New model of negative carbon utilization in coal mine goafs and its feasibility and prospects for application

Over hundreds of years, the global coal mining has created 24.236 billion cubic meters of underground goaf, which not only wastes billions of square meters of land resources but also poses significant safety hazards and environmental risks. Combining the treatment of mined-out areas with carbon dioxide (CO2) storage can provide the new idea for solving the above problems in a low-carbon way. Therefore, based on an analysis of the status of mined-out areas and CO2 storage principles, this paper proposes a method of using high-water materials to solidify supercritical CO2 and fill mined-out areas. The feasible, safety and carbon fixing capacity of using high-water materials to solidify CO2 and fill mined-out areas has been proved by theoretical analysis and indoor experiment. Combining the estimated underground mined-out area space of major coal-producing countries globally, proving that solidifying and sealing CO2 in mined-out areas has significant application prospects. Finally, the issues and technical difficulties faced in promoting the use of high-water material to solidify supercritical CO2 and fill mined-out areas are pointed out. The research results have important significance for major coal-producing countries worldwide to achieve "carbon peak and carbon neutrality".