Study on Adsorption Characteristics of Coal Under Different Crushing Degrees-Taking Chengzhuang No.3 Coal As an Example

This study examines the adsorption characteristics of coal under varying degrees of fragmentation using Chengzhuang No.3 coal as a case study. The research explores how fragmentation impacts the adsorption capacity of gases like methane (CH₄) and carbon dioxide (CO₂), which is critical for optimizing gas extraction and predicting coal and gas outburst risks. Coalbed methane (CBM) is a significant energy resource but poses safety risks in mines due to potential explosions. Previous studies have focused on the effects of coal metamorphism on adsorption capacity, often neglecting the impact of fragmentation on pore structure. This study collected 500 grams of coal samples from Chengzhuang No.3 seam, crushing them into 5-60 mesh and 60-80 mesh sizes for analysis. Experimental methods included scanning electron microscopy (SEM) to analyze pore characteristics, low-temperature nitrogen adsorption to determine pore size and type, and high-pressure CH₄ and CO₂ adsorption experiments to measure adsorption capacity. SEM revealed metamorphic pores, dissolution pores, and flat slit pores in the coal. Low-temperature nitrogen adsorption showed a significant hysteresis loop, indicating complex pore structures. High-pressure adsorption experiments demonstrated that increased fragmentation enhances adsorption capacity, with finer coal samples showing higher adsorption rates. CO₂ exhibited greater adsorption capacity than CH₄ due to its stronger interaction with coal. The study concludes that fragmentation increases adsorption capacity by expanding pore volume and specific surface area. This finding is essential for improving gas extraction processes and mitigating coal and gas outburst risks.