Performance of iron ore oxygen carrier modified by biomass ashes in coal-fueled chemical looping combustion

The modification of oxygen carrier by low-cost biomass ash shows great potential to reduce the economic and environmental costs associated with oxygen carrier preparation and biomass ash disposal. In this study, three biomass ashes a wheat stalk ash (WSA), a corn stalk ash (CSA), and a soybean stalk ash (SSA) were selected as the modifiers to evaluate their potential to improve the reactivity of a iron ore produced from the Mining Area C (MAC) of Western Australia. A lignite coal ash-modified MAC iron ore was also prepared to make a comparison. The reactivity performance of ash-modified samples and the cyclic behavior of the selected best candidate were evaluated in a laboratory-scale fluidized-bed reactor system with coal as fuel. The results showed that MAC iron ore loaded with different ashes showed different degrees of improvement in its reactivity. SSA-modified MAC iron ore behaved the best due to the highest K2O content and the total contents of K2O, CaO, and Na2O in SSA as well as its great resistance to melting. The higher loading content of SSA in MAC iron ore resulted in more coal gasification products converted to CO2 and H2O at a faster reaction rate. The cyclic test of MAC-20SSA showed that it performed well both in its reactivity and physical structure. Stable outlet gas concentrations were achieved and MAC-20SSA exhibited good resistance to sintering. It can be inferred that SSA is a promising low-cost modifying agent to enhance the performance of oxygen carrier while reducing the environmental impact associated with its disposal. (c) 2016 Society of Chemical Industry and John Wiley & Sons, Ltd