Pore structure and mineral composition characteristics of coal slime before and after ashing and the effects on CO adsorption.

To realize the resource utilization of solid waste (coal slime) and further the dual carbon goals, utilizing coal slime and coal ash as adsorbates for CO capture is crucial. This study employed low-temperature N adsorption, low-pressure CO adsorption, X-ray diffraction, X-ray fluorescence, and isothermal adsorption tests to assess coal slime and coal ash's pore/mineral composition characteristics. Subsequently, the influence on CO adsorption was analyzed to reveal the CO adsorption mechanisms of pores and clay minerals, and CO molecule adsorption behavior. The results showed that: (1) ashing led to reductions in total pore volume, specific surface area, micropore volume, and micropore specific surface area, accompanied by substantial decreases in micropores and mesopores; (2) ashing generated high-temperature stable mineral species, including quartz, andalusite, hematite, and gypsum, while all calcite decomposed into CaO; (3) coal slime exhibited greater CO adsorption capacity than coal ash, influenced by pore structure and clay minerals; (4) the adsorption behavior of coal slime and coal ash likely aligns with micropore filling theory, suggesting CO is adsorbed within the 0.30-1.47 nm pore structure. This research contributes to optimizing coal by-product utilization in mining areas and exploring adsorbate materials for CO sequestration in abandoned goaf.