| 摘要 |
<p>PURPOSE:To efficiently immobilize heavy metals by subjecting collected dust and ashes contg. the heavy metals to an alkaline treatment in the presence of an iron salt. CONSTITUTION:Slaked lime C is sprayed as an alkali from a powder ejection device 12 into the exhaust gas E from a treatment furnace to make the acidic gas in the exhaust gas non-polluting. The dust of the exhaust gas added with this alkali is captured by an electrostatic precipitator 13. The captured ashes A are stored in an ash storage tank 15, are discharged from a constant rate feeder 16 and are put into a reactor 1. After iron sulfate B in an aq. soln. state is added from a tank 2 to these ashes A, the ashes are heated by using a heater 6 while air is added thereto from an air introducing port 4; in addition, the ashes are continuously stirred by using a stirrer 7 and are taken out of a discharge port 9. The ashes are then pelletized by using an ash treatment device 10. Consequently, the elution preventive treatment of the heavy metals is perfectly carried out. The alkali is effectively utilized for removing the harmful materials in the exhaust gas and preventing the elution of the heavy metals from the dust collecting ashes.</p> |
