Abstract:
Global warming and other environmental issues due to the increasing CO2 in the atmosphere have raised concerns about reducing CO2 emissions. CO2 sequestration using Chemical looping combustion (CLC) is a technology with inherent greenhouse gas (CO2) separation. This technique involves transferring oxygen from combustion air to fuel without direct interaction using metal oxide as an oxygen carrier. Steel industry waste such as ferrochrome slag consists of transition metal oxides that can be an attractive and inexpensive oxygen carrier for chemical looping combustion. The present work explores the possibility of oxidation of ferrochrome slag, pure Fe turning, and their mixtures using CO2 in the CLC process. TG experiments were performed using ferrochrome slag, pure Fe turning, and their mixture in varying weight ratios (1:1, 1:2, and 2:1) at 800 °C, 900 °C, and 1000 °C (isothermal and dynamic temperature program) in the presence of 40% CO2 and 60% Ar gas mixture. The oxidized samples were investigated using SEM–EDS and XRD to analyze the phases and composition. Furthermore, thermodynamic calculations were performed using FactSage 7.1 software to aid the understanding of the oxidation mechanism. The results show that Slag–Fe mixtures gain significant mass due to Fe3O4 spinel formation. In addition, the oxidized Slag–Fe samples also constitute MgAl2O4 spinel with Fe and Cr solubility. The oxidation kinetics is found to increase with temperature and Fe content in the mixtures. The study effectively demonstrates that CO2 can be utilized for the oxidation of Slag–Fe turning mixtures.