Experimental study on physical and mechanical properties and U(VI) leaching characteristics of fiber-reinforced uranium tailing geopolymer-solidified bodies.

A uranium tailing pond in southern China is the largest in Asia. For historical reasons, uranium tailings stored in the pond have been in an acidic environment for a long time, which has caused great difficulties for decommissioning treatment of the pond. In this study, uranium tailings were taken from the beach surface of the pond as the research object. Then, 11 kinds of solidified samples of uranium tailings with different compositional ratios were prepared using water glass and sodium hydroxide, as alkali activators, and mixed with metakaolin, fly ash, and PVA or basalt fibers. The resulting solidified samples were examined in terms of microscopic characterization, compressive strength, tensile strength, resistivity, and U(VI) leaching. The results showed that, with increased fiber content, the compressive strength of samples first increased and then decreased, while the tensile strength increased continuously. The body volume resistivities first increased and then decreased and, with increased time, the leaching rate decreased continuously and finally tended to stabilize. The compressive strength and volume resistivity of samples were negatively correlated with the U(VI) leaching rate and cumulative leaching fraction. Considering the physical mechanics and U(VI) leaching resistance properties of these bodies, the best fiber proportion was concluded to be the addition of 0.2-wt% PVA fiber and 0.6-wt% basalt fiber. [ABSTRACT FROM AUTHOR]