Effect of Ca(OH)2 grouting on the property of alkali-activated solidified uranium tailing slags
The uranium tailings pond has a large volume and loose uranium tailing slags,which pose the risk of dam failure and diffusion of radioactive contamination.To address these issues,Ca(OH)2 grouting combined with sodium hydroxide and metacolinite-water glass was utilized to solidify granite-type uranium tailing slags.The impact of injected Ca(OH)2 mass fraction on the compressive strength,uranium leaching and radon exhalation of alkali-activated granite-type uranium tailings was investigated through microscopic morphology and physical and chemical analysis.Additionally,the solidification mechanism was elucidated.The experimental results showed that when the uranium slag was injected with 15.0％Ca(OH)2,the standard triaxial compressive strength reached 6.8MPa after curing for 28d,which was a significant improvement of 4.4 times compared to the sample without Ca(OH)2 injection.Additionally,adding Ca(OH)2 reduced uranium leaching rate by 89％and radon exfiltration rate by 52％.SEM and XRD analysis indicated that compared with the control group,more gels of C-S-H and C-A-H and polymers of C-A-S-H were formed in the sample with Ca(OH)2 mass fraction of 15.0％,which was the dominent reason for the improvement of compressive strength of solidified uranium tailing slags and the decrease of uranium leaching and radon exhalation.The research results laid a theoretical foundation for the application of alkali excitation in the reinforcement of granite-type uranium tailing slags.
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