The Mobility Of Semi-Volatile Trace Elements From Size Segregated Fly Ash Particles Generated During Pulverized Coal Combustion

Fly ash generated from pulverized coal (PC) combustion has a wide size range, including some fine aerosols. Of particular concern is the abundance and mobility of elements present in the smaller size fractions of the ash, commonly referred to as PM2.5. These particles are usually enriched with toxic trace species which are classified as hazardous air pollutants (HAPs) under the amended clean air act (CAA). Interest in the control of PM2.5 is motivated mainly by health considerations and also due to their role impacting the performance of air pollution control devices such as selective catalytic reducers (SCRs). The three trace elements (TEs) of interest for this study are arsenic (As), selenium (Se) and antimony (Sb). Some of the factors governing the partitioning and mobility of these three TEs in fly ash have been examined for specific experimental conditions. These include the effect of ash particle size, leaching fluid pH, changes to combustion conditions and differences in coal rank. This research encompasses data from the testing and analysis of samples derived from a laboratory combustion scale system as well as a commercial utility boiler. With respect to major limitations, a given elements speciation in ash is not identified even though it is a critical parameter in determining its overall toxicity