硼铁精矿的碳热还原动力学

为了揭示硼铁精矿的碳热还原机理,以高纯石墨为还原剂,进行硼铁精矿含碳球团等温还原实验,并采用积分法进行动力学分析.还原温度分别设定为1000、1050、1100、1150、1200、1250和1300益,配碳量即C/O摩尔比=1.0.当还原度为0.1<α<0.8时,温度对活化能和速率控制环节有重要影响：还原温度≤1100益时,平均活化能为202.6 kJ·mol-1,还原反应的速率控制环节为碳的气化反应；还原温度>1100益时,平均活化能为116.7 kJ·mol-1,为碳气化反应和FeO还原反应共同控制.当还原度α≥0.8时(还原温度>1100益),可能的速率控制环节为碳原子在金属铁中的扩散.碳气化反应是含碳球团还原过程中主要速率控制环节,原因在于硼铁精矿中硼元素对碳气化反应具有较强烈的化学抑制作用.

Carbothermic reduction kinetics of boron-bearing iron concentrate

In order to deeply understand the carbothermic reduction mechanism of boron-bearing iron concentrate, the isothermal reduction of boron-bearing iron concentrate/carbon composite pellets was performed with high purity graphite as a reductant, and was kinetically analyzed by the integration method. The reduction temperature was set as 1000, 1050, 1100, 1150, 1200, 1250 and 1300℃, and the C/O molar ratio was 1. 0. When the reduction degree ranged from 0. 1 to 0. 8, the reduction temperature had important effect on the apparent activation energy and rate controlling step. If the reduction temperature was not greater than 1100℃, the aver-age apparent activation energy was 202. 6 kJ·mol-1 , and the rate controlling step was carbon gasification. But if the reduction tempera-ture was higher than 1100℃, the average apparent activation energy was 116. 7 kJ·mol-1 , and the reduction rate was the mixed control of carbon gasification and FeO reduction reaction. When the reduction degree was not less than 0. 8 ( reduction temperature>1100℃) , the reduction might be controlled by carbon diffusion in metallic iron. Carbon gasification is the main rate controlling step for the reduction of the composite pellet due to the intense chemical inhibition effect of boron in the boron-bearing iron concentrate on carbon gasification.