Research on the active sealing and promoting extraction technology of high-gas mine working face return air corner...

To address the issue of excessive gas concentration in the return corner under "U"-shaped ventilation in high-gas mine working faces, the 317 working face of Wangjialing Mine was selected as the research object, and a combination of theoretical analysis, numerical simulation, and engineering experiments was employed to analyze the causes of gas accumulation, construct a 3D model to simulate gas distribution and flow in the goaf, and develop a novel active sealing-extraction-enhancement device, which was then tested in the field. The research results indicate that: (1) Air leakage in the goaf, sudden stress release due to delayed collapse of hard and relatively hard roof strata, and operations such as coal release and shield advancement during mining are the leading causes of rapid and large-scale gas emissions from the goaf, which can lead to a sharp increase in gas concentration in the return corner. (2) Simulation revealed the gas migration patterns, identifying a gas-rich zone near the return side where the concentration approached 1.5%, showing that the gas concentration in the return corner of the 317 working face in Wangjialing Mine is relatively high. (3) Field tests confirmed that under normal conditions, goaf gas extraction via buried pipelines effectively maintains the return corner gas concentration below 0.8%. However, during abnormal emissions, this conventional method responds too slowly. When the T₀ sensor in the corner detects an abnormal increase in methane concentration, the active sealing, extraction, and enhancement device is activated. The device rapidly blocks the gas emission pathway using a compressible airbag while simultaneously increasing the negative extraction pressure, reducing the methane concentration in the return corner from 0.88% to 0.19% within 3.5 s. Even under abnormal gas emission conditions, the device can quickly reduce gas concentration, effectively eliminating gas concentration exceedance phenomena and ensuring safe and efficient production at the working face.