Attrition of binary mixtures of solids in a jet attrition unit

The attrition of binary mixtures of iron powder, as a representative oxygen carrier, and limestone, as a CO₂ sorbent, was investigated to examine the interactions of two different solid species. An air-jet apparatus based on ASTM D5757, with several improvements, was used to test particle attrition for various times (3, 6 and 12 h), temperatures (20, 250 and 500 °C), gas flow rates (6, 8 and 10 LPM)and particle mixture compositions (Iron:Limestone mass ratios 1:0, 0.75:0.25, 0.5:0.5, 0.25:0.75 and 0:1). Attrition was affected by the fluidization velocity in relation to the minimum fluidization velocities of the two species, and the mixture mass ratio. High temperature increased the generation of iron fines, while reducing the production of limestone fines. As expected, increasing the air flow rate led to the generation of more fines of both iron and limestone.