【作者】 李娜；

【导师】 徐中慧；

【作者基本信息】 西南科技大学 ， 安全科学与工程， 2019， 硕士

【摘要】 核能在缓解能源危机的同时,产生的放射性废物严重威胁人类的生命安全。目前,如何对高放废液（HLW）进行有效处理和处置引起了海内外学者的广泛关注。地聚合物因具有独特的网络状结构可用于固化处理核废液,但鲜有学者对其进一步陶瓷化进行研究。因此,本论文通过对比粉煤灰及偏高岭土基地聚合物的物理特性以及矿物组成的变化,阐明高温陶瓷化的演变特性。利用4A沸石、硅酸钾和偏高岭土为原料制备陶瓷,对模拟核素锶、铯进行固化,并研究了陶瓷固化体的物理特性和抗浸出性能,结合矿物组成、微观形貌及分子组分分析,阐明了陶瓷固化体的性能及固化机理。以此为依据,进一步对含核沸石添加量对陶瓷固化体性能带来的影响展开研究,以期为地聚合物陶瓷固化高放废液大规模工业化应用提供一定的理论与实践基础。本论文研究表明:偏高岭土基地聚合物样品较粉煤灰样品具有更好的耐高温性能,在高温1200℃左右,偏高岭土基地聚合物有大量白榴石相生成,样品结构平整光滑,气孔率实现最小值,抗压强度急剧提升。碱金属钾离子半径较大,使得钾-基偏高岭土地聚合物样品在1100℃率先出现白榴石晶相衍射峰,气孔率为1.21%,抗压强度提升至47.76 MPa,较钠-基偏高岭土地聚合物样品高出12.98 MPa,更适用于制备陶瓷固化体。含锶沸石、含铯沸石的两组地聚合物陶瓷固化体致密性好,具有很好的机械性能和抗浸出（离子扩散）性能。两组地聚合物陶瓷固化体在900℃开始,样品气孔率明显减小,体积密度增大,在1100℃有大量光滑稳定的陶瓷相结构生成,内部结构致密,两组陶瓷固化体样品强度分别提高至81.33 MPa和91.45 MPa,在去离子水、卤水、硅酸盐水中较原样表现出更好的抗浸出性能,浸出率均低于工业标准值,具有很好的长期稳定性。含核沸石添加量对陶瓷固化体性能影响较为明显,含核沸石添加量在60%时,沸石中碱金属参与反应,降低样品的熔融温度,1100℃时局部熔融生成新的霞石相,含核沸石添加量在70%-90%时,有大量霞石、白榴石等陶瓷相的生成,物相分析表明游离SiO₂熔融成玻璃相,填补孔隙,样品抗压强度提升。在高浓度卤水溶液中,含核沸石掺量为90%时,样品在整个浸出周期内浸出率均满足工业限值,可实现高放废液的安全处置。更多还原

【Abstract】 Although nuclear energy can alleviate the energy crisis,the radioactive waste brings a seriously threat to human life.At present,how to treat high-level liquid waste（HLW）effectively has attracted widespread attention from domestic and foreign scholars.Geopolymers with unique network structure can be used for curing radioactive waste liquor,but few scholars have made further research on its ceramization.In this paper,the characterization of geopolymer under high temperature was investigated,such as physical properties and mineral composition of fly ash and metakaolin-based geopolymers.The physical properties and leaching resistance of the ceramic solidification bodies that prepared by 4A zeolite,potassium silicate and metakaolin were studied.Combined with the mineral composition,micromorphology and molecular structure results,the properties and mechanism of the geopolymer ceramic solidification body were analysed.Meanwhile,the influence of zeolite content on the properties of ceramic solidification was further discussed.The results can provide a theoretical basis for the large-scale industrial application of high polymer liquid solidification waste liquid.The research of this paper shows that the metakaolin-based geopolymer has better resistance to high temperature han the fly ash-based geopolymer.At high temperature of 1200℃,the metakaolin-based geopolymer has a large amount of leucite phase,and the sample structure is temper and compact.The compressive strength of the sample is sharply increased.Since the K-based metakaolin-based geopolymer sample first appears peak of the leucite ceramic crystal phase at the 1100℃ for the ionic radius of the alkali metal K⁺is larger than the Na⁺ion radius,the metal bond is weakened.The porosity is 1.21%,and the compressive strength is improved to 47.76 MPa,which is 12.98 MPa higher than the Na-based metakaolin-based geopolymer sample,and that can be used to prepare ceramic solidification bodies.The two groups of geopolymer ceramic solidification bodies prepared by the cerium-containing zeolite and the cerium-containing zeolite have good compactness,mechanical strength and leaching resistance.At 900℃,The porosity of the sample is decreased significantly,the bulk density increased,and a large number of smooth and stable ceramic phase structures were formed at 1100℃ for the internal structure is dense,and the strength of the two sets of ceramic solidification samples were respectively increased to 81.33 MPa and 91.45 MPa.In addition,it shows better leaching resistance in deionized water,brine and silicate water.The leaching rate is lower than the industry standard value and has good long-term stability.The effect of the radionuclide zeolite on the performance of the ceramic solidification body is obvious.When the content of the radionuclide zeolite is 60%,the alkali metal in the zeolite participates in the reaction to reduce the melting temperature of the sample.The new nepheline phase is produced at 1100℃ for local melting of the sample,and the porosity increases,resulting in a sharp decrease in compressive strength.When the amount of radionuclide added is between 70%and 90%,a large number of ceramic phases are generated,such as nepheline and leucite.Phase analysis showed that free SiO₂ participates in the reaction and melts into a glass phase to filling the pores due to the molten,and increasing the compressive strength of the sample.In the high concentration brine solution,when the content of the radionuclide zeolite is90%,the leaching rate of the sample in the entire leaching period satisfies the industrial limit.The safe disposal of high-level liquid waste can be realized.更多还原