Strong Gas Extraction From Working Face Goaf Fire Prevention Technology Research

At present coal mining has presented the trend of deep mining, in other word mining depth is more and more deep. As the production increased, more and more problems have appeared. Gas emission increasing and natural disasters have been the main problems which threaten the safety of coal mining. So fire prevention is more and more important for extraction of gas.Extraction of gas from coal seam of spontaneous combustion will change the flow pattern which would lead to coal spontaneous combustion more easily.Extraction of gas has different effect on goaf flow. Different gas extraction method depending on different location of the drainage hole has a different effect on the flow of goaf gas, making the leakage state change greatly. The description of the phenomenon of goaf air leakage under different extraction methods laid a theoretical foundation for disaster prevention.Porosity and permeability are important factors of coal spontaneous combustion and gas migration. In the process of coal mining caving coal and rock in mining space are accumulated and formed the mined-out area. Its internal hulking degrees and the caving height, size and shape of the rock and so on have extremely close relationship. As the working face advanced, the deep part of the mined-out area was compacted and rock caving height gradually decreased, which make the porosity and permeability in mined-out area also became smaller. Through the research of coal and rock stress and strain and the Klinkenberg, it is concluded that it has influence to porosity and permeability.According to the actual project, adopting FLUNET software to simulate the high and low drilling drainage, ground well, buried pipe in upper corner under different extraction methods showed the rule of "three zones" distribution and gas migration.The suggestions of better gas extraction method and fire prevention mechanism have been provided.The simulation of Zhu Ji 1242(1) working face proved the numerical simulation feasible. Through the applying the technology of high ground drilling and alley pumping buried pipes, the gas extraction obtain more efficient production and good fireproof effect. The average daily output of 5733 ton has been achieved.