Study on the influence of positive pressure ventilation on air leakage in shallow coal seam and comprehensive treatment technology of air leakage

Shallow and close-distance buried coal seam group is greatly affected by mining, and the phenomenon of multiple dimensions of air leakage and interconnection of channels is common in the coal mining face. Under the action of positive or negative pressure ventilation, a larger air leakage pressure difference is easily formed at both ends of the air leakage channel, resulting in an increasing air leakage volume in working face, the extension of the "three zones" in goaf, and the increasing risk of spontaneous combustion. This paper took Jitujing 12 coal in Daliuta Coal mine, a typical positive pressure ventilation mine, as the research object. It was concluded that the influencing factors of air leakage in shallow coal seam were as follows: air leakage channel formed by mining fissure, air leakage pressure difference formed by positive pressure ventilation, the ventilation mode and the natural wind pressure effect. The air leakage status and mode of the 12203 fully mechanized caving face under mining were investigated. It was concluded that the air leakage of the working face was mainly manifested as: surface collapse crack air leakage, face cutting, lanes and goaf air leakage in working face. Based on this, a comprehensive, multi-coverage and three-dimensional air leakage control technology was proposed. This technology was based on optimization of ventilation system, supported by grouting and spraying technologies in coal and rock fissure of roadway, coal pillar leakage risk control technology, and goaf end leakage risk control technology of working face, strengthened by local positive pressure leakage risk control technology, hydraulic flushing seam plugging technology and filling hole plugging technology, and based on the concept of foundation optimization, middle support and end treatment. The actual application was conducted in the 12203 caving face, and the air leakage volume reduced from 55-70 m3/min to 6-20 m3/min at the initial mining period, with a comprehensive reduction of 80.3%, which proved that this technology can effectively control air leakage, and provide technical reference for air leakage control in similar mine. © 2023 Coal Science and Technology. All rights reserved.