Properties and microstructure of sintered incinerator bottom ash

The fraction of incinerator bottom ash with a particle size less than 8 mm produced at a commercial municipal solid waste incinerator was wet milled, dried, compacted and sintered at a range of temperatures to form ceramic materials. The effects of milled ash particle size distribution, powder compaction pressure and sintering temperature were investigated, and the materials formed characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TG/DTA). The main minerals present in the milled ash were quartz NOD and calcite (CaCO3). Sintered densities of materials produced from ash milled to 95% less than 27 mum increased from 1.38 to 2.63 g/cm(3) on increasing the sintering temperature from 1020 to 1080 degreesC. Firing above 1080 degreesC caused a rapid decrease in density and sample expansion. The principal crystalline phase present in the high-density material was diopside (CaMgSi2O6). This work shows that a significant fraction of incinerator bottom ash can be processed to form sintered materials with properties controlled by ash particle size distribution and sintering conditions. (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.