Due to the low coalification degree of lignite, the colloid-like properties and loose characteristics lead to low energy utilization efficiency and seriously hinder the correct understanding of the original pore structure and its mechanical behavior. As a standard process for physical property test, removing the moisture in the pores by drying will cause the lignite to shrink sharply, destroying its original pore structure. Also, for test methods that need to be performed under high pressure, such as mercury intrusion porosimetry (MIP), the soft and loose texture of lignite will cause it to be significantly compressed, making the test results inaccurate. Aiming at the conventional lignite testing process problems, an optimized scheme suitable for lignite was proposed. By rapid freezing and sublimation at low temperatures, freeze-drying can effectively prevent the collapse of lignite. The solid-state of water protects the lignite's primary structure and shape and minimizes volume shrinkage. The average shrinkage rate of lignite sample after freeze-drying is only 9.72%, while that after hot air-drying is 34.8%. Therefore, dehydration by freeze-drying can be an effective method to protect the pore structure of lignite. Based on correcting the syneresis problem, the piecewise linear interpolation method is used to correct the compression effect of lignite. The corrected result excludes the increased pore volume due to the compression of the lignite skeleton. Also, it avoids the under-correction of the low-pressure part and overcorrection of the high-pressure part in the conventional correction method. Based on the corrected nitrogen adsorption and MIP results, the nuclear magnetic resonance (NMR) surface relaxivity of lignite is calculated. The average surface relaxivity value of the samples is 42.8 μm/s, which is significantly greater than that of medium and high-rank coals. The corrected NMR pore size distribution is closer to the actual pore size distribution of lignite. Finally, based on the analysis and correction of the problems in pore property testing of lignite, the improved workflow suitable for lignite is proposed, which provides some referential significance for the correct understanding of its actual physical property.

由于褐煤煤化程度低，其胶体性质和松散特性导致能源利用效率低，严重阻碍了对原始孔隙结构及其力学行为的正确认识。作为物理性能测试的标准流程，通过干燥去除孔隙中的水分会使褐煤急剧收缩，破坏其原有的孔隙结构。另外，对于需要在高压下进行的测试方法，例如压汞法（MIP），褐煤柔软松散的质地会使其被明显压缩，使测试结果不准确。针对常规褐煤检测过程中存在的问题，提出了一种适用于褐煤的优化方案。通过在低温下快速冷冻和升华，冷冻干燥可有效防止褐煤崩塌。水的固态保护褐煤的主要结构和形状，并最大限度地减少体积收缩。褐煤样品冷冻干燥后的平均收缩率仅为9.72%，而热风干燥后的平均收缩率为34.8%。因此，冻干脱水是保护褐煤孔隙结构的有效方法。在修正脱水收缩问题的基础上，采用分段线性插值法修正褐煤的压缩效应。校正结果不包括由于褐煤骨架压缩而增加的孔隙体积。也避免了传统校正方法中低压部分校正不足和高压部分校正过度的问题。基于校正后的氮吸附和 MIP 结果，计算褐煤的核磁共振(NMR)表面弛豫率。样品的平均表面弛豫值为42.8 μm/s，明显大于中高阶煤。校正后的 NMR 孔径分布更接近褐煤的实际孔径分布。最后，在对褐煤孔隙性能测试中存在的问题进行分析和修正的基础上，提出了适用于褐煤的改进工作流程，为正确认识其实际物性提供了一定的参考意义。校正后的 NMR 孔径分布更接近褐煤的实际孔径分布。最后，在对褐煤孔隙性能测试中存在的问题进行分析和修正的基础上，提出了适用于褐煤的改进工作流程，为正确认识其实际物性提供了一定的参考意义。校正后的 NMR 孔径分布更接近褐煤的实际孔径分布。最后，在对褐煤孔隙性能测试中存在的问题进行分析和修正的基础上，提出了适用于褐煤的改进工作流程，为正确认识其实际物性提供了一定的参考意义。