The influence of vitreous waste entropy on sintering process.

There is a fairly large range of waste that is partially or fully vitrified e.g.,: fly ashes, granulated slag, glass cullet. As long as they are not loose, after milling these wastes are an interesting raw material for the production of sintered ceramics. In this application, attention is usually paid to their fluxing effect during sintering, due to the high content of alkali oxides and iron oxide. The high entropy of these raw materials resulting from the large proportion of glassy phase is usually neglected. In this paper, we shown that during the sintering of glassy wastes their entropy decreases, which is mainly the result of their devitrification and previous glass transformation. Both the sintering process and the processes associated with the drop in glass entropy are exothermic. Their simultaneous coexistence causes that they can accelerate each other. The influence of high entropy of vitreous wastes on the acceleration of the sintering process was demonstrated with use of thermal studies such as DTA/TG and high temperature microscopy. The fly ash, ground cullet and their mixture were used as glassy wastes. [ABSTRACT FROM AUTHOR]