| Coal-free column-free forward mining has significant advantages in early preparation,resource input,and reduction of waste of lost coal,but the air leakage in the goaf area is serious,and it is more likely to cause mine fires caused by spontaneous combustion of abandoned coal.Based on this,it is of great significance to study the wind leakage law in the goaf area of the forward mining face without coal column,and then formulate the wind control technology to prevent the occurrence of mine fires according to the research results.The research work in this paper is based on the proposed mining face of N1217 in Ningtiaota Coal Mine and the forward mining method without coal column,and the research is carried out by combining theoretical analysis,numerical simulation and laboratory experiments.By analyzing the characteristics of 2GN00 construction method and geological environment,the danger of "one link and three prevention" of the proposed mining face was studied.It is concluded that the use of coal-free column forward mining,"wind control and fire prevention" is the focus of the one-way and three-prevention work.Using Fluent software to simulate the wind flow field in the segmented goaf area,it is obtained that the pressure distribution in the goaf shows a U-shaped symmetrical trend,the inlet pressure is the largest,the outlet of the return trough is the smallest,and the roadway is gradually reduced along the wind flow direction,the goaf decreases along the strike direction and increases along the tendency,and the oxygen in the goaf is mainly distributed near the inlet and return trough and the working face.The air leakage channel is distributed throughout the air intake alley and the working face,and in the goaf area near the working face,the air flow flows from the top of the goaf to the return channel.At about 50 m near the working face of the intake trough,the wind flow is diverted,resulting in a swirl.There is also wind flow into the goaf area within about 20 m of the front section of the work,and the air leakage volume of this section is large,which can reach more than 70% of the total air leakage volume,which is the main air leakage channel.In the process of advancing the forward mining work without coal column,the air leakage rate in the goaf will reach 52.03% or even higher.After considering the air leakage,the air supply capacity of the pre-mining,midmining and late mining periods of the working face was about 538.46 m3/min,1675.28m3/min and 1959.56 m3/min,respectively.An integrated wind control system of "air supply-plugging-monitoring" for the forward mining face without coal column has been formulated.Staged plugging measures are adopted,and the air flow quality of the working face and the temperature of the goaf are monitored at the same time,and then the obtained data is transmitted to the intelligent control platform of the mine ventilation network for real-time regulation.Figure48 Table15 Referenc75... |
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