Examination of the use of binderless zeolite blend as backfill materials to enhance CO2 adsorption in coal mine working face

The release and accumulation of CO 2 in the working face of the coal mine is a major safety concern and requires an effective means to avoid the incidence of the mine. This present study therefore sought to develop a self-CO 2 adsorbing backfill (SCAB) material to remove CO 2 from the working environment, and simultaneously mitigate the movements of the surrounding rock layers. SCAB was formulated using coal mine solid waste activated with an alkali activator, and binderless 4 A zeolite was embedded in the backfill body. The total CO 2 adsorption capacity was investigated using a CO 2 flow-through method under ambient pressure and temperature conditions. The adsorption plateau was found in stages II and III respecting the predetermined curing time and zeolite contents. The maximum adsorption capacity was 143.8 mg-CO 2 /g-SCAB, resulting in an increase of up to 82 % in UCS compared to reference samples. The underlying mechanism was discovered in morphological analyses.1) The well distribution of zeolite in the SCAB body provided as diffusive pathways and adsorption sites for CO 2 after standard curing. 2) The adsorbed CO 2 underwent a desorption stage when the CO 2 concentration decreased and reacted to the cementitious matrix of the SCAB body. 3) More CaCO 3 crystals were generated and filled in the micro spaces of the SCAB body, which contributed to an increase in compressive strength. This study developed an effective approach to remove CO 2 gas from the working face of the coal mine during backfilling. Adsorbed CO 2 improved the strength of the material, provided as a novel multi-function backfill mining for sustainable green coal mining technology.