Synthesis of glass-ceramics using glass cullet and vitrified industrial by-products

This study concerns the recycling of inorganic waste materials for the production of glass-ceramics and the evaluation of the developed physical properties. Four industrial by-products were selected due to their mass production: (i) two high calcium lignite fly ashes, (ii) slag derived from the production of Fe–Ni and, (iii) steel slag. In order to examine the role of the SiO2 in the crystallization process, glass cullet and Egyptian sand were added. Thermal treatment, at 1450 °C, enables the production of glasses using mixtures of these materials at appropriate proportions. The crystallization was achieved by heating at 900, 950 and 1000 °C. The produced materials were examined concerning their structure by X-ray diffraction and scanning electron microscopy (SEM-EDS). The results showed that the crystalline phase is greatly depending on the structure of the raw material and the thermal process, influencing accordingly the hardness of the final products.