INTERAKCJA ODPADÓW POWĘGLOWYCH I ODPADÓW ELEKTROWNIANYCH ORAZ JEJ WPŁYW NA CHEMIZM ROZTWORÓW POROWYCH W SKŁADOWISKU

Abstract

INTERACTION OF COAL MINING WASTES AND POWERPLANT COAL ASH AND ITS EFFECT ON THE PORE SOLUTION CHEMISTRY IN A DISPOSAL SITEAbstract. This study was aimed at elucidating the mode of interaction of coal mining waste and coal ash, exemplified in the Przezchlebie fly ash impoundment, where 12 years after closure, acidification of dewatered material and pore solutions occurred, along with development of the phase III of weathering defined as time-delayed extensive release of macro-components and trace elements. 15 years after closure, the impoundment was covered with a layer of coal mining waste, 1–3mthick. Sampling along vertical profiles was performed 13 years later. The study was focused on analysis (with use of ICP-MS) of pore solutions extracted from the samples and hydrogeochemical simulation of the obtained data with use of the USGS/PHREEQC Interactive v. 2.15.0 computer program. It was found that the cover of coal ash at the stage III of weathering transformations with freshly generated sulfidic mining waste and infiltration of water from the upper layer of coal mining wastes resulted in the renewed alkalization of coal ash and recurrence of a state of equilibrium processes to the phase II (dissolution), and even to the phase I (wash-out). Presumably, the effects of a marked acidification of the coal mining waste layer will be shown in the coal ash much later, but the process intensity due to occurrence of an external source of acidification (acid rock drainage- ARD) might be considerably stronger than that observed in the natural system.