Glass and glass-ceramics from red mud tailings: Understanding the evolution mechanism

Large quantities of red mud tailings cause serious negative impacts to both the environmental sustainability and public health. Eco-friendly utilization of tailings can address this issue and achieve its commercial value. We reported an approach to preparing transparent basic glass and opaque glass-ceramics utilizing red mud tailings as the starting material. Crystallization kinetics, phase transition, microstructure evolution, and performances of glass-ceramics were studied. The crystallization activation energy was calculated to be only 125.5 kJ/mol, which made the transformation from red mud tailings to glass-ceramics much easier. The Avrami coefficient of crys-tallization was calculated to be around 2, revealing that one-dimensional bulk crystallization occurred in glass -ceramics. Fluorapatite crystals having a one-dimensional morphology were found to generate in glass-ceramics, which endowed the glass-ceramics with superior performances, such as the density of 2.7 g/cm3, the crack resistance of 2.43 MPa m1/2, and the Vickers hardness of 643.67 HV. These results and findings demonstrate that hazardous red mud tailings could become eco-friendly glass and glass-ceramics for construction applications.