Effects of thin Covers on the Release of Coal Gangue Contaminants

The effects of the different ecological covers on the release of coal gangue contaminants were evaluated by the batch pot of experiments. The tests were carried for 12 weeks on the coal gangue by different approaches, which were the coverings with 1-2 cm artificial matrix that contained acid buffer and plant ameliorant(Tr1: thin matrix cover), 1-2 cm slurry of artificial matrix (Tr2: thin coating), and control groups(CK), and planted Lolium perenne, Chenopodium ambrosioides L, and sporopollen of Funaria hygrometrica Hedw on the surface layer, respectively. During the pot experiments, the leachates were collected and analyzed for pH, electrical conductivity (EC), and concentration of Fe, Mn, Cu, Zn, SO42-, F-. The results showed that the coal gangue was uninterruptedly oxidized to form acidic when it was exposed to open air, and 3 or 5 weeks later, dissolution of Fe, Mn, Cu, Zn and SO42-, F-in the coal gangue started and increased significantly, and this is a typical acid mine drainage (AMD) formation process. Compared to the CK, thin matrix cover could retard the allotted time of the production of acidity and release of contaminants, but was easily invalid to long-term. The pH of thin coating was at a high value with time, and the concentration of Fe, Mn, Cu, Zn, SO(4)(2-)and F-reduced significantly. The data indicated that the thin coating could effectively stop or retard the production of acidity and the release of contaminants generated by coal gangue. It suggests that thin coating covers on the coal gangue could be a suitable method for pollution abatement and controlling on-site. (C) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of International Materials Science Society