不锈钢尘泥球团煤基直接还原动力学

Kinetics of coal-based direct reduction of stainless steel dust pellets

研究了不锈钢尘泥球团在温度分别为1 100、1 150、1 200、1 250℃时的煤基直接还原反应动力学。采用随机成核和随后生长、化学反应控制、相界面反应和n(n=1、2、3、4)维扩散模型及其相应动力学机制函数对反应过程进行拟合,并结合X-射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等手段对不锈钢尘泥球团煤基直接还原过程的物相组成、显微结构及元素分布进行表征和分析。研究结果表明:反应初期铁氧化物还原速率较快,随后逐渐减慢,当反应至40 min后,反应趋向于平衡。在1 100~1 250℃温度范围内反应遵从随机成核和随后生长及A_(1)(α)=-ln(1-α)机制函数,碳的气化反应和界面化学反应是尘泥球团煤基直接还原反应的限制性环节,该反应活化能E为47.423 kJ/mol,线性相关系数为0.996。

The kinetics of coal-based direct reduction reaction of stainless steel dust pellets at 1 100, 1 150, 1 200, 1 250 ℃ were studied. The reaction process was fitted by random nucleation and subsequent growth, chemical reaction control, phase interface reaction, n(n=1, 2, 3, 4) dimensional diffusion model and the corresponding kinetic mechanism function. By means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS), the phase composition, microstructure and element distribution of stainless steel dust pellets during coal-based direct reduction process were characterized and analyzed. The results show that the reduction rate of iron oxide is fast at the initial stage of the reaction, and then gradually slows down. When the reaction reaches 40 min, the reaction tends to equilibrium. In the temperature range of 1 100-1 250 ℃, the reaction follows random nucleation, subsequent growth and A_(1)(α)=-ln(1-α) mechanism function. The gasification reaction and interfacial chemical reaction of carbon are the limiting links of the coal-based direct reduction reaction of du-mud pellets. The activation energy E of the reaction is 47.423 kJ/mol, and the linear correlation coefficient is 0.996.