IMPROVING THE DECONTAMINATION OF RUTHENIUM WITH SHORT CHAIN HYDROXAMIC ACTD AS COMPLEXING AGENT

The ruthenium decontamination factor in Purex process falls quickly with recycles of TBP. So it is necessary to change the chemical states of RuNO complexes in order to improve DF_(Ru) in the uranium purification cycle. The retention of RuNO complexes in TBP-kerosenelaurohydroxamic acid is observed to be quite large in our previous work. Therefore, water-soluble short chain hydroxamic acid is used as complexing agent to decrease the distribution coefficient of Ru. Hydroxamic acid can transform RuNO complexes into inextractable species by TBP-kerosene in certain conditions. The result of cascade experiment indicates that the ruthenium decontamination can be increased by a factor of 40—50. Acidity has more influence on the effect of pretreatment. The heigher acidity is, the worse the effect will be. The pretreatment is first carried out in low acidic solution, then extractive acidity is increased. In this way,the distribution of Ru can be decreased obviously. After pretreatment, the acidity of solution is in creased to 2 mol/l HNO_3 and aged for 40 hours, then extracted by 30％(V/V)TBP-kerosene, the distribution of Ru has no much increase. It illutrates that the RuNO-hydroxamic acid is rather stable. Short chain hydroxamic acid can be destroyed easily in evaporative process.