The geochemical Variation of Mine Water and the Efficiency of the Passive Treatment System in the Hanchang Coal Mine, Korea

초록

Samplings of waters from each stage of passive treatment system, seepage from the waste rock dump, and spring near the Hanchang coal mine of Kangwon Province were carried out seasonally and analyzed to evaluate the geochemical variation of mine water and the efficiency of the passive treatment system. Sulfur isotope compositions were measured to identify the sulfate reduction processes in the SAPS (Successive Alkalinity Producing System). The mine drainages from the Hanchang mine adit showed pH higher than 6.5 but increased iron and sulfate concentration. Spring waters near the mine were acidic (pH 3.29 ~ 4.57) and showed high concentration of aluminum and sulfate. The sulfate isotope composition of spring water was similar with that of the waste rock dump seepage. Low pH and high metal concentration of spring water indicated the possibility of the groundwater contamination by seepage from the waste rock dump. The acidity removal efficiency of the SAPS was 16.65g/m2/day as an average and the iron removal efficiency was 12.08g/m2/day as an average. However, no appreciable decrease of sulfate concentration and almost similar sulfur isotope compositions of water from each stage of the treatment system might suggest incomplete or very poor sulfate reduction by sulfate reducing bacteria. Also the removal efficiency of acidity in the SAPS and the aerobic wetland decreased during the winter.