炼铁过程熔融渗碳行为研究

Study on Melting Carburization Behavior of Flash Ironmaking

传统高炉冶炼过程中铁水最终含碳量是饱和的,而闪速炉中反应是在物料漂浮阶段发生,没有固态料柱的压迫作用,无法发生高炉炉缸内固体炉料与铁水的渗碳作用,最终铁水含碳量未知。为此对闪速炼铁炉中熔池底部渗碳反应进行了研究。首先,对铁碳相图进行了理论研究,基于此理论分析探讨了反应时间、焦炭粒径、焦炭床层高度及原料失重率等因素对铁水最终含碳量的影响。得出了最佳工艺条件为反应时间240 min、焦炭粒径5~8 mm、焦炭加入量70 g、原料失重率26%,在此最佳工艺条件下含碳量最大为4.73%。为了进一步探究渗碳过程中铁碳合金中元素的分布规律,对含碳量为4.73%的铁碳合金进行了SEM-EDS表征,结果显示条棒状石墨碳呈凝聚态不规则嵌布在铁碳合金中,在石墨碳边缘呈现两种不同衬度,分别为FeC相和Fe3C相。

The final carbon content of the molten iron is saturated during the traditional blast furnace smelting process.However,the reaction in the flash furnace occurs at the stage of material floating and the carburizing effect of the solid charge and the molten iron in the blast furnace cannot occur without the compression of the solid material column,thus the final carbon content of molten iron is unknown.In order to obtain the final carbon content during flash inromaking,carburizing reaction at the bottom of the molten pool in flash ironmaking was studied.Firstly,the theoretical study of the iron-carbon phase diagram was investigated.The effect of reaction time,coke particle size,coke bed height and weight loss rate of the raw materials on the final carbon content of molten iron were investigated based on this theoretical analysis.The optimum conditions were as follows:carburization time was 240 min,coke particle size was 5~8 mm,coke addition amount was 70 g.The material weight loss rate was 26% and the maximum carbon content was 4.73% under the optimum conditions.In order to further explore the changes of elements in iron-carbon alloy during carburizing,the SEM-EDS characterization of carburized iron with a carbon content of 4.73% was detected,indicating that the rod-like graphite carbon is irregularly embedded in the iron-carbon alloy in a condensed state,and two different contrasts(FeC phase and Fe3C phase)were presented at the edge of the graphite carbon.