四价铀预处理改善钌的去污

PRETREATMENT WITH U(Ⅳ) SOLUTION FOR IMPROVING THE DECONTAMINATION OF RUTHENIUM

在低酸条件下以四价铀溶液代替硝酸肼进行保温预处理,可使30％TBP-煤油萃取RuNO硝酸根配合物的分配系数(D_(Ru))降低一个数量级。料液预处理后调至2.0mol/l HNO_3介质放置40h,D_(Ru)值还略有下降,这说明预处理过程中形成的不易被TBP萃取的钌化合物是稳定的。

The ruthenium decontamination factor in Purex process falls quickly in successive TBP cycles. So,it is necessary to change the chemical states of RuNO complexes in order to improve DFRU in the uranium purification cycle. Hydrazine nitrate is being used to transform RuNO complexes into inextractable Ru(Ⅲ) and Ru( Ⅳ). However, hydrazine nitrate may be inverted into hydrazoic acid which is dangerous and can bring an unstable factor. Pretreat-ment using U (Ⅳ) solution provides another method to improve the decontamination of ruthenium in Purex process.0. 02mol/l U(Ⅳ ) solution can transform RuNO complexes into inextractable species by heating in water bath. The DRu can be decreased by a factor of 10 - 20. U( Ⅳ) pretreatment does not bring any harmful chemical in process.The acidity has a very large influence on the effect of pretreatment. The higher the acidity is,the worse the effect will be.