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.

To investigate the gas conversion mechanism in the zero-reforming process of coke oven gas and establish reasonable parameter control ranges, a multi-component multiphase coupled reaction equilibrium system involving CH ₄ was developed, based on the actual composition of coke oven gas. Thermodynamic analysis of this gas-based shaft furnace multiphase coupling reaction equilibrium system was conducted using the Gibbs free energy minimization method and MATLAB software. Results indicate that during coke oven gas reforming, under conditions of 100–1,100 °C and 1–8 atm pressure, adjusting the addition of H ₂ O, CO ₂ , and O ₂ increases the content of H ₂ + CO (the effective components of reducing gas), enhances CH ₄ conversion rate, and controls carbon deposition. The initial H ₂ O amount primarily affects equilibrium H ₂ concentration, while initial CO ₂ and O ₂ amounts primarily affect equilibrium CO concentration. As their addition increases, the concentrations of specific equilibrium components vary. When the reducing gas satisfies H ₂ +CO ≥ 90 %, CH ₄ conversion rate ≥ 90 %, and H ₂ /CO ratio ≈ 8, the optimal additive ranges are: H ₂ O at 4.76–18 %, CO ₂ at 2.91–18 %, and O ₂ at 1.71–3.61 %. Simultaneously, initial parameters can be adjusted to meet direct reduced iron production requirements and carbon deposition control. This study provides a theoretical reference for regulating coke oven gas self-reforming to produce hydrogen-rich reduction process gas.