Research On Pu-foam Film Preventive Technology Of Coal Spontaneous Combustion In Fully Mechanized Sublevel Caving Roadways

Because of the unique features of fully mechanized sublevel caving mining method, the coal seam in fully mechanized mining workface is more likely to be the victim of spontaneous combustion, which set a severe roadblock for the development of this mining technology. Research shows that roadways are the most frequently suffered areas. Through analysis of coal spontaneous combustion mechanism and influential factors, the conclusion that the control of air leakage and void ratio can be effective in preventing coal seam spontaneous combustion is drawn.The subject of this dissertation is the preventive technology, which aims to form an insulation layer with little thickness that made of PU-foam film on the coal wall through operation of spraying. It can effectively control air leakage and diminish the void ratio. In addition, the PU-foam film can penetrate the cracks and fill them in the coal wall with certain compressive strength and flexibility, which guarantee the insulation layer's integrity. All of the above make an excellent sealing work.At first, an research on spontaneous combustion principles of fully mechanized sublevel caving technology is made to point out that roadways are the most frequently suffered areas from spontaneous fires. Then, the model of spontaneous combustion is built based on analysis of coal spontaneous combustion mechanism and influential factors, which lead to the conclusion that controlling air leakage and void ratio is an effective way to prevent spontaneous fire disasters. Next, a detailed discusses is made about how to make the PU-foam film material in the lab. The process is experiment plan(uniform design)—plan execution—data processing(partial least-square regression analysis)—operation optimization—formula optimization—final formula. After successfully made the PU-foam film sealing material, the research group selected a specific site to apply this preventive technology in a certain mine site, both on ground and underground. Through fixing problems occurred during the spraying process, the construction techniques are improved, which is beneficial to promoting the coal spontaneous combustion preventive technology.