The discharge of acidic water has become an environmental issue of great concern worldwide. In order to investigate the characteristics and mechanism of acidic water induced by pyrite in sulfur-rich mines, indoor static precipitation and dynamic leaching simulation experiments were carried out under the conditions of pyrite content, rock particle size, media combination, and ambient temperature. At the same time, this paper used the gray correlation method to quantitatively analyze the influencing factors. The results showed that the degree of groundwater acidification was negatively correlated with the rock particle size and temperature and positively correlated with the pyrite content. The quantitative analysis of the effect of each factor on acid mine drainage pH was pyrite content > temperature > rock size. When considering different media conditions, the combined effect of the three media on reducing the acidification degree of mine water was limestone > gangue > coal. In addition, dynamic leaching and static soaking have different effects on the acidification of the mine water, with the latter acidifying more rapidly. It is also concluded that although pyrite enrichment was the main controlling factor affecting the acidification of mine water in nature, complexation of trivalent iron ions adsorbed in the formation was more likely to be the main causal mechanism for the rapid acidification of mine water in coal mining areas.
The thermal storage temperature and water-rock interaction process of the Lushan convective geothermal system (Qinling stratigraphic zonation fracture zone in China) are clarified by using surface cold water and geothermal fluid as the research objects. In this study, a conceptual model of the temperature profile of the geothermal system in the study area was developed using surface temperature inversion, the cation temperature scale, the SiO2 temperature scale method, the mineral equilibrium phase method, the silicon-enthalpy model, the FixAl method, and the Cl-enthalpy model. The inversion temperature at the surface is in the range of 33-39°C, and the temperature difference indicates the direction of the Checun-Lushan fracture. The study area is recharged from atmospheric precipitation, and the temperature of the recharge area is approximately 5.8–7.7°C (the temperature of the alkali field is approximately 10°C), and the recharge elevation is approximately 1200 m. The thermal storage pattern in the study area is near-surface hydrothermal thermal storage transferred to shallow thermal storage and then to deep thermal storage. The near-surface hydrothermal thermal storage temperature is at a constant temperature of 60°C, and the shallow thermal storage temperature is calculated by K-Mg and Li-Mg geothermometers to be between 99 and 112°C. The thermal storage temperature is simulated using the FixAl method, with deviation values ranging from 2.9% to 15.0%. The silicon-enthalpy model calculates the deep thermal storage temperature to be between 181 and 230°C. The mixing ratio of geothermal water in the study area is extremely high, with a cold water mixing ratio of 85.4–94.8%. The home ground fluid temperature was estimated to be approximately 282°C using the Cl-enthalpy model. The main thermally controlled conductivity channel in the study area is the Checun-Lushan fracture zone. The water vapor formed by convection at depth moves upward to approximately 5 km to form a deep thermal reservoir, and this convection and upward movement cause it to mix with cold water from the fracture zone to form a shallow thermal reservoir, which moves to the near-surface, forming a hydrothermal-type reservoir, which is later discharged in the form of a spring. The conceptual model of geothermal system temperature established in this study provides a basis for further development and utilization of Lushan hot springs and provides guidance for future thermal storage temperature calculations of convection-type geothermal systems in uplifted mountains.
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