Impact of Humidity and Freeze–Thaw Cycles on the Disintegration Rate of Coal Gangue in Cold and Arid Regions: A Case Study from Inner Mongolia, China

Coal extraction in China is increasingly moving towards colder regions such as Xinjiang and Inner Mongolia. However, these mines face land restoration challenges due to a scarcity of fertile topsoil. This study explores the potential of coal gangue, a mining byproduct, as a viable substitute for topsoil. The study examines the effects of humidity fluctuations and freeze–thaw cycles, both individually and in combination, on the weathering disintegration of coal gangue. Coal gangue samples were subjected to controlled laboratory conditions simulating environmental factors. Fourteen interventions were analyzed, and the findings indicated that the combined application of humidity and freeze–thaw cycles significantly accelerated the disintegration process, outperforming the individual interventions. In addition, it was found that significant temperature variations caused the moisture and salts within the gangue to expand, which affected the rate of disintegration. The study showed that the rate of weathering disintegration was significantly higher in conditions of saturated humidity–freeze–thaw cycles compared to unsaturated humidity conditions. This highlights the essential role of ice crystals in accelerating the weathering process during temperature fluctuations. This study highlights the importance of humidity over temperature in the weathering and disintegration of coal gangue. It also suggests that freeze–thaw cycles can enhance this process. The study provides valuable insights for the management and utilization of coal gangue in cold and arid regions.