Valorization of Industrial Wastes for the Production of Glass–Ceramics

In the present experimental study, the valorization potential of various industrial wastes, namely fly ash, red mud and ferronickel slag was investigated for the production of CaO–Al2O3–Fe2O3–SiO2 glass–ceramics. Glass was first produced in alumina crucibles at 1300 and 1500 °C and then cast in stainless steel moulds. After cooling, glass was pulverized, uniaxially pressed at 60 MPa and used for the production of glass–ceramics in the form of disks. The chemical composition of glass and the sintering temperature affected the properties, namely microstructure, porosity, compressive strength, Vickers microhardness and linear thermal expansion coefficient of the produced glass–ceramics. The leaching potential of hazardous elements present in glass–ceramics was investigated with the Toxicity Characteristics Leaching Procedure test, their chemical stability was evaluated through immersion of specimens in distilled water, simulated acid rain solution and seawater for a maximum period of 1 month, while their structural integrity was assessed according to ASTM standard C1262-10. Several analytical techniques, namely X-ray Diffraction, Scanning Electron Microscopy, Differential Thermal Analysis and Fourier Transform Infrared Spectroscopy (FTIR) were used to provide insights on the microstructure of the produced glass–ceramics.