Application of open-pit and underground mining technology for residual coal of end slopes

Given the conditions of residual coal from the boundary of a flat dipping open-pit mine, which uses strip areas mining and inner dumping with slope-covering, we propose an open-pit and underground integrated mining technology for residual coal of end slopes. In the proposal a conveyance road and ventilation conveyance near the slope are built, corresponding to the pit mining area and the surface coal mine dump, as well as an interval haulage tunnel and air-inlet tunnel. The outcome shows that such mining method may reduce the effect to slope stability from underground mining, it does not affect the dumping advance and has a high recovery rate of residual coal resources. The working face is timbered by single hydraulic props, transported by a scraper conveyor and supported by coal walls. This method of mining is one of layered top coal caving, with high resource recovery, low production cost where positive economic benefit can be realized.