稀土元素萃取分离提纯技术发展现状与展望

Development Status and Prospect of Rare Earth Extraction and Separation Technology

稀土元素的性质极相近,在稀土矿物中一般有15种左右的稀土元素共生,分离提纯难度大,化工材料消耗高。中国稀土工作者根据稀土资源的特点,开发了一系列具有原创性、处于世界领先地位的稀土分离提纯技术,成就了中国稀土生产大国的国际地位。本文梳理了工业上应用的主要稀土萃取分离工艺技术特点、优缺点及适用性,其中,碳酸氢镁皂化萃取分离提纯稀土技术将镁盐废水及CO_(2)气体循环利用,不但从源头解决了稀土分离过程中氨氮、高盐废水污染难题,而且大幅降低生产成本,适用于P_(5)0_(7), P_(2)0_(4)酸性磷类萃取剂在硫酸体系、盐酸体系中萃取分离稀土元素,具有良好的应用前景。进一步介绍了稀土分离提纯新方法、新技术研究进展;针对高端应用对稀土纯度等要求不断提高,以及环境治理方面面临的严峻压力和挑战,提出了稀土分离提纯领域的重点研究发展方向。

About 15 rare earth elements are generally distributed in the rare earth ores, which are very difficult for separation and purification with relatively high chemical consumptions. According to the characteristics of the rare earth resources, a series of the world′s leading processes for the separation and purification of rare earths have been originally developed by Chinese researchers, establishing China′s international dominant position for rare earths production. In this paper, the technical characteristics, advantages and disadvantages, and adaptability of the main industrial processes for the solvent extraction and separation of rare earths were introduced. Among them, the separation and purification process using magnesium bicarbonate asa saponification agent can recycle magnesium salt wastewater and CO_(2) gas, whichnotonly solves the problems of the ammonia-nitrogen pollution and the discharge of high-salinity wastewater from the source, but also largely reduces the production costs, and as such, the process can be employed for the separation and purification of all kinds of rare earth ores. Finally, the new methods and technologies of rare earth separation and purification are introduced. The key research and development directions for the separation and purification of rare earths were pointed out according to the increasing demands for the rare earth purity in high-end applications and the serious challenges in the environmental management.