B_(2)O_(3)对氧化焙烧过程赤铁矿连晶程度的影响

Effect of B_(2)O_(3)on degree of hematite crystallization during oxidation roasting

在焙烧过程中加入B_(2)O_(3)有利于得到低熔点化合物,提高球团强度和降低还原膨胀,使球团的冶金性能得到提高,但B_(2)O_(3)对赤铁矿的结晶和连晶程度的影响机理还缺少较为深入的研究。因此,为探明B_(2)O_(3)对赤铁矿连晶程度和赋存规律,通过在Fe_(3)O_(4)纯试剂中加入不同比例的B_(2)O_(3)纯试剂,经混合、压片和氧化焙烧后形成赤铁矿。模拟磁铁矿球团焙烧形成赤铁矿球团的过程,采用SEM-EDS、XRD、XPS等手段研究不同B_(2)O_(3)含量对焙烧压片中赤铁矿的连晶程度、晶体长大情况和微观结构的影响,结合拉曼光谱分析B_(2)O_(3)对赤铁矿晶体结构的影响,并对其微观结构、结晶度和晶粒尺寸进行了测定,最后针对不同B_(2)O_(3)含量对赤铁矿的连晶程度的影响进行了讨论和总结。研究结果表明,B_(2)O_(3)对氧化焙烧过程赤铁矿连晶程度有着先促进后抑制的作用,适量加入B_(2)O_(3)能够促进赤铁矿晶体长大和连晶程度的增长,当添加B_(2)O_(3)质量分数为6%、焙烧时间为40min时,赤铁矿的结晶程度最好,结晶度可达83.68%。XPS检测显示,随着B_(2)O_(3)含量的增加,赤铁矿中Fe^(3+)的比例逐渐升高,Fe^(3+)的比例最高可达92.53%。B_(2)O_(3)添加量进一步增加时,B_(2)O_(3)对渣相的流动性和渣相量的影响也进一步增加,渣相将赤铁矿晶粒浸润,抑制晶粒长大和晶粒间的连晶。通过拉曼光谱对赤铁矿晶体结构的检测结果显示,随着B_(2)O_(3)含量的增加,赤铁矿晶体的LO模式和Eu模式的峰强增加,这表明晶格缺陷引起的对称性破坏增加,晶体无序度更高,缺陷更高。

Adding B_(2)O_(3)to the raw materials in the ball preparation process is beneficial for obtaining low melting point compounds,improving the ball strength,and reducing reduction swelling,thus enhancing the metallurgical performance.However,there is still a lack of in-depth research on the mechanism of how B_(2)O_(3)affects the crystallization and crystal continuity of hematite.Therefore,in order to understand the influence of B_(2)O_(3)on the crystal continuity and occurrence pattern of hematite,different proportions of B_(2)O_(3)pure reagents were added to Fe_(3)O_(4)pure reagents.The mixture was then pressed,oxidized,and transformed into hematite,simulating the process of hematite formation in the roasting of magnetite pellets.SEM-EDS,XRD,XPS,and other methods were used to study the influence of different B_(2)O_(3)contents on the crystal continuity,crystal growth,and microstructure of hematite in the roasting pellets.Raman spectroscopy was used to analyze the effect of B_(2)O_(3)on the crystal structure of hematite.Furthermore,the microstructure,crystallinity,and grain size were determined.Finally,the impact of different B_(2)O_(3)contents on the crystal continuity of hematite was discussed and summarized.The research results show that B_(2)O_(3)has a promoting effect on the crystal continuity of hematite during the oxidation roasting process,followed by inhibitory effects.The proper addition of B_(2)O_(3)can promote crystal growth and enhance the crystal continuity of hematite.When the mass percent of B_(2)O_(3)is 6%and the roasting time is 40minutes,the crystallinity of hematite is the best,reaching 83.68%.XPS analysis demonstrates that as the B_(2)O_(3)content increases,the proportion of Fe^(3+)in hematite gradually increases,with Fe^(3+)accounting for up to 92.53%.As the B_(2)O_(3)content further increases,the influence of B_(2)O_(3)on slag fluidity and slag phase content increases.The slag phase infiltrates the hematite grains,inhibiting grain growth and crystal continuity.Raman spectroscopy analysis of the hematite crystal structure reveals that with the increase in B_(2)O_(3)content,the peak intensities of the LO mode and Eumode of hematite increase,indicating an increase in symmetry disruption caused by lattice defects,higher crystal disorder,and corresponding higher defect content.