Technology and application of damage reduction mining and ecosystem restoration of open-pit coal mines in eastern grassland area

The eastern grassland region is an important coal energy base in China, and coal development has made great contributions to the energy security supply of the northeast region and the economic development of China. In response to the problems of cold and arid climate, thin soil and low vegetation disturbance resistance in the eastern grassland area, and the large-scale development of coal has led to the degradation of the local grassland and the decline of water level, we have carried out research on the loss reduction mining and ecosystem restoration in the eastern grassland area, put forward the ecological restoration concept of loss reduction at the source - process control - end treatment in the open pit coal mine, and developed the technologies of loss reduction by mining, material deployment and storage across time and space, and “ecological window” collaborative restoration. The research has developed the technologies of mining loss reduction, inter-temporal material deployment and storage, and “ecological window” collaborative restoration, and has been applied and demonstrated in the shengli open pit mine and baorixile open pit mine. The results show that: the slope angle of the original drainage work gang of the shengli open pit mine has been increased by 2.9° and the ecological restoration can be carried out 0.9 years earlier, and the area covered by the quarry has been reduced by 75.2 hm²; only in the south gang of the baorixile open pit mine, the implementation of the freeze-period mining-rapid backfill technology has recovered 695 500 tons more coal resources, accounting for 2% of the annual production capacity, and 2.4 hm²/a less land acquisition while meeting the production capacity of the open pit mine. The results of the study provide an opportunity for similar open-pit mines to reduce the amount of coal resources. The research results provide technical support for similar open pit mines to carry out damage reduction mining and ecological restoration work, and have wide application and promotion value.