Cement Bonded Fine Hematite Particles and Carbide Slag as Oxygen Carriers for Chemical Looping Combustion

In this work, cement bonded fine hematite particles and carbide slag (CCIO) were proposed to act as oxygen carrier (OC) for chemical looping combustion (CLC) process. In the tests with CO/N2 as fuel, undecorated iron ore (UIO) and carbide slag decorated iron ore (CSIO) were used for comparison. The results showed that the CCIO oxygen carrier showed better and stable reactivity than UIO, while a lower and continuously decreasing reactivity for CSIO was obtained due to sintering occurring on its surface. The decoration ratio for CCIO was optimized, and the results indicated that CCIO20 displayed the best performance. The investigations on reactivity of UIO and CCIO20 were further conducted with bituminous coal as fuel, and gaseous products, carbon conversion processes and oxidation processes for these two samples were studied comparably. The results indicated that CCIO20 showed better performances than UIO. Twenty cyclic redox tests were performed for UIO and CCIO20, and the results showed better and more stable reactivity for CCIO20. Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were used to characterize the physical and chemical properties of these two samples, and the results showed that the newly formed phase Ca2Al2SiO7 among combined OC particles exhibited better stability, which contributed to the enhanced reactivity for CCIO20.

Automated summary

In this study, cement bonded fine hematite particles and carbide slag were used as oxygen carrier for chemical looping combustion. The experiments compared undecorated iron ore and carbide slag decorated iron ore, and found that the CCIO oxygen carrier exhibited better and stable reactivity. Further investigation with bituminous coal as fuel showed that CCIO20 outperformed undecorated iron ore. The physical and chemical properties analysis revealed that the newly formed phase Ca2Al2SiO7 in CCIO20 contributed to its enhanced reactivity.