The Melting Mechanism of Hydrogen Direct Reduced Iron in Liquid Slag

The heating and melting of hydrogen direct reduced iron (H‐DRI) in liquid slag is investigated experimentally at 1923 K. For the experiments, slags comprising the CaO‐SiO 2 ‐MgO‐FeO‐Al 2 O 3 system are first premelted at 1923 K in alumina crucibles. The molten slag bath is subsequently used to submerge samples of 7 g of H‐DRI with different degrees of reduction (90.4–99.8%). Following the submersion, the slag bath and the H‐DRI sample are quenched at different times (5–10 s). It is found that the liquid slag penetrates the porous network of the H‐DRI. The penetration is found to increase with lower reduction degrees. The reaction‐enhanced capillary action theory is proposed to explain the dependence. The reasoning is validated by a cold model consisting of a quartz capillary, water, and solid sugar. The slag penetration also enhances the heat transfer and the dephosphorization rate. The present findings can, therefore, aid in optimizing the hydrogen‐based steelmaking route.