分离化学性质相似的稀土元素极其困难。主要的工业方法是溶剂萃取,具体来说是液-液逆流萃取。该工艺利用了稀土离子在水相和含有络合剂的不混溶有机相之间分配系数的细微差异。通过数百个阶段的重复,可以分离出高纯度的单个元素。

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分离化学性质相似的稀土元素极其困难。主要的工业方法是溶剂萃取,具体来说是液-液逆流萃取。该工艺利用了稀土离子在水相和含有络合剂的不混溶有机相之间分配系数的细微差异。通过数百个阶段的重复,可以分离出高纯度的单个元素。
The process relies on the principle of differential partitioning. The rare-earth elements, typically as trivalent ions ([latex]RE^{3+}[/latex]) in an acidic aqueous solution, are brought into contact with an organic solvent (like kerosene) containing an extractant. Common extractants include organophosphorus compounds like tributyl phosphate (TBP) or di-(2-ethylhexyl)phosphoric acid (D2EHPA). The extractant forms a complex with the rare-earth ions, making them soluble in the organic phase. Due to the lanthanide contraction, the stability of these complexes, and thus their tendency to move into the organic phase, varies slightly across the series. Lighter lanthanides (like lanthanum) are more basic and prefer the aqueous phase, while heavier lanthanides (like lutetium) are more acidic and have a greater affinity for the organic extractant.
在逆流系统中,水相和有机相沿相反方向流经一系列级联(混合澄清器)。在每个级联中,元素根据其分配系数在两相之间重新分配。这种多级级联放大了单级分离系数,最终使相邻的稀土元素分离至纯度超过99.99%。萃取剂的选择、水相的pH值和温度是关键参数,需要精心控制,以优化特定元素的分离效果。该方法取代了早期费力得多的分级结晶技术,并实现了现代技术所需的稀土大规模生产。
稀土元素分离的溶剂萃取法
(如果日期未知或不相关,例如“流体力学”,则提供其显著出现的近似估计)
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