Selective Ion Migration and Kinetics Mechanisms of Crystallization on Microwave Heating Process from Bayan Obo Iron Slag Glass Ceramics

The collaborative preparation of slag glass–ceramics using iron tailings and fly ash is an important approach to achieving high-value recycling of solid waste. In this study, a method of microwave-assisted heat treatment for preparing slag glass–ceramics was introduced to enhance crystallization efficiency and reduce energy consumption. The relationship between the microstructure and properties of glass–ceramics under the non-thermal effect of microwaves was investigated using traditional XRD, Raman, SEM, and other analytical techniques, and the structural evolution rule of the microcrystalline phase was obtained through in situ tracking tests. The migration and diffusion mechanism of CaF2 and Fe2O3 under the catalytic effect of the microwave electromagnetic field was innovatively studied. The results show that microwave treatments improved crystallization efficiencies, enabling the augite to crystallize uniformly in the glass. Due to the interaction of microwave energy with the absorbing medium in glass ceramics, Ca2+ and F− ions preferentially migrate and aggregate, resulting in the “micro-focusing effect” and a decrease in crystallization activation energy. In addition, the microwave electric field accelerated the diffusion of Fe ions, targeted and regulated the silica glass network to polymerize and form the augite.