Sintered materials from incinerator secondary residues

The possibility to obtain new eco-compatible building materials by milling, pressing and direct sintering of secondary raw materials (SRM) derived from a physical/mechanical treatment of municipal solid waste incinerator (MSWI) bottom ashes is discussed. The chemical compositions and particle size distribution of used SRM press powders were evaluated using XRF analysis and by laser granulometer, respectively. The thermal and densification behaviours were studied by non-isothermal DTA-TG and dilatometric techniques. The degrees of sintering, obtained at different temperatures of heat-treatment in the rage 1020 - 1140°C, were defined by measuring the linear shrinkage, the water absorption and the density variation (by gas pycnometer). The formed crystal phases were evaluated with X-ray Diffraction (XRD). The structure of the materials (surfaces and fractures) was observed by Scanning Electron Microscopy (SEM). With respect to the traditional building ceramics the new materials are characterised by totally different micro-structures and phase composition. The analysis of our results highlights also that the studied compositions are characterized by narrow sintering intervals, located between the solidus and liquidus temperatures of the main crystal phases. High crystallinity of obtained specimens, small water absorption and relatively low sintering temperatures can be considered as promising initial results to obtain low-cost building materials with elevate mechanical properties from direct densification of SRM from MSWI ashes. © SGEM2010 All Rights Reserved by the International Multidisciplinary Scientific GeoConference SGEM Published by STEF92 Technology Ltd