MgO对含钾钠氟球团还原膨胀性能的影响

Effect of MgO on reduction swelling index of pellets containing K,Na and F

包头铁精矿球团中含有钾、钠、氟等有害元素,造成球团还原异常膨胀。而MgO可有效地降低球团还原膨胀率。采用压团、焙烧、分段还原法(Fe_2O_3→Fe_3O_4、Fe_3O_4→Fe_xO、Fe_xO→Fe),测量铁氧化物各还原阶段的还原膨胀率,采用光学显微镜及SEM观察焙烧试样和还原产物的形貌。研究结果表明,MgO促进了铁酸镁的形成,抑制了氟质量分数低的试样在Fe_2O_3→Fe_3O_4阶段的还原膨胀;但MgO抑制了铁酸钙的形成,反而促进了氟质量分数高的试样在Fe_2O_3→Fe_3O_4阶段的还原膨胀;MgO对第二阶段还原膨胀率的影响因试样中钾、钠、氟质量分数不同而有所差异;MgO抑制了铁晶须生长,降低了第三阶段的还原膨胀率。

The harmful elements K,Na and F in iron ore from Baotou will result in abnormal reduction swelling of pellet which can be resisted effectively by the Mg O content. The reduction swelling index in stages（Fe2O3→Fe3O4,Fe3O4→FexO,FexO →Fe） was measured,the optical microscope and scanning electron microscope were used to study the morphology of roasting and reduction samples. It was found that Mg O promoted the formation of magnesium ferrite and suppressed the reduction swelling index of sample with 0.3% F content during Fe_2O_3→Fe_3O_4. While the reduction swelling index was accelerated by Mg O in sample with 0.6% F content during Fe_2O_3→Fe_3O_4. The effect of Mg O content on the reduction swelling index during the transformation of Fe_3O_4→FexO was impacted by the content difference of K,Na and F. Mg O inhibits the reduction swelling index of the third stage by suppressing the growth of iron whiskers.