Key technologies and approaches for water resource conservation and utilization in arid to semi-arid open-pit coal mining areas in the northern sand prevention belt of China

BackgroundThe northern sand prevention belt (NSPB) of China is primarily distributed in arid and semi-arid regions such as Xinjiang, Inner Mongolia, Ningxia, and Gansu. This belt exhibits scarce rainfall and intense evaporation, which lead to a shortage of water resources and vulnerable ecosystems. In recent years, the large-scale development of open-pit coal mines has caused increasingly violent mining disturbance in this belt, as well as increasingly prominent issues such as a decline in regional groundwater levels and ecological contradictions. To address technical challenges in balancing coal exploitation and water resource conservation in this belt, there is an urgent need to develop a technology system for water resource conservation in open-pit coal mining areas. Methods and Results This study investigated the distribution of open-pit coal mines in the NSPB and revealed the regional hydrogeological characteristics such as rainfall, evaporation, water-bearing media, water inflow, and water quality in three typical regions of the NSPB: eastern Inner Mongolia, western Inner Mongolia, and northern Xinjiang. It developed key technologies for the conservation of multiple water sources, including surface water, groundwater, atmospheric condensate water, and mine water in open-pit coal mining areas. These key technologies include (1) a multi-level mine water storage model that integrates surface reservoirs, reinjection into the Quaternary aquifer, and subsurface reservoirs; (2) the interception and storage of surface water; (3) the efficient capture and utilization of atmospheric condensate water; (4) groundwater source control dominated by curtain grouting, and (5) the artificial reconstruction of ecological aquifers in open-pit mining areas. As a result, a technology for three-dimensional water resource conservation in open-pit mining areas is formed. Additionally, this study explored technologies for the treatment of substantial suspended solids in mine water, low-cost and large-scale mine water treatment, and novel ecological precision irrigation in open-pit mining areas. ConclusionsBy establishing a three-dimensional, low-cost, efficient, large-scale, and replicable model for the conservation, treatment, and utilization of water resources for open-pit coal mines in the NSPB and developing a proactive and systematic technical integration system for the conservation, storage, and utilization of surface and subsurface water resources, this study contributes greatly to address the ecological restoration challenges in mining areas characterized by drought and scarce rainfall in the NSPB. The results of this study hold great significance for ensuring water supply for ecological conservation and restoration in the NSPB and for serving national strategies such as energy security and ecological civilization construction.