Leaching of As and Se from coal fly ash: fundamental study for coal fly ash recycling.

Coal fly ash (CFA) is a useful recycled resource for uses such as cement raw material. To manage and evaluate safety for effective utilization of CFA, the leaching concentration and amounts of toxic elements in CFA need to be determined. In this study, 38 types of CFA and aged CFA generated in Japan were used to measure the occurrence and leaching concentration range of As and Se.

Classification of coal fly ash based on pH, CaO content, glassy components, and leachability of toxic elements.

Coal fly ash (CFA), a by-product generated from coal-burning power plants, readily leaches toxic elements into aquatic environments. The present study describes a classification system for CFA based on the chemical composition of CFA and leachability of toxic elements, which can promote the safe and effective utilization of CFA for uses such as fly ash cement. To classify CFA samples, the CaO content, leachate pH, leachability of toxic elements such as B, As, and Se, and the acid- and alkali-soluble Si and Al in glassy components were determined for ten types of CFA samples produced in Japan.