Compacted bentonite is regarded as a suitable buffer/backfill material in a high-level radioactive waste disposal repository due to its low permeability, high swelling, and strong adsorption capacity, but the bentonite powder is difficult to compact to a high density only by increasing the compaction energy. Hence, a proposal is made to improve the compactness of bentonite by changing its grain size distribution. To obtain bentonite granules with different sizes, a granulation method is proposed in this paper, in which bentonite powders experience the processes of wetting and drying into plate bentonites, which are then crushed into granules. Furthermore, in this paper, the hydromechanical behavior of granular bentonite is evaluated to verify the feasibility of the method for preparing granules. For this purpose, the granular and original bentonite powder with similar grain sizes were prepared; then, various laboratory tests, including measurements of free swelling ratio, swelling pressure, water retention capacity, and compactness, were carried out. The test results show that the free swelling ratio, swelling pressure, permeability coefficient, and water retention capacity of granular bentonite are almost similar to those of original bentonite, and after compaction, the maximum dry densities of granular and original bentonites are 1.72 and 1.64 g/cm³ at the optimum moisture content (20%) and the energy consumption was reduced by 38% with the void ratio decreased from 1.30 to 0.8 compared with the original bentonite. It indicates that, compared with the original bentonite, the hydromechanical behavior of granular bentonites changed a little, but its compaction performance has been significantly improved. To investigate the differences in pore size distributions of granular bentonite and original bentonite, MIP and NA tests were performed on samples produced with the wetting-drying agglomerate method, and the results show that the pores with a size of 10.0 μm almost disappear and the pores mainly exist with a size of approximately 1.0 μm. It can be verified that preparing granules by the wetting-drying agglomeration method is feasible, the granulation process has little effect on the hydromechanical properties of bentonite, and after granulation, not only the compactness is improved but also the energy consumption is saved.

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粒状膨润土的制备及其造粒行为对膨润土流体力学性能的影响

压实的膨润土由于其低渗透性，高溶胀和强吸附能力，被认为是高级放射性废物处置库中合适的缓冲/回填材料，但是仅通过增加膨润土粉末就很难将其压实成高密度。压实能量。因此，提出了通过改变膨润土的粒度分布来提高膨润土的致密性的提议。为了获得不同尺寸的膨润土颗粒，提出了一种造粒方法，其中膨润土粉末经历湿润和干燥成板状膨润土的过程，然后将其粉碎成颗粒。此外，本文还对膨润土颗粒的水力学行为进行了评估，以验证制备该颗粒方法的可行性。以此目的，制备了粒度相似的粒状和原始膨润土粉末。然后，进行了各种实验室测试，包括自由溶胀率，溶胀压力，保水能力和密实度的测量。试验结果表明，粒状膨润土的自由溶胀率，溶胀压力，渗透系数和保水能力与原膨润土基本相似，压实后，粒状和膨润土的最大干密度分别为1.72和1.64 g。 /厘米³在最佳水分含量（20％）和能量消耗降低了38％和与原来相比膨润土空隙率降低从1.30至0.8。这表明，与原始膨润土相比，粒状膨润土的水力力学行为有所变化，但其压实性能得到了明显改善。为了研究在粒状膨润土和原膨润土的孔径分布的差别，MIP和NA测试是在与所述润湿干燥的附聚物的方法制造的样品进行，并且结果表明，尺寸为10.0孔 μ米几乎消失，并且毛孔主要存在与大小大约为1.0的 μ米 可以证明，采用湿-干团聚法制备颗粒是可行的，制粒过程对膨润土的水力学性能影响很小，制粒后不仅提高了致密性，而且节约了能源。