Fly ash from powder plants located in S.Brazil is not suitable to produce glass & glass-ceramic materials. The fly ash melting temperature & the viscosity of the formed liquid are high. Resulting glass shows a dark colour as a consequence of the fly ash composition. The blast furnace slag shows a strong basic character; therefore, during melting, corrosive processes are favoured that involve liquid contaminations & wear in the refractory surfaces & obtained glasses show an accelerated crystallisation process that generates large crystals that result in defect formation in the crystallised pieces. However, the fly ash & blast furnace slag combination in suitable proportions allows obtaining glasses at appropriate melting temperatures. The corrosive effect from the melted glass on the refractories is decreased, & the glass viscosity apparently decreases.
