稀土浸出液络合超滤过程研究

发布时间：2018-05-09 22:29

  本文选题：稀土浸出液 + 络合超滤　； 参考：《江西理工大学》2015年硕士论文

【摘要】：近年来络合-超滤耦合技术已广泛应用于金属离子分离浓缩方面的研究。该技术应用于稀土离子浓缩分离具有无沉淀剂加入、络合剂可回收再利用、无酸溶过程、无二次污染且富集液中稀土离子浓度高等特点。本课题以稀土浸出液为研究对象,考察了可能影响稀土浸出液络合超滤过程的因素,以期为络合-超滤技术在低浓度稀土浸出液分离浓缩中的实际应用提供理论依据。本文首先以阴离子聚丙烯酰胺(APAM)、聚丙烯酸钠(PAASS)和聚乙烯亚胺(PEI)为络合剂,考察了三种络合剂与模拟稀土浸出液的络合超滤行为。讨论了三种络合剂预处理过程,以及络合p H值、装载比L(络合剂与稀土离子质量比)和外加Al3+浓度对络合超滤行为的影响。结果如下:(1)经过预处理后三种络合剂截留率均达到100%;(2)对于PAASS和PEI而言,近中性范围更易于络合反应的进行;(3)PAASS和PEI的最佳装载比L=0.75;(4)APAM不适宜作为RE3+的络合剂;(5)Al3+浓度对稀土浸出液络合超滤过程有较大影响,实际稀土浸出液络合超滤前必须除杂。在对模拟稀土浸出液络合超滤行为研究的基础,以除杂后的实际稀土浸出液为研究对象,考察了其与PAASS络合超滤过程。实验确定了中和水解除杂的最佳p H为7.1,并且讨论了络合p H、装载比L、操作压力ΔP和温度T对络合超滤过程的影响,同时还对浓缩和解络实验进行了分析。结果表明:(1)PAASS与实际稀土浸出液最佳络合条件:p H=6-7,装载比L=1.0;(2)PAASS与实际稀土浸出液最佳超滤条件:操作压力ΔP=0.6Mpa,温度T=25-30℃;(3)通过络合超滤浓缩来提高浸出液中稀土离子浓度是可行,解络2小时后,渗透液中稀土离子浓度Cp,RE为1367mg/L,解离率为71.2%。对PAASS与稀土离子络合反应分析发现:PAASS可能通过COO-基团与RE3+络合,且络合方式多样;络合反应可用一级动力学反应来描述,对应的反应速率常数k1=0.0357;PAASS与稀土离子络合反应属朗格缪尔吸附,由实验数据拟合可得到线性方程相关性系数R2=0.997,Langmuir常数K=0.133。
[Abstract]:In recent years, complex-ultrafiltration coupling technology has been widely used in the separation and concentration of metal ions. The application of this technology to the separation of rare earth ions is characterized by the addition of no precipitator, the recovery and reuse of the complex agent, the absence of acid dissolution process, the absence of secondary pollution and the high concentration of rare earth ions in the enrichment solution. Taking rare earth leachate as the object of study, the factors that may influence the complexation ultrafiltration process of rare earth leachate were investigated in order to provide a theoretical basis for the practical application of complex-ultrafiltration technology in separation and concentration of low concentration rare earth leachate. In this paper, the complexation ultrafiltration behavior of three kinds of complexing agents with simulated rare earth leachate was investigated with anionic polyacrylamide (APAM), sodium polyacrylate (PAASS) and polyethyleneimide (PEI) as the complexing agents. The effects of complex pH value, loading ratio L (mass ratio of complexing agent to rare earth ion) and the concentration of Al3 on the complexation ultrafiltration behavior were discussed. The results were as follows: (1) after pretreatment, the rejection rates of the three kinds of complexing agents reached 100%) for PAASS and PEI, In the near neutral range, it is easier to carry out the complexation reaction. The optimum loading ratio of PEI and PASS is less suitable to be used as the complexing agent of RE3. The concentration of Lian5Al3 has a great influence on the complexation ultrafiltration process of rare earth leachate, and it is necessary to remove the impurities before the complexation ultrafiltration of rare earth leachate. Based on the study of complex ultrafiltration behavior of simulated rare earth leachate, the complex ultrafiltration process with PAASS was investigated by taking the actual rare earth leaching solution after impurity removal as the research object. The optimum pH value of neutralization hydrolysis was determined to be 7.1, and the effects of complexation pH, loading ratio, operating pressure 螖 P and temperature T on the complexation ultrafiltration process were discussed. At the same time, the enrichment and desorption experiments were also analyzed. The results show that the optimal complexation conditions: 1: pHH6 ~ 7, the best ultrafiltration conditions between the loading ratio of L ~ (1.0) O ~ (2 +) PAASS and the actual rare earth leachate are as follows: operating pressure 螖 P _ (0.6) Mpaand temperature T _ (25 ~ 30 鈩，

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