title: Effects of chemical composition of fly ash on efficiency of metal separation in ash-melting of municipal solid waste.
abstract: In the process of metal separation by ash-melting, Fe and Cu in the incineration residue remain in the melting furnace as molten metal, whereas Pb and Zn in the residue are volatilized. This study investigated the effects of the chemical composition of incineration fly ash on the metal-separation efficiency of the ash-melting process. Incineration fly ash with different chemical compositions was melted with bottom ash in a lab-scale reactor, and the efficiency with which Pb and Zn were volatilized preventing the volatilization of Fe and Cu was evaluated. In addition, the behavior of these metals was simulated by thermodynamic equilibrium calculations. Depending on the exhaust gas treatment system used in the incinerator, the relationships among Na, K, and Cl concentrations in the incineration fly ash differed, which affected the efficiency of the metal separation. The amounts of Fe and Cu volatilized decreased by the decrease in the molar ratio of Cl to Na and K in the ash, promoting metal separation. The thermodynamic simulation predicted that the chlorination volatilization of Fe and Cu was prevented by the decrease in the molar ratio, as mentioned before. By melting incineration fly ash with the low molar ratio in a non-oxidative atmosphere, most of the Pb and Zn in the ash were volatilized leaving behind Fe and Cu.
authors.affiliation: Laboratory of Solid Waste Disposal Engineering, Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628, Japan. t-okada@u-fukui.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tomikawa
mesh_terms: D002712:Chlorides / Q000737:chemistry; D060729:Coal Ash / Q000737:chemistry*; D003300:Copper / Q000032:analysis / Q000737:chemistry; D004867:Equipment Design; D017745:Incineration; D007501:Iron / Q000032:analysis / Q000737:chemistry; D007854:Lead / Q000032:analysis / Q000737:chemistry; D008670:Metals / Q000032:analysis / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D012037:Refuse Disposal / Q000295:instrumentation / Q000379:methods; D012964:Sodium / Q000737:chemistry; D062611:Solid Waste; D015032:Zinc / Q000032:analysis / Q000737:chemistry
chemical_list: D002712:Chlorides; D060729:Coal Ash; D008670:Metals; D062611:Solid Waste; D007854:Lead; D003300:Copper; D012964:Sodium; D007501:Iron; D015032:Zinc; D011188:Potassium