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Study of ashes from a medical waste incinerator in China: Physical and chemical characteristics on fly ash, ash deposits and bottom ash

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In this study, the composition and physicochemical properties of fly ash, air preheater deposits, and bottom ash from a typical medical waste incinerator (MWI) were analyzed. The MWI unit studied consists of a rotary pyrolyser, followed by a vertical cylindrical combustor, featuring an extractor grate above which granular material is fluidized. Fly ash consisted mainly of Ca, Al, Si, Mg, Na, O, C, Cl, and S; the chlorine content in fly ash from this MWI was higher than that in the fly ash generated by a municipal solid waste incinerator (MSWI). Bottom ash consisted mainly of CaCO3, SiO2, and Ca(OH)2, and the major components measured in fly ash and in air preheater ash deposits were CaCO3, CaSO4, NaCl, KCl, SiO2, and Ca2Al2SiO7. The carbon content of fly ash was positively correlated with the specific surface area. The porous structure is much more pronounced in fly ash and deposits than in bottom ash. Ash deposits showed low pH-values, fly ash and especially bottom ash were found to be basic. High contents of chloride and Ca in the fly ash lowered the ash melting point when compared with that in the fly ash generated by the MSWI. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 496–504, 2013