铀尾矿库浅层土壤中核素U的析出及固定试验

Precipitation and Immobilization Test of Nuclear U in Shallow Soil of Uranium Tailings Pond

试验以湖南某大型铀矿冶尾矿库为研究对象,在开放体系下间歇式的半动态淋滤试验,特别考察了酸雨条件下铀尾矿库浅层土壤核素U的析出机理。通过Fick扩散理论;并运用有限元回归方法分析核素U在不同固定添加剂的固定效果。试验结果显示,铀尾矿库浅层土壤在模拟酸雨条件下析出机理以表面洗脱为主导作用,使用固定添加剂后析出机理以表面溶解为主导作用。以石灰为固定添加剂,铀在第20 d后重新析出;析出液中铀含量随时间增加而不断递增,以石灰和磷酸氢二胺为组合固定添加剂;其固定效果优于石灰单独作用的固定效果;其结果表明铀的析出浓度低于尾矿库中铀浓度的排放限值。

A large-scale uranium tailings pond in Hunan Province was selected as the object of study.Under the open system,it was used the intermittent semi-dynamic leaching test.The leaching mechanism of different stabilizers on nuclide U in the shallow soil of uranium tailings pond under acid rain conditions was studied.According to the Fick diffusion theory,it used the finite element regression method to analyze the immobilization effect of nuclide U in different fixed additives.The results showed that the leaching mechanism of the shallow soil in the uranium tailings pond under the condition of simulated acid rain leaching was dominated by surface elution.After adding the stabilizer,the leaching mechanism was the main effect.With lime as a stabilizer,uranium was re-precipitated that the content of uranium in the precipitate increased with time on the 20th day.With lime and dihydrogen phosphate diamine as a stabilizer,the immobilization effect is significant,uranium leaching concentration has been lower than limits of uranium concentration in tailings.