Abstract

Uranium tailings are radioactive and toxic solid wastes that could contaminate waters, soils and sediments. Actually the risk of contamination is poorly known due to the lack of knowledge on the mobility of contaminants, especially the influence of acid rain on leaching, transformation and speciation of contaminants. Here, we studied the effect of simulated rain at different pH on the transport and transformation of Mn, Sr, Pb and U from uranium tailings. Semi-dynamic leaching tests and sequential extraction were conducted for Mn, Sr, Pb and U to determine their leaching patterns and to determine their speciation in uranium tailings. Results show that Mn, Sr, Pb and U become more leachable with decreasing rain pH. The release of these metals is initially rapid and then reaches a near steady state. After leaching with simulated rain, concentrations of metal-exchangeable and metal-carbonate fractions in tailings are highly reduced. The process governing the leaching of Mn and U is mainly wash-off, whereas the leached Sr and Pb are dissolution-controlled.

中文翻译：

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不同pH下模拟降雨下铀尾矿中铀和重金属的迁移和转化。

摘要

铀尾矿是放射性和有毒的固体废物，可能污染水，土壤和沉积物。实际上，由于缺乏对污染物迁移率的了解，尤其是酸雨对污染物的浸出，转化和形成的影响，人们对污染的风险知之甚少。在这里，我们研究了模拟降雨在不同pH值下对铀尾矿中Mn，Sr，Pb和U的迁移和转化的影响。对锰，锶，铅和铀进行了半动态浸出试验和顺序萃取，以确定它们的浸出模式并确定其在铀尾矿中的形态。结果表明，随着雨水pH值的降低，Mn，Sr，Pb和U的浸出率更高。这些金属的释放最初是迅速的，然后达到接近稳定的状态。经过模拟雨淋之后 尾矿中金属可交换馏分和金属碳酸盐馏分的浓度大大降低。控制Mn和U浸出的过程主要是淋洗，而浸出的Sr和Pb受溶出控制。