Fan Wanlong, Peng Zhiwei, Tian Ran, Luo Guanwen, Yi Lingyun, Rao Mingjun
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China.
Materials (Basel). 2024 Aug 6;17(16):3896. doi: 10.3390/ma17163896.
This study proposed a strategy to prepare metalized pellets for direct steelmaking by hydrogen cooling reduction (HCR) of iron ore pellets with a focus on the effect of H flow rate on the process. It was demonstrated that increasing H flow rate could effectively enhance the reduction performance of iron ore pellets. However, due to the influence of the countercurrent diffusion resistance of gas molecules, too high H flow rate no longer promoted the reduction of the pellets when the maximum reduction rate was reached. The reduction swelling index (RSI) of the pellets initially increased and then decreased with increasing H flow rate. This change was associated with the decreased content of FeSiO in the metalized pellets and the changes in porosity and iron particle size. The compressive strength (CS) decreased continuously, showing a sharp decline when the H flow rate reached 0.6 L/min. It was attributed to the significant increases in porosity and average pore size of the metalized pellets, with the presence of surface cracks. When the H flow rate was 0.8 L/min, the metalized pellets had the optimal performance, namely, reduction degree of 91.45%, metallization degree of 84.07%, total iron content of 80.67 wt%, RSI of 4.66%, and CS of 1265 N/p. The findings demonstrated the importance of controlling the H flow rate in the preparation of metallized pellets by HCR.
本研究提出了一种通过铁矿石球团氢气冷却还原（HCR）制备直接炼钢用金属化球团的策略，重点关注氢气流量对该过程的影响。结果表明，提高氢气流量可有效提高铁矿石球团的还原性能。然而，由于气体分子逆流扩散阻力的影响，当达到最大还原速率时，过高的氢气流量不再促进球团的还原。球团的还原膨胀指数（RSI）最初随氢气流量增加而升高，随后下降。这种变化与金属化球团中FeSiO含量的降低以及孔隙率和铁颗粒尺寸的变化有关。抗压强度（CS）持续下降，当氢气流量达到0.6 L/min时出现急剧下降。这归因于金属化球团的孔隙率和平均孔径显著增加，且存在表面裂纹。当氢气流量为0.8 L/min时，金属化球团具有最佳性能，即还原度为91.45%、金属化率为84.07%、总铁含量为80.67 wt%、RSI为4.66%、CS为1265 N/p。研究结果表明了在通过HCR制备金属化球团过程中控制氢气流量的重要性。
