Experimental Study on the Melting of Hydrogen‐Reduced Iron Ore Pellets in Electric Arc Furnace‐Type Slags

Hydrogen direct reduced iron ore pellets (H‐DRI) are an increasingly relevant raw material for electric‐arc furnace steelmaking as steelmakers strives to reduce CO 2 emissions. Understanding the melting behavior of carbon‐free H‐DRI pellets in slag is needed to facilitate efficient industrial melting operations. The present study focuses on the role of slag during heating and subsequent melting of H‐DRI pellets. Experiments where single H‐DRI pellets are submerged in EAF slags with different FeO, Al 2 O 3 , and MgO contents have been done and evaluated. Results show that, within the experimental range, fastest melting progression is achieved with low FeO, high Al 2 O 3 content slags. At the most favorable conditions, 80% apparent melting is reached after 15 s, in contrast to 50% under least favorable conditions. This is likely due to differences in thermal conductivity of the slag. In pilot‐scale EAF trials where carbon‐free H‐DRI pellets is melted by continuous operation, melting performance improved with increasing FeO content. This can be explained by a decreasing viscosity which facilitated convective heat transfer. Therefore, the combination of experimental and pilot‐scale results shows that convection is the dominating heat transfer mechanism in the industrial case why it should be the focus of future research and development efforts.