Comparison of leaching of metals from ground ashes prepared by steam gasification and incineration of the 60–340 mm MSW fraction

Abstract

Abstract Comparison of leachability of a set of 31 elements from ashes prepared by laboratory-scale experiments of incineration and allothermal steam gasification of the residual from mechanical treatment of municipal solid waste (RMT-MSW) has been discussed in terms of the oxygen potential ( R T l n p O 2 ) of high temperature (HT) process. Both incineration and steam gasification enable elimination of organic components and carbonaceous residue from the waste. The essential difference between ashes from oxygen incineration and steam gasification consists in (1) higher leachability of metals from gasification ash by diluted (2 M) inorganic acids (HCl, HNO3) and (2) preservation of metallic form of copper in gasification process. Grinding and fractioning of ashes revealed that pieces of metallic Al were accumulated mainly in the coarser grains, but also in fine fraction 0.16 0.50 mm after incineration and 63% of Al, 84.% of Cu and 80% of Zn – in the ash grains o > 0.16 mm after gasification, with 3.80% and 14.8% of the ash mass, respectively. Contrary to incineration, 82% of copper was accumulated in fraction 0.16