Hydrogeochemical evolution of Taiyuan Formation limestone water under the disturbance of water inrush from karst collapse column in Taoyuan Coal Mine, China

Abstract

The project implementation of water inrush and its treatment ensures the safe mining of coal mines, but also causes certain disturbance to the hydrogeochemistry of primary limestone water. Based on the water inrush event in Taoyuan Coal Mine of Huaibei coalfield in 2013, the water rock interaction mechanism of Taiyuan Formation limestone water (namely, ‘Taihui water’) was discussed. The results showed that: (1) the relationship of cation mass concentration before and after water inrush was Na+ + K+ > Ca2+ > Mg2+; the correlation of anionic mass concentration before water inrush was SO42− > HCO3− > Cl−, while it was HCO3− > SO42− > Cl− after the event. Before the event, the main water quality types were SO4•Cl-Ca and SO4•Cl-Na; after the event, they mainly included HCO3-Na and SO4•Cl-Na; (2) There is a strong positive correlation between mineral saturation index and pH value, that is, minerals are easy to dissolve under acidic conditions, while alkaline conditions will inhibit the dissolution and transformation of minerals; (3) The hydrogeochemical processes of limestone aquifer mainly included cation exchange, carbonate dissolution, pyrite oxidation, sulfate and silicate dissolution. HIGHLIGHTS The hydrogeochemical characteristics of Taiyuan Formation limestone water disturbed by water inrush of collapse column was analyzed.; Based on saturation index, ion combination ratio and correlation analysis method, the evolution of hydrogeochemistry under the influence of water inrush was discussed.; The relationship between saturation index and TDS and pH value was studied.;

Keywords

• huaibei coalfield
• hydrochemical evolution
• hydrogeochemistry
• karst water
• water inrush event