Recovery process of rare earths, Al, U, and Th from ionic rare earth purification residue using sequential alkaline leaching, acid leaching solvent extraction and stripping

IF 4.8 2区材料科学 Q1 METALLURGY & METALLURGICAL ENGINEERING

Hydrometallurgy Pub Date : 2025-06-24 DOI:10.1016/j.hydromet.2025.106524

Qiaofa Lan , Xiaolin Zhang , Fei Niu , Donghui Liu , Youming Yang

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引用次数: 0

Abstract

Ionic rare earth purification residue (PR) originates from refining of ionic rare earth ores and is predominantly composed of rare earth elements (REEs), aluminum (Al), and silicon (Si). This is a recyclable secondary resource. It provides substantial challenges due to its classification as low-level radioactive waste (LLW). Recognizing the distinctive properties of PR, this paper describes a highly efficient process for the recovery and enrichment of Al, REEs, uranium (U), and thorium (Th) through a multistep process encompassing alkali digestion, hydrochloric acid leaching, sole extractant enrichment and separation. At a controlled temperature of 70 °C, the Al digestion efficiency reached 88.9 %. The alkali digestion residue underwent hydrochloric acid leaching, yielding leaching efficiencies of 99.9 %, 99.4 %, and 99.0 % for REEs, U(VI), and Th(IV), respectively. Notably, the amount of insoluble residue was reduced by 90 %, and it was transformed from LLW into general solid waste residue. Additionally, the utilization of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (HEHEHP) as the sole extractant provided 100 % extraction efficiencies for U(VI) and Th(IV). After stepwise stripping processes, the purities of both U(VI) and Th(IV) exceeded 90 %. The REEs were precipitated as RE₂(C₂O₄)₃ and subsequently calcined to produce rare earth oxides with a recovery of 90.1 % and a purity of 97.4 %. This comprehensive scheme addressed the persistent challenges associated with long-term storage and radiological environmental risk.

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顺序碱浸、酸浸、溶剂萃取、汽提从离子型稀土提纯渣中回收稀土、Al、U、Th的工艺研究

离子型稀土提纯渣（PR）是离子型稀土矿提纯后的产物，主要由稀土元素（ree）、铝（Al）和硅（Si）组成。这是一种可回收的二次资源。由于它被归类为低放射性废物（LLW），因此带来了巨大的挑战。认识到PR的独特性质，本文描述了一种通过碱消化、盐酸浸出、单萃取剂富集和分离等多步骤过程回收和富集Al、ree、铀(U)和钍（Th）的高效工艺。在70℃的控制温度下，铝的溶出效率达到88.9%。碱溶渣进行盐酸浸出，稀土、铀（VI）和钍（IV）的浸出效率分别为99.9%、99.4%和99.0%。值得注意的是，不溶性废渣的量减少了90%，并由LLW转化为一般固体废渣。此外，利用2-乙基己基膦酸单2-乙基己基酯（HEHEHP）作为唯一萃取剂，对U（VI）和Th（IV）的萃取效率为100%。分步溶出后，U（VI）和Th（IV）的纯度均超过90%。稀土元素以RE2(C2O4)3的形式析出，煅烧制得稀土氧化物，回收率为90.1%，纯度为97.4%。这一综合方案解决了与长期储存和辐射环境风险相关的持续挑战。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Hydrometallurgy 工程技术-冶金工程

CiteScore

9.50

自引率

6.40%

发文量

144

审稿时长

3.4 months

期刊介绍： Hydrometallurgy aims to compile studies on novel processes, process design, chemistry, modelling, control, economics and interfaces between unit operations, and to provide a forum for discussions on case histories and operational difficulties. Topics covered include: leaching of metal values by chemical reagents or bacterial action at ambient or elevated pressures and temperatures; separation of solids from leach liquors; removal of impurities and recovery of metal values by precipitation, ion exchange, solvent extraction, gaseous reduction, cementation, electro-winning and electro-refining; pre-treatment of ores by roasting or chemical treatments such as halogenation or reduction; recycling of reagents and treatment of effluents.