METHOD OF INSOLUBILIZING HEAVY METALS CONTAINED IN FLY ASH DISCHARGED FROM GARBAGE INCINERATOR.

摘要

A method of insolubilizing noxious heavy metals contained in the fly ash collected from a waste gas discharged from a garbage incinerator. In order to make insolubilize the heavy metals, a chelating agent and water are added to the ash, and these materials are kneaded together to obtain a kneaded mass. This mass has a high alkalinity due to an alkaline substance added to the waste gas for the purpose of removing hydrogen chloride therefrom. The quantity of the water to be added to the ash is regulated so as to lower the pH value of the kneaded mass to 12 or below, whereby the reaction between the heavy metals and the chelating agent in the kneaded mass is promoted. Thus, the heavy metals are converted into water-insoluble chelate compounds owing to this reaction.