Hydrochemical Characteristics and Reverse Hydrogeochemical Modeling of Taiyuan Formation Limestone Groundwater of Sunan Mining Area in Huaibei Coalfield

Abstract

Taiyuan Formation limestone groundwater is the main aquifer threatening the safety of exploration under deep mining in the Huaibei coalfield. Therefore, acknowledging the hydrochemical characteristics and constructing reverse hydrogeochemical modeling are crucial for predicting and preventing mine water hazards. In this study, the mathematical statistical analysis, Piper threeline diagram, Gibbs diagram, ion proportional relationship, Chlorine-Alkali index, and the reverse hydrogeochemical modeling were employed for determining the hydrochemical characteristics and the formation mechanism. The results revealed that the hydrochemical types of groundwater samples were SO 4 .Cl-Ca.Mg and HCO 3 .Cl-Na, respectively. The water-rock interactions were primarily influenced by the leaching and the cation exchange, with these processes being more intense in the eastern region. Through reverse hydrogeochemical modeling, the water-rock interactions in the process of groundwater runoff were quantitatively verified, viz. the calcite and the dolomite were saturated and precipitating, while the gypsum and the halite were unsaturated and still dissolving. Furthermore, the simulations of mass transfer in groundwater runoff indicated that the dissolution and the leaching of gypsum, dolomite and halite, positive ion exchange, the precipitation of calcite, and the dissolution of CO 2 gas predominantly occurred along four simulated flow paths. These results offered a scientific foundation for the prevention and controlling of mine water hazards in deep mining contexts.