Existence of Cl in municipal solid waste incineration bottom ash and dechlorination effect of thermal treatment.
Municipal solid waste incineration (MSWI) is widely used in Japan, through which large amount of incineration residues are produced. The recycle/reuse of the incineration residues is troubled by many factors. This paper studied the MSWI bottom ash with the principal focus on Cl. Both bulk analysis and microanalysis methods have been carried out. The bulk analysis disclosed a particle-size dependent pattern of the Cl content in the bottom ash and the insoluble Cl is essentially in the form of Friedel's salt (3CaO·Al(2)O(3)·CaCl(2)·10H(2)O). The microanalysis revealed that Cl preferentially exists in the quench phase of the individual bottom ash particle. Since Friedel's salt and the other quench products are thermally unstable, a series of thermal treatments were carried out to decompose such Cl-bearing phases. The experimental results showed the total Cl content in the MSWI bottom ash was reduced by 55.46% after a 4-h heating process at 1000°C. The removal of the soluble Cl (originally as alkali salts) by the thermal process was found to be more effective. However, the insoluble Cl content in the heated sample was barely lowered owing to the formation of calcium chlorocalumite (11CaO·7Al(2)O(3)·CaCl(2)) in the course of heating.
Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka, 819-0395, Japan. Electronic address: yang@doc.kyushu-u.ac.jp.
Shuo
S
Yang
Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Amirhomayoun
A
Saffarzadeh
Department of Urban and Environmental Engineering, Graduate School of Engineering, Kyushu University, 744, Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Takayuki
T
Shimaoka
Energy & Environmental Development Department, Takuma Co., Ltd., 2-2-33 Kinrakuji-cho, Amagasaki, Hyogo 660-0806, Japan.
Takashi
T
Kawano
D002713:Chlorine / Q000032:analysis*; D060729:Coal Ash / Q000032:analysis*; D006358:Hot Temperature; D017745:Incineration; D007564:Japan; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis; D012037:Refuse Disposal; D013050:Spectrometry, Fluorescence; D013052:Spectrometry, X-Ray Emission; D013696:Temperature
D060729:Coal Ash; D052638:Particulate Matter; D002713:Chlorine
Chloride; Dechlorination; MSWI bottom ash; SEM/EDX; Thermal treatment