Unveiling the Carbonation Behavior and Microstructural Changes of Magnesium Slag at 0 ℃

Abstract

Magnesium slag (MS) is an industrial byproduct with high CO2 sequestration potential. This study investigates the carbonation behavior and microstructural changes of MS during wet carbonation at 0 °C. XRD, TG, FTIR, SEM, and BET techniques were used to characterize the phase composition, microstructure, and porosity of MS samples carbonated for different durations. The results showed that the main carbonation products were calcite, vaterite, and highly polymerized silica gel, with particle sizes around 1 μm. The low-temperature environment retarded the carbonation reaction rate and affected the morphology and crystallization of calcium carbonate. After 480 min of carbonation, the specific surface area and porosity of MS increased substantially by 740% and 144.6%, respectively, indicating improved reactivity. The microstructure of carbonated MS became denser with calcite particles surrounded by silica gel. This study demonstrates that wet carbonation of MS at 0 °C significantly enhances its properties, creating an ultrafine supplementary cementitious material with considerable CO2 sequestration capacity.