Study on mechanism of pressure relief and selection of key equipment for protective layer of semi-coal rock working face

Exploration of protective seam is an effective method to solve gas outburst problems in coal seams which have high gas outburst and low permeabllity.H owever,conventional protective layer mining is difficult to implement in coal mines when a protective seam thicker than 0.8 m does not exist.The realization of pressure r elief and permeability increase in lower protected seam is also a problem.In this paper,a method of semi-coal rock protective laying mining in thin coal seam is propose d.The relationship between mining height of semicoal rock and pressure relief of lower coal seam was analyzed.Numerical simulation was conducted in Shaqu Coal Min e and the results show that the expansion deformation rate of the protected coal seam is linearly proportional to the thickness of protective coal seam.The semicoal roc k protective laying mining was carried out on No.22201 working face of Shaqu Coal Mine.It is found that the working face advanced602.6 m in total and 3.05 m daily on average and the total coal production was about 181 020 tons during the 7 months period implementing the method.The field practice suggests that equipment in workin g face and roadway is able to meet the production needs and the semicoal rock working face can be mined safely and efficiently.