The use of a low-cost oxygen carrier prepared from red mud and copper ore for in situ gasification chemical looping combustion of coal

In this work, cement bonded fine waste particles (<0.1 mm) of copper ore and red mud are used as a kind of low-cost oxygen carrier (OC) for potential application in in situ gasification chemical looping combustion (iG-CLC) of coal. The mixing ratio of copper ore to red mud is selected as 10.9:89.1 (by mass) based on the consideration of thermoneutrality in the fuel reactor, and the cement content accounts for 20 wt% in the prepared OC. The CLC performance with coal char as fuel indicates that this OC can facilitate the char gasification process and exhibits good reactivity towards char gasification products, which can be ascribed to the catalytic effect of alkali metal contents on char gasification and the excellent oxygen transfer capability of the OC. Moreover, when lignite is used as fuel, the escape of pyrolysis products would decrease the CO₂ yield in comparison to that with lignite char as fuel, and the OC still exhibits better CLC reaction performance than pure red mud. Additionally, the effect of coal/char type on the combustion efficiency is also investigated. Twenty cyclic redox tests with lignite as fuel show that this OC maintains stable redox reactivity and good anti-agglomeration property. Overall, this work demonstrates that the proposed OC can be attractive for industrial application in iG-CLC processes.