It is extremely meaningful to study the damage behaviour of lignite for safe operation during the drying process. In this study, a single hard lignite particle (SHLP) was prepared for drying. The drying characteristics of an SHLP were described, and its drying kinetics were studied from the perspective of the drying model and effective diffusion coefficient (D_eff). The development of surface cracks in drying were obtained, and the changes in surface damage were quantitatively described by relative crack rate (RCR). The results showed that the drying process for an SHLP was divided into three stages following the slope of the drying curve. The rapid removal of a large proportion of moisture mainly occurred in stage I. The Page model is the best model for describing the drying of an SHLP. In addition, D_eff increased with increasing drying time. High temperature promoted the moisture transfer from the inside to the surface of an SHLP. Finally, surface cracks on the SHLP developed rapidly in the early drying stage; specifically, the primary cracks widened and lengthened, and the small cracks mainly attached to the primary cracks. In the later drying stage, cracks shrank and cracks in the branch structure closed. High drying temperature made the RCR of an SHLP reach the maximum value more quickly in stage I.

中文翻译：

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褐煤单粒干燥过程中的去湿行为及其表面损伤定量表征

研究褐煤在干燥过程中的破坏行为对于安全操作具有极其重要的意义。在这项研究中，制备了单个硬褐煤颗粒 (SHLP) 用于干燥。描述了SHLP的干燥特性，从干燥模型和有效扩散系数（D _eff）的角度研究了其干燥动力学。获得了干燥过程中表面裂纹的发展情况，并用相对裂纹率（ RCR）定量描述了表面损伤的变化。）。结果表明，SHLP的干燥过程按照干燥曲线的斜率分为三个阶段。大部分水分的快速去除主要发生在第一阶段。Page模型是描述SHLP干燥的最佳模型。此外，D _eff随着干燥时间的增加而增加。高温促进了 SHLP 内部的水分转移到表面。最后，SHLP表面裂纹在干燥初期迅速发展；具体来说，主裂纹变宽变长，小裂纹主要附着在主裂纹上。在干燥后期，裂缝收缩，分支结构中的裂缝闭合。高干燥温度使RCRSHLP 在第一阶段更快地达到最大值。