| 摘要 |
PURPOSE:To reduce the elution of lead, by treating the fly ash generated from a waste incineration plant by adding the reducing agent to lead contained in the fly ash to said ash and allowing the reducing agent to act on lead in the fly ash to convert lead to hardly soluble hydroxide. CONSTITUTION:Ferric sulfate is thrown in a reducing agent dissolving tank 1 as a reducing agent and stirred by a stirrer 2 and a recirculation pump 3 to prepare an aqueous solution having predetermined concn. Subsequently, said aqueous solution is supplied to a kneader 5 by a water adding pump 4 to be kneaded with fly ash and cement and the kneaded mixture is sent to a molding machine 6 to be molded into a predetermined shape to obtain a pellet making fly ash harmless. As the reducing agent, ammonia, sodium sulfite and hydroxyamine can be used other than ferric sulfate. By this treatment, the elution preventing effect of lead can be enhanced to a large extent.
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