Accelerated carbonation of ladle furnace slag and characterization of its mineral phase

Ladle furnace slag is a high-calcium-based alkaline industrial solid waste inefficiently stacked at the site, which consumes large amount of land and pollutes water resources. Carbonation of refining slag not only solves the problem of poor compactness and poor stability of the refined slag as a product, but also eliminates waste and reduces greenhouse gases. Experiments were conducted to explore factors that affect the carbonation of refining slag. The optimal reaction conditions were found to be temperature of 20 °C, liquid-solid ratio of 5, aeration rate of 600 ml/min, and stirring speed of 700 rpm. The slag with less than 88 μm particle size showed the best carbonation effect with 39.6% degree of carbonation. XRD, SEM, FT-IR, and DG-DTA methods were used to investigate the changes in mineralogical characteristics with time in the carbonation process of refining slag. Variations in mineral phase with time were analyzed by semi-quantitative relative intensity ratio (RIR) method. TGA-DTG analysis quantified the Ca conversion, CO2 absorption, and also estimated the CaCO3 mass at different time periods.