Huang Min, Hu Ke, Li Xiang, Wang Yun, Ouyang Jinbo, Zhou Limin, Liu Zhirong
State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China.
School of Chemistry, Biological and Materials Science, East China University of Technology, Nanchang 330013, China.
Toxics. 2022 Aug 12;10(8):469. doi: 10.3390/toxics10080469.
In order to realize sustainable development, it is beneficial to explore an appropriate process to recover the radionuclides contained in tantalum-niobium slag. By micro-mineralogical analysis and roasting experiments, the effect of uranium-thorium leaching from a refractory tantalum-niobium slag is investigated. The uranium and thorium content in the slag is 2.26 × 10 mg/kg and 7.84 × 10 mg/kg, which have large recovery value. As the surface area and pore size of the slag are very small, the leaching agent cannot fully penetrate the particles. Various methods of characterization are used to analyze the mineralogical properties of roasted slag at different temperatures. The leaching ratio of U-Th is 90.84% and 96.62% at the optimum roasting temperature of 500 °C, which are about 39% and 27% higher than original samples. The oxidants Fe, O and Mn can also promote the conversion of insoluble U(IV) to soluble U(VI). Roasting reduces the content of organic C and S, thereby preventing reduction of U(VI), and increasing pore size as well as specific surface area also promote radionuclide leaching. Thus, the roasting method at 500 °C can destroy the surface wrapping structure of radionuclides, reduce the internal density of minerals, and improve uranium-thorium leaching ratio significantly. It is of great practical significance to reduce the radioactive hazard of waste tantalum-niobium slag and to strengthen the sustainable utilization of resources by suitable process improvement techniques.
为实现可持续发展，探索一种合适的工艺来回收钽铌矿渣中所含的放射性核素是有益的。通过微观矿物学分析和焙烧实验，研究了从难处理钽铌矿渣中浸出铀钍的效果。该矿渣中铀和钍的含量分别为2.26×10毫克/千克和7.84×10毫克/千克，具有较大的回收价值。由于矿渣的表面积和孔径非常小，浸出剂无法充分渗透颗粒。采用各种表征方法分析不同温度下焙烧矿渣的矿物学性质。在500℃的最佳焙烧温度下，U-Th的浸出率分别为90.84%和96.62%，比原始样品分别高出约39%和27%。氧化剂Fe、O和Mn也能促进不溶性U(IV)向可溶性U(VI)的转化。焙烧降低了有机C和S的含量，从而防止U(VI)的还原，同时增大孔径和比表面积也促进了放射性核素的浸出。因此，500℃的焙烧方法可以破坏放射性核素的表面包裹结构，降低矿物的内部密度，并显著提高铀钍浸出率。通过合适的工艺改进技术降低废钽铌矿渣的放射性危害并加强资源的可持续利用具有重要的现实意义。
