采用赤铁矿配加 SiO2制成的团块进行直接还原,研究了微细粒嵌布赤铁矿直接还原焙烧及其分选机理,应用 X射线衍射扫描电镜及能谱等对还原产物进行分析.结果表明,SiO2含量较低时,SiO2对微细粒嵌布赤铁矿直接还原影响较小,SiO2含量增加时,还原团块金属化率、分选指标显著降低.还原温度较高时,SiO2对微细粒嵌布赤铁矿的直接还原-分选的影响加大.采用反应活性较好的烟煤作还原剂,能提高还原过程中铁氧化物还原速率,加快铁氧化物的还原,降低 SiO2对还原-分选指标的影响.SiO2含量升高,还原焙烧产物中硅酸铁含量增加,金属铁含量减少,同时金属铁颗粒粒径也随之减小,SiO2的存在对微细粒嵌布赤铁矿直接还原有显著的不利影响,适宜的还原温度和良好的还原煤有利于改善微细粒嵌布赤铁矿直接还原-磁选指标.
The mechanism of direct reduction roasting and separation of micro-fine disseminated hematite was in-vestigated by hematite briquette with SiO2 and the reduction products were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM)and energy spectrum analysis (EDS).The results show that low SiO2 con-tent has less effect on micro-fine disseminated hematite direct reduction,while the metallization ratio of reduction briquette and separation indexes decrease significantly with increasing the SiO2 content.SiO2 has larger effect on direct reduction-separation when temperature is higher.By using bitumite with better reactivity as reductant, the iron oxide reduction rate during reduction process increases,the reduction of iron oxide is accelerated,and the effect of SiO2 on reduction-separation indexes is reduced.The XRD and SEM-EDS results show that with the increase of SiO2 content,ferric silicate content in reduction product increases,the number of iron crystals decreases,and the iron crystals size becomes smaller.Then SiO2 has a significantly adverse impact on micro-fine hematite direct reduction. And appropriate reduction temperature and suitable reductant coal can improve the reduction-separation indexes.
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