Coal mining technology without village relocation by isolated grout injection into overburden

In order to improve the coal mining efficiency with backilling and reduce the backilling cost, the technology of isolated grout injection into overburden w as proposed based on the characteristics of layered strata movement and its control demands. Based on the structure of overburden key stratum, the rational width of W ork face was designed, and isolated coal pillars with some width were left between adjacent work faces. The grout was injected into the mining- induced overburden wit h high pressure through surface boreholes, which could form a compact area at the center of work face, conjunction with the isolated coal pillars to maintain the stabiliz ation of the key strata, thus surface subsidence value was reduced and the coal resources under villages were extracted without village relocation. The technology of is olated grout injection into overburden had been applied in 12 mining blocks of the eight coal mines at Huaibei Mining Area, China, where more than 7. 8 millin tons of coal was extracted.