炭化工艺参数对铁焦冶金性能的影响

摘要：复合铁焦被认为是实现低碳高炉炼铁的革新技术之一。为了获得高质量的铁焦，需要采用适宜的炭化工艺条件。研究了炭化工艺参数对铁焦机械强度、反应性和反应后强度等冶金性能的影响，并对炭化后铁焦的金属化率、微观结构和碳微晶结构进行了解析。结果表明，炭化温度的升高可以提高铁焦的抗压强度和反应性。当温度为900～1000℃时，铁焦的抗压强度和反应性较优。炭化时间的延长可以使铁焦的抗压强度提高，反应性降低。当炭化时间为3～4h时，铁焦抗压强度和反应性较优。升温速度越快，铁焦的机械强度越低。适宜的升温速度为:Ⅰ段（室温至550℃）小于7℃/ min，Ⅱ段（550℃至1000℃）小于5℃/min。为防止铁焦冶金性能因碳气化溶损反应而劣化，在CO和CO2混合炭化气氛中，CO2与CO体积比(V(CO2)/V(CO))应控制在0.11以下。在优化的炭化工艺条件下，制备的铁焦抗压强度大于3500N，反应性大于60%，反应后强度在16%左右。

Effect of carbonization process parameters on metallurgical properties of iron coke

Utilization of iron coke is considered to be an innovative technology to realize low carbon blast furnace (BF) ironmaking. In order to obtain high quality iron coke, appropriate carbonization process conditions need to be adopted. Effect of carbonization process parameters on the metallurgical properties of iron coke, such as mechanical strength, reactivity and post reaction strength, was systematically studied, and the metallization rate, microstructure and carbon crystallites structure of iron coke were analyzed. The results show that the increase of carbonization temperature can improve the compressive strength and reactivity of iron coke. The compressive strength and reactivity of iron coke are better when the temperature is 900-1000℃.The extension of carbonization time can improve the compressive strength and reduce the reactivity of iron coke. When carbonization time is 3-4h, the compressive strength and reactivity of iron coke are better. The faster the heating rate is, the lower the mechanical strength of iron coke is. The appropriate rate of heating is less than 7℃/min in section Ⅰ (room temperature to 550℃) and less than 5℃/min in section Ⅱ (550℃ to 1000℃).In order to prevent the metallurgical properties of iron coke from deteriorating due to gasification dissolution reaction, the volume percentage of CO2 to CO (V(CO2)/V(CO)) should be controlled below 0.11 in the mixed carbonization atmosphere of CO and CO2. Under the optimized carbonization process conditions, the compressive strength of iron coke is more than 3500N, the reactivity is more than 60%, and the post reaction strength is about 16%.