Flow Characteristics and Hydration Behavior of CaO Powder for Basic Oxygen Furnace Injection Under Humidity and Temperature Environments

We investigated the effects of relative humidity (30–80%) and temperature (5–35 °C) on the flow characteristics and hydration behavior of CaO powder used for basic oxygen furnace injection. We measured the untapped and tapped densities, angle of repose, and particle-size distribution to analyze the flow characteristics. Furthermore, microstructural characterization and phase analysis were performed to study the hydration behavior. The packing characteristics changed and the flowability of the CaO powder decreased under high-relative-humidity conditions, whereas no noticeable changes were observed with variations in temperature. In particular, large agglomerated particles were observed at 80% relative humidity, and the Ca(OH)2 phase fraction reached 56.9% in the relative-humidity series. These results indicate that the decrease in CaO powder flowability under high-humidity conditions is associated with hydration-related microstructural changes and moisture-promoted interparticle agglomeration, in addition to changes in the overall hydration state.