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利用各种分析手段对膨润土的物理特性进行了表征 .X射线衍射分析表明钠基膨润土呈典型的六方晶胞 ,晶胞参数是 :a轴 4 .913,c轴 5 .4 0 5 ;差热分析曲线在低温区和高温区有明显的吸热峰出现 ;元素分析钠、钾离子的含量大于钙、镁离子的含量 ,在性能上表现为钠质膨润土具有较强的离子交换能力 ;显微分析表明其表面呈皱隙状 ,测定比表面积高达 2 4 .5 2m2 /g;吸水率测定表明膨胀率大 ,说明它具有密封功能 ,可有效阻滞地下水的渗入 .利用SF6示踪技术 ,通过采集不同时间段取样池样品 ,分析样品中示踪气体浓度 ,绘制取样池示踪气体浓度随时间的变化关系曲线 ,根据费克扩散定律计算扩散系数 .实验结果表明 ,随着压实膨润土密度的增大 ,示踪气体扩散系数迅速减小 ,当密度大于 1.8g/cm3 时 ,扩散系数降至 10 -9m2 /s.研究结果表明 ,膨润土性能优化是通过在膨润土中添加适量的活性炭 ,可明显改善其对气体的阻滞能力 ;增加其对放射性气体滞留能力 ;添加少量的石英砂增加其机械性能、导热性和减少蠕变性 ,将引起对气体阻滞能力的下降 .综合考虑 ,在膨润土中各添加 5 %活性炭和石英砂 ,既对气体具有较好的滞留能力 ,又具有较好的工程特性 .
The physical properties of bentonite were characterized by various analytical methods.X-ray diffraction analysis showed that sodium bentonite is a typical hexagonal unit cell with unit cell parameters of 4.913 for a-axis and 5.554 for c-axis; Analytical curves show obvious endothermic peaks in low and high temperature regions. The content of sodium and potassium in elemental analysis is greater than that of calcium and magnesium ions, which shows that sodium bentonite has strong ion exchange ability in performance. The analysis showed that the surface was crepe-like, the specific surface area was measured as high as 24.52m2 / g, the water absorption showed that the expansion rate, indicating that it has a sealing function, which can effectively block the infiltration of groundwater. Using SF6 tracer technology, According to the Fick diffusion law, the diffusion coefficient was calculated.The experimental results show that with the density of the compacted bentonite, the concentration of the tracer gas in the sample tank, The diffusion coefficient decreases to 10 -9 m 2 / s when the density is greater than 1.8 g / cm 3 .The results show that the performance of bentonite is optimized by adding Adding a suitable amount of activated carbon can significantly improve its ability to block gases, increasing its ability to retain radioactive gases, adding a small amount of quartz sand to increase its mechanical properties, thermal conductivity, and creep reduction, Decline.A comprehensive consideration, adding 5% activated carbon and quartz sand in bentonite, not only has better retention of gas, but also has good engineering properties.