2007 Volume 18 Issue 5 Pages 314-324
The characteristics of riddling ash from stoker-type municipal solid waste incinerator were investigated. The contents of Cu, Zn and Pb in riddling ash were greater than that in other MSWI residues, and the contents of precious metals, such as Au and Ag, were nearly equal to their ores. There was a correlation between grate type and the contents of Cu, Zn and Pb in riddling ash. The contents of Cu, Zn and Pb in riddling ash for the reciprocating flat grate type were greater than that of the parallel swing grate type. It was confirmed that 20-60% of Cu, Zn and Pb in MSW were discharged as riddling ash. Analysis by XAFS spectroscopy at beam line BL01B1 in SPring-8 led us to consider that the predominant chemical states of Cu, Zn, Pb and Ag in riddling ash under drying and combustion zone are metallic states. It is considered possible for riddling ash to be come a source of non-iron materials by separating it from bottom ash because of the large amounts of Cu, Zn, Pb and precious metals contained in it.
