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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。
Baotou iron concentrate pellets contain harmful elements such as potassium, sodium, fluorine, resulting in the abnormal expansion of the pellet reduction. MgO can effectively reduce the pellet swelling rate. The reduction and expansion of iron oxides were measured by pressure-reducing, calcining and segmented reduction methods (Fe 2 O 3 → Fe 3 O 4, Fe 3 O 4 → Fe_xO, Fe_xO → Fe). The morphology of calcined samples and reduced products were observed by optical microscope and SEM appearance. The results showed that MgO promoted the formation of magnesium ferrite and suppressed the reduction and expansion of the samples with low fluorine content in the Fe_2O_3 → Fe_3O_4 phase. However, MgO inhibited the formation of calcium ferrite and promoted the test of high fluorine content Like Fe_3 → Fe_3O_4 phase of the reduction and expansion; MgO on the second stage of the reduction and expansion rate of the sample due to potassium, sodium and fluorine mass fraction differences; MgO inhibited the growth of iron whiskers, reducing the third stage The reduction of expansion.