Transformation Of Arsenic, Lead, Cadmium And Chromium In Coal-fired Power Plant

Coal-fired power plant is a major emission sources of heavy metal pollution. Due to differences in physical and chemical properties of heavy metals, part of heavy metals emit with flu gas, part of heavy metals enrich in fly ash and bottom ash during combustion. Since arsenic, lead, cadmium and chromium is volatile, advanced environmental protection equipment (SCR, ESP, FGD) can not capture them effectively. It is a great pollution to the environment emitting heavy metals without control. In this work, we focused on the transformation behavior of arsenic, lead, cadmium and chromium in coal-fired power plant.Because of low concentration and high volatility of heavy metals, it is very difficult to detect these trace metals in coal, ash and flu gas quickly. A microwave technique for digesting samples and testing concentration of arsenic, lead, cadmium and chromium by AFS and ICP were developed. Quantities of samples were analyzed efficiently and accurately with this method.The transformation behavior of arsenic, lead, cadmium and chromium were investigated in coal-fired power plant.The post-combustion products, fly ash, bottom ash and FGD slurry,were studied. EPA method 29 was applied to study the release character of arsenic, lead, cadmium and chromium in flue gas. Result shows that arsenic and lead are enriched in fly ash, cadmium and chromium, mainly exist in fly ash and bottom ash.In order to explore the mechanism of arsenic-rich in fly ash, the content of unburned carbon, calcium, magnesium and iron in fly ash samples are also analyzed. The results suggest that the chemical adsorption by calcium-based compound in fly ash plays a major role in arsenic adsorption.