The changes in the micro-scale pore structure during the acid leaching of sandstone uranium ore significantly affect its reactive transport parameters, which, in turn, directly influence the leaching efficiency of uranium. Consequently, understanding and managing the dynamic evolution of the pore structure of sandstone at micro-scale during acid leaching is beneficial for enhancing the leaching efficiency of uranium. This paper employs a dynamic continuous water-rock reaction experiment on sandstone uranium ore to simulate the in-situ acid leaching process. Additionally, X-ray micro-computed tomography (μCT) scanning was utilized to produce three-dimensional (3D) images at various leaching stages. Subsequently, image processing techniques were employed to characterize and parameterize the pore structure within these images. The results revealed that, during the leaching process, mineral dissolution led to an increase in the interconnected pores, while there was a decrease in the isolated pores. Nonetheless, at the leading edge of the sandstone uranium ore, detachment of mineral grains occurred during the leaching process along the direction of fluid flow. The migration of mineral grains resulted in a reduction of interconnected pores and an increase in the isolated pores. The analysis of 3D images indicated that porosity, permeability, the percentage of connected pore area and the reactive surface area exhibited similar variation trends throughout the leaching process. Furthermore, the permeability, the percentage of connected pore area and the reactive surface area displayed a positive correlation with porosity. The study holds valuable insights to develop a deeper understanding of the evolutionary patterns regarding the pore structure during the in-situ acid leaching of sandstone uranium ore.

中文翻译：

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砂岩铀矿酸浸过程中孔隙结构和反应输运参数的演变


砂岩铀矿酸浸过程中微观孔隙结构的变化显着影响其反应输运参数，进而直接影响铀的浸出效率。因此，了解和管理酸浸过程中微观尺度砂岩孔隙结构的动态演化有利于提高铀的浸出效率。本文采用砂岩铀矿动态连续水岩反应实验来模拟原位酸浸过程。此外，还利用 X 射线微计算机断层扫描 (μCT) 扫描来生成各个浸出阶段的三维 (3D) 图像。随后，采用图像处理技术来表征和参数化这些图像内的孔隙结构。结果表明，在淋滤过程中，矿物溶解导致连通孔隙增加，而孤立孔隙减少。尽管如此，在砂岩铀矿石的前缘，浸出过程中矿物颗粒沿流体流动方向发生脱离。矿物颗粒的迁移导致连通孔隙减少，孤立孔隙增加。 3D图像分析表明，在整个浸出过程中，孔隙率、渗透率、连通孔面积百分比和反应表面积表现出相似的变化趋势。此外，渗透率、连通孔隙面积百分比和反应表面积与孔隙率呈正相关。 该研究为更深入地了解砂岩铀矿石原位酸浸过程中孔隙结构的演化模式提供了宝贵的见解。