还原剂对高磷鲕状赤铁矿直接还原过程铁还原的影响

Effects of reductants on iron reduction in the direct reduction process of high-phosphorus oolitic hematite

采用添加脱磷剂直接还原焙烧--磁选的工艺制备直接还原铁,研究了不同还原剂对高磷鲕状赤铁矿直接还原过程铁还原的影响.实验结果和扫描电镜分析表明,还原剂中固定碳和挥发分含量对于焙烧产物中金属铁晶粒的聚集、增多和长大以及所得还原铁指标影响较大.焦炭和无烟煤所得焙烧产物中金属铁晶粒与脉石矿物结合较紧密,难以在磨矿过程中实现单体解离.褐煤所得焙烧产物中金属铁晶粒出现明显的连接和长大,且与脉石矿物界限分明,嵌布粒度较粗,有利于铁颗粒与脉石矿物的解离,从而其铁回收率较其他还原剂高.

Direct reduction iron was prepared by adding dephosphorization agents during a direct reduction roasting-magnetic separation process,and the effects of reductants on the direct reduction process of high-phosphorus oolitic hematite were studied.Experimental results and SEM analysis show that the aggregation and growth of iron crystals,the increase of iron crystals＇ amount and the index of the reduced iron with a reductant can be influenced by the contents of fixed carbon and volatile in the reductants.When the reductant is coke or anthracite,iron crystals and gangue minerals are more closely combined in the roasting products,thus it is difficult to achieve monomeric liberation during the grinding process.When lignite is used as a reductant,the obvious connection and growth of iron crystals appear,coarser iron crystals form,and the boundary between iron crystals and gangue minerals is clear in the roasting products.Thus the liberation of iron crystals from gangue minerals is easier and the recovery of iron is higher than that obtained with other reductants.