Utilization of various iron-containing ores and wastes as oxygen carriers in the chemical looping combustion process and comparison of their performances

In this study, chemical looping combustion (CLC) performances of iron-containing ores and wastes were investigated using gaseous fuels (CO, H2 and syngas) in a laboratory-scale batch fluidized bed reactor connected to a programmable logic control system. Red mud, copper converter slag, and process waste (remaining after the extraction of nickel from laterite ore) were used as wastes, siderite and laterite were used as ores. In addition, the chemical looping combustion performance of oxygen carriers synthesized by mechanochemical method using red mud and hematite as active phases and colemanite and zinc borate as support phases in TGA connected to the programmable logic control system was also investigated. As a result of experiments with calcined red mud, calcined copper converter slag, calcined siderite and calcined process waste, the average gas conversion efficiency for all gas compositions was obtained at 86%, 87%, 92% and 88%, respectively. Depending on the amount of boron-containing support phase used in the oxygen carriers obtained by mechanochemical synthesis, it either did not affect the chemical looping combustion performance of the active phases at all or caused agglomeration and decreased their performance. Laterite ore was tried as raw and calcined, but sufficient gas conversion efficiency could not be obtained for both forms. Necessary conditions for obtaining the reduction degree suitable for thermodynamic constraints for calcined process waste were not found applicable. In this study, red mud, copper converter slag, and siderite ore used as oxygen carriers are promising in terms of use in large-scale chemical looping combustion systems considering their cheap and their performance in experiments with gaseous fuels in laboratory-scale chemical looping combustion systems. Moreover, the reuse of industrial wastes provides that the chemical looping combustion system is an environmentally friendly combustion process in terms of the oxygen carrier.