Mineralogical, Chemical, and Leaching Characteristics of Coal Combustion Bottom Ash from a Power Plant Located in Northern Poland

摘要

The present research is focused on chemical and mineralogical characterization of bottom ashes produced during coal combustion in a power plant operating in northern Poland. On the basis of these results we estimate a potential environmental hazard and try to find a possible application for studied materials. Bulk chemical composition of all studied bottom ash samples is homogenous and SiO_7 and Al_2O_3 are the major components of samples and together with Fe_2O_3 represent more than 70 wt. %. All ashes were thus classified as type F ashes. CaO and SO_3 concentrations are relatively low and reach up to 3.1 and 0.32 wt. %, respectively. The total concentrations of trace elements in the studied bottom ash samples are generally lower than those reported for the coal from different countries. The highest concentration of trace elements was noted for Co and Pb (up to 84 and 76 mg·kg~(-1), respectively), and the lowest for Hg and Se (up to 0.2 and 2 mg·kg~(-1)). Studied samples of bottom ash are mostly composed of mullite and quartz with some minor amounts of hematite and traces of calcite. Two types of leaching experiments (using distilled water and 0.05 mol/L of EDTA solution) show that the mobility of select inorganic pollutants (Co, Cu, As, Ni, Zn, and Pb) is relatively low and together with the results of total element concentration in bottom ash indicate that the potential risk associated with the release of trace elements from studied wastes is negligible. Therefore, studied wastes could be successfully used as a secondary raw material.