Syngas production through multi-cycle chemical looping of chromite mines waste: A sustainable approach to mitigate CO2 emissions

Abstract

One of the major contributors to global warming is the CO2 emissions from the steel industry. In the primary steel making process, coal/coke is used for reduction purposes that lead to CO2 emissions. Replacing coke with other reducing agents like syngas (H2 and CO) could be a possible approach to reduce CO2 emissions. One effective route for the generation of syngas in a sustainable way is the chemical looping method. In this work, we have investigated the utilization of laterite ore (a mining waste) as an Oxygen carrier for the chemical looping reforming of methane. Multiple redox cycles in the presence of methane and air as reducing and oxidizing agents were performed in DSC-TG to determine the performance of the oxygen carrier. The reacted samples formed in the reaction were analyzed using XRD and SEM. The product gases generated during the reaction were also analyzed using gas chromatography. The results of the reactivity analysis showed that H2 and CO gases were continuously formed during the reforming reaction of methane. The phase analysis of reacted samples in XRD and SEM clearly showed the formation of stable chromite and reduced iron oxide phases. The oxygen carrier showed good stability, and a total hydrogen yield of 203.9 ml/g of OC after 20 cycles of redox reaction were observed. In addition, the theoretical yield of the reacted sample after the first cycle was calculated and compared with the experimental H2 yield at different cycles. A thermodynamic-based simulation study is also reported in this work. The syngas generated from the reforming reaction is used to pre-reduce the Iron bearing ore materials in a blast furnace. The results showed a significant decrease in the CO2 emissions and coke rate could be achieved in primary steelmaking by integrating a chemical looping process with a blast furnace. This study effectively shows the utilization of laterite ore as an oxygen carrier for generating syngas through a chemical looping reforming process to mitigate CO2 emissions.