Water-Rock Interaction In Coal-bearing Strata And Environmental Effect Of Coal Mine Water

The heavy-metal contamination of coal mine water was investigated, and the pollution source, the leaching behavior and mechanism of heavy metal elements were studied using the Xuzhou-Datun coal mine district. Site investigation, data collection, sampling and testing, physical modeling experiments and numerical modeling were applied from the Mineralogy, Petrology, Geochemistry, Interface Chemistry, Environmental Chemistry points of view. Following the flow path of ground water in the study area, which are surface water- carbonate water- coal mine water- surface water, the geochemistry environment, water-rock/water-coal interaction process of the limestone strata and the coal-bearing strata, leaching behavior and controlling mechanism of trace elements in the limestone strata, roof/floor of the coal, coal seam were discussed. As the result of the physical and computer modeling, the leaching behavior model of Hg/As/Se/Cr and some other metal elements were set up. The impact mechanisms of pH/Eh/temperature/ion strength on trace elements leaching were discussed. It is concluded that: the Hg, As, Se concentration were high in the coal mine water so contaminated the coal mine water and concentration of Pb, Cd, Cu, Zn etc were low; the heavy metal elements were mainly came from the coal-bearing strata, the host rock was the main source of Se, As, Cr, the Hg leaching mainly related to the coal seam; adsorption was the most important mechanism that control trace elements leaching behavior, and the oxidation-dissolution could be the controlling mechanism if the adsorption was weak; the pH, Eh, ion strength of solution and ion-exchange, complexation and humic substance adsorption impact or control the leaching process.