3 solution, which resulted in a solution pH of 1.5. The addition of oxalic acid to selectively precipitate the REEs followed by roasting of the precipitate generated a product containing >98% rare earth oxides. More than 95% of the Cu and Zn were recovered from the residual liquid using Na2S at pH 2 and 3, respectively. The CuS and ZnS contents in the corresponding concentrates were 60% and 58%, respectively. The majority of the Co and Ni remained in the residual liquid. Based on these findings, a process flowsheet was developed to recover the REEs and critical metals from AML.

中文翻译：

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从酸性矿山渗滤液中回收稀土元素和关键金属的工艺开发

摘要 酸性矿山渗滤液 (AML) 可能是制造先进电子产品和可再生能源技术所需的稀土和其他关键元素的重要来源。对从处理含大量黄铁矿的烟煤的选煤厂收集的天然渗滤液进行了系统研究。浸出液含有 1.96 ppm 的总 REE、2.52 ppm Zn、2.15 ppm Ni、1.22 ppm Cu、0.77 ppm Co 和 25 ppm Mn。使用简单的 pH 控制进行连续沉淀，产生了含有 0.82% 总 REE、1.08% Zn、0.91% Ni、0.50% Cu、0.34% Co、7.1% Mn 的预浓缩物。通过使用 10 M HNO 3 溶液重新溶解来进一步处理预浓缩物，这导致溶液 pH 值为 1.5。添加草酸以选择性沉淀 REE，然后对沉淀物进行焙烧，生成含有 >98% 稀土氧化物的产物。分别在 pH 2 和 3 下使用 Na2S 从残余液体中回收超过 95% 的 Cu 和 Zn。相应精矿中的 CuS 和 ZnS 含量分别为 60% 和 58%。大多数 Co 和 Ni 保留在残留液体中。基于这些发现，开发了从 AML 中回收 REE 和关键金属的工艺流程。