Research Of Coal Gangue Storage Impact On Surface And Shallow Groundwater Environment

The coal mining subsidence seeper with coal gangue natural storage in Panji Huainan was chosen as the research object. The mining area owns multi coal seams and thick cumulative mining thickness, thus leading to lot of subsidence with large area and amplitude. In additional, the quaternary loose layer is thick, the middle clay layer is of good impermeability and the shallow underground water is of high level. Through the atmospheric precipitation and surface runoff, it formed a different pattern of coal mining subsidence seeper area. At present, the use of coal gangue filling reclamation is an important technology in ecological restoration of mining area, but the coal gangue contains a variety of minerals and elements. The water body would be affected after long-term leaching, soak, diffusion and the forth. Furthermore, the human health, animal and plants growth would be compromised through biological enrichment and food chain. Thus, the research of coal gangue natural storage influence on the surface and shallow underground water environment has important practical significance for water comprehensive utilization and management and ecological restoration in mining area.Through data collection and field investigation, different types of coal gangue samples was collected, the basic elements characteristics in coal gangue were analyzed. The storage test field of crude block gangue,mixed gangue, washing gangue were established and artificial monitoring holes was drilled to collect different types coal gangue leaching liquid samples. According to the storage conditions, time and range, the subsidence seeper was divided into different areas and surface water samples of corresponding storage areas were collected. It analyzed water quality temporal and spatial range characteristics. The research results showed:(1) The content presentation of F, Pb2+, Mg2+in different types coal gangue is block gangue> mixed gangue> washing gangue. The difference of Cr6+content in coal gangue is smaller and the presentation is washing gangue> crude block gangue> mixed gangue. The Fe content presentation is mixed gangue> crude block gangue> washing gangue. The Mn2+is mixed gangue> crude block gangue> washing gangue. The Ca2+is washing gangue> mixed gangue> crude block gangue.(2) Coal gangue effect on water quality is mainly concentrated in the early storage stage. The mixed gangue impact degree on water quality is higher than washing gangue and crude block gangue. Couppled with the increase of storage time, the Pb2+, Cr6+, Fe, Mn2+content in the leachate has a significant reduction, and the pH、 F, Ca2+, Mg2+, SO42-is smaller on the whole.(3) The content presentation of Ca2+, Mg2+, SO42-in surface water and all the indicators in shallow underground water has a significant reduction and a slight increase and then tend to basic stable. The content presentation of pH, F, Pb2+, Cr6+, Fe, Mn2+has a slight increase and then tend to a basic stable trend.(4) The water in coal gangue natural storage area is basically presented weak alkaline. It increased the amount of alkali anion and reduce the water total hardness through flocculation, sedimentation and other physicochemical effects.(5) The main factors of coal gangue effect on water quality include coal gangue types and weathering degree, element content and occurrence state in coal gangue, storage time and range, temperature, atmospheric precipitation and evaporation, surface runoff, hydrodynamic circulation conditions and the forth.