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

Abstract

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.