关于两种微生物协同加固铀尾砂及防止铀元素迁移的试验研究

Experimental Study on Synergistic Reinforcement of Uranium Tailings by Two Microorganisms and Prevention of Uranium Migration

加固铀尾矿坝时防止铀元素的扩散和迁移至关重要。将微生物诱导碳酸钙沉淀(MICP, microbial induced carbonate precipitation)技术与放射性污染防治相结合,同时使用巴氏芽孢杆菌和地衣芽孢杆菌两种微生物,通过微生物矿化作用产生的碳酸钙加固铀尾砂,研究该过程对铀尾砂中铀元素的固化作用。结果表明:经过14 d的注浆加固,巴氏芽孢杆菌与地衣芽孢杆菌的协同试验组和巴氏芽孢杆菌的单独试验组渗透系数分别降低至初始值的12.5%与13.9%,铀尾砂渗滤液中铀的质量浓度分别降低至0.056 mg/L与0.071 mg/L,在不同围压的三轴剪切试验中,应力-应变曲线的峰值比原尾砂提高两倍以上。证实地衣芽孢杆菌对铀尾砂中铀元素的迁移及对砂土的加固均有明显的改善作用,为铀尾矿库的砂土加固与污染防治提供了技术支撑和参考依据。

It is very important to prevent the diffusion and migration of uranium elements when reinforcing uranium tailings dam. Microbial induced carbonate precipitation(MICP) technology was combined with the prevention and control of radioactive contamination. At the same time, Bacillus pasteurii and Bacillus licheniformis were used to reinforce uranium tailings by calcium carbonate produced by microbial mineralization, and the solidification effect of this process on uranium in uranium tailings was studied. The results show that after 14 days of grouting reinforcement, the permeability coefficient of the synergistic test group of Bacillus pasteurii and Bacillus licheniformis reduces to 12.5% of the initial value, meanwhile, the test group of Bacillus pasteurii is 13.9% of the initial value, and the mass concentration of uranium in the leachate of uranium tailings reduces to 0.056 mg/L and 0.071 mg/L respectively. In the triaxial shear test with different confining pressures, the peak value of the stress-strain curve is more than twice that of the original tailings. It is proved that Bacillus licheniformis can obviously improve the migration of uranium in uranium tailings and the reinforcement of sand. The study can provide a technical support and a reference for sand reinforcement and pollution prevention of uranium tailings reservoir.