Study on the sequestration capacity of fly ash on CO2 and employing the product to prevent spontaneous combustion of coal

• Published in: Fuel (Guildford) 2023-02, Vol.334, p.126378, Article 126378
• Main Authors: Shao, Xu, Qin, Botao, Shi, Quanlin, Yang, Yixuan, Ma, Zujie, Xu, Yizhen, Hao, Mingyue, Jiang, Zhe, Jiang, Wenjie
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Fly ash slurry; Mineralization sequestration; Spontaneous combustion of coal
• ISSN: 0016-2361
• DOI: 10.1016/j.fuel.2022.126378

•Employing carbonated fly ash slurry to prevent the spontaneous combustion of coal.•The carbonated fly ash slurry inhibits the oxidation reactivity of coal.•The carbonated slurry lowers the specific surface area and pore volume of coal.•The amount and rate of CO2 sequestration are gained by novel calculation methods. An innovative approach of utilizing fly ash waste to sequester CO2 and employ the carbonated slurry to prevent spontaneous combustion of coal (SCC) in mining areas is proposed. This paper examines the CO2 sequestration capacity of fly ash based on novel calculation methods, and the functions of carbonated fly ash (CFA) slurry on the microstructure of coal and the inhibitory properties of SCC is investigated. Kinetic experiments demonstrate that the quantity of CO2 sequestration and the initial rate of CO2 sequestration increment generally with the initial CO2 pressure and the water-to-solid ratio. CO2 sequestration of the fly ash (Class F) amounts to 54.9 g/kg and the initial rate of CO2 sequestration gained 0.035 mol/kg/s at an initial CO2 pressure of 20 bar and a water-to-solid ratio of 6. The specific surface area and pore volume of the coal treated by the filtrate of CFA slurry were diminished. When the water-to-solid ratio of the slurry is 6 and the slurry-to-coal ratio reaches 3: 1, the crossing point temperature increments by 13.8 ℃ compared with the origin coal. The risk of SCC greatly diminishes based on the evaluating index I of the propensity of SCC, and CFA slurry demonstrates a great suppression function on SCC. The approach proposed in this paper effectively actualizes the combination of CO2 sequestration, utilization of solid waste, and prevention of SCC.