有机膦酸萃取分离重稀土研究
发布时间：2019-07-09 17:34
【摘要】：稀土是重要的战略性资源,广泛应用于军工、航天、能源、医药、农业以及功能材料等多个领域。随着高精尖技术的发展,对单一高纯稀土的需求量越来越大。溶剂萃取是稀土萃取分离提纯过程中的重要手段。本文以高纯二(2,4,4-三甲基戊基)次膦酸(L272)作萃取剂,用仲辛醇作改质剂,研究了不同比例的L272/仲辛醇体系对重稀土(Er、Tm、Yb、Lu)的萃取分离性能及萃取机理。采用NMR(~(31)P)、IR对复配萃取剂进行了表征,用ICP测定重稀土离子的浓度。另外,还测定了复配萃取剂的表面张力、密度及溶解性。结果表明：L272与仲辛醇按照9：1(v/v)复配得到的萃取剂(L972)在萃取分离重稀土过程中性能最佳,平均分离系数(β)可达8.05,平均饱和容量为0.14mol/L;萃取过程大部分为阳离子交换机理,部分为缔合机理,萃合物的结构组成通式为：LnCl3-n(HA2)n(n代表logD-pH的斜率)。系统研究了盐酸体系中L972对重稀土的萃取性能。结果表明,固定其他条件,在平衡pH=2、O/A=1:1、t=12min条件下,L972对重稀土的萃取率可达到最大；采用不同浓度的盐酸对饱和负载有机相进行反萃,最佳反萃酸度为3mol/LHCl;固定其他条件,在pH=1.5、O/A=1:1、t=9min条件下,L972对重稀土的平均分离系数(p)最大。此外,还研究了非稀土杂质铁、铝、硅对L972萃取重稀土的影响。结果表明：铁、铝的存在,明显降低重稀土的萃取率,而且在pH较低时就产生乳化,其反萃也很困难。尽管L972对硅的萃取率较低,但是负载硅极难反萃,多次反萃,最大反萃率只能达到40%,因而硅会在有机相中不断累积,严重影响连续萃取过程中L972的萃取性能；另一方面,一旦在萃取过程中形成硅胶,这种胶状物很难去除或破乳。和现有稀土萃取剂相比,L972萃取重稀土时在选择性、饱和容量、分相效果和反萃难易度全面优于Cyanex272;其选择性和反萃难易度明显高于P507,而饱和容量及分相效果与P507相当。本论文的研究结果有望推动稀土分离纯化技术的发展。
[Abstract]:Rare earth is an important strategic resource, widely used in military industry, aerospace, energy, medicine, agriculture and functional materials and other fields. With the development of high precision technology, the demand for single high purity rare earth is increasing. Solvent extraction is an important method in the process of rare earth extraction and purification. In this paper, the extraction and separation properties and extraction mechanism of heavy rare earth (Er,Tm,Yb,Lu) in different proportion of L272 / secondary octanol system were studied by using high purity bis (2, 4, 4-trimethyl pentyl) hypophosphonic acid (L272) as extractant and secondary octanol as modifier. The complex extractant was characterized by NMR (~ (31) P), IR), and the concentration of heavy rare earth ions was determined by ICP. In addition, the surface tension, density and solubility of the compound extractant were also measured. The results showed that the extractant (L972) prepared by the combination of L272 and secondary octanol at 9:1 (v 鈮，
本文编号：2512316
[Abstract]:Rare earth is an important strategic resource, widely used in military industry, aerospace, energy, medicine, agriculture and functional materials and other fields. With the development of high precision technology, the demand for single high purity rare earth is increasing. Solvent extraction is an important method in the process of rare earth extraction and purification. In this paper, the extraction and separation properties and extraction mechanism of heavy rare earth (Er,Tm,Yb,Lu) in different proportion of L272 / secondary octanol system were studied by using high purity bis (2, 4, 4-trimethyl pentyl) hypophosphonic acid (L272) as extractant and secondary octanol as modifier. The complex extractant was characterized by NMR (~ (31) P), IR), and the concentration of heavy rare earth ions was determined by ICP. In addition, the surface tension, density and solubility of the compound extractant were also measured. The results showed that the extractant (L972) prepared by the combination of L272 and secondary octanol at 9:1 (v 鈮，
本文编号：2512316
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