Hydrogen ( \({\hbox {H}}_{{2}}\) )-based fluidized bed reduction is a promising route for carbon-neutral ironmaking, but defluidization caused by interparticle sticking of \({\hbox {H}}_{{2}}\) -Direct Reduced Iron (DRI) remains a major challenge. The present study examines the influence of sticking behavior and flowability on fluidized bed stability during \({\hbox {H}}_{{2}}\) reduction. Experiments with hematite- and goethite-based ores revealed distinct fluidization behaviors. The hematite-based ore exhibited defluidization at 750 \(^{\circ }\) C to 850 \(^{\circ }\) C due to whisker-induced Fe layer formation, while the hematite-goethite-mixed ore remained stable without whisker formation. Quantitative rheological analysis confirmed that defluidization correlated with a transition from “Easy-Flowing” to “Cohesive” regime when interparticle cohesion exceeded a critical threshold. To prevent the defluidization, ore blending strategies were explored as a mean to satisfy the rheological properties identified in the present study. A 20 pct blending of hematite-goethite-mixed ore effectively ensured “Easy-Flowing” regime and lowered the chance of cohesion below the critical value, ensuring stable fluidization. These findings provide key insights into the sticking mechanisms of \({\hbox {H}}_{{2}}\) -DRI and highlight the critical powder characteristics necessary to achieve a stable and efficient \({\hbox {H}}_{{2}}\) reduction process.
