Geochemical Genesis and Acid Production Potential Assessment of Acid Mine Drainage in Abandoned Mine Sites: An Integrated Study Based on Geochemical Static Tests and Mineralogical Analysis

The oxidation of sulfide minerals in the presence of oxygen and water, facilitated by microbes, is the principal cause of acid mine drainage (AMD). Static testing for the quantitative assessment of the acidic potential and acid-neutralizing capacity of mineral samples has been thoroughly investigated; the extent of its accuracy remains uncertain. This study involved 329 ore samples from 34 drill holes from abandoned mining sites and conducted laboratory static tests and mineralogical analysis. Static testing and mineralogical characterization identified a significant positive correlation between total sulfur and net acid generation (NAG), confirming that sulfide oxidation is the dominant mechanism for acid production. Furthermore, the strong positive correlation between calcium content and acid-neutralizing capacity (ANC) demonstrates that the buffering capacity stems mainly from carbonate dissolution, with negligible contribution from silicate weathering. The effectiveness of a detailed acid-generating potential discrimination chart was also assessed. Through the examination of acid drainage samples and groundwater from the research area, with their stable isotope and Deuterium excess (D-excess) properties, hydrochemical classifications were established, and sources of acid drainage were evaluated. This comprehensive method pinpoints the main “acid-generating sources” in the abandoned mining sites, elucidating the geochemical origins of acid drainage in the research area. It offers a case study and analytical framework for employing static test findings from abandoned mining sites to evaluate acid-generating potential in those areas.