High temperature co-treatment of bottom ash and stabilized fly ashes from waste incineration

Bottom ashes from two Danish municipal solid waste incineration plants were heated at 900 degreesC with iron oxide stabilized air pollution control re sidues at actual mass flow ratios (9:1), simulating a treating method for t he residues. The two residues were cotreated, producing one combined stream that may be utilized as a secondary road construction material. Scanning e lectron microscope analysis and grain size distribution analysis indicated that sintering of the particles did not occur. Batch leaching tests at liqu id/solid 10 I/kg at a range of pH-values (6-10) quantified with respect to Cd, Cr and Pb revealed significant positive effects of co-heating the ashes , although Pb showed slightly increased leaching. At a liquid/solid ratio o f 10 I/kg the leachate concentrations were still low at pH 7-10 and the rel ease of Pb was, thus, not expected to limit the utilization of the mixed as hes. The process, thus, fixates the metals in the solid residues without al tering the leaching properties of the bottom ash too significantly. (C) 200 1 Elsevier Science Ltd. All rights reserved.