LEACHANT PH EFFECTS ON THE LEACHABILITY OF METALS FROM FLY-ASH

The leachability of metals from fly ash produced by a coal-fired elect ric plant and a municipal waste incinerator under acidic conditions wa s experimentally investigated. The results of these column-leaching ex periments show that a decrease in the pH of the leachant favors the ex traction of metal ions from solid particles of both coal combustion fl y ash and municipal waste incinerator fly ash. The significant increas e in the extraction of cadmium, chromium, zinc, lead, mercury, and sil ver ions from the ash is attributed to the instability of the mineral phases that contain these metals under acidic conditions.