抄録
With an increase in molten fly ash emission from municipal solid waste incinerators such as gasification and melting processes, suitable treatments of the molten fly ash by separation as well as stabilization of heavy metals involved are required. In general, a large amount of heavy metals such as lead, zinc and copper are contained in molten fly ash, at concentrations much higher than those involved in natural ores. Therefore, separation technologies for effective recovery of these heavy metals from solid wastes are required to achieve material recycling system. The present paper is concerned with the separation of heavy metals from molten fly ashes by applying chloride-induced volatilization. Molten fly ash soaked with hydrochloric acid was subjected to heating experiments at 1123K in a N2 atmosphere. Experiments were also conducted to investigate the characteristics of heavy metals volatilization with inorganic chloride compounds such as NaCl, KCl and CaCl2 as chlorinating agents contained in the model ashes. When the molten fly ash soaked in hydrochloric acid was heated at 1123K, almost 100% of lead and zinc, and 35-60% of copper were volatilized. When heavy metal oxides; PbO, ZnO and CuO, mixed with CaCl2, NaCl and KCl were heated at 1123K, only lead and copper were volatized. The effect of chlorinating condition on the volatilization of lead, zinc and copper in molten fly ash was also investigated.
