Release of soluble ions and heavy metal during fly ash washing by deionized water and sodium carbonate solution.

Two municipal solid waste incineration fly ashes were selected for washing by deionized water and NaCO solution for comparison. Results showed that the benefits of washing were two folds: (1) Washing was able to reduce the contents of Cl and SO while increased the contents of CaO, SiO, AlO etc.; (2) Washing by NaCO solution showed increased stability of heavy metals (Cr, Ni, Cd, Cu, Zn and Pb) and fly ash was safe for later reuse.