Abstract This study systematically evaluated the separation performance of thorium, uranium, and rare earths when coal and coal byproduct were utilized as a non-traditional feedstock for rare earth production. A synthetic solution was prepared following the elemental composition of a strip solution generated from coarse coal refuse and used throughout the study. Various separation techniques including selective precipitation, solvent extraction, and a modified experimental protocol incorporating the two were applied to extract rare earths while minimizing the non-selective recovery of thorium and uranium into the product stream. Test results indicate that selective precipitation was effective for the removal of thorium at a pH value approaching 5 while solvent extraction preferentially removed uranium from rare earths. Therefore, a modified experimental protocol consisting of both selective precipitation and solvent extraction was subsequently developed and implemented. The findings following the modified experimental protocol indicate that extractant concentration, solvent extraction feed pH, and organic to aqueous (O/A) ratio all played a significant role in the removal of uranium. Among all the tests conducted, the best separation performance was achieved using a one-stage precipitation at a pH value of 4.8, 50 v% TBP, solvent extraction feed pH of 3.5, and an O/A ratio of 3, which corresponded to an overall rare earth, thorium, and uranium recovery of 79.6%, 0%, and 3.1%, respectively.

中文翻译：

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从粗煤废料产生的剥离溶液中分离钍、铀和稀土

摘要 本研究系统地评价了将煤和煤副产品用作稀土生产的非传统原料时钍、铀和稀土的分离性能。根据从粗煤废料产生的剥离溶液的元素组成制备合成溶液，并在整个研究中使用。各种分离技术包括选择性沉淀、溶剂萃取和结合这两者的改进实验方案被应用于提取稀土，同时最大限度地减少钍和铀进入产品流的非选择性回收。测试结果表明，选择性沉淀在 pH 值接近 5 时对去除钍是有效的，而溶剂萃取优先从稀土中去除铀。所以，随后开发并实施了由选择性沉淀和溶剂萃取组成的修改后的实验方案。根据修改后的实验方案得出的结果表明，萃取剂浓度、溶剂萃取进料 pH 值和有机物与水相 (O/A) 的比率都在去除铀方面发挥了重要作用。在进行的所有测试中，在 pH 值为 4.8、50 v% TBP、溶剂萃取进料 pH 值为 3.5 和 O/A 比为 3 的条件下，使用一级沉淀获得最佳分离性能，这对应于稀土、钍和铀的总体回收率分别为 79.6%、0% 和 3.1%。根据修改后的实验方案得出的结果表明，萃取剂浓度、溶剂萃取进料 pH 值和有机物与水相 (O/A) 的比率都在去除铀方面发挥了重要作用。在进行的所有测试中，在 pH 值为 4.8、50 v% TBP、溶剂萃取进料 pH 值为 3.5 和 O/A 比为 3 的条件下，使用一级沉淀获得最佳分离性能，这对应于稀土、钍和铀的总体回收率分别为 79.6%、0% 和 3.1%。根据修改后的实验方案得出的结果表明，萃取剂浓度、溶剂萃取进料 pH 值和有机物与水相 (O/A) 的比率都在去除铀方面发挥了重要作用。在进行的所有测试中，在 pH 值为 4.8、50 v% TBP、溶剂萃取进料 pH 值为 3.5 和 O/A 比为 3 的条件下，使用一级沉淀获得最佳分离性能，这对应于稀土、钍和铀的总体回收率分别为 79.6%、0% 和 3.1%。