Downhole Treatment and Reuse Project of Goaf Water Gushing in the First Mining Area of China Coal Pingshuo Underground No.3 Mine

In view of the difficult technical problems of high ground treatment costs, difficult safety hidden danger treatment and high environmental protection risks of water gushing in the goaf with intermediate mineralization degree (high salt content, high hardness) in the first mining area of China Coal Pingshuo underground No. 3 mine, this research proposes a ceramic membrane ultrafiltration process (with a pore size of 100-200 nm), constructs an intensive modular water treatment system (with a design scale of 2000 m³/d) in downhole idle roadways. This scheme is priority selected after technical and economic comparison with the traditional "flocculation + sedimentation + filtration" process. The operating data indicates that the effluent suspended solids (SS) is ≤ 0.3 mg/L, the turbidity is ≤ 0.15 NTU, the system recovery rate is stable at 95%, and the annual treated reused water is 627 000 m³ (calculated based on 1900 m³/d and 330 d of annual operation). The comprehensive benefits is significant: in the aspect of economy, the annual net income is 6.082 5 million yuan, the investment payback period is about 1.42 years; In the aspect of environment, the annual reduction of SS emissions is 20.58 t; The project achieves dual guarantees of on-site efficient reuse of water resources and safe production in downhole limited spaces, forms a complete solution of "technology type selection - modular design - benefit evaluation", providing a technical template for the integrated development of green development and safe production in coal mines.