Production of glass-ceramics from MSW-fly ash and Dexing copper mine-tailing: Crystallization kinetics, structure, properties and immobilization of heavy metals

Abstract

To reduce the environmental pollution from MSW-fly ash and Dexing copper mine-tailing and realize their maximum utilization, this research used them to synthesize novel eco-friendly glass-ceramics. Effects of different nucleation-crystallization temperatures on the crystal evolution, microstructure, properties, leaching behavior of heavy metals were discussed. The findings indicate that the crystallization activation energy E is 381 kJ/mol, and the crystallization mechanism is two-dimensional crystallization controlled by diffusion with an increasing nucleation rate. The difference in the nucleation-crystallization temperature will affect the precipitation and growth of crystal (CaAl2Si2O8) in this glassy system, and further affect the microstructure and properties of the prepared glass-ceramics. Furthermore, because the glass-ceramics is the combination of glass and crystal, an obvious immobilization effect for heavy metals Fe, Mn and Cr can be obtained in our glass-ceramics. Apart from the high immobilization efficiencies for heavy metals, our glass-ceramics also show low density (2.715–2.761 g/cm3) and water absorption (0.026–0.045%), high Vickers hardness (5.72–6.39 GPa), good chemical stability (kH2SO4: 3.68–28.72%, kNaOH: 0.01–0.96%), which confirms the potential and feasibility of the MSW-fly ash-Dexing copper mine-tailing-derived glass-ceramics as building decoration material.