Site Type Classification and Ecological Restoration Technology Selection of Open-Pit Coal Mine Dumps in Grassland Mining Area

In order to study the counterpoint configuration about the types of mining sites and ecological restoration technologies, open-pit coal mine dumps that had been ecologically restored, since many years, in the grassland mining area in western Inner Mongolia, were selected. A comprehensive evaluation of slope protection effect, vegetation restoration effect, soil improvement effect and engineering technology cost was carried out in order to classify the types of sites for open-pit coal mine dumps and to determine their counterpoint ecological restoration technology, so as to provide theoretical guidance and technical support for ecological restoration of the grassland mining area in western Inner Mongolia. The research results are as follows: (1) Soil thickness, slope gradient and slope aspect are the dominant factors affecting the site conditions of the dump site. Base on this, the dump site of the open-pit coal mine in the grassland mining area of western Inner Mongolia was divided into 9 types of sites. (2) For half-shade and half-sunny to thick soil gentle slope, we primarily recommend plant grid slope protection + planting + sowing + sprinkler irrigation, and the second recommendation is hexagonal brick slope protection + mortar masonry ditch + sowing + sprinkler irrigation; for half-shade and half-sunny to medium-thick soil gentle slope, we primarily recommend masonry skeleton slope protection + mortar masonry ditch + sowing + sprinkler irrigation, and the second recommendation is sowing + vegetation blanket coverage + sprinkler irrigation; for half-shade and half-sunny to thin soil gentle slope, it is recommended to use gravel capping + mortar masonry ditch. For sunny thick soil gentle slope, we primarily recommend eco bag blocking + planting + sowing + vegetation blanket coverage + sprinkler irrigation, and the second recommendation is eco bag blocking + sowing + grass curtain coverage grass curtain coverage + sprinkler irrigation; for sunny thick soil steep slope, it is recommended to use plant grid slope protection + mortar masonry retaining wall + sowing + sprinkler irrigation. For shade thick soil gentle slope, we primarily recommend eco bag blocking + planting + sowing + vegetation blanket coverage + sprinkler irrigation is preferred, and the second recommendation is planting bag stacking + mortar masonry retaining wall + sprinkler irrigation; for shade medium-thick soil gentle slope, it is recommended to use eco bag blocking + corrugated pipe drainage + sowing + vegetation blanket coverage + sprinkler irrigation; for the shade medium-thick soil steep slope, we primarily recommend eco bag blocking +sowing + grass curtain coverage + sprinkler irrigation, and the second recommendation is eco bag blocking + corrugated pipe drainage + sowing + vegetation blanket coverage + sprinkler irrigation. For thick soil platform, use of planting + sowing + sprinkler irrigation is recommended. The research results provide a scientific basis for selection of ecological restoration technologies in the grassland coal mining area in western Inner Mongolia. At the same time, with respect to the semi-arid grassland mining area with relatively fragile habitats, this research be of great significance to improve the greening benefits of the mining area and for improving the mining area and surrounding ecological environment.