Indirect Aqueous Mineral Carbonation of Samples of Linz-Donawitz Slag from the Steel Industry in Eastern India

In this study, aqueous mineral carbonation of Linz-Donawitz (LD) slag waste from Rourkela, Bokaro, and Tata steel industries was undertaken at a room temperature of 30°C and elevated CO2 pressure (9 bar) to assess the feasibility and quantification of carbonation primarily as CaCO3. Also, the effect of physical, i.e., sonication (40 kHz) and chemical activation (1 M NH4Cl, CH3COONH4, and NH4NO3) on calcium dissolution/extraction and its carbonation was compared with control, i.e., without chemical activators. Calcium dissolution from LD slag samples (solid:liquid ratio 1 g/50 mL) showed a significant increase in all samples, i.e., 23.92, 25.60, and 20.90 mg/L for Rourkela, Bokaro, and Tata LD slag samples, respectively. XRD and FTIR analyses of carbonated LD slag residue confirmed calcite formation. Thermal gravimetric analysis/differential scanning calorimetry analysis of carbonated samples showed a relatively high degree of carbonation for the Rourkela, Bokaro, and Tata LD slag samples with chemical activators, CH3COONH4 (56%), NH4NO3 (55%), and control (48%), respectively. The present work estimates CO2 capture in LD slag samples to be 0.126, 0.084, and 0.153 kg/kg, respectively. The research findings highlight the scope of mineral carbonation of LD slag samples at relatively low pressure and temperature using physical and chemical activators.