CO₂ sequestration potential of typical solid wastes from coal mining bases and their application pathways

Against the backdrop of the “dual carbon” goals, the mineralization and sequestration of CO₂ from solid waste is a key approach to simultaneously advancing the resource utilization of solid waste and CO₂ sequestration. However, there has been a lack of systematic assessment of the mineralization and sequestration potential of multi-source solid waste from coal production bases and the regional variations therein. To address the needs for resource utilization and carbon sequestration of typical solid waste in coal-producing regions, a method for assessing the potential of solid waste mineralization and CO₂ sequestration was developed. The theoretical upper limits for carbon sequestration capacity of different types of solid waste were estimated, and regional sequestration potential was quantified. Through analysis of mineral composition and chemical characteristics, the mineral composition basis of typical solid waste and differences in their reactivity were revealed. The results indicate that solid waste derived from raw coal exhibits relatively low mineralization reactivity and requires activation pretreatment to enhance mineralization efficiency. In contrast, solid waste derived from modified coal and certain metallurgical solid wastes possess high mineralization potential and can serve as highly efficient substrates for mineralization reactions. Building on this, the theoretical carbon sequestration capacity of various solid wastes was calculated based on their mineral composition and stoichiometric relationships; a model for assessing mineralization sequestration potential was established; and CO₂ sequestration potential was estimated in conjunction with regional solid waste generation volumes. We further analyzed the effects of feedstock composition, reaction conditions, environmental factors, and equipment performance on mineralization efficiency; proposed the technical approach of “sequestering carbon with waste, treating waste with carbon, and backfill waste with air”; identified technical directions for multi-pathway synergy; and analyzed the main challenges facing large-scale application in terms of feedstock suitability, high-efficiency mineralization reactors, and policy standards. Through systematic elucidation of solid waste mineralogy and quantitative assessment of mineralization sequestration potential, this study provides a scientifically grounded evaluation methodology, with the aim of offering theoretical support and technical reference for promoting large-scale solid waste utilization and efficient CO₂ sequestration in coal mining bases.