Hydration resistance and mechanism of regenerated MgO–CaO bricks

Abstract

Regenerated MgO–CaO refractory brick samples were prepared from spent MgO–CaO bricks and fused magnesia. Hydration resistance was investigated by hot water experiment, and its hydration reaction mechanism and hydration kinetic model were explored. The results showed a superior hydration resistance of regenerated samples. Ca(OH)₂ was the only new generated phase after the hot water experiment, and it is indicated that the hydration of free CaO was the key point. Impurity elements Si, Fe, Al in the spent MgO–CaO bricks had enhanced the hydration resistance through decreasing free CaO content and improving the density of regenerated samples. Meanwhile, it is found that hydration reaction mainly occurred on the surface of regenerated samples, which was controlled by diffusion of H₂O, and the diffusion rate constant K was 0.70 × 10⁻⁶ s⁻¹.