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对真空蒸馏法深度脱除精镉中铊和铟进行了理论分析和实验研究,考察了蒸馏温度对Tl和In脱除效果的影响,并探讨了钢质材料中Fe元素对实验结果的影响。理论分析表明,在真空条件下,Tl和In与Cd均具有分离的可能性,且分离效果较好,即利用真空蒸馏法获得更高纯度的金属Cd是可行的。实验结果表明,随着蒸馏温度的升高,Cd的挥发率呈快速增加趋势,挥发物中的Tl含量增加迅速,Tl的脱除率减小幅度较大,挥发物中In含量增加缓慢且保持在较低水平,In的脱除率减小的幅度较小,挥发物中Fe含量一直保持在较低水平,含量始终保持在1×10~(-8)以下,说明利用钢质材料对提高精Cd纯度不会产生影响;当系统压力为2~5 Pa,蒸馏温度为643 K,保温时间为7 h条件下,精Cd的挥发率为16.21%,挥发产物中Tl含量为2.83×10~(-7),Tl的脱除率为99.76%,In的含量为2.327×10~(-7),In的脱除率为97.97%,可获得纯度为99.9999%的金属Cd。
The removal of thallium and indium from refined cadmium by vacuum distillation was studied theoretically and experimentally. The effect of distillation temperature on the removal of Tl and In was investigated. The effect of Fe on the experimental results was also discussed. The theoretical analysis shows that Tl, In and Cd have the possibility of separation under vacuum, and the separation effect is better. It is feasible to obtain higher purity metal Cd by vacuum distillation. The experimental results showed that with the increase of distillation temperature, the volatilization rate of Cd showed a rapid increase. The content of Tl in the volatiles increased rapidly and the removal rate of Tl decreased greatly. The In content in the volatiles increased slowly and remained At lower levels, the removal rate of In decreases less, and the content of Fe in the volatiles remains at a lower level, and the content remains below 1 × 10 -8, indicating that the use of steel material to improve When the system pressure is 2 ~ 5 Pa, the distillation temperature is 643 K and the incubation time is 7 h, the volatilization rate of fine Cd is 16.21% and the content of Tl in volatiles is 2.83 × 10 ~ (-7), the removal rate of Tl is 99.76%, the content of In is 2.327 × 10 -7, the removal rate of In is 97.97%, and the metal Cd with purity of 99.9999% can be obtained.