Abstract: Guided by the “dual-carbon” goals, the green and low-carbon transformation of the coal industry is an inevitable trend, and the coordinated realization of efficient coal-based solid waste disposal and CO₂ emission reduction is a key breakthrough in this transformation. A coal-based solid waste CO₂ mineralization and slurry filling technology that serves both solid waste disposal and carbon sequestration is analyzed for its carbon reduction benefits. Three scenarios including goaf collapse and solid waste stockpiling, full gangue slurry filling and coal-based solid waste CO₂ mineralization and slurry filling are established. The carbon emission accounting boundaries and applicable conditions of the three scenarios are defined, carbon emission accounting and economic benefit evaluation models are constructed, and their carbon emission reduction effects are compared. A typical coal mine is taken as the experimental mine, and the advantages of CO₂ mineralization and slurry filling in carbon reduction and economic benefit improvement are clarified. The results show: ① For the goaf collapse and solid waste stockpiling scenario, the carbon emission boundary includes surface subsidence and stockpiled waste reducing carbon sinks, coal gangue transportation, coal gangue spontaneous combustion, and goaf gas emission. The economic costs comprise solid waste disposal costs, carbon trading costs, and costs for managing goaf geological disasters; For the full gangue slurry filling scenario, carbon emissions mainly originate from fuel and electricity consumption during gangue transportation and slurry filling, while economic benefits comprise carbon trading costs, full gangue slurry filling costs, and gangue resource utilization benefits; For the coal-based solid waste CO₂ mineralization and slurry filling scenario, the carbon accounting boundary covers CO₂ and coal-based solid waste transportation emissions, material input emissions, mineralization-alkali-reduction filling emissions, and the negative emissions from carbon mineralization, with economic benefits assessed from carbon trading revenue, coal-based solid waste resource utilization benefits, and mineralization-alkali-reduction filling costs. ② Comparative analysis of the three scenarios at a case coal mine shows that in the goaf collapse and stockpiling scenario, coal gangue spontaneous combustion contributes 58.8% of total carbon emissions; In the full gangue slurry filling scenario, the carbon emissions per ton are 0.015 63 t (in terms of CO₂ equivalent), with emissions mainly from electricity and fuel consumption; The carbon emissions per ton of fly ash CO₂ mineralization and slurry filling are −0.025 60 t. Compared to the goaf collapse and stockpiling scenario, the full gangue slurry filling scenario reduces carbon emissions by 95.8%, while the CO₂ mineralization and slurry filling scenario further reduces emissions by 263.8% relative to the full gangue slurry filling scenario, achieving a net negative carbon effect and demonstrating remarkable carbon reduction performance.