Crystal phase separation and microstructure of a thermally treated vitrified solid waste

The vitrification method was used to stabilize a solid industrial waste residue rich in iron and lead oxides. Upon devitrification of the glass products, the effect of batch composition on the ability to produce glass-ceramic materials was investigated by electron microscopy techniques. The crystallization and microstructural evolution of the vitreous products was explored with respect to the annealing conditions. In the course of vitrification, ferric oxide functioned as a glass network former, contributing to the structural integrity of the vitreous matrix. After thermal treatment of the vitrified products, at temperatures determined by differential thermal analysis, Pb8Fe2O11, PbFe12O19 and Fe2O3 were the dominant crystal phases detected in the glass-ceramic products, the former characterized as a new structure. The distribution of iron and lead oxides among different crystalline phases was found to be the dominant parameter determining the efficiency of lead captivation into the volume of the devitrified products, whereas in glass products lead is diffused in the amorphous matrix.