典型铁精矿低温低碳制备含铁炉料的技术研究
Technical research on low-temperature and low-carbon preparation of iron-bearing burdens from typical iron concentrates
-
摘要: 现阶段铁前工序降碳压力显著,冷固结球团工艺具有较高的降碳潜力。为响应钢铁行业“双碳”目标,本文针对4类典型铁精矿,系统考察成型水分、成型线压力以及铁精矿类型对冷固结球团强度的影响,并结合扫描电镜-能谱仪(SEM-EDS)、压汞法表征微观孔隙结构演变,揭示影响冷态强度的机制。结果表明,在研究范围内,降低成型水分、提高成型线压力可显著增强冷固结球团性能,适宜的成型水分和成型线压力分别为4.5%和9.80 kN/mm。成型水分升高会削弱颗粒间机械咬合,致使生球和固结球强度同步降低,而提高成型线压力可通过促进颗粒重排、增大颗粒间接触面积,促进形成更粗、更连续的黏结桥,从而显著提高冷固结球团强度。铁精矿粒度对成型阶段和固结阶段强度的作用相反,铁精矿的平均粒度越细,生球强度越高,固结球强度越低。在适宜成型-固结参数下,4种精矿制备的冷固结球团均实现生球落下强度不小于4次/(0.5 m·P)、固结球强度不小于2 500 N/P、转鼓强度不小于85%,满足高炉炉料的冷态强度要求,具有工程应用潜力。Abstract: Significant carbon emission reduction pressure is imposed on the pre-ironmaking processes at the present stage, and a high carbon reduction potential is possessed by the cold-bonded briquetting process. In response to the dual-carbon goals of the iron and steel industry, the effects of forming moisture, forming linear pressure and iron concentrate type on the green briquette strength and consolidated briquette strength of cold-bonded briquettes are systematically investigated with four typical types of iron concentrates adopted. The evolution laws of microscopic pore structures are characterized via SEM-EDS and mercury intrusion porosimetry, and the influencing mechanisms of cold-state strength are clarified. Within the research scope, the performance of cold-bonded briquettes is obviously improved by reducing forming moisture and increasing forming linear pressure, and the optimal forming moisture and forming linear pressure are determined as 4.5% and 9.80 kN/mm, respectively. The mechanical interlocking force between particles are weakened by the increase of forming moisture, so that the strengths of green briquettes and consolidated briquettes are decreased synchronously. With increasing forming line pressure, particle rearrangement is promoted, the contact area between particles is increased, and the interparticle bonding bridges are strengthened, thereby improving the strength of cold-bonded briquettes. Opposite effects on the strength in the forming stage and consolidation stage are exerted by the particle size of iron concentrates. Higher green briquette strength and lower consolidated briquette strength are obtained with finer average particle size of iron concentrates. Under optimized forming and consolidation parameters, cold-bonded briquettes prepared from four kinds of iron concentrates are enabled to reach the dropping strength of green briquettes no less than 4 times/(0.5 m·P), consolidated briquette strength no less than 2 500 N/P and tumbler strength no less than 85%. All prepared briquettes are qualified to meet the cold-state strength requirements of blast furnace burden, and favorable engineering application prospects are presented.
下载: