Abstract:

China is abundant in rare earth resources with wide distribution and complete range of types. However, a large amount of wastewater contained rare earth ions and other pollutants is produced by rare earth leaching and acid precipitation processes. The health of people and ecological environment could be affected dramatically, if wastewater was discharged into rivers or groundwater. Extraction technology is widely used in the separation of rare earth elements. However, the traditional extraction technology and equipment has several disadvantages, for instance, large consumption of extractant, serious loss of solvent entrainment, low extraction efficiency, and easy emulsification etc. In recent, gas-liquid-liquid microdispersion extraction technology is an important research content in the fields of microfluidics, microchemicals, and microanalysis, which has the unique advantages of fast mass transfer and short phase separation time. This review introduced the research progress of gas-liquid-liquid microdispersion extraction technology in the field of enrichment and recovery of low-concentration rare earth ions. These contents included the preparation and regulation law of gas-liquid-liquid double emulsion, the flow pattern of three-phase flow in microchannels, and the application of gas-liquid-liquid microdispersion technology in the field of rare earth ion extraction and recovery and the scale-up of gas-liquid-liquid microdispersion extraction technology. The current research results reveal that the gas-liquid-liquid microdispersion extraction technology has unique advantages in the extraction and recovery of low-concentration rare earth ions, which is expected to solve the problem of rare earth leaching tailings treatment. This study summarized the research progress in the above aspects, and prospected the future development direction.

Key words: rare earth elements, extraction, gas-liquid-liquid microdispersion extraction, microfluidics, enrichment and recovery

摘要：

我国稀土矿产资源分布广泛，种类丰富齐全。但稀土开采过程中的酸沉、浸出等流程会产生大量富含低浓度稀土离子等污染物的废水，该部分废水若排放进入地下水体或河流，会对生态环境和人民的身体健康造成严重的影响。萃取技术在稀土离子分离领域应用广泛，然而传统的萃取技术和设备若在大相比下操作将存在萃取剂耗量大、溶剂夹带损失严重、萃取效率低、易乳化等弊端。气液液微分散技术近年来成为微流控、微化工、微分析等领域的重要研究内容。其应用于萃取过程具有传质速度快、分相时间短的独特优势。本文介绍了气液液微分散萃取技术在低浓度稀土离子富集回收领域的研究进展，具体包括气液液微分散体系的微流控制备方法和调控规律、多相微分散体系的流型、气液液微分散萃取技术在低浓度稀土离子萃取回收领域的应用及其过程放大研究。已有的研究结果表明气液液微分散萃取技术在低浓度稀土离子富集回收领域展现出了独特的优势，有望解决稀土浸矿尾液处理的难题。本文主要针对以上几个方面的研究进展进行综述，并对其未来的发展方向进行了展望。

关键词: 稀土, 萃取, 微萃取, 微流控, 富集回收