Characterization of Porosity Changes during Reaction of Coke and Coke Analogues with CO₂ Using Micro‐Computer Tomography.

Understanding the porosity of coke and how it changes during reaction is key for understanding coke reactivity and minimizing coke consumption in the blast furnace. The change in porosity of coke and coke analogue samples after reaction with CO2 is assessed using high‐resolution micro‐computer tomography (micro‐CT) scans. High‐resolution micro‐CT scans (2.35 μm voxel−1) are carried out before and after reaction with CO2 at 1100 °C. 3D micro‐CT measurements are validated against standard 2D measurements, and used to quantitatively assess the porosity evolution in the samples. The porosity and pore connectivity of the coke and analogue samples increase in reaction with CO2. Most of the increase in porosity occurs in the pores <60 μm. Inert maceral‐derived component (IMDC) regions in coke A are more reactive than reactive maceral‐derived component (RMDC) regions. This is possibly related to the higher proportion of fine pores in unreacted IMDC compared to RMDC. Characterization of larger coke and coke analogue samples using micro‐CT at lower resolution (9.65–16.72 μm voxel−1) allows the rate‐controlling mechanism to be determined as likely to be mixed control, with both chemical reaction and pore diffusion‐controlling reaction rate. This finding demonstrates that high‐ and lower‐resolution micro‐CT datasets should be considered complementary. [ABSTRACT FROM AUTHOR]