SiO2对CaO-Fe2O3熔体结晶矿物组成及显微结构的影响

摘要：由于近年来低品位铁矿石的使用量增加，导致烧结过程中SiO2含量升高。SiO2是烧结矿中主要的脉石成分，其含量的变化与烧结矿最终质量密切相关。运用X射线衍射、光学显微镜和SEM-EDS方法研究了SiO2对CaO-Fe2O3熔体结晶矿物组成及显微结构的影响。研究结果表明，随着SiO2含量的增加，CaO-Fe2O3-SiO2熔体结晶产物中CaFe2O4(CF)含量减少而富铁铁酸钙(SFC)含量增加，CaFe2O4和SFC分别以块状和板条状析出，SFC的晶体结构随着SiO2含量的增加从Ca36Fe144O25-2向SFCA-I转变；当SiO2的质量分数超过3.0%时，椭圆状的Ca2SiO4（C2S）从熔体中结晶，其含量随SiO2含量的增加而增加，另有大量圆点状玻璃相分布于铁酸钙基体表面。

Effect of SiO2 on composition and microstructure of crystal products of CaO Fe2O3 melt

Recently, usage of low grade iron ore is increasing, which leads to the increase of SiO2 content in iron ore sintering process. SiO2 is the main gangue component in sintering blends. The changes of its content are closely related to the quality of final iron ore sinter. Effect of SiO2 on composition and microstructure of crystal products of CaO-Fe2O3 melt were investigated by X-ray diffraction, optical microscopy and SEM-EDS. The results show that, with increasing of SiO2 content, the content of CaFe2O4 decreases whereas the content of Fe rich calcium ferrite (SFC) increases. CaFe2O4 and SFC crystallize from melt with block and strip morphologies respectively. The crystal structure of SFC transforms from Ca36Fe144O25-2to SFCA-I with increasing of SiO2 content. When the SiO2 content exceeds 3.0 mass%, oval Ca2SiO4 crystallizes from melt and its content increases with increasing of SiO2 content. In addition, there are amount of glass phases distribute in the phase of calcium ferrite with dot morphology.