离子液体浮选分离模拟乏燃料中的稀土元素

Separation of Rare Earth Elements From Simulated Spent Fuels by Flotation Process Using Ionic Liquid

从乏燃料中高效分离稀土元素(中子毒物)是实现乏燃料再生循环利用的关键步骤。利用双有机相离子液体选择性浮选分离乏燃料中的稀土元素,使氧化铀和稀土氧化物几乎不被溶解,实现两者固相之间的分离,避免了二次废液的产生,具有节能和环保的双重意义。以2-乙基己基膦酸单-2-乙基己基酯(P507)为稀土元素的捕收剂、煤油或油酸为稀释剂,以1-丁基-3-甲基咪唑六氟磷酸盐([C4mim][PF6])和1-丁基-3-甲基咪唑双三氟甲烷磺酰亚胺盐([C4mim][Tf2N])两种离子液体作为浮选体系的另一相,优化得到了浮选分离稀土氧化物的最佳条件。结果发现:浮选分离去除率随着混合物中初始Nd含量以及浮选次数的增加而增加。另外,对所有稀土元素与U3O8分别组成的二元体系混合物进行了浮选分离研究,发现在相同条件下,该体系对不同稀土元素的分离也不同,浮选分离的去除率与稀土氧化物的密度有一定的相关性。在此基础上,利用浮选机开展了工艺化的初步探索,发现该浮选体系对Nd的去除率可达80%以上。

Effective separation of rare earth elements(REs, neutron poisons) from spent nuclear fuels is the key step in recycle of spent nuclear fuel. In the present study, the organic two-phase with ionic liquid used for the flotation separation of rare earths from simulated spent fuels was provided firstly. U3O8 and rare earths oxide will not be dissolved in these liquids during the flotation process. The flotation system contain kerosene(oleic acid) as an diluent, P507 as collector,[C4mim][PF6] and [C4mim][Tf2N]. The optimal experimental condition of flotation separation was obtained. Rare earths oxide will be removed from the mixture and the amount will be minimized after several flotation cycles. It was found that the density of rare earth oxide(REO) had important influence on the ratio of REs removal from the mixture. Based on above, the flotation separation using one stage flotation machine was also conducted. The results show that the ratio of Nd removal can reach more than 80%.