(1. 中南大学 资源加工与生物工程学院，长沙 410083；
2. 华菱集团 涟源钢铁公司，娄底 417009)
摘 要: 采用光学显微镜、莱卡图像分析软件对低品位赤铁矿煤基直接还原产品中金属铁晶粒尺寸进行检测。利用Hillert晶粒长大动力学模型对低品位赤铁矿煤基直接还原过程中铁晶粒的长大行为进行研究。结果表明：在还原温度为1 200 ℃、还原时间为5~120 min时，金属铁晶粒的生长速率常数k为1.155 μm2/min；在1 200 ℃时，球团还原过程中，金属铁晶粒的平均尺寸D(μm)与还原时间t(min)的关系式为D=exp(0.565ln T+0.072)。在还原时间为120 min时，还原球团金属铁晶粒的平均尺寸D(μm)与还原温度T(K)的关系式为D=exp(-8 995 845ln T+ 8.899)。在还原温度1 000~1 200 ℃范围内，还原球团的金属铁晶粒生长表观活化能为132.53 kJ/mol。
关键字: 低品位赤铁矿；直接还原；铁晶粒；晶粒尺寸
（1. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China;
2. Lianyuan Iron and Steel Company, Valin Group, Loudi 417009, China）
Abstract:The size of metal iron grain of low grade hematite during coal based direct reduction was tested using optical microscope and Leica image analysis software. The growth behavior of metal iron grain was investigated using Hillert grain growth dynamic model. The results show that the growth rate constant of metal iron grain is 1.155 μm2/min when reduced at 1 200 ℃ for 5-120 min. The relationship between the average size of metal iron grain D(μm) and reduction time t(min) is D=exp(0.565ln T+0.072) at reduction temperature of 1 200 ℃. The relationship between the average size of metal iron grain D(μm) and reduction temperature T(K) is D=exp(-8 995 845ln T+8.899) when reduced for 120 min. The apparent activation energy of metal ferrous grain growth is 132.53 kJ/mol in a reduction temperature range from 1 000 ℃ to 1 200 ℃.
Key words: low grade hematite; direct reduction; iron grain; grain size
