Evaluating the Feasibility of Coal Combustion Ash for Stabilizing Aluminum from Acid Mine Drainage (AMD).

Acid mine drainage (AMD) generally showed low pH causing environmental pollution such as yellow boy and aluminum whitening. The main objective of this study is to evaluate the feasibility of coal combustion ash (CCA) for neutralization of AMD occurred from mine dump. In laboratory test, Kyeong-dong mine wastes mixed with CCA at different ratio (10, 20, 30, 40, 50%, w/w). The mixtures were saturated with distilled water (16 h, water contents 35%), and the extracts were analyzed for pH and Al concentration. Field test was conducted in Kyeong-dong mine dump. In field plots (W: mine waste only, WC20M: mine waste + CCA 20% mixture, WC40M: mine waste + CCA40% mixture, WC40MD: mine waste + CCA 40% mixture + fresh soil layer), runoff and leachate were collected after rain for two years and analyzed for pH and Al concentration. Results showed that pH was increased (0%: 4.33 to 50%: 12.07) and Al concentration was decreased (0%: 25.9 mg L^-1 to 50%: 0.09 mg L^-1) with varied mixing ratio of CCA. In case of field test, pH of runoff in plot W was 5.42 while high pH was observed in plot WC40M at 7.37. Concentration of Al was decreased (W: 0.42 mg L^-1, WC40M: 0.13 mg L^-1) with CCA addition. Result of MINTEQ modeling showed that solid form of aluminum (Al(OH)₃, AlOHSO₄, Al₄(OH)₁₀SO₄, KAl₃(SO₄)₂(OH)₆, AlOHSO₄ and KAl₃(SO₄)₂(OH)₆) would be formulated in W plot. In conclusion, application of CCA to mine wastes can increase pH causing aluminum concentration decreasing with formation of solid aluminum precipitation.

Keywords: Acid mine drainage, Aluminum, Coal combustion ash, Whitening, MINTEQ,

Corresponding author: Jae E. Yang, Email:yangjay@kangwon.ac.kr, Tel:82-33-250-6446