CMP流程处理高放废液后的锕系镧系的分离研究
STUDY ON THE SEPARATION OF ACTINIDES AND LANTHANIDES RECOVERED FROM HIGH-LEVEL LIQUID WASTE(HLLW) BY CMP PROCESS
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摘要: 研究了以HDEHP为萃取剂、DTPA为络合剂,在0.2—0.5mol/l HNO_3酸度下实现An~?(Ⅲ)、Ln~(2?)(Ⅲ)分离的工艺条件。结果表明,Am(Ⅲ)、Gd(Ⅲ)和 En(Ⅲ)的分配比和HDEHP浓度的平方成正比,和酸度的3次方成反比。随温度的升高和料液中金属离子起始浓度的增大而降低。Am(Ⅲ)、Gd(Ⅲ)和En(Ⅲ)的萃取反应热依次为-7.1×10~3J·mol~(-1),-9.2×10~3J·mol~(-1)和-1.9×10~3J·nol~(-1)。采用1.0 mol/l HDEHP-煤油为萃取剂,pH3.2-3.6,0.15 mol/l DTPA-2 mol/l 乳酸为反萃剂,用模拟料液进行串级实验。Am(Ⅲ)近100％被回收,和Am(Ⅲ)共存于水相的Ln~(2?)(Ⅲ)少于3％。根据实验结果提出了概念流程。Abstract: The work investigates the technique conditions for the separation of An(Ⅲ) and Ln (Ⅲ) withinthe acidity range of 0. 2--0. 5 mol/l HNO_3. The effects of varying HDEHP, DTPA, H~+ and initialmetal ion concentrations, and temperature are studied. The results show that the distribution ratio ofAm(Ⅲ), Gd(Ⅲ) and Eu(Ⅲ) are proportional to the second power of HDEHP concentration, and in-versely proportional to the third power of H~+ concentration, respectively. The extraction enthalpies ofAm(Ⅲ), Gd(Ⅲ) and Eu(Ⅲ) are -7.1×10~3 J·mol~(-1), -9.2×10~3 J·mol~(-1) and -1.9×10~3 J·mol~(-1) in turn. 1.0 mol/l HDEHP--kerosen is used for coextraction of An (Ⅲ) and Ln(Ⅲ), and a lac-tic acid--DTPA mixture solution is used for selective striping of An(Ⅲ). Counter--current cascade ex-periments are performed. Nearly 100% An(Ⅲ) is recovered, less than 3% Ln(Ⅲ) remains with An(Ⅲ). A conceptual flowsheet for the separation is suggested.
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Keywords:
- Actinides ,
- Lanthanides ,
- Seperation
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