Research progress on fly ash foundation technology to prevent and control spontaneous combustion of coal in mines

Coal is the main energy source in China, which is also an important guarantee for the safety and stability of the national power supply as well as economic development. However, the coal combustion process for power generation will produce a large amount of fly ash, and the long-term piling of fly ash solid waste will seriously pollute the soil, water, atmosphere, and ecological environment, on the contrary, the fly ash can be used as a raw material for the prevention and control of coal spontaneous combustion disasters in mines. However, the current application of fly ash in the field of mine fire prevention was certainly limited, such as small amount of scattered utilization, low technical content, low added value, etc. The current scale of harmless pre-treatment and fire prevention and utilization of fly ash is still unable to meet the requirements of the national “carbon peaking and carbon neutrality” target for solid waste resource utilization and green mine construction. For further promote the efficient, high-value, and large-scale utilization of fly ash to realize the rapid development of fly ash-based fire prevention materials and technologies, this paper summarizes the principle, classification, latest development, and application effects of fly ash slurry, fly ash gel, fly ash foam and other fire prevention technologies. Based on the above analysis, this paper condenses three key problems that need to be solved, such as the separation of hazardous substances and valuable components in fly ash solid waste, the precipitation and plugging of pipes during long-distance transportation of highly concentrated fly ash slurry, and the law of seepage and accumulation of fly ash-based fire prevention materials in the goaf. In order to improve the effectiveness of fly ash solid waste in preventing spontaneous combustion of coal and to meet the national requirements for green mines as well as intelligent mine construction under the “carbon neutrality and emission peak” target, this paper proposes the development direction of “Long-lasting for fire prevention-Synergistic carbon sequestration – Intelligent control” for fly ash solid waste in the field of fire prevention technology. Future research will focus on the low-cost and long-lasting fire prevention fly ash solid waste-based materials, integrated fly ash fire prevention technology with mineralized CO₂ sequestration and fire prevention, and intelligent fly ash fire prevention material application systems, which will promote the high-value and large-scale reuse of fly ash waste in the field of fire prevention, finally improving the efficiency of preventing and controlling of spontaneous combustion disasters in coal mines, and ensuring the safe and efficient mining.