Removal techniques for heavy metals from fly ash

This study reviews different technologies for extraction of heavy metals from fly ash. With this perspective processes like bioleaching using microbes, carrier in pulp method, chemical extraction via acids, alkaline leachates and chelating agents, chloride evaporation process, electrodialytic and thermal treatments were studied thoroughly. A comprehensive comparison of all the techniques is also done by studying in detail their reaction conditions, metals leached and percentage extraction achieved. The study concluded that depending on the type of fly ash and metal under consideration determines the suitability of the process adopted for detoxification of fly ash. In addition to these, factors like cost, time and energy also define the final selection process.