人工模拟降雨条件下典型铀尾渣浸出特性研究

Leaching Characteristics of Typical Uranium Tailings Under Simulated Rainfall

堆浸产生的铀尾渣经过石灰中和处理后仍存在向外界环境释放迁移核素U的风险,通过设计模拟降雨条件下的静态浸出试验,探究U浸出释放的影响因素。结果显示,核素U在尾渣中呈离散型分布,在浸出过程中钠长石会发生局部溶解,矿物中部分难溶态的U可以释放出来;次生矿物二水石膏除了包裹作用外,还可以将小颗粒的石英、钠长石等沉淀下来,二水石膏的溶解-沉淀在一定程度上会影响核素U的释放迁移。另外,低pH高含氧量的浸泡条件可以提高U的浸出量,而充足的浸泡时间、低的固液比可以使U释放更加充分;尾渣粒径越小矿物内部和表面的U越容易浸出。

After neutralization with lime,uranium tailings from heap leaching still have the risk of nuclide U release and migration to the environment.Through the design of static leaching experiment under simulated rainfall,the influence factors of U leaching release were explored.The results show that the nuclide U is distributed discretely in the tailings.During the leaching process,albite will be partially dissolved,and some insoluble U in the mineral can be released.In addition to the inclusion,the secondary mineral dihydrate gypsum can also precipitate small grains of quartz and albite.The dissolution precipitation of dihydrate gypsum will affect the release and migration of nuclide U to a certain extent.In addition,the soaking conditions of low pH and high oxygen content can improve the leaching amount of U,while sufficient soaking time and low solid-liquid ratio can make U release more fully;the smaller the particle size of tailings,the easier the leaching of U on the inner and surface of minerals.