Research progress of coal spontaneous combustion process characteristics and prevention technology

Coal is the main source of energy in China, but coal mining faces a serious threat from spontaneous combustion disasters. Spontaneous combustion of coal not only burns a large amount of coal resources, but also easily causes serious accidents such as gas burning and explosion, causing huge economic losses and heavy casualties. In order to further improve the ability of coal mine enterprises to prevent and control spontaneous combustion disasters of coal and promote the safe and efficient mining of coal resources in China, the research status of coal spontaneous combustion theory was analyzed, and the main methods and technologies of coal spontaneous combustion monitoring and early warning were summarized, while the conventional fire prevention technologies of coal mines were compared and analyzed. Moreover,the latest development of fire prevention technology used for spontaneous combustion of coal was introduced and the application effects were exhibited. In addition, the future development and research direction in the spontaneous combustion characteristics of coal and prevention technology were also proposed. This paper described the theoretical basis of spontaneous combustion characteristics of coal in detail, mainly including the low-temperature oxidation process mechanism of coal spontaneous combustion, the segmented process characteristics of spontaneous combustion of coal, and the spontaneous combustion characteristics of coal under special conditions. At the same time, the principles of monitoring and early warning technologies including the marker gas method, temperature measurement method, and tracer gas method used for spontaneous combustion of coal were summarized, and their advantages and disadvantages of various technologies were also compared. Based on the above spontaneous combustion theory, monitoring and early warning, in view of the limited effects of conventional grouting and inert gas injection on prevention and control of coal spontaneous combustionand difficulty in meeting the problems of safe and efficient mining in mines, three-phase hindered foam technology and gel foam covering oxygen insulation technology, inorganic solidified foam plugging and wind control technology, thickened mortar and other anti-extinguishing technologieswere developed. At the same time, it was proposed to use the liquid nitrogen (liquid carbon dioxide) to quickly extinguish and cool the high temperature fire area of coal spontaneous combustion. In addition, in order to meet the new requirements of mine fire prevention and control for intelligent and precise mining of coal mines, it was proposed in the aspects of mine fire monitoring index information and early warning intelligence, fire source identification and prevention technology control precision, and green fire prevention materials greening