亚硝气用于1BP料液的调价

由1BP料液制备2AF料液的过程中需要氧化去除1BP中还原剂,同时将Pu(Ⅲ)氧化至Pu(Ⅳ)。以气液并流模式在玻璃填料柱中研究了亚硝气对模拟1BP料液中还原剂的氧化情形,考察了亚硝气用量、料液停留时间、HNO_3浓度和温度对模拟1BP料液中还原剂氧化率的影响。结果表明:25℃时,在羟胺、肼浓度均约为0.08mol/L,c(HNO_3)=1.5mol/L、ρ_0(U(Ⅳ))=1.26g/L、Pu(Ⅲ)(以Fe(Ⅱ)代替)质量浓度为8.76g/L的1BP料液中,当N_2O_4液体为还原剂总量的1.2倍(摩尔比)、停留时间为3min时,1BP料液中还原剂的氧化率达到99.9%以上,Pu(Ⅲ)的氧化率在99.9%以上。

Conditioning of 1BP by Nitrous Gases

PUREX process was the only commercialized hydrometallurgy reprocessing process, which could recycle the uranium and plutonium in spent nuclear fuel successfully. Pu(Ⅲ) should be oxidized to Pu(Ⅳ) before it was extracted into TBP-diluent in plutonium purification cycle of PUREX process. Meanwhile, the reductants in 1BP feed, such as hydroxamine, hydrazine and U(Ⅳ) should be oxidized. Previous research showed that N₂O₄ was an excellent and salt-free oxidant to the reductants. Therefore, oxidation of the reductants by nitrous gases mentioned above were studied in glass packed column in a gas liquid concurrent flow model. The results show that the dosage of N₂O₄, the reaction time in column and reaction temperature have significant impact on the oxidation of the reductants. When the residence time of the 1BP feed in glass column is 3 min and the dosage of N₂O₄ is 1.2 times higher than that of the total reductants, more than 99.9% of reductants are oxidized, and the oxidation rate of Pu(Ⅲ) is also higher than 99.9%.