Comparison of transient shrinkage behaviours between binary/ternary- FeO-rich oxides in CO/H2

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Using clean energy in the ironmaking industry is expected to reduce the negative impacts on our environment. H2, one of the most important clean energies, has a great potential to partially replace CO in the blast furnace process, thus cutting down CO2 emission. In order to unravel the distinct effects on the shrinkage behaviour between CO and H2, four binary- FeO-rich oxides and four ternary- FeO-rich oxides were employed to compare their performance under the simulated blast furnace cohesive zone conditions. The results show that the formed olivine and solid solution have the intention to dominate the shrinkage of packed bed below 900°C, while the formed spinel compounds with higher melting point determine the shrinkage above 1300°C. In comparison to CO, H2 has a faster gaseous reduction rate. Therefore, the higher quantity of reduced iron and less disintegration of coke in the packed bed simultaneously suppresses the shrinkage between 900°C and 1000°C. Besides, the much slower iron carbonization rate in H2 postpones the re-accelerating of shrinkage as a result of melting and dripping to higher temperatures.