MgO对白云鄂博铁精矿球团还原膨胀性的影响

Effect of MgO on reduction swelling of Bayan Obo iron ore pellets

由于含有较多的K、Na、F等有害元素,白云鄂博铁精矿球团出现还原异常膨胀,甚至是灾难性膨胀,因此限制了其在球团工艺中的应用。随着选矿技术的进步和白云鄂博西矿的开发,白云鄂博铁精矿中K、Na、F等有害元素逐年降低,为实现100%白云鄂博铁精矿球团生产提供了契机。为了排除其他组分对球团组织及性能的影响,选用纯化学试剂MgO作为添加剂,以白云鄂博铁精矿为原料,经过造球、焙烧制得白云鄂博铁精矿球团,采用矿相显微镜、SEM-EDS等手段研究了MgO对白云鄂博铁精矿球团组织与性能的影响。随着白云鄂博铁精矿中MgO含量的增加,球团中含镁磁铁矿逐渐增加,赤铁矿含量有所降低,渣相量变化不明显。当MgO含量增加时,白云鄂博铁精矿球团孔隙率有所增加,导致球团的抗压强度呈现下降趋势。当MgO质量分数由1.5%提高到4.5%时,球团的抗压强度由2720.2 N降低到2000.0 N左右。随着MgO添加量的增加,白云鄂博铁精矿球团的还原膨胀率呈下降趋势,球团的还原膨胀率由大于35.9%下降到26.5%。提高白云鄂博铁精矿球团中的MgO含量可以改善球团的还原膨胀性能。

Due to the presence of more harmful elements such as K,Na and F,the Bayan Obo iron ore pellets show abnormal reduction swelling or even catastrophic swelling,which limits its application in pelletizing process.With the progress of beneficiation technology and the development of Bayan Obo west mine,the harmful elements such as K,Na and F are reduced year by year,which provides an opportunity for the realization of 100% Bayan Obo iron concentrate pellet production.In order to eliminate the influence of other components,pure chemical reagent MgO was selected as additive,and Bayan Obo iron ore was used as raw material to prepare Bayan Obo iron ore pellets by balling and roasting.The effects of MgO on the microstructure and properties of Bayan Obo iron ore pellets were studied by means of mineral phase microscope and SEM-EDS.With the increase of MgO content,the content of magnesium-bearing magnetite increases gradually,the content of hematite decreases,and the change of slag phase volume is not obvious.When the content of MgO increases,the porosity of Bayan Obo iron ore pellets increases,resulting in a downward trend in the compressive strength of pellets.When the mass percent of MgO increased from 1.5% to 4.5%,the compressive strength of the pellets decreased from 2720.2 N to about 2000.0 N.With the increase of MgO addition,the reduction swelling rate of Bayan Obo iron ore pellets showed a downward trend.When the MgO content increased from 1.5% to 4.5%,the reduction swelling rate of pellets decreased from more than 35.9% to 26.5%.Increasing the MgO content in Bayan Obo iron ore pellets can improve the reduction swelling performance of pellets.