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采用赤铁矿配加SiO_2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,SiO_2含量较低时,SiO_2对微细粒嵌布赤铁矿直接还原影响较小,SiO_2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,SiO_2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SiO_2对还原-分选指标的影响。SiO_2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,SiO_2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 hematite and SiO_2 agglomerates were directly reduced. The direct reduction roasting and its separation mechanism were studied. The reduction products were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The results show that SiO 2 has little effect on the direct reduction of micro-grained hematite when the content of SiO 2 is low. When the content of SiO 2 is increased, the metallization rate and sorting index of the reduced agglomerate decrease significantly. When the reduction temperature is high, the effect of SiO_2 on the direct reduction-sorting of micro-grained hematite increases. The use of bituminous coal with better reactivity as reductant can increase the reduction rate of iron oxide in the reduction process, accelerate the reduction of iron oxide and reduce the influence of SiO_2 on reduction-sorting index. The content of SiO 2 increases, the content of silicic acid in reduced roasting products increases, the content of metallic iron decreases, meanwhile, the particle size of metallic iron decreases, and the presence of SiO 2 has a significant adverse effect on the direct reduction of micro-grained hematite , Suitable reduction temperature and good reduction of coal help to improve the direct reduction of the fine grained hematite - magnetic separation indicators.