【摘要】：稀土是重要的戰(zhàn)略性資源,廣泛應(yīng)用于軍工、航天、能源、醫(yī)藥、農(nóng)業(yè)以及功能材料等多個(gè)領(lǐng)域。隨著高精尖技術(shù)的發(fā)展,對(duì)單一高純稀土的需求量越來(lái)越大。溶劑萃取是稀土萃取分離提純過(guò)程中的重要手段。本文以高純二(2,4,4-三甲基戊基)次膦酸(L272)作萃取劑,用仲辛醇作改質(zhì)劑,研究了不同比例的L272/仲辛醇體系對(duì)重稀土(Er、Tm、Yb、Lu)的萃取分離性能及萃取機(jī)理。采用NMR(~(31)P)、IR對(duì)復(fù)配萃取劑進(jìn)行了表征,用ICP測(cè)定重稀土離子的濃度。另外,還測(cè)定了復(fù)配萃取劑的表面張力、密度及溶解性。結(jié)果表明：L272與仲辛醇按照9：1(v/v)復(fù)配得到的萃取劑(L972)在萃取分離重稀土過(guò)程中性能最佳,平均分離系數(shù)(β)可達(dá)8.05,平均飽和容量為0.14mol/L;萃取過(guò)程大部分為陽(yáng)離子交換機(jī)理,部分為締合機(jī)理,萃合物的結(jié)構(gòu)組成通式為：LnCl3-n(HA2)n(n代表logD-pH的斜率)。系統(tǒng)研究了鹽酸體系中L972對(duì)重稀土的萃取性能。結(jié)果表明,固定其他條件,在平衡pH=2、O/A=1:1、t=12min條件下,L972對(duì)重稀土的萃取率可達(dá)到最大；采用不同濃度的鹽酸對(duì)飽和負(fù)載有機(jī)相進(jìn)行反萃,最佳反萃酸度為3mol/LHCl;固定其他條件,在pH=1.5、O/A=1:1、t=9min條件下,L972對(duì)重稀土的平均分離系數(shù)(p)最大。此外,還研究了非稀土雜質(zhì)鐵、鋁、硅對(duì)L972萃取重稀土的影響。結(jié)果表明：鐵、鋁的存在,明顯降低重稀土的萃取率,而且在pH較低時(shí)就產(chǎn)生乳化,其反萃也很困難。盡管L972對(duì)硅的萃取率較低,但是負(fù)載硅極難反萃,多次反萃,最大反萃率只能達(dá)到40%,因而硅會(huì)在有機(jī)相中不斷累積,嚴(yán)重影響連續(xù)萃取過(guò)程中L972的萃取性能；另一方面,一旦在萃取過(guò)程中形成硅膠,這種膠狀物很難去除或破乳。和現(xiàn)有稀土萃取劑相比,L972萃取重稀土?xí)r在選擇性、飽和容量、分相效果和反萃難易度全面優(yōu)于Cyanex272;其選擇性和反萃難易度明顯高于P507,而飽和容量及分相效果與P507相當(dāng)。本論文的研究結(jié)果有望推動(dòng)稀土分離純化技術(shù)的發(fā)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，

本文編號(hào)：2512316