Study on chemical characteristics and resource utilization of mine water: taking Zhangji Coal Mine as an example

Because of mining activities, a large amount of mine water was pumped to the surface, caused serious waste of water resources and environmental pollution. This paper took samples of mine water from different sources in Zhangji Coal Mine of Huainan coalfield, and selected 7 ion contents of Ca²⁺, Mg²⁺, Na⁺+K⁺, Cl⁻, SO₄ ²⁻, CO₃ ²⁻, HCO₃ ⁻, added pH, TDS, EC, TH to 11 chemical indexes as the basis of water quality detection. Then, the hydrochemical characteristics of mine water had been studied such as ion composition, dynamic change, correlation, afterwards, the water quality evaluation would been carried out. Finally, according to the relationship between sodium adsorption ratio (SAR) and EC, the risk levels of salinization and sodium toxicity of mine water in Zhangji Coal Mine were divided, and the ways of resource utilization of mine water in study area were determined. It is concluded that the TDS content of well water in Zhangji Coal Mine was 255.47-7 291.74 mg/L, with an average of 2 346.60 mg/L, which was seriously over standard. The highest contribution of TDS ion composition was Na⁺ and K⁺; The results of water quality classification showed that the proportion of mine well water of class V in the study area was as high as 81%; The relationship between sodium adsorption ratio (SAR) and EC showed that 79.3% of the water samples were distributed in S3-E4 AND S4-E4 areas. The mine water in Zhangji Coal Mine had high risk of salinization and sodium toxicity and was not suitable for agricultural use. The mine water area could only be used as general industrial water area, indirect contact entertainment water area or general landscape water area.