Selective Separation of Light and Heavy Rare Earth Elements from the Pregnant Leach Solution of Apatite Ore with D2EHPA
Selective Separation of Light and Heavy Rare Earth Elements from the Pregnant Leach Solution of Apatite Ore with D2EHPA
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DOI：
10.4236/jmmce.2018.65037
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
Ariuntuya Battsengel;Altansukh Batnasan;Kazutoshi Haga;A. Shibayama
中科院分区：
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作者：
Ariuntuya Battsengel;Altansukh Batnasan;Kazutoshi Haga;A. Shibayama
不同的分离技术，如溶剂萃取，离子交换和沉淀，经常用于从酸浸获得的浸出液中回收稀土元素（REEs）。由于需要能够处理更大体积的稀释富集溶液，溶剂萃取被普遍认为是分离稀土元素的最合适的商业技术。本研究的重点是开发的选择性分离的轻，重稀土元素从贵浸出液中获得的磷灰石矿石在1 M硫酸（H2SO 4）浸提溶剂萃取。考察了三种不同的有机磷萃取剂（二（2-乙基己基）磷酸（D2 EHPA）、2-乙基己基膦酸单（2-乙基己基）酯（PC 88 A）和磷酸三丁酯（TBP））对有机磷萃取效果的影响，考察了萃取剂浓度、有机/水相比、稀释剂种类、pH值、萃取时间和反萃剂浓度等因素对萃取效果的影响。结果表明，D2 EHPA通过两级萃取过程选择性地分离浸出液中的轻稀土（LREE）和重稀土（HREE）。在第一阶段的溶剂萃取中，>90%（0.05 g/L）的HREE被1.8 M D2 EHPA煤油萃取，而绝大多数（>95%）的LREE保留在萃余液中。在第二阶段中，用溶解在煤油中的1.8 M D2 EHPA在pH 1.6下从萃余液中萃取>93%（1.01 g/L）的LREE。在第一和第二阶段萃取后，分别用4 M H2SO 4和1 M H2SO 4溶液反萃取负载有D2 EHPA的HREE（>95%）和LREE（>90%）。研究了中稀土元素在萃取过程中的分布规律。
Different separation techniques such as solvent extraction, ion exchange, and precipitation are often used for recovery of rare earth elements (REEs) from pregnant leach solutions obtained from acid leaching. Solvent extraction is generally accepted as the most appropriate commercial technology for separating REEs due to the need to be able to handle larger volumes of diluted pregnant solutions. This study focused on the development of selective separation of light and heavy REEs from the pregnant leach solution obtained from leaching of apatite ore in 1 M sulfuric acid (H2SO4) using solvent extraction. Three different commercial organophosphorus extractants (di-(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A) and tributyl phosphate (TBP)), and the influences of experimental parameters such as extractant concentration, organic/aqueous phase ratio, diluent type, pH, extraction time and stripping agent concentration were examined. Results showed that light REEs (LREEs) and heavy REEs (HREEs) in the pregnant leach solution were selectively separated with D2EHPA via a two-stage extraction process. In the first-stage of solvent extraction, >90% of (0.05 g/L) HREEs was extracted with 1.8 M D2EHPA in kerosene while the vast majority (>95%) of LREEs was remained in raffinate. In the second-stage, >93% (1.01 g/L) of LREEs was extracted from the raffinate with 1.8 M D2EHPA dissolved in kerosene at pH 1.6. HREEs (>95%) and LREEs (>90%) loaded with D2EHPA after the first and second-stage of extraction were stripped by 4 M H2SO4 and 1 M H2SO4 solutions, respectively. Distribution of middle rare earth elements (MREEs) was discussed through the extraction processes in this study.