Investigation of the attrition behaviour of an iron oxide oxygen-carrier under inert and reacting conditions

This work investigates the attrition in a fluidised bed of an oxygen carrier for chemical looping combustion made from the agglomeration of powdered haematite. Two types of attrition tests were performed: (i) in situ tests in a fluidised bed, and (ii) ex situ impact tests on particles recovered from the fluidised bed experiments. Of primary interest was the effect of repeated reduction and oxidation on the rate of attrition of the particles. The fresh particles exhibited excellent resistance to wear with only minor abrasive attrition occurring. However, subjecting the carrier to repeated cycles of reduction to Fe3O4 and reoxidation to Fe2O3 altered the structural integrity of the particles, resulting in a greater rate of attrition after 10 cycles. The recovered particles also showed severe fragmentation at impact velocities which could be withstood by fresh particles.