Chenchen Lan

Under the background of “carbon peaking” and “carbon neutralization”, the green transformation of iron and steel enterprises is imminent. The hydrogen-rich smelting technology of blast furnaces is very important for reducing energy consumption and CO₂ emission in ironmaking systems, and it is one of the important directions of green and low-carbon development of iron and steel enterprises. In this paper, the research status of the thermal state, reduction mechanism of iron-bearing burden, coke degradation behavior, and formation of the cohesive zone in various areas of blast furnace after hydrogen-rich smelting is summarized, which can make a more clear and comprehensive understanding for the effect of H₂ on blast furnace ironmaking. Meanwhile, based on the current research situation, it is proposed that the following aspects should be further studied in the hydrogen-rich smelting of blast furnaces: (1) the utilization rate of hydrogen and degree of substitution for direct reduction, (2) combustion behavior of fuel in raceway, (3) control of gas flow distribution in the blast furnace, (4) operation optimization of the blast furnace.

The thermodynamic and kinetic behaviors of carbothermal reduction of copper slag under different basicity were studied. The results show that the reduction process of Fe and Zn in copper slag is mainly endothermic reaction. The initial reaction temperature with C is lower than that with CO. The metallization rates of Fe and Zn at various temperatures gradually increase with the increase of basicity. With increasing basicity, the reduction rate of copper slag at each heating rate and the reduction degree at 1573 K gradually increase, and the initial reaction temperature gradually decreases. The increase of basicity from 0.06 to 1.20 makes the reaction activation energy decrease by 93.54 kJ mol⁻¹. The carbothermal reduction process of copper slag at each basicity conforms to the diffusion model, and the mechanism function is f(α) = (3/2)(1−α)^4/3[(1−α)^−1/3−1]⁻¹. The increase of basicity has a positive catalytic effect on the carbothermal reduction process of copper slag.

The high-temperature simulation tests of softening and melting zone under different w (Cl ^- ) were carried out, and based on the density functional theory, the influence mechanisms of chlorine on softening and melting behaviors of BF burden were analyzed. The results show that with the increase of w (Cl ^- ) which bring in by sinter, the softening start temperature and softening end temperature of BF increase, and the softening temperature range becomes small, the melting start temperature increases, the dropping temperature decreases, the melting temperature range becomes small too. The softening and melting zone of BF narrows. With the increase of w (Cl ^- ), the maximum pressure difference and the comprehensive permeability index both decrease, the permeability of the softening and melting zone enhances. The main reason for the increase of permeability is that the chlorine atom makes the Fe-O bond length increase, the stability of the structure is destroyed, the adsorption capacity of CO molecule on FeO surface is promoted, the reducing speed of FeO increases. Although chlorine can effectively reduce the reduction degradation of sinter in the BF and improve the permeability of the softening and melting zone, the metallurgical enterprises should still eliminate or reduce the chlorine element into the BF.