Experimental Study On Mechanical Properties And Water Resistance Of Uranium Tailings Cement Solidified Body

Due to the development of atomic energy and the defense industry,the demand for uranium and metallurgical products is increasing,leading to an increase in the amount of uranium tailings.The accumulated uranium tailings will not only cause pollution of the surrounding environment,but also threaten the health of the surrounding residents.In this paper,combined with the actual situation of an uranium tailings pond in the south and the demand for decommissioning,the cement solidification technology is used to solidify the uranium tailings with cement,slag powder and fly ash as cementing materials,and the uranium tail sand solidified body is studied.Confined compressive strength,leaching resistance and porosity and their relationship.The main research contents include the following aspects:(1)Attribute analysis of uranium tailings,including chemical composition,water content,particle size and phase analysis of uranium tailings;research on physical and chemical properties of cement,slag powder and fly ash.According to the above admixture physical and chemical properties,the mixture ratio design,the uranium tailings cement solidified body with different admixtures and different mixing ratios,the mixture of fly ash,slag powder and fly ash and slag powder(the mass ratio of the two is 2:1)Replacing 15%,20% and 25% of the cement content respectively to form a solidified body of uranium tailings cement.(2)The unconfined compressive strength of samples of different ages,different ratios and different admixtures,and the leaching resistance of uranium samples were studied.The leaching rate of uranium on day 42 was calculated and passed the nuclear magnetic resonance experiment.Porosity of samples with different proportions and different admixture solidified bodies was obtained.The results show that the best compressive strength effect is cement solidified with 25% fly ash,the strength value is 12.91 MPa.The slag powder and fly ash blended with 25% have the lowest compressive strength and the strength value is 7.33 MPa.(3)Ten uranium tailings cement solidified bodies with different proportions and admixtures leach more uranium in acidic condition than in alkaline condition.According to the leaching rate of different admixtures at different ages,the leaching rate of uranium tailings solidified with cement alone on the 42 nd day was 1.36×10-5cm/d,which was higher than that of nuclide 42 nd day in the national standard.The leaching rate of uranium with fly ash,slag powder and compound fly ash and slag powder conformed to the national standard.The lowest leaching rate was that with 25% fly ash and porosity is also the smallest.The porosity is 4.93×10-6cm/d.(4)Through nuclear magnetic resonance experiments on 10 groups of uranium tailings cement solidified body,it is found that the best blending of 25% fly ash is low,and the porosity is also low.When 15% slag powder is mixed,the compressive strength is the largest and the porosity is the least;When 15% fly ash and slag powder are mixed,the compressive strength is the largest and the porosity is the smallest.Comprehensive analysis of the compressive strength,uranium leaching rate and porosity of the solidified body,the cement solidified with fly ash is better than the three admixtures,and the best is to incorporate 25% fly ash uranium tailings cement solidified body.