Temperature-Driven Carbonation of Steel Slag for Carbon Capture and Storage (CCS) Applications

This study investigates the effect of temperature on the carbonation efficiency, mineral transformation, and microstructural changes of steel slag to enhance its potential for carbon capture and storage. Carbonation experiments were conducted at 25°C, 40°C, and 80°C. Results show that calcium carbonation efficiency increased with temperature, peaking at 81.62% at 40°C before slightly declining at 80°C. XRD analysis revealed dominant calcite formation at all temperatures, with the highest siderite content observed at 40°C. SEM and EDX analyses confirmed more uniform carbonate layers and reduced porosity at elevated temperatures, particularly at 80°C. TGA/DTG analysis supported these findings, showing higher CO₂ retention and distinct thermal decomposition behavior in carbonated samples. Overall, 40°C was identified as the optimal temperature for efficient and energy-effective carbonation. The study highlights steel slag's potential as a low-cost, reactive material for CO₂ mineralization under moderate temperature conditions.