Distribution of trace elements in feed coal and combustion residues from two coal-fired power plants at Huainan, Anhui, China

The rapid expansion of coal-fired power plants (CFPPs) in China has produced huge volume of toxic elements associated combustion residues, which pose great threat to local environment. In this study, feed coal, fly ash, bottom ash and FGD gypsum samples were collected from two different CFPPs at Huainan, Anhui, China. Feed coal and combustion residues were morphologically and mineralogically characterized by scanning electron microscopy equipped with energy-dispersive microanalyser and X-ray diffraction. Concentrations of thirteen major and trace elements in these samples were determined by inductively coupled plasma atomic emission spectrometry (B, Ti, Mn, Ni and Zn), inductively coupled plasma mass spectrometry (Cd, Co, Cr, Cu, Pb, Sn and V) and atomic fluorescence spectroscopy (As). The results show that most of the trace elements were concentrated in the fly ash, only Fe and Mn were enriched in the bottom ash. The diameters of ash particles removed by the electrostatic precipitator were in an inverse relationship with the enrichment factors of most trace elements. To address possible exposure of combustion residues in the environment, laboratory controlled leaching tests were carried out on fly ash and gypsum to understand the environmental behaviors of these elements. Both fly ash and gypsum were identified as not-hazardous wastes.