Effect of Hydrogen Addition on Softening and Melting Reduction Behaviors of Ferrous Burden in Gas-Injection Blast Furnace

The softening and melting reduction behaviors of ferrous burden in a gas-injection blast furnace (BF) have been investigated experimentally with the assistance of H₂. The results indicate that the initial softening temperature of the burden in the BF is lower than that in the traditional BF, while the opposite trend is observed for its melting and dripping temperatures, thus widening the softening range and narrowing the melting zone. As a result, the permeability of the stock column is apparently improved, owing to the decreased amount of the produced melt. After H₂ gas is added, the thickness of the iron shell of the burden pellet increases, and the quantity of its liquid wüstite core decreases due to the higher reduction degree. The reduction rate of iron oxides is much faster than the carburization rate with the H₂ addition, and the dripping behavior of the ferrous burden is determined by the carburization with a high reduction potential. After taking into account the effects of H₂ addition on the iron oxide reduction rate, melt quantity, burden microstructure, and energy consumed by the gas-injection BF, it has been concluded that the optimal H₂ content lies in the range between 10 and 15 pct.