Volatility and mobility of some trace elements in coal from Shizuishan Power Plant

The volatility and mobility of eleven trace elements (Hg, As, Se, Pb, Cr, Cd, Mo, Ni, Co, U and Th) in coal from Shizuishan Power Plant were investigated. Column leaching tests on bottom ash and fly ash by sulfuric acid for 60 h were conducted. The contents of trace elements in input coal, bottom ash, fly ash and leaching solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectroscopy (AFS). The volatility of trace elements during coal combustion was calculated based on the trace elements concentration in coal, ash and the ash yield of the raw coal. The results demonstrate that over 50% of As, Pb, and Hg volatilize to the atmosphere. Leaching test results indicate that the maximum leaching proportion of As, Cd, Ni, and Mo is 1.8%-6.2%. Based on the volatility and leaching characteristics, the volatilization and migration model of trace elements in the process of combustion and leaching was established. The results show that volatility of trace elements is the main pollution sources on environment in Shizuishan Power Plant. The concentration of Pb, Cd, Mo, Co, Ni, and Cr in leachate is extremely high and they are potentially harmful elements to the environment.