Sintered glass-ceramics from incinerator fly ashes. Part II. The influence of the particle size and heat-treatment on the properties

A composition obtained by mixing MSW ashes with sand and glass cullet was melted at 1500 degreesC and quenched in water. The obtained frit was sieved and separated in different fractions: L (large, 2-5 mm), I (intermediate, 1-2 min) and S (small, <1 mm). The sintering of the glass particles, carried out in an alumina mould, occurred in the 700-950 degreesC range. The curve of the crystal growth rate as a function of the temperature was obtained by means of 1 h heat-treatment in the 850-1050 degreesC range. The crystal growth started at 850 degreesC and the maximum rate, 0.013 min/min, occurred at 1020 degreesC. The ferrobustamite crystal phase was evaluated by XRD analysis and observed by optical microscopy. The mechanical, thermal and chemical properties of the L, I and S glass-ceramics were measured and discussed. They resulted to be influenced by the grain size of the glass particles and by the percentage of crystal phase. (C) 2003 Elsevier Science Ltd. All rights reserved.