To remove by evaporation heavy metals in a fly ash by a method wherein before charging the fly ash or the like into a melting furnace of an apparatus for solidification by melting, a heating atmosphere is adjusted, and a pretreatment for heating the fly ash or the like is executed.
A pretreating device 3 is installed between a hopper 1 and an ash feeder 2 for feeding the fly ash 30 or the like and a plasma melting furnace 4, and the fly ash 30 or the like is fed into a muffle via an intermediate room 10 a of the pretreating device 3. Then, the fly ash 30 or the like fed into the muffle is heated to a specific temperature by a heater 13. At that time, an inside of the muffle is adjusted at a specific oxygen partial pressure by feed of a nitrogen gas from a vacuum pump 7 and a gas feed of piping 8, the fly ash 30 or the like is heated while it is transferred from an inlet side of the muffle to its outlet side with a conveying belt 11, and besides chlorides of heavy metals are evaporated from in the fly ash 30 to remove the heavy metals.
KUNII KAZUTAKA
SODO TATSUHIKO
MURAKOSHI KOJI
