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探讨了铀、钍形成的三个天然放射系对氯化稀土比放的影响。指出长寿命核素的作用与短寿命核素不同,后者依赖于其母体,本身不能独立存在,因此它们对比放的贡献应视为母体对比放贡献的一部分。故在降低氯化稀土的比放时,应当只考虑长寿命核素的净化。净化对象限于U、Th、Ra、Ac、Po、Pa、Pb等七个元素。结合独居石碱分解优溶浸取稀土,硫酸钡沉镭的流程,提出用锌还原水解的方法除去氯化稀土中微量的铀与钍,並且探讨了该法的条件。由于反应对温度变化敏感,采用不同的聚沉剂效果相近,认为反应的机理是一个水解过程。因为pH对硫酸钡载带钡的效率没有显著影响,所以这一过程可以和镭的净化结合进行,方法简单有效。实验结果指出,~(227)Ac的子体对氯化稀土的α—比放有不可忽视的影响,在净化时必须考虑。放化分析表明~(210)Pb对α—比放有影响,但硫酸钡对~(210)Pb的载带效率不高,可在硫酸钡沉淀时加入硝酸铅以载带~(210)Pb。无论是~(210)Po还是~(231)Pa,在二次硫酸钡沉淀载带时,都可被除去。
The effects of three natural radiation systems formed by uranium and thorium on the specific release ratio of rare earth chloride were discussed. It is pointed out that long-lived nuclides, unlike short-lived nuclides, rely on their precursors and can not stand alone in their own right. Therefore, their contribution to contrast should be considered as part of the parent’s contribution to contrast. Therefore, in reducing the specific release of rare earth chloride, should consider only the purification of long-lived nuclides. Purification object is limited to U, Th, Ra, Ac, Po, Pa, Pb and other seven elements. Combined with the monolithic decomposition of the optimal solution leaching of rare earth, barium sulfate radium, the proposed method of zinc reduction and hydrolysis of trace rare earth chloride to remove uranium and thorium, and discussed the conditions of the law. As the reaction is sensitive to temperature changes, the effect of using different coagulants is similar, and the reaction mechanism is considered to be a hydrolysis process. Because pH has no significant effect on the barium sulfate loading of barium sulfate, this process can be combined with the purification of radium, and the method is simple and effective. The experimental results show that the (227) Ac progeny have an unnegligible effect on the α-ratio of rare earth chlorides, which must be considered when purifying. The results of radiochemical analysis showed that ~ (210) Pb affects the α-ratio, but the loading efficiency of ~ (210) Pb with barium sulfate is not high. Lead nitrate can be added to precipitate barium sulfate to support 210 Pb . Both ~ (210) Po and ~ (231) Pa can be removed during secondary barium sulphate precipitation.