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本文研究了在铁(Ⅱ)-EDTA体系中快速还原铀(Ⅵ)的条件和测定矿石中微量铀的方法。在含有EDTA的微酸性介质中,铁(Ⅱ)可将铀(Ⅵ)迅速地还原至四价。四价铀离子可在4M盐酸中用偶氮胂Ⅲ显色后测定。铀(Ⅳ)-偶氮胂Ⅲ络合物在660nm呈最大吸收,克分子吸光系数为1.02×10~5,当log(I_0/I)=0.001时,桑德尔(Sandell)灵敏度为0.00233μgU/cm~2,铀浓度为0～2μg/ml,符合朗伯特-比尔定律。钍、铜、钛、锆和大量稀土干扰测定。用742强碱性阴离子交换树脂从硫酸介质中吸附铀,可使微克量铀与大量共存离子分离。方法用于测定矿样中n×10~(-4)%铀时,标准偏差不大于0.3×10~(-4)%,精密度在±7%以内。
In this paper, the conditions of rapid reduction of uranium (Ⅵ) in iron (Ⅱ) -EDTA system and the determination of trace uranium in ore are studied. Iron (Ⅱ) can rapidly reduce uranium (Ⅵ) to tetravalent in slightly acidic medium containing EDTA. Tetravalent uranium ions in 4M hydrochloric acid with arsenazo Ⅲ color determination. The maximum absorption of uranium (Ⅳ) - arsenazo Ⅲ complex at 660 nm is 1.02 × 10 ~ 5. When log (I_0 / I) = 0.001, the sensitivity of Sandell is 0.00233 μgU / cm ~ 2, uranium concentration 0 ~ 2μg / ml, in line with the Lambert-Beer law. Th, Cu, Ti, Zr and a large number of rare earth interference determination. 742 strongly basic anion exchange resin adsorption of uranium from the sulfuric acid medium, can make a small amount of uranium and coexisting ions uranium separation. When the method is applied to the determination of n × 10 ~ (-4)% uranium in ore samples, the standard deviation is not more than 0.3 × 10 ~ (-4)% and the precision is within ± 7%.