LEACHABILITY OF HEAVY METALS (Fe, Zn and Ni) FROM COAL MINE ROCKS

The majority of heat and energy delivered to Polish houses derive from coal combustion. The exploitation of underground resources is connected with excavation of huge quantities of metal-rich waste rocks. These metals may be released to the environment and contribute to the pollution of water and soil systems which is dangerous for biota and human health. The mobility and bioavailability of metals depend on their chemical form. In present work, we determined geochemical speciation of Fe, Ni and Zn in samples of waste rocks from five coal mines from both USCB and LCB. The most abundant metal in easily-extractable phases (water-soluble, exchangeable, acid-soluble) was Zn (MF(Zn) = 24.4 divided by 53.4) followed by Ni (MF(Ni) = 5.1 divided by 19.2) and Fe (MF(Fe) = 0.2 divided by 3.6). The mobility of Fe was similar in rocks originating from both coal basins (K-W, p = 0.2253), Ni was higher in LCB whereas Zn in USCB rocks (K-W, p < 0.05). It was also found that during first years of storage and exposure to natural weathering, only a small portion of metals was released to the environment as the total concentrations and fractionation of Fe, Ni and Zn were similar in fresh and weathered coal waste rocks from Wesola and Murcki coal mines, up to 3 and 15 years of weathering, respectively.