PURPOSE: To make noxious heavy metal-containing dust innoxious, by melting heavy metal dust scattered, when fly ash containing a noxious heavy metal generated from an incineration plant is melted and solidified, along with phosphate to convert the same to a vitreous form.
CONSTITUTION: Noxious heavy metals such as Pb, Cd, Cr or Cu or salts thereof are contained in fly ash generated when household waste is incinerated, and melted, solidified and made innoxious because of their fine size. At this time, a part of the heavy metals is present as chloride with a relatively low m.p. and easy to scatter as dust. This dust is collected by a dust collector and phosphate such as sodium hydrogen phosphate is added as solidifier to the dust in an equivalent amount or more on the basis of heavy metal chloride therein. The resulting mixture is melted at a temp. higher than the m.p. of heavy metal chloride with a max. m.p. but lower than the b.p. of heavy metal chloride with a min. b.p. in the dust and solidified to be converted to an innoxious vitreous solid substance.
KAWASAKI MICHIO
SHIMIZU KOUJI
HOSHIKAWA HIROSHI
FUJI ELECTRIC CO LTD