材料期刊网

前人研究表明,二次赤铁矿是导致烧结矿低温还原粉化的主要因素,它的生成与烧结原料中MgO含量有关,但其影响机理尚不明确.通过热重法测定不同MgO和Fe2O3比例试样在升温-恒温-降温过程中质量变化,定量地了解MgO对Fe2O3向Fe3O4转变的影响.同时结合XRD分析和光学显微镜观察,揭示了矿物和相结构变化,研究了烧结过程中MgO对二次赤铁矿生成的抑制机理.结果表明,加入MgO后,它与Fe2O3反应形成了铁酸镁和含镁磁铁矿,前者促进了升温过程含镁磁铁矿生成,而后者低温下比磁铁矿更稳定,抑制了降温过程磁铁矿氧化,减少了二次赤铁矿的生成.因此,明确了加入少量MgO改善烧结矿低温还原粉化性能的主要原因.

Previous researches show that the secondary hematite is a main factor to result in low temperature reduction degradation of sinter,and its formation relates with MgO content in raw materials of sinter,but the mechanism has been not very clear until now.The mass changes of samples with different proportions of MgO and Fe2O3 during heating-up,constant temperature sintering and cooling process were measured to understand quantitatively the effect of MgO content on transformation between Fe2O3 and Fe3O4 by a thermogravimetric method,simultaneously the X-ray diffraction (XRD) and the optical microscopy (OM) were used to follow the changes of mineral phase and microstructures in samples for investigation of the mechanism of MgO depressing the secondary hematite formation in sintering process of iron ores.The results show that after addition of MgO which reacts with Fe2O3 to form magnesium ferrite and magnesioferrite,the former promotes the formation of the magnesioferrite during the heating-up process and the latter is more stable than the magnetite in low temperature to depress the oxidation of magnetite in the cooling process,so resulting in decreasing of the secondary hematite in sinter.Therefore,it make clear the reason to improve the low temperature reduction degradation of sinter after addition of MgO in the raw materials.