On the use of a highly reactive iron ore in Chemical Looping Combustion of different coals

Coal combustion using the Chemical Looping technology can be carried out under different configurations. This paper focuses on the in situ gasification Chemical Looping Combustion (iG-CLC). In this technology, it is especially important the selection of the oxygen carrier as there may be losses in the drainage of coal ashes. Finding low-cost oxygen carriers has become a relevant research focus. Several Fe-based materials have been tested including minerals and industrial residues. In this work, a highly reactive iron ore that had already shown promising characteristics for coal combustion was used in a continuous 500 Wth CLC unit. Its performance in the combustion of anthracite, bituminous coal and lignite was evaluated and compared with the results for other Fe-based materials, such as ilmenite or a bauxite waste. The combustion efficiency obtained with the Tierga iron ore was the highest reported to date which makes this carrier a promising candidate for further scale-up. Moreover, the high CaO content of this material led to analyze its relevance for sulphur removal during the first hours of operation. High sulphur retention capacity was observed but this capacity decreased with time as the calcium oxide was both saturated and lost as fines during operation.