【摘要】 利用氧化物沉淀-减压蒸馏耦合法研究FLiNaK熔盐体系中氟化物的蒸发行为及稀土Nd的分离。高温下氧化物CaO与稀土氟化物NdF₃反应形成难溶于熔盐的稀土氧化物,通过减压蒸馏蒸发、收集冷凝FLiNaK熔盐,提高稀土与熔盐的分离度,促进熔盐的回收利用。研究表明,含有NdF₃（w=3%）的FLiNaK熔盐中加入CaO,730°C下反应6 h,n（NdF₃）:n（CaO）=1:3时NdF₃的转化率达95%。X射线衍射（X-ray Diffraction,XRD）分析表明生成的Nd₂O₃主要沉淀在熔盐的底部。经730°C高温沉淀、930°C熔盐蒸馏,冷凝盐中稀土Nd的去污因子达9.4′105,而未经沉淀处理Nd的去污因子为3.1′104,表明高温沉淀蒸馏耦合法使稀土NdF₃转化为氧化物Nd₂O₃,显著增大稀土与FLiNaK的分离度,提高收集盐的纯度。更多还原

【Abstract】 Background: Low pressure distillation is a promising technology for the recovery and purification of carrier salts（Li F-Be F2） in the thorium based molten salt reactors（TMSR）. Purpose: This study aims to compare the separation behavior of NdF₃ before and after adding the oxidant CaO in FLiNaK molten salt. Methods: Precipitation-distillation coupled method was employed in purification of molten salt. Then the X-ray Diffraction（XRD） was applied to the analysis of the produced NdF₃ in the molten salt. Results: At high temperature, CaO was confirmed to react with NdF₃ and form rare earth oxide Nd₂O₃ insoluble in molten salt. At 730 °C, the conversion rate for Nd was up to 95%. After the precipitation reaction, the separation rate under low pressure distillation was compared with the preceding one. The decontamination factor of Nd was deduced to 9.4×105 whilst the value was 3.1×104 without adding CaO. Meanwhile, the evaporation rate also was improved after precipitation. Conclusion: The combination of the precipitation and distillation treatment is an effective way to achieve the high throughput performance in the salt separation process.更多还原