Parameter Optimization and Application of Gas Extraction Technology by Buried Pipes in Goaf of Multi-roadway U-type Working Face.

The gas extraction method by buried pipes in closed connection roadways of goaf was proposed. It was intended to solve large gas emission quantity and over-limit gas concentration at the upper corner in the goaf of highly gassy mine. The study object was 81307 fully mechanized mining face in Baode Coal Mine. The gas distribution characteristics in the goaf during no extraction and those during gas extraction by buried pipes under different extraction parameters were numerically simulated via COMSOL Multiphysics, and the best layout parameters of buried pipes in the goaf were determined. A field optimization experiment was carried out for the extraction parameters. Results showed that the extraction measure by buried pipes could effectively solve the aforementioned over-limit gas concentration at the upper corner when the layout spacing of closed connection roadways was 100 m, extraction pressure was −32 kPa, diameter of extraction pipe was 800 mm, and extraction flow was 600 m³/min. During the experiment, the average gas concentration at the upper corner was 0.38% and that in the return airway was 0.29%. Both of which were lower than the national safety standard, thus reaching the goal of safety production. [ABSTRACT FROM AUTHOR]