China Institute for Radiation Protection, Taiyuan, Shanxi, 030006, China; College of Environmental Science and Engineering, Taiyuan University of Technology, Jinzhong, 030600, China.
China Institute for Radiation Protection, Taiyuan, Shanxi, 030006, China.
J Environ Radioact. 2023 Dec;270:107300. doi: 10.1016/j.jenvrad.2023.107300. Epub 2023 Sep 25.
A large number of radionuclides remain in uranium tailings, and U, Ra and Pb leach out with water chemistry, causing potential radioactive contamination to the surrounding environment. In this paper, uranium tailings from a uranium tailings pond in southern China were collected at different depths by means of borehole sampling, mixed and homogenised, and analysed for mineral and chemical composition, microscopic morphology, U, Ra and Pb fugacity, static leaching and dynamic leaching of U, Ra and Pb in uranium tailings at different pH conditions. The variation of U, Ra and Pb concentrations in the leachate under different pH conditions with time was obtained, and the leaching mechanism was analysed. The results showed that the uranium tailings were dominated by quartz, plagioclase and other minerals, of which SiO and AlO accounted for 65.45% and 13.32% respectively, and U, Ra and Pb were mainly present in the residue form. The results of the static leaching experiments show that pH mainly influences the leaching of U, Ra and Pb by changing their chemical forms and the particle properties of the tailings, and that the lower the pH the more favourable the leaching. The results of dynamic leaching experiments during the experimental cycle showed that the leaching concentration and cumulative release of U, Ra and Pb in the leach solution were greater at lower pH conditions than at higher pH conditions, and the leaching of U, Ra and Pb at different pH conditions was mainly from the water-soluble and exchangeable states. The present research results are of great significance for the environmental risk management and control of radioactive contamination in existing uranium tailings ponds, and are conducive to ensuring the long-term safety, stability and sustainability of uranium mining sites.
大量的放射性核素残留在铀尾矿中，铀、镭和铅随水化学浸出，对周围环境造成潜在的放射性污染。本文采用钻孔取样的方法，从中国南方某铀尾矿库不同深度采集铀尾矿，混合均匀，分析了矿物和化学成分、微观形貌、铀、镭和铅的逸度，以及不同 pH 值条件下铀尾矿中铀、镭和铅的静态浸出和动态浸出。得到了不同 pH 值条件下浸出液中 U、Ra 和 Pb 浓度随时间的变化规律，并对浸出机理进行了分析。结果表明，铀尾矿以石英、斜长石等矿物为主，其中 SiO 和 AlO 分别占 65.45%和 13.32%，U、Ra 和 Pb 主要以残渣形式存在。静态浸出实验结果表明，pH 值主要通过改变铀、镭和铅的化学形态和尾矿颗粒性质来影响其浸出，pH 值越低越有利于浸出。在实验周期内的动态浸出实验结果表明，在较低 pH 值条件下，浸出液中 U、Ra 和 Pb 的浸出浓度和累积释放量较大，不同 pH 值条件下 U、Ra 和 Pb 的浸出主要来自于水溶性和可交换态。本研究结果对现有铀尾矿库放射性污染的环境风险管理和控制具有重要意义，有利于确保铀矿开采场地的长期安全、稳定和可持续性。
