Effect of CaO/SiO2 ratio on the preparation and crystallization of glass-ceramics from copper slag

Glass-ceramics were synthesized successfully from iron-rich copper slag and the iron was recovered in the same process so that iron-rich copper slag was recycled efficiently. The influence of CaO/SiO2 ratio on the preparation of glass-ceramics was emphasized using differential scanning calorimetry (DSC), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the residual iron concentration of the quenched glass is less than 1.43 mass% and Fe concentration in recovery of copper slag is more than 96.6 mass%, highlighting that the iron is extracted effectively from copper slag. Crystallization kinetics result shows an increase in the activation energies of crystallization with an increase in CaO/SiO2 ratio up to 0.38 and subsequently a decrease with further increase in CaO/SiO2 ratio up to 0.42. Anorthite with lamellar shape and diopside with irregular column shape are developed as the major phases in all the glass-ceramics samples with different CaO/SiO2 ratios. The increase in CaO/SiO2 ratio hinders the crystal growth of lamellar anorthite but benefits the formation of diopside crystals. For CaO/SiO2=0.42, the optimal comprehensive properties of the glass-ceramics are achieved: low porosity of 0.11%, low bibulous rate of 0.04%, high density of 2.75 g/cm and high hardness of 85.75 HBa.